Poster Session B
Tuesday, February 14, 2017
1
PB-1
Nitrogen Lewis Acids
Alla Pogoreltsev, Yuri Tulchinsky, Mark Gandelman
Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Lewis acids and their interactions with Lewis bases are widely used in many aspects of chemistry. Although
many chemical elements can serve as central atom of Lewis acids, nitrogen-centered compounds are usually
considered as Lewis bases due to their lone pair of electrons having relatively high energy.
Recently, our group demonstrated that N-heterocyclic nitrenium ions can coordinate to various transition metal
centers[i], possessing a Lewis basic feature. The availability of vacant pp-orbital of nitrenium species suggests
that it also might be involved in s-interactions with Lewis bases, possessing a Lewis acidic character.
Here we present the first examples of reactivity of nitrenium species towards Lewis bases. This represents a
first example of robust, stable and stereoelectronically modifiable nitrogen Lewis acids, which form welldefined adducts with Lewis bases.[ii] Moreover, this reactivity provides a new type of stable organic
compounds, called triazanes, bearing all-saturated three consecutive nitrogen atoms.
[i]
(a) Tulchinsky, Y.; Iron, M. A.; Botoshansky, M.; Gandelman, M. Nature Chem. 2011, 3, 525. (b)
Tulchinsky, Y.; Kozuch, S.; Saha, P.; Botoshansky, M.; Shimon, L.; Gandelman, M. Chem. Sci. 2014, 5, 1305.
(c) Tulchinsky, Y., Kozuch, S., Saha, P., Mauda, A., Nisnevich, G., Botoshansky, M., Shimon, L., Gandelman,
M. Chem. Eur. J. 2015, 21, 1-13.
[ii]
Pogoreltsev, A., Tulchinsky, Y., Fridman, N., Botoshansky, M., Gandelman, M. JACS, in press.
2
PB-2
Novel Access Towards Chiral α-trifluoromethyl Alcohols
Andrii Varenikov, Mark Gandelman
Chemistry, Technion - Israeli institute of Technology, Haifa, Israel
Fig. 1. Reaction scheme/center
Fluorine-containing organic compounds are of high interest to the chemical community, as fluorinated
molecules exhibit significantly different chemical and physical properties, comparing to non-fluoriated
analogs.1 One of the important families of fluorinated compounds are α-trifluoromethyl alcohols. These
compounds, in their enantiopure form, have found wide and important applications, especially in bio-medical
and pharmaceutical fields.2,3 Current methods for the preparation of these alcohols are based on
enantioselective reduction of the corresponding trifluoromethyl ketones using expensive chiral boranes or chiral
iridium catalysts.
We have developed an approach to access these compounds via completely different disconnection utilizing an
easily prepared substrate 1 as a starting material. Performing the asymmetric stereoconvergent cross-coupling
reaction with this building block, containing protected alcohol group at the reaction center, we can prepare
(after deprotection) a target CF3-substituted alcohol in a facile and efficient manner.
Namely, applying nickel-catalyzed Hiyama cross-coupling reaction to the substrate 1, various protected allylor benzyl(α-trifluoromethyl) alcohols could be obtained in excellent yields and enantioselectivity (ee), while
during further deprotection of the alcohol ee remains unaffected.
References
1] Alonso, C.; Martinez de Marigorta, E.; Rubiales, G.; Palacios, F.; Chem. Rev. 2015, 115, 1847-1935
2] Garcia-Martinez, C.; Taguchi, Y.; Oishi, A.; Hayamizu, K.; Magn. Reson. Chem., 1998, 36, 429-435
3] Goldberg, R.D.; De Lombaert, S,; Aiello, R.; Bourassa, P.; Barucci, N,; Zhang, Q.; Paralkar, V.;
Valentine, J.; Zavadoski W.; Bioorg. Med. Chem. Lett., 2016, 26, 1124-1129.
3
PB-3
Sunscreen Assisted Photochemical Divergence
Revannath Sutar1, Ofer Reany1, Gabriel N. Lemcoff2
1
Department of Natural Sciences, The Open University of Israel, Ra'anana, Israel
2
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Many photochemically induced processes are essential for the existence of life; but other biochemical reactions
triggered by UV light may lead to DNA damage and degradation. To protect us from this, chemists have
developed sunscreens in the form of external creams which deflect or absorb these harmful radiations.
Moreover, some organisms are able to produce special molecules that absorb light to prevent harmful events,
and there is even speculation that the highly efficient UV absorption by nucleic bases was one of the selection
processes that determined how life on earth evolved. Inspired on this, we thought it would be an appealing goal
to achieve control over photochemical synthetic pathways, depending on whether molecular sunscreens are
present or not.
In this study, we explore the property of light-absorbing organic molecules that can screen UV-irradiation to
achieve selective organic transformations. Thus, by starting out with simple allyl alcohols and acrylates,
sequential photoinduced cross-metathesis (UV-A), followed by UV-C irradiation in the presence of latent
catalyst cis-Ru 1 led to butenolides (2) or levulinates (3). Several examples of the photo-chemo-selective
pathway are demonstrated, including the synthesis of two natural products and important precursors towards
different natural products simply by UV-irradiation either in the presence or absence of a molecular sunscreen.
4
PB-4
Enantioselective Oxidative Homo- and Cross-Coupling of 2-Naphthols
Catalyzed by Chiral Iron Phosphate Complexes
Sachin Narute, Doron Pappo
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
1,1`-bi-2-naphthols (BINOLs) are an important class of compounds. The synthesis of optically pure BINOLs
with C1-symmetry generally requires the induction of asymmetry by a chiral catalyst via an oxidative radicalanion coupling mechanism. Asymmetric synthesis of the BINOLs, especially having no substitution at 3, 3`
positions is the most challenging process due to competitive oxidative racemization of resulting BINOLs. To
address this issue, a novel chiral iron phosphate system has been developed and for the first time successfully
applied for synthesis of enantio-enriched C1 and C2 symmetric BINOLs with the 3 and 3` positions available for
further chemical modifications. On the basis of kinetic and racemization studies, we postulated the coupling of
2-naphthol involves an intermolecular oxidative radical-anion coupling by iron bisphosphate complex.
References:
1] Egami, H.; Katsuki, T. Am. Chem. Soc. 2009, 131, 6082–6083.
2] Li, X.; Hewgley, J. B.; Mulrooney, C. A.; Yang, J.; Kozlowski, M. C. Org. Chem. 2003, 68, 5500–5511.
3] Libman, A.; Shalit, H.; Vainer, Y.; Narute, S.; Kozuch, S.; Pappo, D. Am. Chem. Soc. 2015, 137, 11453–
11460.
4] Gaster, E.; Vainer, Y.; Regev, A.; Narute, S.; Sudheendran, K.; Werbeloff, A.; Shalit, H.; Pappo, D. Chem.
Int. Ed. 2015, 54, 4198–4202.
5] Parnes, R.; Kshirsagar, U. A.; Werbeloff, A.; Regev, C.; Pappo, D. Lett. 2012, 14, 3324-3327.
6] Narute, S.; Parnes, R.; Toste, F. D.; Pappo, D. (Communicated)
5
PB-5
Poly-Substituted Furans and Benzofurans from Simple β-Ketosulfoxide Scope
and Mechanistic Insights
Regev Parnes, Doron Pappo
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Poly substituted furans and benzofurans are highly important class of heterocycles which possess biologically
active characteristics and synthetic importance. These highly valuable components have a complex structural
motif and the synthesis of such, in a simple and straight forward manner remains a desired goal for synthetic
chemists over the years. In this work, we demonstrate direct synthesis of tetra and tri - substituted furans and
substituted benzofurans derived from -ketosulfoxide and 1,3-dicarbonyl derivatives or phenols respectively.
In both heterocycles full control on the different substituents can be achieved depend on the selected
reactant`s structure.
References:
1] Regev Parnes and Doron Pappo Lett.2015, 2924-2927.
2] Regev Parnes, Sachin Narute and Doron Pappo Lett.2014, 16 (22), 5922–5925.
6
PB-6
Transforming the Conjugated Backbone: from Oligofurans to
Oligonaphthalenes
Sunita Phatangare, Ori Gidron
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Oligoarenes are conjugated aromatic backbones which constitute an important class of organic compounds,
with promising applications in organic electronics and catalysis. While the synthesis of unsubstituted
oligophenylenes was recently demonstrated,[1] the introduction of monodispersed functionalized oligoarenes in
a highly-selective manner remains a significant challenge. Oligofurans, which are oxygen-containing analogs of
the intensively studied oligothiophenes, were recently introduced as a new class of organic electronic
materials.[2] Unlike oligothiophenes, oligofurans can undergo Diels-Alder cycloaddition, and we were therefore
interested in utilizing their reactivity for the introduction of new π-conjugated backbones.
Herein we report the conversion of long oligofurans to oligonaphthalenes, by multiple Diels-Alder
cycloadditions with benzyne precursors.[3] Consequent deoxygenation of the formed cycloadducts resulted in
the formation long oligonaphthalenes, containing up to 6 units. This reaction, with formation of up to 12 new
carbon-carbon bonds in a single step, represents a unique example for the conversion of long π-conjugated
backbones, while retaining the π-conjugation.
References:
[1] A. Abdulkarim, F. Hinkel, D. Jansch, J. Freudenberg, F. E. Golling, K. Mullen, J. Am. Chem. Soc. 2016,
DOI: 10.1021/jacs.6b10254.
[2] O. Gidron, M. Bendikov, Angew. Chem. Int. Ed. 2014, 53, 2546-2555.
[3] S. Phatangare, O. Gidron, in preparation.
7
PB-7
Remote Functionalization and Chirality Transfer: Stereoselective Access to
Polyfunctional Acyclic Aldehydes bearing Quaternary Centers
David Pierrot, Jeffrey Bruffaerts, Ilan Marek
The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry and Lise
Meitner-Minerva Center for Computational Quantum Chemistry, Technion - Israel Institute of
Technology, Haifa, Israel
The access to stereocontrolled and functionalized quaternary stereocenters is challenging owing to its high
steric hinderance.1 Yet, remote functionalization proved to be an efficient strategy to overcome these synthetic
issues.2 Based on the combined use of cyclopropylmethanol,3 and Heck reaction,4 we anticipated that the strain
release of cyclopropyl moieties would drive the Heck reaction of alcohol 1 towards the formation of the
aldehyde 2 (Scheme 1).
Scheme 1 Access to polyfunctional aldehydes through remote Heck reaction
To our delight the transformation was highly diastereoselective, providing a single (E)-diastereomer. The
efficiency of the approach is supported by a straightforward and modular synthesis of vinyl
cyclopropylmethanol.5 A representative scope and mechanistic insight will be presented.
1. I. Marek, Y. Minko, M. Pasco, T. Mejuch, N. Gilboa, H. Chechik, J.P. Das, J. Am. Chem. Soc. 2014, 136,
2682.
2. a) J. Bruffaerts, D. Pierrot, I. Marek, Org. Biomol. Chem.2016, 14, 10325; b) A. Vasseur, J. Bruffaerts, I.
Marek, Nature Chem. 2016, 8, 209.
3. a) A. Marsawa, D. Didier, T. Zabrodski, M. Schinkel, L. Ackermann, I. Marek, Nature 2015, 505, 199 ; b) A.
Vasseur, L. Perrin, O. Eisenstein, I. Marek, Chem. Sci. 2015, 6, 2770.
4. a) E.W. Werner, T.-S. Mei, A.J. Burckle, M.S. Sigman, Science 2012, 338, 1455 ; b) T.-S. Mei, H.H. Patel,
M.S. Sigman, Nature 2014, 508, 340.
5. a) D. Didier, P.-O. Delaye, M. Simaan, B. Island, G. Eppe, H. Eijsberg, A. Kleiner, P. Knochel, I. Marek,
Chem. Eur. J. 2014, 20, 1038 ; b) D. Müller, I. Marek, J. Am. Chem. Soc. 2015, 137, 15414.
8
PB-8
Anion Binding and Transport Activity of semithio-Bambus[6]uril
Ofer Reany1, Ehud Keinan2
1
Department of Natural Sciences, The Open University of Israel, Raanana, Israel
2
The Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Ion transport across the cell membrane is essential for maintaining the cell ion homeostasis and regulating key
processes of life. Generally, nature achieves these tasks using membrane proteins and large macromolecular
assemblies. Otherwise, small synthetic molecules, which function as ion transporters, could be used as
therapeutic agents for treating anion channelopathies.
As cyclic hexamer of dimethyl-glycoluril (i.e., 1; X=O) connected by methylene bridges, the bambus[6]uril, 2,
strongly binds anions in its interior.[1] Realizing that this property reflects the electrostatic landscape of the
glycoluril molecular surface, we envisioned that the replacement of either one oxygen atom or both by another
heteroatom, such as sulfur or nitrogen, i.e., 3 or 4, respectively, would significantly modify its anion binding
properties and afford novel transporting opportunities.[2]
Here we report the first example of bambusuril-based anion transporter. Semithio-bambus[6]uril, 3 can
accommodate and transport chloride across lipid bilayer membranes in a leakage-free anion-selective manner.
The present experimental results[4] opens a plethora of transportation opportunities based on the synthetically
accessible and modifiable bambusuril structure[5] and design of synthetic unimolecular anion channels based on
semiaza-bambusurils.[6]
References:
1] Yawer, M. A.; Havel, V.; Sindelar, V. Angew. Chem. Int. Ed. 2015, 54, 276.
2] Solel, E.; Singh, M.; Reany, O.; Keinan, E. PCCP, 2016, 18, 13180.
3] Singh, M.; Solel, E.; Keinan, E.; Reany, O. Chem. Eur. J. 2015, 21, 536.
4] Lang, C.; Mohite, A.; Deng, X.; Dong, Z.; Xu, J.; Liu, J.; Keinan, E.; Reany, O. submitted
5] Singh, M.; Parvari, G.; Botoshansky, M.; Keinan, E.; Reany, O. Eur. J. Org. Chem. 2014, 933.
6] Singh, M.; Solel, E.; Keinan, E.; Reany, O. Chem. Eur. J. 2016, 22, 8848.
9
PB-9
Cobalt Catalyzed Aerobic Oxidative Cross Coupling of Phenols
Hagai Reiss, Doron Pappo
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Oxidative coupling reactions under aerobic condition are highly desired methods in organic chemistry;
specifically the cross coupling of two phenolic components affording biphenol products, which are important
for natural products synthesis.
Cobalt complexes are known to fixate oxygen, this characteristic enables us to carry out reactions under aerobic
conditions with catalytic amount of metal complex. Designing various complexes can help us control the
selectivity and efficiency of the coupling reaction in the manner of over oxidation, reaction rate and catalyst
loading.
This study was initiated by cross-coupling between 2-methoxy-4-methylphenol and 6-bromo-2-naphthol using
cobalt porphyrin as catalyst, under oxygen atmosphere, to obtain the desired biphenol in 57% yield. Further
optimization revealed that changing the nucleophile to 2-naphthol and the catalyst to cobalt salen, increased the
yield to 87% under air.
10
PB-10
Mechanism of Crystallization of Perylene diimides in Aqueous Media
Shaked Rosenne, Haim Weissman, Boris Rybtchinski
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
Classical nucleation theory (CNT) has dominated description of crystalline nucleation and growth. While CNT
offers valuable insight into processes taking place during crystallization, it has substantial shortcomings.
Alternative nucleation mechanisms have been proposed mending CNT’s shortcomings1,2.
In this contribution, we present experimental monitoring of the entire crystallization process of a representative
simple aromatic compound - perylene diimide. Our study correlates spectroscopic and structural measurements,
allowing us to identify key stages in crystal evolution. Our findings support a two-step nucleation mechanism
rather than one step nucleation as described by CNT. Our studies provide fundamental insights into the
formation of crystalline phases, and suggest strategies to control crystallization of organic molecules.
References
(1) Vekilov, P. G. Nucleation. Cryst. Growth Des. 2010, 10, 5007–5019.
(2) De Yoreo, J. J.; Gilbert, P. U. P. a.; Sommerdijk, N. a. J. M.; Penn, R. L.; Whitelam, S.; Joester, D.; Zhang,
H.; Rimer, J. D.; Navrotsky, A.; Banfield, J. F.; Wallace, a. F.; Michel, F. M.; Meldrum, F. C.; Colfen, H.;
Dove, P. M. Crystallization by particle attachment in synthetic, biogenic, and geologic environments. Science.
2015, 349, aaa6760.
11
PB-11
Preparation and Characterization of Green High Energy Aminotetrazolium
Dihydroborate and Closo-(B12H12)-2 Salts
Pessia Sharon, Carmit Alexenberg, Michal Afri, Dan Grinstein, Aryeh A. Frimer
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Substantial interest has developed in insensitive munitions (IM) - high energy compounds which are relatively
stable to detonation. Ideally, the IM should be an environmentally friendly or “green” explosives as well,
releasing neither smoke nor toxic gases when detonated. Other desired properties are high crystal density and
heat of formation. Two class of compounds which would seem to answer all these criteria, are tetrazolium
dihydroborate and closo-(B12H12)-2 salts. The latter are rich in nitrogen and/or boron and produce primarily N2
and boron oxides on oxidative decomposition. These materials are thermally stable and insensitive to electrical
discharge, friction and impact. We have focused our efforts on the aminotetrazolium derivatives because of the
high percentage of nitrogen atoms. A variety of nitrogen-rich and metal-free dihydrobis(1,2,4-triazolyl)borate,
dihydrobis(5-aminotetrazolyl)borate 1 and 2 and closo- (B12H12)-2 salts 3 of aminotetrazole derivatives were
prepared as shown below.
12
PB-12
NMR Signal Amplification through Host:Guest Binding Kinetics
Ronit Shusterman-Krush1, Liat Avram-Biton2, Amnon Bar-Shir1
1
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
CEST (chemical exchange saturation transfer) is an NMR methodology by which the NMR signal of low
concentration moieties is amplified through a saturation transfer mechanism. This methodology has been
widely used in MRI-based applications for molecular imaging[1]. Although the CEST methodology have been
proposed for 1H-NMR, the ability to use it with other NMR-observable nuclei[2],[3] is an advantage for several
fields in science, from host:guest chemistry to molecular MR imaging.
Here we employ the CEST technique in the 19F-NMR framework to amplify signals from extremely low and
sometimes “undetectable” 19F-guests in cucurbit[n]uril (CB[n]) hosts. The proposed approach, which is termed
guest exchange saturation transfer (GEST), is performed to study the binding kinetics in host:guest systems.
Specifically, 19F-GEST effect of CB[7] as the host and several 19F-anesthetics as potential guests is shown. A
significant GEST effect arising from CB[7]:fluoroxene host:guest system was observed, with the ability to
amplify the 19F-NMR signal of extremely low concentrations of complexed guest (µM) by a factor of x1000.
Moreover, the effect of the salt content and the temperature on the obtained GEST outcome is discussed.
Finally, the potential of ‘GEST’ to be used in molecular 19F-MRI applications is demonstrated. To summarize,
the feasibility of applying the CEST methodology in 19F-NMR and MRI frameworks through host:guest
molecular systems was demonstrated, along with the clear potential of the 19F-GEST methodology to study
host:guest interaction[4].
[1] A. Bar-Shir et al., ACS Chemical Biology 2015, 10, 1160-1170.
[2] A. Bar-Shir et al., Journal of the American Chemical Society 2015, 137, 78-81.
[3] M. Schnurr et al., Angew Chem Int Ed Engl 2015, 54, 13444-13447.
[4] L. Avram et al., Chemical Science 2016.
13
PB-13
A Unique Pd–Catalysed Heck Arylation as a Remote Trigger for
Cyclopropane Selective Ring–Opening
Sukhdev Singh, Jeffrey Bruffaerts, Alexandre Vasseur, Ilan Marek
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Nowadays, the development of novel organic transformations tends towards more flexible, efficient and
economical strategies, as well as the induction of high levels of stereoselectivity. In this context, the concept of
remote functionalization has recently drawn great attention as it meets all these criteria. 1 For instance, previous
studies have identified Heck intermolecular arylations of olefins as a potential remote trigger for distant
functionalizations via chain–walking processes.2-6 Hereby, we report the unprecedented Heck regioselective
arylation of terminal olefins 1 as a distant trigger for the ring-opening of cyclopropanes. This Pd–catalysed
unfolding of the strained cycle, driving force of the chain–walking process, remarkably proved its efficiency
and versatility, as the reaction proceeded regardless of the molecular distance between the initiation (double
bond) and termination (alcohol) sites in 1. Moreover, employing stereodefined polysubstituted cyclopropane
provide access to sophisticated stereoenriched acyclic scaffolds in good yields. Conceptually, we demonstrated
that merging catalytically a chain walking process with a selective C–C bond cleavage represents a powerful
approach to construct linear skeleton possessing two stereogenic centers.
1] Vasseur, A.; Bruffaerts, J., Marek, I. Nature Chem. 2016, 8, 209.
2] Molpolder, J. B.; Heck. R. F. A. Org. Chem. 1976, 41, 265.
3] Larock, R. C.; Leung, W. Y.; Stoltz–Dunn, S. Tetrahedron Lett. 1989, 30, 6629.
4] Werner, E. W.; Mei, T.–S., Burckle, A. J., Sigman, M. S. Science 2012, 338, 1455.
5] Mei, T.–S.; Patel, H. H.; Sigman, M. S. Nature 2014, 508, 340.
6] Didier, D. et al. Eur. J. 2014, 20, 1038.
14
PB-14
Self-Assembly of Enzyme-Responsive Amphiphilic Polymer-Dendron Hybrids
into Micelles with Different Hydrophilic Shells
1
Gadi Slor1,2, Roey J. Amir1,2
Department of Organic Chemistry, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
In the recent years, a lot of attention is directed towards the study and development of nano-sized carriers,
which can encapsulate or covalently bind molecular cargo within their cores. One of the promising applications
for these kinds of carriers is in the field of drug delivery. For this use, there is a need for nano-carriers that
could disassemble on demand under specific conditions, causing the release of their molecular cargo at the
designated target site. Typically, these kind of nano-carriers are formed by the self-assembly of amphiphilic
block copolymers into micelles or vesicles in aqueous media. There are numerous examples for stimuliresponsive micelles and vesicles that disassemble due to changes in temperature, pH, light irradiation and
recently enzymatic activation. Enzymes are very appealing trigger due to their catalytic nature, specificity and
the fact that in many cases there is an overexpression of disease associated enzymes in diseased tissues. In
previous works of our group we presented amphiphilic block copolymers based on hydrophilic PEG linked to a
hydrophobic enzyme-responsive dendron. These PEG-dendron hybrids self-assembled in aqueous media into
micelles, which disassembled after activation with specific enzyme. In this work, we expand the variety of
hydrophilic polymers that can be used for the preparation of amphiphilic polymer-dendron hybrids. The effect
of polymer composition and charge on the assembly and disassembly were thoroughly studied using various
techniques. The results demonstrate the modularity of our synthetic design and open the way for enzymeresponsive polymeric micelles with adjustable hydrophilic shell and surface properties.
15
PB-15
Mechanism of the Copper/TEMPO Catalyzed Aerobic Oxidation of Alcohols
Alex Szpilman1, Mark A. Iron2
1
Department of Chemical Sciences, Ariel University, Ariel, Israel
2
Department of Chemical Research Support, Weizmann Institute of Sciences, Rehovot, Israel
Identifying the mechanism of a catalytic reaction is paramount for designing new and improved catalysts.
Several alternative catalytic cycles for the copper-TEMPO catalyzed aerobic oxidation of alcohols to the
corresponding aldehydes or ketones were examined in their entirety using density functional theory at the
SMD(CH3CN)-RIJCOSX-DSD-PBEB95/def2-TZVP//DF-PBED3BJ/def2-SVP level of theory.[1] A novel
catalytic cycle in which TEMPO remains coordinated to copper throughout, was identified as the most likely
mechanism. There are three components to the catalytic cycle: (1) hydrogen transfer from the alkoxy ligand to
coordinated TEMPO (2) oxygen activation with formation of a peroxo complex, and (3) alcohol activation with
transfer of the O–H proton to the peroxo ligand. The oxidation takes place via a six-membered intramolecular
hydrogen transfer transition state. Importantly, this is not the rate determining step. Instead, the rate
determining step involves oxygen activation and/or the initial alcohol activation.
[1] Mechanism of the Copper/TEMPO Catalyzed Aerobic Oxidation of Alcohols Mark A. Iron and Alex M.
Szpilman* Chemistry a European Journal, 2016, In Press (HOT paper)
16
PB-16
Nucleophilic C(sp )-H Bond Functionalization in Heteroarоmatics as an Atomand Stage-Efficient Synthetic Tool to Obtain Novel Heterocyclic Derivatives
2
Mikhail Varaksin1,2, Oleg Chupakhin1,2, Valery Charushin1,2
Department of Organic and Biomolecular Chemistry, Ural Federal University, Ekaterinburg,
Russia
2
Laboratory of Heterocyclic Compounds, Institute of Organic Synthesis, Ekaterinburg, Russia
1
Two principal approaches to modify heteroaromatics by means of incorporation of a nucleophilic fragment
through displacement of the C-H bond will be considered.
The first one is based on catalytic activation of the C-H bond. It involves the step of deprotonation followed by
the formation of organometallic intermediates, which then react with nucleophiles into the final products (1).
The second approach suggests a direct nucleophilic attack at unsubstituted carbon of an heteroaromatic ring
leading to the σH-adducts followed by either two electrons oxidation (“Addition-Oxidation” Protocol 2.1) or
elimination of good-leaving group (“Addition-Elimination” Protocol 2.2).1,2
Both schemes involve the departure of proton, however the sequence and the ways of activations differ.
It has been well documented that the metal-free coupling reactions provide a good complementary basis for
metal-catalysed cross-coupling reactions, as illustrated by many examples from the chemistry of biologically
active compounds, macrocyclic derivatives, polymers, free stable radicals, metallocenes, carboranes, etc.3-7
1] Charushin, V.N.; Chupakhin, O.N., Eds. Metal Free C-H Functionalization of Aromatics.
Nucleophilic Displacement of Hydrogen. In Top Heterocyclic Chemistry, Maes, B. U. W., Cossy, J.,
Poland, S., Series Eds.; Springer: Heidelberg, New York, Dordrecht, London, 2014; Vol. 37.
2] Chupakhin, O.N.; Charushin, V.N. Tetrahedron Lett. 2016, 57, 2665−2672.
3] Varaksin, M.V.; Chupakhin, O.N.; Charushin, V.N. et al. J. Org. Chem. 2012, 77, 9087.
4] Varaksin, M.V.; Chupakhin, O.N.; Charushin, V.N. et al. Macroheterocycles 2013, 6, 308.
5] Chupakhin, O.N.; Varaksin, M.V. et al. J. Org. Chem. 2009, 74, 2870.
6] Utepova, I.A.; Chupakhin, O.N.; Charushin, V.N. et al. J. Org. Chem. 2014, 79, 8659.
7] Varaksin, M.V.; Chupakhin, O.N.; Charushin, V.N. et al. Organometallics 2015, 34, 5285.
The study was supported by the RSF (Project № 14-13-01177) and the RFBR (Project № 16-03-00958).
17
PB-17
Development of Correlative Cryo-soft X-ray Tomography (Cryo-SXT) and
Stochastic Reconstruction Microscopy (STORM). A Study of Cholesterol
Crystal Early Formation in Cells
Neta Varsano1, Tali Dadosh2, Sergey Kapishnikov4, Eva Pereiro5, Eyal Shimoni2,
Xueting Jin6, Howard S. Kruth6, Leslie Leiserowitz3, Lia Addadi1
1
Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Research, Weizmann Institute of Science, Rehovot, Israel
3
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
4
Department of Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Berlin,
Germany
5
MISTRAL Beamline−Experiments Division, ALBA Synchrotron Light Source, Barcelona,
Spain
6
Experimental Atherosclerosis Section, National Heart, Lung and Blood Institute,
National Institutes of Health, Bethesda, Maryland, USA
Atherosclerosis, the major precursor of cardiovascular disease, is characterized by the deposition of excessive
cholesterol in the arterial intima. 1 Atherosclerotic plaques build up in arteries in a slow process that initiates
with uptake of LDL particles by macrophage cells leading to deposition of cholesterol monohydrate crystals
and cell death.1 Precipitation of cholesterol crystals is a crucial part of the pathological progression. 2
We suggested that the initial step in atherosclerosis development may be from cholesterol domains segregating
in cell membranes and serving as nucleation sites for the formation of 3-dimensional (3D) cholesterol crystals
3,4
. To verify whether this process can be relevant to in vivo processes, we have developed a high resolution
correlative method combining cryo-soft X-ray tomography (cryo-SXT) and stochastic optical reconstruction
microscopy (STORM). 5 The approach provides 3D information on large cellular volumes at 70 nm resolution. 5
Cryo-SXT morphologically identifies and localizes aggregations of carbon-rich materials, while STORM
identifies specific markers on the desired epitopes, enabling colocalization between the identified objects and
the cellular environment. Using a specific antibody (MAB 58B1) which labels cholesterol crystals 6, we
identify and image crystals at a very early stage (200-400 nm) on the cell plasma membrane and in intracellular
locations. This technique can in principle be applied to other biological samples where specific molecular
identification is required in conjunction with high resolution 3D-imaging
[1]Kruth, H. S. Curr. Mol. Med. 2001, 1, 633.
[2] Tangirala, Rajendra K., W. Gray Jerome, N. L. Jones, Donald M. Small, W. J. Johnson, J. M. Glick, F. H.
Mahlberg, and G. H. Rothblat. J. Lipid Res., 1994 35, 93.
[3] Ong, D. S.; Anzinger, J. J.; Leyva, F. J.; Rubin, N.; Addadi, L.; Kruth, H. S. J. Lipid Res. 2010, 51, 2303.
[4] Ziblat, R.; Fargion, I.; Leiserowitz, L.; Addadi, L. Biophys. J. 2012, 103, 255
[5]Varsano, N., Dadosh T., Kapishnikov S. Pereiro E. Shimoni E. Jin X., Kruth, H. S. Leiserowitz L, and
Addadi L. J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b07584
[6] Addadi, L., Rubin, N., Scheffer, L. and Ziblat, R., 2008.. Acc. Chem. Res., 2008, 41,254.
18
PB-18
Towards New Reactive Phosphenium Cations
Solomon Volodarsky, Yael Gottlieb, Roman Dobrovetsky
Chemistry, Tel Aviv University, Tel Aviv, Israel
Electronically stabilized phosphenium cations of type (1) have been known for about 40 years. These molecules
showed interesting chemistry as π-accepting ligands in electron rich transition metal complexes. Their reactivity
with small molecules was also probed, however, turned out to be rather limited. This motivated us to design
new reactive phosphenium cations capable of activating small molecules, such as H2, CO, NH3, R3SiH etc. and
hopefully transform them to value-added products. We present two distinct approaches to achieve the desired
goals. The first approach is to synthesize sterically encumbered phosphenium cations (2) which are not
stabilized electronically, and thus expected to be more reactive towards small molecules. Noteworthy,
phosphenium cations of type 2 are still unknown. The second approach is to synthesize geometrically
constrained phosphenium cations (3), which based on computations should be more reactive than 1. Advances
in synthesis and utility of 2 and 3 along with theoretical predictions are presented herein.
19
PB-19
Following Homolytic Mechanochemical Kinetics with a Pyrenyl Nitrone
Spin-Trap
Feng Wang, Charles E. Diesendruck
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
The mechanochemical stability of a polymer is a fundamental parameter when choosing the ideal material for
many different uses where mechanical stress may induce molecular weight reduction. The use of
mechanophores has significantly improved the detection of mechanochemical reaction, but their incorporation
to different polymers can be synthetically challenging. Alternatively, we return to the old strategy of using spin
traps to quantify the radicals produced as a consequence of mechanochemical homolytic bond scission events.
Several new spin-traps have been developed in recent decades, and pyrenyl nitrones have been shown to
effectively bind radicals, providing a spectroscopic methodology to follow radical concentration. Here we
demonstrate the use of these probes as excellent tools to follow mechanochemical depolymerization using
online UV-Vis spectra. In order to confirm if the probe is really providing meaningful relative results between
polymers, we compared the degradation rate constants calculated from UV-Vis spectra with that calculated
from the molecular weight decay based on GPC traces. The rates show a direct correlation, indicating the probe
is indeed providing correct information.
20
PB-20
A Chiral Metal-Organic Frameworks: Evolution of Morphology and
Crystallization on Surface
Qiang Wen, Shira Hamami, Maria Chiara Di Gregorio, Linda J. W. Shimon, Michal Lahav,
Milko E. van der Boom
Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
A chiral Metal-organic frameworks (MOFs) are obtained from a pyridine-based tetrahedral ligands. The
resulting MOFs show a homogeneous hexagonal morphology, the size of which can be tuned by changing the
concentration of ligands and metal salts. Time-dependent experiments reveal the crystallization process go
through a kinetic phase, which dissolve into solution as crystallization goes on. The chiral MOFs can grow on
pyridine-modified silicon surface with orientation. Microstructure analyzes show there are defects between the
interface and MOFs.
21
PB-21
The Difluoromethyl Bioisoster. Is it Always a “Lipophilic Hydrogen Bond
Donor”?
Dina Yeffet, Gali Sod-Moriah, Anat Berliner, Dafna Amir, Daniele Marciano,
Eytan Gershonov, Sigal Saphier, Yossi Zafrani
Organic Chemistry, Israel Institute for Biological Research, Ness-Ziona, Israel
The fluorine atom plays an important role in many fields due to its unique combination of small size, high
electronegativity, low polarizability and hydrophobicity. Advances in synthetic methods, has made the less
abundant CF2H group more accessible. This group is especially interesting because of its attenuated
lipophilicity increase and H-bonding ability. Just how significant is the tendency of CF2H to donate its ahydrogen and is it sensitive to other functions in the molecule? Also, how is the lipophilicity induced by this
group, affected by the molecular structure of specific compounds? Can it really be used as a lipophilic
bioisoster of OH as suggested? In this work we prepared a series of difluoromethyl anisoles and thioanisoles,
and studied their drug-like properties; hydrogen bonding and lipophilicity. Using the Abraham`s solute 1H
NMR analysis we have determined their hydrogen bond acidity parameter A (0.085-0.126) and found that, the
difluoromethyl group acts as a hydrogen bond donor on a scale similar to that of thiophenol, aniline and amine
groups, but not as that of the hydroxyl one. The measured A values were found to correlate with the Hammett s
constants of different substituents, with EWG causing an increase in the hydrogen bond acidity. Although the
difluoromethyl group is considered a lipophilicity enhancing group, we found that the range of the experimental
∆logP depends on the aryl substituents. Here too, a linear correlation was found between the observed ∆logP
and Hammett σ constants, with EWG leading to a decrease in lipophilicity. These findings will enable rational
design of fluorinated drug candidates with added metabolic stability or higher binding affinity obtained without
an increase in lipophilicity using more precise design rules.
22
PB-22
Brook Rearrangement as a Carbenoid-Trigger for Ring Expansion of
Cyclopropanes to Access Stereo-Defined Highly-Substituted Cyclobutenes
Fa-Guang Zhang, Ilan Marek
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Cyclobutenes represent an important class of structural motifs owing to their presence in many natural products
as well as bioactive compounds.Meanwhile, they have also proven to be versatile synthetic intermediates to
structurally complex molecules for their high reactivity because of the ring strain.However, efficient methods
for the construction of cyclobutenes are still quite limited, especially for stereo-defined highly-substituted
ones.In sharp contrast, numerous cyclopropanes’ stereoselective preparations are well established, so the ring
expansion of cyclopropanes holds a great promise for the efficient construction of cyclobutenes.In this study,
the regio- and diastereoselective copper-catalyzed carbomagnesiation of cyclopropenyl ethers, followed by
nucleophilic addition to an acyl silane,Brook rearrangement and ring expansion to give the corresponding
cyclobutene as a single isomer in a one-pot operation. Our methodology provides a facile and novel route to
access stereo-defined cyclobutenes, particularly poly-substituted ones, bearing a quaternary carbon stereocenter
with a high enantiomeric ratio. Additionally, this unique ring expansion paves an attractive way to further
understand and make use of classic Brook rearrangement, especially as a feasible carbenoid-trigger.
23
PB-23
Synthesis and Characterization of P-Si and P-Sn Protected Phosphasilenes and
their Anion-Radicals
Boris Minkovich, Dmitry Bravo-Zhivotovskii, Yitzhak Apeloig
Schulich Faculty of Chemistry and the Lise Meitner-Minerva Center for Computational
Quantum Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Compounds with a multiple bond between silicon and heavier main-group elements have recently attracted
much attention because of their unique reactivity and electronic properties. In spite of extensive research
functionalized unsaturated compounds are still rare. Among them (Cp*)(CO)2Fe-P=SiR2,1 HP=SiR22 and RZnP=SiR22 were reported. Silyl and tin substituents are functional/protecting groups and are in wide use in organic
and inorganic chemistry. For example, Si and Sn- metal exchange reactions are used for P-Li bond formation,
i.e., (R3Sn/Si)3P + MeLi→(R3Sn/Si)2PLi + Me-Sn/SiR3.3
We report the synthesis and multinuclear NMR characterization of P-Si and the first P-Sn -protected
phosphasilenes R2Si=P-R’ (1a-c), where R=tBu2MeSi and R’=tBuMe2Si(a), Me3Sn(), Bu3Sn(c), by LiF
elimination from corresponding lithium phosphides 2a-c. Reduction of phosphasilenes 1a-c with Li metal or
R3SiLi in hexane or THF yields persistent anion-radicals 3a-c. In contrast, the reaction of 1b,c (R’=R3Sn) with
(Me3Si)3SiK in hexane produces quantitatively (Me3Si)3Si-SnR3 accompanied by an NMR-silent elusive
species which we believe to be R2Si=P-K (5); the corresponding anion-radicals 3b and 3c were not detected.
We are currently studying the properties and reactions of the novel 1, 3 and 5.
(1) Driess, M.; Pritzkow, H.; Winkler, U. J. Organomet. Chem. 1997, 529, 313.
(2) Driess, M.; Block, S.; Brym, M.; Gamer, M. T. Angew. Chem. Int. Ed. Engl. 2006, 45, 2293.
(3) (a) Becker, G.; Schmidt, H.; Uhl, G.; Uhl, W.; Regitz, M.; Rösch, W.; Vogelbacher, U.-J. In Inorg. Synth.;
John Wiley & Sons, Inc.: 2007, p 243; (b) Schumann, H.; Rösch, L.; Schmidt-Fritsche, W. Zeitschrift für
Naturforschung B 1978, 33, 1186.
24
PB-24
Reaction between Silenyl Lithium and Main Group Organometalics:
Transmetallation vs. Addition
Daniel Pinchuk, Yosi Kratish, Alexander Kaushansky, Dmitry Bravo-Zhivotovskii,
Yitzhak Apeloig
Chemistry, Schulich Faculty of Chemistry and the Lise Meitner-Minerva Center for
Computational Quantum Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
The study of the structure, properties and reactivity of doubly-bonded silicon compounds has made tremendous
progress, but many challenges remain. Recently we reported the isolation of silenyl lithium 1. Now we report
the synthesis of the first silenyl metals 3 and the first 1,2-dimethalomethylsilanes 4.
Reaction of 1 with MX2 (MX2=MgCl2, MgBr2 ZnCl2, HgCl2, HgF2) leads to a complex mixture of products
including silenyl radical 2 and a metallic residue (Scheme, path a). Reaction of 1 with 1 equivalents of RMX
(tBu2MeSiZnCl, tBuMe2SiZnCl, EtZnCl, tBuHgCl, tBu2MeSiMgBr) in toluene at 00C gave after stirring for 30
minutes the trasmetallation silenyl metal products: 3a-e, respectively (path b). Reaction of silenyl lithium 1
with 2 equivalents of (tBu2MeSi)2M (M=Zn) in toluene at 00C gave after stirring for 30 minutes 3 (path c). In
contrast, reaction of 1 with 2 eq of (tBuMe2Si)2M (M=Zn, Hg, Li, Mg, Na) in toluene yields 4: the first solventseparated ion pair of a 1,2-dimethalomethylsilanes (path d). We are currently studying the reactions of the novel
3 and 4.
25
PB-25
One Step Formation of Reduced-Graphene-Oxide/CoTMPyP based Electrodes
for Oxygen Reduction Reaction
Tsion Raz-Ohaion1, Israel Zilbermann1, Eric Maimon1, Armand Bettelheim2
1
Chemistry department, Nuclear Research Center Negev, Beer-Sheva, Israel
2
Chemical Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Effective Oxygen Reduction Reaction (ORR) is essential for the development of clean energy fuel cells. The
existing Pt-based catalysts are highly efficient but too expensive and rare for mass production. Therefore, low
cost non-precious metals catalysts are necessary.
The ORR catalysis using carbon-supported transition metal porphyrins is well known for decades, yet their low
activity and stability towards ORR are not sufficient for usage in fuel cells. Recently, graphene and its
derivatives, and especially heteroatom doped graphene, have shown promising catalytic ORR activity. The
incorporation of Cobalt-porphyrin into a graphene functionalized electrode could supposedly combine the
advantages of both catalysts.
In this work we present a simple one step strategy to prepare graphene/Co-porphyrin catalyst on electrode
surface instead of the tedious layer-by-layer methods reported so far. Our method is based on the direct
electrochemical reduction on glassy carbon of graphene-oxide (GO) in the presence of CoTMPyP (Cobalt5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin) in the solution. While electrostatic interaction and p-p
stacking adsorb the CoTMPyP to the GO in the solution, the electrodeposition of the GO encage the CoTMPyP
on the electrode surface.
The ORR activity of glassy carbon electrode that was functionalized using this method was characterized by an
onset potential of -0.05V and +0.37V vs. Ag/AgCl in 0.1M NaOH and in 0.1M H2SO4 respectively, while
reduced-GO functionalized electrode, without CoTMpyP, was characterized by an onset potential of -0.16V and
-0.20V vs. Ag/AgCl in the same solutions. Surprisingly, the usage of N-doped-GO have not yielded better
results with onset potentials of only -0.13V and +0.15V vs. Ag/AgCl in the alkaline and acidic solutions
respectively.
26
PB-26
Electrochemical Properties of Europium(III), Samarium(III) and Cerium(III)
in Tetrabutylammonium Chloride Ionic Liquid
Tsion Raz-Ohaion1, Yeshayahu Ben-Eliyahu1, Armand Bettelheim2, Philippe Moisy3,
Laurence Berthon3
1
Chemistry Department, Nuclear Research Center Negev, Beer-Sheva, Israel
2
Chemical Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
3
Nuclear Energy Division, RadioChemistry & Processes Department, CEA, Bagnols-Sur-Ce`ze
Cedex, France
The Electrochemical behavior of the trivalent lanthanides europium(III), samarium(III) and cerium(III) in
tetrabutylammonium chloride (Bu4NCl) was investigated by cyclic voltammetry at glassy carbon working
electrode in 398 K.
The cyclic voltammograms of Eu(III) and Sm(III) consisted of quasi-reversible waves occurring at -0.15V and 1.23 V (vs. Ag wire) respectively, attributed to the reduction to the divalent states. Cyclic voltammogram of
Ce(III) shows oxidation peak potential of 1.14V (vs Ag wire) occurring very close to the potential window
limit. The reversed reduction of Ce(IV) consists of two reduction peaks at -0.42V and -0.62V (vs. Ag wire)
possibly due to addition of chloride ligand. Since the reference potential of the Ag wire within Bu4NCl is
somewhat vague, FeCp2/FeCp2+ redox potential was measured as an internal reference and was found to be
0.62V vs the Ag wire.
The diffusion coefficients of the trivalent lanthanides in Bu4NCl were determined to be of the order of ∼10−10
cm2/s by cyclic voltammetry and the electron transfer coefficients (ks) were determined to be of the order of
∼10−4 cm/s.
27
PB-27
Tailor-Made n-Steroblock Copolymers of Poly(lactic acid) by a Truly Living
Polymerization Catalyst
Tomer Rosen1, Israel Goldberg1, Vincenzo Venditto2, Moshe Kol1
1
School of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
Dipartimento di Chimica e Biologia, Università degli Studi di Salerno, Salerno, Italy
Poly(lactic acid) (PLA) is a biodegradable polymer prepared by the catalyzed ring opening polymerization of
lactide. An ideal catalyst should enable a sequential polymerization of the lactide enantiomers to afford
stereoblock copolymers with predetermined number and lengths of blocks. We recently introduced a new
family of magnesium based catalysts that combine extremely high activity with a true-living nature, which
gives access to PLA materials of unprecedented microstructures. Full consumption of thousands of equivalents
of L-LA within minutes gave PLLA of expected molecular weights and narrow molecular weight distributions.
Precise PLLA-b-PDLA diblock copolymers having block lengths of up to 1000 repeat units were readily
prepared within 30 min, and their thermal characterization revealed a stereocomplex phase only with very high
melting transitions and melting enthalpies. The one pot sequential polymerization was extended up to precise
hexablocks having ‘dialed-in’ block lengths which have not been reported before. These truly-living catalysts
may open the way to next-generation PLA-based materials having vast potential for applications in material
science.
References:
Rosen, T; Goldberg, I; Venditto, V; Kol, M. In preparation
Rosen, T; Goldberg, I; Venditto, V; Kol, M. J. Am. Chem. Soc. 2016, 138, 12041-12044
28
PB-28
The Mysteries of CAAC-bearing Sulfur-Chelated Ruthenium Precatalysts for
Olefin Metathesis
Illya Rozenberg, Gabriel N. Lemcoff
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Ruthenium-based precatalysts for olefin metathesis are among the most studied complexes in terms structureactivity relationship in the field of organometallic catalysis. All the ligands around the metal center have been
modified with achievement of the significant impact on the catalyst’s stability, activity and selectivity. One of
the reasons for the high success of this family of catalysts is the strong sigma electron donation of the Nheterocyclic carbene (NHC). Bertrand et al. have recently developed even stronger sigma donating ligands, the
cyclic(alkyl)(amino)carbene ligands (CAAC).[1] Replacing the NHC by CAAC in olefin metathesis precatalysts
by Bertrand and Grubbs led to a remarkable impact on stability and activity of the complexes.[2]
In our lab we developed latent precatalysts that are based on sulfur chelated to metal center and exist in two
isomeric forms: inactive stable cis-Cl2 and reactive trans-Cl2. The activation of the complex to reactive form
can be easily achieved by irradiation with 350nm light.[3] We have shown that the reason for the stability of the
inactive form is the strong trans influence of the NHC ligand.[4] Thus, the use of this new ligand for our family
of catalysts may lead to improving the properties of latency and activity at the same time. Herein, we present
the synthesis and unexpected properties of sulfur-chelated complexes bearing CAAC ligands.
* X-ray structure was solved by Prof. Israel Goldberg, TAU
References:
[1] M. Soleilhavoup, G. Bertrand, Accounts of Chemical Research 2015, 48, 256-266
[2] D. R. Anderson, V. Lavallo, D. J. O`Leary, G. Bertrand, R. H. Grubbs, Angewandte Chemie International
Edition
2007,
46,
7262-7265
V. M. Marx, A. H. Sullivan, M. Melaimi, S. C. Virgil, B. K. Keitz, D. S. Weinberger, G. Bertrand, R. H.
Grubbs, Angewandte Chemie International Edition 2015, 54, 1919-1923.
[3] A. Ben-Asuly, A. Aharoni, C. E. Diesendruck, Y. Vidavsky, I. Goldberg, B. F. Straub, N. G. Lemcoff,
Organometallics
2009,
28,
4652-4655
A. Aharoni, Y. Vidavsky, C. E. Diesendruck, A. Ben-Asuly, I. Goldberg, N. G. Lemcoff, Organometallics
2011, 30, 1607-1615
[4] C. E. Diesendruck, E. Tzur, A. Ben-Asuly, I. Goldberg, B. F. Straub, N. G. Lemcoff, Inorganic Chemistry
2009, 48, 10819-10825
29
PB-29
The Dense Phase Reaction Mechanism – A New Pathway for Multi-Molecular
Reactions
Roy E. Schreiber, Ronny Neumann
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
Classical kinetics in the gas and solution phases require chemical reactions to go either through unimolecular or
bimolecular elementary steps. Elementary reactions involving three molecules or above are considered
impractical due to the statistical improbability of a simultaneous collision involving more than two species. An
inherent assumption in this theory is that of an `ideal` medium, meaning that there are no intermolecular
interactions between reactant molecules. This assumption is increasingly shown to be naïve for many
solutions1, where transient or at times permanent supramolecular species are shown to form.
We now show a new mechanistic model for chemical reactivity that is adapted from recent advances in the
understanding of homogeneous crystal nucleation2. Here, a dynamic supramolecular aggregate of reactant
molecules is first formed which induces a simultaneous reaction between multiple molecules. Experimental
evidence for this mechanism will be shown in the self-assembly reaction of a polyoxometalate molecule where
a seemingly elementary 6th order reaction was observed.
In this reaction, a molecule containing one tungsten atom, [WO2F4]-2 reacts with silicon dioxide in aqueous
solution to form a single type of atomically precise 18 tungsten molecule [H2F6NaW18O56]-7. An overview of
the whole formation mechanism will be shown, with an emphasis on the dense phase reaction step.
References
(1) Sedlák, J. Phys. Chem. B 110, 4329-4338 (2006).
(2) J. De Yoreo et al., Science 349, 6760-1 -6760-6 (2015).
30
PB-30
Orthogonal Photo-Isomerization of Sulfoxide-Chelated Ruthenium Precatalyst
Noy Nechmad, Gal Segalovich, Gabriel N. Lemcoff
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Ruthenium precatalysts have been proven to be very efficient in olefin metathesis reaction due to their stability
towards moisture and air, broad functional group tolerance and high modularity. Thus, much attention is
devoted to the modification of these precatalysts in order to achieve novel properties.
In our group,¹ a family of latent precatalysts having a sulfur chelated to metal center was developed. These
complexes have two isomeric forms that can be switched by irradiation with 350nm light, from the stable
inactive cis-dichloro to the active trans-dichloro.
Herein we show the development of chelated ruthenium sulfoxide complexes and the investigation of not just
their cis to trans isomerization process, but also from Ru-S=O to Ru-O=S binding mode; as well as the effect of
these isomerizations on the reactivity of the complexes. The rationale behind this new family of complexes is
based on the studies that show that ruthenium sulfoxide complexes can undergo isomerization from Ru-S=O to
Ru-O=S by irradiation by UV light, and the known reduced affinity of oxygen-ruthenium linkages compared to
sulfur-ruthenium².
References:
¹ ª A. Ben-Asuly, E. Tzur, C. E. Diesendruck, M. Sigalov, I. Goldberg, N. G. Lemcoff, Organometallics, 2008,
27, 811.
ᵇ A. Ben-Asuly, A. Aharoni, C. E. Diesendruck, Y. Vidavsky ,M. Sigalov, I. Goldberg, N. G. Lemcoff,
Organometallics, 2009 28, 4652.
² B. A. McClure, J. J. Rack, Angew. Chem. Int. Ed., 2009, 48, 8556.
31
PB-31
Carbometalltion/Oxidation of Cyclopropenes: an Oasis of Diastereomerically
and Enantiomerically Enriched Cyclopropanols and Aldehydes Possessing
Quaternary Carbon Stereocenters
Marwan Simaan, Ilan Marek
Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
The diastereoselective carbocupration reaction of various cyclopropenes followed by addition of oxenoid
leads to the formation of diastereomerically enriched 2,2,3-trisubstituted and 2,2,3,3-tetrasubstituted
cyclopropanol derivatives. Ring fragmentation of the copper cyclopropanolate leads to acyclic aldehydes
derivatives possessing a-tertiary and a-quaternary carbon stereocenters in a single-pot operation. The use of
enantiomerically enriched starting materails paves the road to the production enantiomerically enriched final
products.
32
PB-32
From Frustrated Carbene-Borane Lewis Pairs to Anionic N-Heterocyclic
Carbene Ligands
Matthias Tamm
Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig,
Braunschweig, Germany
Frustrated carbene-borane Lewis pairs, which are prevented from normal adduct formation by steric factors,
were recently shown to exhibit a very strong propensity for the activation of small molecules such as
dihydrogen, ammonia, tetrahydrofuran, alkynes, white phosphorus and sulfur [1] In the absence of substrates,
however, self-deactivation and irreversible formation of abnormal carbene-borane adducts is observed, which
paved the way to the develoment of anionic carbenes bearing a weakly coordinating anionic borate moiety in
the backbone (WCA-NHC). These systems proved to be a useful addition to the com-paratively small family of
anionic N-heterocyclic carbenes (NHCs) [2] and have found useful applications as ancillary ligands in
homogeneous catalysis [3-5].
References
[1] Review: “N-Heterocyclic Carbenes in FLP Chemistry”, E. L. Kolychev, E. Theuergarten, M. Tamm, Top.
Curr. Chem. 2013, 334, 121-155.
[2] Review: “Anionic N-Heterocyclic Carbenes: Synthesis, Coordination Chemistry and Applications in
Homogeneous Catalysis (In memory of Guy Lavigne)”, A. Nasr, A. Winkler, Matthias Tamm, Coord. Chem.
Rev. 2016, 316, 68-124.
[3] “Anionic N-Heterocyclic Carbenes That Contain a Weakly Coordinating Borate Moiety”, S. Kronig, E.
Theuergarten, C. G. Daniliuc, P. G. Jones, M. Tamm, Angew. Chem. Int. Ed. 2012, 51, 3240-3244.
[4] “Iridium(I) Complexes with Anionic N-Heterocyclic Carbene Ligands as Catalysts for the Hydrogenation of
Alkenes in Non-Polar Media”, E. L. Kolychev, S. Kronig, K. Brandhorst, M. Freytag, P. G. Jones, M. Tamm, J.
Am. Chem. Soc. 2013, 135, 12448-12459.
[5] “Palladium(II) Complexes with Anionic N-Heterocyclic Carbene–Borate Ligands as Catalysts for the
Amination of Aryl Halides”, A. Winkler, K. Brandhorst, M. Freytag, P. G. Jones, M. Tamm, Organometallics
2016, 35, 1160-1169.
33
PB-33
Selective Recognition and Precipitation of Cs+ ions from Aqueous Solutions
Guy Yardeni2, Ravell Bengiat1, Israel Zilbermann2,3, Joseph Almog1
1
Casali Centre for Applied Chemistry, The Institute of Chemistry,
The Hebrew University of Jerusalem, Jerusalem, Israel
2
Chemistry, Nuclear Research Center Negev, Beer-Sheva, Israel
3
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Ninhydrin is a widely used reagent in forensic science for the visualization of latent fingerprints and in
biochemical research of amino acids. A spin-off from its classic use has revealed its unique ability in forming
3-dimensional vase-shaped compounds, which were thus named vasarenes, in a facile one-pot reaction with
polyhydroxy aromatics1. An intriguing characteristic of these structures is their selective affinity, binding and
precipitation of ion-pairs of type M+F-, where M being a large monovalent cation2,3.
Our recent research has involved the design and synthesis of new analogues that are water-soluble, from
polycarbonyl componds other than ninhydrin. The new ligands, which are readily obtained from alloxan and
polyhydroxy aromatics, have shown a promising potential for the challenging task of binding and precipitation
of the extremely soluble Cs+ ions from aqueous solutions. The binding process is highly selective; no other
alkali metal ion reacts with these ligands. The specific affinity rests in a supramolecular interaction between the
vasarene analogue and the large Cs+ cations.
From a practical point of view the new receptors may be used for the design of a sustainable salts-separation
tool4.
(1) Almog, J.; Rozin, R.; Klein, A.; Shamuilov-Levinton, G.; Cohen, S. Tetrahedron 2009, 65 (38), 7954–7962.
(2) Almog, J.; Gavish-Abramovich, I.; Rozin, R.; Cohen, S.; Yardeni, G.; Zilbermann, I. Eur. J. Inorg. Chem.
2012, 2012 (28), 4427–4432.
(3) Bengiat, R.; Gil, M.; Klein, A.; Bogoslavsky, B.; Cohen, S.; Dubnikov, F.; Yardeni, G.; Zilbermann, I.;
Almog, J. Dalton Trans. 2016, DOI: 10.1039/C5DT04171F.
(4) Bengiat, R.; Klein, A.; Gil, M.; Bogoslavsky, B.; Cohen, S.; Yardeni, G.; Zilbermann, I.; Almog, J.
IUCrData 2016, 1 (2), x160261.
34
PB-34
Nitrenium-Based Iridium Complexes
Heroot Levy Vahav, Alla Pogoreltsev, Yuri Tulchinsky, Mark Gandelman
Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
N-heterocyclic carbenes are well known and commonly used as ligands in organometallic chemistry. However,
their analogue ligands based on isoelectronic nitrogen cation atom has only recently been accomplished by our
group. A new type of cationic nitrenium-based PNP pincer ligands, bearing two phosphine based arms,
successfully coordinates to neutral, cationic and dicationic late transition metal centers (Scheme 1).[1]
Scheme 1. Pincer type nitrenium ligands coordinate to a variety of late transition metals in different oxidation
states.
Nitrenium ligands, contrary to NHC, bear positive charge on the central nitrogen atom. The coordination of
those ligands to a transition metal renders the metal center electrophilic. This effect is enhanced when the
nitrenium is coordinated to the cationic metal species. Here we present the mono- and di-cationic Ir(I)
complexes coordinated to the N-heterocyclic nitrenium cations. Such dicationic (or tricationic) complexes
featuring cation-cation L+-M+ interactions are especially attractive for electrophilic catalysis.[2]
The formation of the nitrenium-metal bond is confirmed in solution, by selective
and/or in the solid state, by X-ray crystallography.
15
N-labelling experiments,
[1] (a) Tulchinsky, Y.; Iron, M. A.; Botoshansky, M.; Gandelman, M. Nature Chem. 2011, 3, 525-531. (b)
Tulchinsky, Y.; Kozuch, S.; Saha, P.; Botoshansky, M.; Shimon, L.; Gandelman, M. Chem. Sci. 2014, 5, 13051311. (c) Tulchinsky, Y.; Kozuch, S.; Saha, P.; Mauda, A.; Nisnevich, G.; Botoshansky, M.; Shimon, L. J. W.;
Gandelman, M. Chem. Eur. J. 2015, 21, 7099−7110.
[2] Unpublished results.
35
PB-35
Asymmetric G-Quadruplex DNA Scaffolds and their Application as
Combinatorial Sensors and Molecular Security Systems
Omer Lustgarten1, Raanan Carmieli2, Leila Motiei1, David Margulies1
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
1
Conventional methods for creating synthetic receptors are generally limited by the need to use water-soluble
building blocks and performing multistep organic synthesis, which complicate using such receptors as
biomimetics and sensors. To address this problem, we have developed a simple, versatile and robust method for
preparing sets of water-soluble synthetic receptors through the self-assembly of oligonucleotides (ODNs) into
asymmetric DNA G-quadruplex structures. By modifying these ODNs with supramolecular recognition
elements and distinct fluorescent reporters (Figure 1) we have demonstrated the possibility of creating a novel
type of pattern-generating fluorescent probes that can discriminate among multiple different analytes, such as
drugs of abuse, in a high-throughput manner. We have also shown that these sensors can function as molecularscale security systems that can authorize four different users simultaneously.
Figure 1. Four DNA strands appended with different linkers and fluorophores can self-assemble into a unique
asymmetric quadruplex structure. The resulting analytical device can generate a wide range of distinct emission
fingerprints upon binding to different analytes.
36
PB-36
A New MCR4 Multicomponent Reaction to Access Chiral Hexa-Substituted
Benzenes towards Development of Inhibitors of Protein Kinases
Tlalit Massarano, Ronit Lavi, Gerardo Byk
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Multicomponent reactions are of special interest because they can generate in a single reaction complex
molecules, such as hetero aliphatic and hetero aromatic polycyclic rings, and can be adapted to parallel
automated synthesis. The synthesis of complex molecules has an advantage when it comes to natural
compounds and their derivatives. Special attention was devoted to Staurosporine, an indolo[2,3-a]carbazole
alkaloid, which acts as non-selective inhibitor of protein kinases and induces apoptosis. Thus, its derivatives
have potential applications for cancer treatment. Structurally, this compound is characterized by a hexasubstituted benzene ring with a fused indole ring and a fused lactam ring with a pendant sugar moiety. Two
recent works deserved as driving forces for the synthetic strategy we present here: the first a conceptually new
strategy for the synthesis of the hexa-substituted benzenes. The key-step of the reaction was the generation in
situ of a furan intermediate which upon the presence of appropriate dienophiles undergoes Diels Alder reaction
resulting in a non-stable intermediate that after rearrangement produces hexa-substituted benzenes [1]. The
second, proposed the formation of substituted furans by reacting barbituric acid with isocyanides and aldehydes
at room temperature[2]. Herein we combined both approaches for obtaining novel hexa-substituted benzenes.
The advantage of the new approach is that chiral derivatives can be easily obtained in one pot. We have
developed a new “Ugi like” MCR4 by using chiral β-keto-γ-lactams as precursors. The reaction can be
performed both in solution and in solid phase. Products display significant biological activity in XTT viability
assays in different cell lines. The mechanism of action will be discussed.
References
1) Janvier, P., Bienaymé, H. and Zhu, J. Angew. Chem. 2002. 114: 4467–4470 (23)
2) Teimouri, M. B.; Bazhrang, R. Bioorganic Med. Chem. Lett. 2006, 16, 3697–3701.
37
PB-37
Oxidative Protein Folding of Modified Disulfide-Rich Proteins
Reem Mousa, Norman Metanis
Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
The in vitro oxidative folding has been extensively studied in the last four decades especially with small
disulfide-rich proteins. One conclusion that these studies provide is that many disulfide-rich proteins follow two
different folding model mechanisms; those seen for bovine pancreatic trypsin inhibitor (BPTI) and for hirudin,
or a combination of the two folding models.
Selenocysteine (Sec) incorporation has been successfully used in protein folding studies including that of BPTI.
Sec`s low redox potential, and pKa, as well as its increased nucleophilicity and electrophilicity can enhance
thiol-disulfide-like exchange reactions that are essential for protein folding. Based on these results we wish to
study the effect of Sec substitution on the folding of hirudin. Wild-type hirudin and its seleno-analogs
containing one or two substitutions at different positions that could form native diselenide bonds have been
prepared using solid phase peptide synthesis (SPPS) and native chemical ligation (NCL). Moreover, we aim to
shed more light on BPTI folding mechanism by using different strategy. BPTI folding mechanism was
extensively studied, in which the reduced protein folds via bifurcated pathway. Roughly half of the reduced
BPTI reach the native state via two intermediates: (N’) that lacks the [5-55] disulfide and N* that lacks the [3051]. Formation of the fully oxidized BPTI requires partially unfolding that reduces the solvent exposed
disulfide bridge [14-38] and rearrangement of theses intermediates. Therefore, we propose that replacing the
[14-38] disulfide bond with highly stable thioacetal, will cause the protein to be trapped at the two stable
intermediates N’ and N*, preventing the formation of the native form (N). This experiment will shed more
light, and answer any further dispute about the folding mechanism of BPTI. Here we show preliminary data
along these lines.
38
PB-38
Accessing Human Selenoproteins through Chemical Protein Synthesis
Reem Mousa, Linoy Dery, Orit Ktorza, Post Sai Reddy, Shahar Dery, Alaa Talhami,
Norman Metanis
Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
The human body contains 25 selenoproteins, which contain in their sequence the twenty-first encoded amino
acid, selenocysteine. About a dozen of these proteins remain functionally uncharacterized or poorly studied.
Challenges in accessing these selenoproteins using traditional recombinant expressions have prevented
biological characterization thus far. Chemical protein synthesis has the potential to overcome these hurdles.
Here we report the first total chemical syntheses of two human selenoproteins, selenoprotein M (SELM) and
selenoprotein W (SELW). The synthesis of the more challenging protein SELM was enabled using recent
advances in the field of selenocysteine chemistry. This approach allows the preparation of selenoproteins in
milligram quantities and in homogenous form, which should open new horizons for future studies to pursue a
fuller biological understanding of their role in health and disease.
39
PB-39
An Image Forming Mirror in the Eye of the Pecten Scallop
Benjamin Palmer1, Anna Hirsch4, Gavin Taylor2, Vlad Brumfeld3, Dvir Gur1,
Michal Shemesh1, Nadav Elad3, Aya Osherov1, Dan Oron5, Steve Weiner1, Lia Addadi1
1
Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
2
Department of Biology, Lund University, Lund, Sweden
3
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
4
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
5
Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
The vast majority of both animal eyes and synthetic image-forming devices use lenses to focus light by
refraction. However, in exceptional cases in nature and in some man-made applications, images are produced
by light reflection.
A case in point is found in the Pecten scallop which has one of the most remarkable visual systems in nature
possessing up to two hundred iridescent eyes along the mantle tissue edges (Fig.1 left). An image is produced
by reflection of light from a concave mirror lining the back of the eye onto the retina residing in the centre of
the eye (Fig.1 middle). CryoSEM microscopy shows that the hemi-spherical mirror is composed of 20 – 30
layers of perfectly tiled square crystals (Fig.1 right). In-situ microspot X-ray diffraction together with electron
diffraction demonstrate that these crystals are crystalline guanine and that the organism uses control over
crystal twinning to produce the unusual square morphology in which the high-refractive index (100) face is
preferentially expressed. This crystal morphology facilitates the tiling of the large area mirror in addition to
ensuring that incident light always impinges on a maximally reflective surface. Optical simulations of the
mirror’s reflectance spectrum demonstrate that it reflects most efficiently blue light and is thus well optimized
for use in the scallops habitat (100 m down) where only blue light penetrates.
This work reveals novel strategies which organisms use to control crystal morphology and organization to
optimize a particular optical function. Such knowledge could be applied in several aspects of material science
in particular in the development of novel synthetic optical devices.
40
PB-40
The New in Vivo Active Polycyclic Aromatic Derivative: 6-(1,3-dithiepan-2-yl)2-Phenylchromane Augments Glucose Uptake in Skeletal Muscle cells and
Stimulates Insulin Secretion from β-Cells by AMPK Activation
Naomi Rozentul1, Yosef Avrahami2, Moran Shubely1, Duha Fahham2, Guy Cohen2,
Olga Viskind1, Shlomo Sasson2, Arie Gruzman1
1
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Pharmacology, The Hebrew University of Jerusalem, Jerusalem, Israel
Diabetes type two (T2D) is not just very frequent metabolic disease. Recently this disease become an epidemic
affecting millions of people around of globe, especially in developed countries and it becomes serious threat for
the health system of entire Western civilization. Treatment of T2D and its complications draw enormous
amount of human working power and government founding. Thus, the effort to create effective antidiabetic
drugs is never stops. Based on our previously reported data a serial of novel polycyclic aromatic compounds
were synthesized. Their effect on the rate of glucose uptake in L6 myotubes under hyperglycemic conditions
was tested. Several compounds dose- and time-dependently increased the rate of glucose uptake in
pharmacologically relevant concentrations. The (6-(1,3-dithiepan-2-yl)-2-phenylchromane) has showed the best
glucose uptake stimulatory effect mediating by AMPK (AMP kinase) activation. Thus, this compound was also
tested as potential activator of insulin secretion in INS-1E cells. Indeed, compound AMPK-dependently
increased the insulin secretion in these cells. In addition, in vitro ADME parameters of the lead compound were
also investigated, which showed its good drugability. Based on obtained so far data, 6-(1,3-dithiepan-2-yl)-2phenylchromane might be used for future development of novel class of antidiabetic drugs with potential bifunctional activity: increasing both rate of glucose uptake in skeletal muscles and insulin secretion from β-cells
41
PB-41
Protein Recognition by Bivalent, ‘Turn-On’ Fluorescent Molecular Probes
Linor Unger-Angel, Leila Motiei, David Margulies
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
We show that the conversion of a known intercalating dye (i.e., thiazole orange) into a bivalent protein binder
could lead to the realization of a novel class of ‘turn-on’ fluorescent molecular probes that detect proteins with
high affinity, selectivity, and a high signal-to-noise (S/N) ratio. The feasibility of the approach is demonstrated
with monomolecular probes that light-up in the presence of three different proteins: acetylcholinesterase
(AChE), glutathione-s-transferase (GST), or avidin (Av) at low concentrations and with minimal background
signal. The way by which such probes can be used to detect individual protein isoforms and be applied in
inhibitor screening, cell imaging, and biomarker detection is described.
42
PB-42
Structure and Formation of Calcium Oxalate Monohydrate Druses in Almond
and Okra Leaves
Maria Pierantoni, Lia Addadi, Steve Weiner
Structural Biology, Weizmann Institute of Science, Rehovot, Israel
Plant leaves produce a variety of calcium oxalate monohydrate crystals with different shapes and sizes. We
know very little about the ways in which these biogenic crystals form. We focus on aggregates of crystals
formed around an organic core (druses), with the aim of characterizing their morphology, structure and
formation mechanism. In the area of the core, micron and submicron sized prismatic crystals are distributed
between organic components (figure 1B). These small crystals represent the starting point for the growth of the
faces forming the final morphology. The crystals grow radially from the core, competing with each other for
growth space (figure 1C); the fastest growing crystals prevail over the others. In okra only eight to ten crystals
contribute to the final morphology (figure 1D). An important role in regulating the crystal organization could be
played by the crystal chamber. Crystals grown in vitro develop a flat prismatic habit. At higher supersaturations
the structures resemble the leaf druses. The expressed crystal faces are the same as those identified in the single
crystals. Formation appears to be in part biologically controlled, and in part inorganically controlled.
Figure 1. SEM images. A-C) Almond druse. A) Section of a druse showing the core and crystals radiating from
it. B) Core: with micron size prismatic crystals (arrowheads) and some organic content (O). C) Crystals
growing radially from the center of the druse. D) Okra druse
43
PB-43
syn-(Me,Me)bimane: A Fluoroscent Ligand for Biologically Important Alkali
and Alkaline Earth Metal Cations
Ankana Roy1, Partha J. Das1, Yael Diskin-Posner2, Michael Firer3, Flavio Grynszpan1,
Michael Montag1
1
Chemical Sciences, Ariel University, Ariel, Israel
2
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
3
Chemical Engineering and Biotechnology, Ariel University, Ariel, Israel
syn-Bimanes have been used in biological systems as fluorescent-labeling agents for various biomolecules (e.g.,
proteins, amino acids, glutathione), due to their non-toxicity, low molecular weight and strong fluorescence.
We have recently shown that one of these heterobicyclic compounds, syn-(Me,Me)bimane, coordinates Pd(II)
in a chelating fashion through its two carbonyl oxygens.[1] This was the first reported case of metal-bimane
coordination, to the best of our knowledge.
We have since expanded our investigations to examine the coordination chemistry of syn-(Me,Me)bimane with
different biologically important alkali and alkaline earth metal cations (e.g., Na+, K+ Li+, Ca2+, Mg2+).
Our study reveals that syn-(Me,Me)bimane exhibits several binding modes. The strongly fluorescent syn(Me,Me)bimane binds M+ and M2+ cations via its carbonyl oxygens, leading to changes in its fluorescent
properties. Spectroscopic evidence (NMR, UV-Vis, fluorescence) demonstrates that bimane coordination is
reversible in solution.
The syntheses of these metal-bimane complexes, as well as their spectroscopic and crystallographic data, will
be presented.
1] Das, P. J.; Diskin-Posner, Y.; Firer, M.; Montag, M.; Grynszpan, F., Dalton Trans. 2016, 45, 1712317131
44
PB-44
Supramolecular Corroles for the Activation of Small Molecules
Woormileela Sinha, Zeev Gross
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
Research on the activation of small molecules such as O2, H2O and CO2 has gained huge impetus in the recent
years. The quest for the development of suitable catalysts for oxygen reduction has developed in order to mimic
the naturally occurring enzymes such as cytochrome C oxidase. Metallocorroles have been recently investigated
to be relevant catalysts for the oxygen reduction reaction because of several intriguing features.1-3 Realizing that
the non-sustainable platinum in fuel cells must be replaced, a recent study focused on first row transition metal
complexes of β-pyrrole brominated corrole.3 The catalytic activity followed the order of Co Fe Ni Mn Cu; the
onset potential of the Co corrole was almost as positive as platinum; and the selectivity to H 2O production
rather than H2O2 was quite high.
In order to make the O‒O bond breaking process more organized, an approach involving proton coupled
electron transfer has been adopted in specially designed corrole frameworks known as Hangman corroles. 1 Our
current research is directed towards the development of simple and bio-mimetic Hangman-like motif in the
metallocorrole framework and measurement of its catalytic activity/selectivity on oxygen reduction. In
particular we wish to compare and comprehend the variation in the catalytic activities upon the introduction of
phenolic groups in judiciously designed metallocorrole frameworks.
REFERENCES
(1) Dogutan, D. K.; Stoian, S. A.; McGuire, R.; Schwalbe, M.; Teets, T. S.; Nocera, D. G. J. Am. Chem. Soc.
2011, 133, 131.
(2) Schechter, A.; Stanevsky, M.; Mahammed, A.; Gross, Z. Inorg. Chem. 2012, 51, 22.
(3) Levy, N.; Mahammed, A.; Kosa, M.; Major, D. T.; Gross, Z.; Elbaz, L. Angew. Chem. Int. Ed. 2015, 54,
14080.
45
PB-45
Photoresponsive Nanoparticles utilizing N,N’-Diacylindigo as Photoswitch
Johannes Ahrens, Tamir Forsht, Rafal Klajn
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
The natural dye indigo can be transformed into a soluble photoswitch by double acylation.[1] The reversible
trans–cis isomerization at the central C=C double bond of such N,N’-diacylindigoids can be induced by visible
light. Here, the synthesis of the first unsymmetric functionalized derivate with a desired anchor group is shown.
By covalent immobilization onto surfaces of magnetic Fe3O4 nanoparticles, new photochromic nanomaterial
was produced. It has been successfully demonstrated that reversible self-assembly of the photoresponsive
nanoparticles can be induced solely by visible light.
[1] Y. Omote, S. Imada, R. Matuzaki, K. Fujiki, T. Nishio, C. Kashima, Bull. Chem. Soc. Jpn. 1979, 52, 3397–
3399.
46
PB-46
Scanning Tunneling Spectroscopy of Reduced Graphene Oxide
Orit Livni1, Dima Cheskis2, Efrat Lifshitz1
1
Department of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
2
Physics Department, Ariel University, Ariel, Israel
Graphene is a two dimensional nanomaterial that has attracted worldwide attention since its discovery in 2004,
and it has become a hot topic mainly due to its outstanding properties and promising applications. Graphene, a
single layer (one-atom thick) two-dimensional (2D) crystal of carbon atoms arranged in a honeycomb lattice,
could be isolated from graphite. As for its electric properties, monolayer of graphene is a semi-metal and its
charge carriers are Dirac fermions near Dirac point. The electronic structure of a single layer of graphene has a
launch point between the conduction and valence bands that are called Dirac point. These unique properties
have stimulated the production of graphene and make it suitable for many applications, such as electronic
devices, photonic devices, energy storage, sensors, and etc.[1, 2]. One of the low cost way to produce graphene
is by chemical exfoliation from graphene oxide. Reducing percent of oxygen reduced graphene oxide (RGO) is
accepted.
In spite of the recent interest in graphene, little is known about the atomic structure and electronic properties of
RGO, a semiconductor with a tunable band gap from 2 to 0.02 eV depending on its reduction level [3]. A few
studies conducted under ambient conditions have been performed to study oxidized graphite [4, 5]. In this
work, we report on our efforts to better characterize RGO deposited onto different substrates. In this initial
study, both ultra-high vacuum scanning tunneling microscopy and spectroscopy techniques were chosen
because they provide reliable topographic and electronic information with atomic scale resolution.
References:
[1] Yi, M., Journal of Materials Chemistry A 2015, 3 (22), 11700-11715.
[2] Eva, Y., Reports on Progress in Physics 2012, 75 (5), 056501.
[3] Shen, Y., Elsevier CARBON 62 (2013) 157 – 164.
[4] Klusek, Z., Appl. Surf. Sci. 108 (1997) 405.
[5] Pandey, D., Surface Science 602 (2008) 1607–1613.
47
PB-47
Contact-Free Polarity Characterization of Crystals by X-Ray Photoelectron
Spectroscopy and Molecular Dynamics Simulations
Elena Meirzadeh1, Liel Sapir2, Hagai Cohen3, Sidney Cohen3, David Ehre1, Daniel Harries2,
Meir Lahav1, Igor Lubomirsky1
1
Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
2
Institute of Chemistry and The Fritz Haber Research Center,
The Hebrew University of Jerusalem, Jerusalem, Israel
3
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
Pyroelectricity is a property of polar materials, encountering surface charge under temperature changes. This
property was confined exclusively for the polar directions of the ten polar crystalline classes 1. However, in
contrast to the generally accepted symmetry restrictions, we found that non-polar crystals of amino acids
exhibit surface pyroelectricity at specific crystal faces2-4.
Conventional pyroelectric measurements are frequently challenging, due to the typically rapid charge
compensation by adsorbed moieties, as well as various difficulties arising as a result of contacts introduction. In
particular, surface pyroelectric measurements are extremely sensitive to the above difficulties and, therefore,
they require complementary measuring techniques. Here we exploit the recent chemically resolved electrical
measurements5 based on x-ray photoelectron spectroscopy, to measure in a non-contact mode6 and, importantly,
under ultra-high vacuum, the bulk and surface pyroelectricity of pure (non-polar) and L-threonine doped (polar)
α-glycine crystals7.
Combined with atomic force microscopy studies, the pyroelectric measurements provide information on various
types of crystal surface reconstructions. Molecular dynamics simulations provide the structure of the near
surface hydrated glycine molecules of the crystal at the molecular level.
(1) Lang, S. B. Phys Today 2005, 58, 31.
(2) Piperno, S.; Mirzadeh, E.; Mishuk, E.; Ehre, D.; Cohen, S.; Eisenstein, M.; Lahav, M.; Lubomirsky, I.
Angew Chem Int Edit 2013, 52, 6513.
(3) Pichon, A. Nat Chem 2013, 5, 551.
(4) Mishuk, E.; Weissbuch, I.; Lahav, M.; Lubomirsky, I. Cryst Growth Des 2014, 14, 3839.
(5) Cohen, H. Applied Physics Letters 2004, 85, 1271.
(6) Ehre, D.; Cohen, H. Applied Physics Letters 2013, 103, 052901.
(7) Meirzadeh, E.; Sapir, L.; Cohen, H.; Cohen, S. R.; Ehre, D.; Harries, D.; Lahav, M.; Lubomirsky, I. J Am
Chem Soc 2016, 138.
48
PB-48
Chloride as a Powerful Auxiliary Reagent in the Electroless Synthesis of Silver
Nanostructures
1
Falk Muench1,2, Wolfgang Ensinger1, Alexander Vaskevich2, Israel Rubinstein2
Department of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
2
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
To facilitate the implementation of nanomaterials, there is a strong need for innovation beyond cleanroom
processing and for flexible, simple and robust synthetic routes to nanomaterial fabrication. Here we
demonstrate the application of a facile wet-chemical method of electroless plating for achieving controlled
preparation of silver nanostructures of varying morphology. The process can be applied to substrates of
different compositions and shapes, can be performed without complex instrumentation, and is readily scalable.
Specifically, we show that the strong interaction between silver and chloride ions can be utilized to adjust the
product morphology, ranging from island-like nanoparticle deposits through closed and shape-controlled thin
films to complex nanostructures derived thereof (Fig. 1). Chloride can be employed to modify the nucleation
process on a seeded substrate. Depending on the nucleation distance and the size of the plated nanoparticles,
island-like, percolated, or closed silver nanofilms can be created. We discuss the effect of chloride addition to
an electroless plating bath on the deposition kinetics and the shape of the deposited particles.[1] Due to the high
conformity of the reaction, it can also be applied to nanomaterial templates, allowing the synthesis of complex
micro- and nano-architectures.[1,2]
Various applications of such nanoparticle films can be envisioned, depending on the silver morphology:
Separated silver nanoparticle films can exhibit defined localized surface plasmon peaks and may be useful for
dark-field microscopy, intensely roughened films can be used to construct self-cleaning coatings,[1] and selfsupporting silver nano-networks can serve as efficient electrocatalysts.[2]
[1] F. Muench, B. Juretzka, S. Narayan, A. Radetinac, S. Flege, S. Schaefer, R.W. Stark, W. Ensinger. New J.
Chem. 2015, 39, 6803–6812.
[2] F. Muench, E.-M. Felix, M. Rauber, S. Schaefer, M. Antoni, U. Kunz, H.-J. Kleebe, C. Trautmann, W.
Ensinger. Electrochim. Acta 2016, 202, 47–54.
Fig. 1. Silver structures prepared by electroless plating. (a) Island-like silver nanoparticle film. (b) Coarse silver
thin film. (c) Shape-controlled silver thin film composed of plates. (d) Template-fabricated silver nanotubenanowire assembly.
49
PB-49
Magnetic Chiral Periodic Mesoporous Organosilica (PMO) Nanoreactors:
Design, Preparation and Applications in Asymmetric Catalysis
Suheir Omar, Raed Abu-Reziq
Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Periodic mesoporous organosilica nanoparticles were synthesized in a sol-gel process under mild conditions.
Their preparation was mediated by hydrolysis and condensation of bridged organo-alkoxysilane precursor
compounds, (OR`)3Si-R-Si(OR`)3, in the presence of a structure directing agent (SDA) which assisted the
creation of uniform pores and structures. In our project, we succeeded to synthesize and characterize different
chiral bridged-silane ligands that were utilized for the preparation of multiple chiral PMO NPs systems based
on two major synthetic routes, either by co-polymerization or post-modification processes. The synthesis
attempts were focused on the preparation of pure chiral PMO NPs that were composed merely of a chiral
bridged organo-alkoxysilane monomer. The preparation of these systems was accomplished by applying
different surfactants and ligands who could finally afford a monodispersed chiral PMO NPs consisted of 100%
bridged-silane precursor. The obtained nanoparticles exhibited a very high surface area that reached up to 1699
m2g-1. In addition, the major advancement in our research was the success – and for the first time- in preparing
magnetic chiral PMO NPs. These nanoparticles were synthesized by a co-polymerization of 1,1`-((1R,2R)-1,2diphenylethane-1,2-diyl)bis(3-(3-(triethoxysilyl)propyl)urea) chiral monomer by an o/w emulsion process, to
give magnetic chiral PMO NPs with magnetite NPs in their cores. The obtained PMO nanoparticles exhibited a
very high surface area that reached up to 1776 m2g-1. The incorporation of these PMO NPs with metal NPs such
as ruthenium, rhodium and palladium can afford a highly attractable system for many catalytic processes. The
potential application of these nanoreactors was demonstrated in asymmetric transformations.
50
PB-50
Magneto-Fluorescent Colloidal Nano-hybride for Multimodal Imaging
Sandip Pahari1,3, Shunit Olszakier1,2, Itamar Kahn1,2, Lilac Amirav1,3
1
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
2
Department of Physiology and Biophysics, The Ruth and Bruce Rappaport Faculty of
Medicine, Technion - Israel Institute of Technology, Haifa, Israel
3
Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa,
Israel
Designing effective nanoparticles that can passively or actively label fine biological structures in various
functional states is a central goal of medicine-oriented nanotechnology development. Since each established
imaging modality has its own drawback, integration of two or more imaging modes in one nanostructure i.e.,
multimodal imaging, can provide complimentary information. In this respect, Hybrid nanostructures can exhibit
several features synergistically and deliver more than one function simultaneously.
Here we present our strategy to fabricate magnetic nanoparticle-based multifunctional nanostructures, which
are integrated with fluorescent quantum dots in a two-step colloidal approach. These hybrid nanostructures
exhibit Para magnetism alongside fluorescence. Direct contact between the semiconductor and magnetic
domains, typical of traditional core-shell or heterodimer structures, can lead to strong electronic coupling,
diminishing the desired optical fluorescence. Hence, our structure comprises an optically active nanoparticle
quantum dot core encapsulated in a hollow shell providing the MRI contrast agent. Such encapsulation of the
quantum dot might also prove to be essential for biocompatibility and toxicity aspects. The hybrid nanoparticle
is successfully applied for single cell neuronal imaging. We expect that the combination of unique structural
characteristics and integrated functions of multicomponent magnetic nanoparticles will lead to new
opportunities in biological and medical imaging.
51
PB-51
Layered Double Hydroxides of the Hydrocalumite-type Intercalated by the
Anionic Forms Transition Metal Ion-Amino Acid Complexes – Syntheses,
Characterization and Catalytic Applications
Istvan Palinko1, Gabor Varga1, Szabolcs Murath1, Akos Kukovecz2, Zoltan Konya2,
Pal Sipos3
1
Department of Organic Chemistry, University of Szeged, Szeged, Hungary
2
Department of Applied and Environmental Chemistry Chemistry, University of Szeged,
Szeged, Hungary
3
Department of Inorganic and Analytical Chemistry Chemistry, Pal Sipos, Szeged, Hungary
Our recent activities in the synthesis and catalytic applications of pristine CaAl- and transition metal ion-amino
acid complex intercalated CaAl-layered double hydroxides (LDHs) are described.
LDHs, because of their relative ease of synthesis, represent inexpensive, versatile, and potentially recyclable
source of a variety of catalyst supports, catalyst precursors or actual catalysts. Hydrocalumite is a subgroup of
LDHs. The name giving mineral has brucite-like main layers, which contain ordered arrangements of Ca2+ and
Al3+ or other trivalent ions, seven- and six-coordinated, respectively, in a fixed ratio of 2:1. The layers are
positively charged, which is compensated by interlayer anions, exchangeable with more or less difficulties.
During our experimental work, host-guest composites were made, where the host was Ca(II)Al(III)-LDH. The
guests were Mn(II)- Cu(II)-, Ni(II)- Fe(III)-amino acid (L-cysteine, L-histidine and L-tyrosine) complex anions.
They were intercalated into the CaAl-LDH.
The obtained materials were characterized by a range of methods including scanning and transmission electron
microscopies, energy-dispersive X-ray analysis, X-ray diffractometry, mid- and far-range infrared, EPR and Xray absorption spectroscopies, thermal analysis and classical analytical methods.
The intercalated metal-amino acid complexes proved to be active and selective in the epoxidation reaction with
peracetic acid, and cis-diol formation when the oxidant was the in situ formed iodosyl benzene. Each complex
anion-containing composite exhibited excellent recycling abilities.
52
PB-52
Three-Dimensional Nanoporous Metallic Networks
Racheli Ron, Adi Salomon
Department of Chemistry, Institution of Nanotechnology, Bar-Ilan University, Ramat-Gan,
Israel
Nanoporous metals are artificial. Therefore, their properties are a direct result of the preparation strategy. We
introduce metals with networked nanoscale inner-architecture in three-dimensions. These networked-metals
(`Netals`) express a peculiar interaction with light which is attributed to surface plasmons excitation. The
interaction of noble-metal networks with the entire solar spectrum and their support on high hot-electron
generation provides them with photo-catalytic abilities. Their combined properties of large-scale, purity,
conductivity, transparency and higher surface area make them appealing from both fundamental-scientific and
technological aspects.
53
PB-53
Nano Sized TiO2 Decorated with Metal Nanoparticles produced by Sodium
Borohydride Reduction
Krishnamoorthy Sathiyan1, Ronen Bar-Ziv2, Tomer Zidki1
Department of Chemical Sciences, Ariel University, Ariel, Israel
2
Department of Chemistry, Nuclear Research Center Negev, Beer-Sheva, Israel
1
This approach focuses on simple technique of synthesizing nano sized TiO2 coated metal nanoparticles without
any template or stabilizer. TiO2 nanoparticles (NPs) with fine particle size are produced by the hydrolysis of
Titanium Tetrachloride (TiCl4) as developed by Rabani et al.1 The resulting TiO2-NPs were decorated with
metal NPs by the addition of metal precursors and reduction using sodium borohydride (NaBH 4) as reducing
agent. TiO2 plays a versatile role in photocatalysis, photodegradation, radiation chemistry and so forth due to its
semiconducting properties. However, the large band gap which needs ultraviolet light for activation is still a
barrier in its application part.2 Recent trends work on overcoming this issue by decorating TiO2 with noble
metal NPs which can trap the electrons for electron hole separation. In our research study we particularly
emphasis on Gold (Au) and Platinum (Pt) metal NPs with TiO2-NPs in aqueous medium. This present method
will have an implications for better enhancement in many catalytic applications like reduction of 4-nitrophenol,
mechanistic study of alkyl radical reactions3 etc.
References:
1] Ruomei Gao, Agnes Safray, Joseph Rabani, Fundamental reactions in TiO2 nanocrystalline aqueous
solutions studied by pulse radiolysis, Radiation Physics and Chemistry 2002, 65, 599-609.
2] Tatiana C. Damato, Caio C. S. de Oliveria, Rômulo A. Ando, Pedro H. C. Camargo, A Facile
Approach to TiO2 Colloidal Spheres Decorated with Au Nanoparticles Displaying Well-Defined Sizes
and Uniform Dispersion, Langmuir 2013, 29, 1642-1649.
3] Ronen Bar-Ziv, Tomer Zidki, Israel Zibermann, Guy Yardeni, Dan Meyerstein, Effect of Hydrogen
Pretreatment of Platinum Nanoparticles on their Catalytic Properties: Reactions with Alkyl Radicals- A
Mechanistic Study, ChemCatChem 2016, 8, 1-5.
54
PB-54
Controlling the Enzymatic Dissociation-Rates of Micelles Using Minimal
Structural Changes
Merav Segal1, Ram Avinery2, Marina Buzhor1, Rona Shaharabani2, Assaf J. Harnoy1,
Einat Tirosh3, Roy Beck2, Roey J. Amir1
1
Department of Organic Chemistry, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
School of Physics and Astronomy, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv,
Israel
3
Department of Physical Chemistry, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
Programmed release of encapsulated biomolecules at the target location is highly desired, yet very challenging.
Enzymes show great promise as triggers for disassembly of nanocarriers, thanks to their observed overexpression in specific diseases. Our group has developed a highly modular design of amphiphilic polymerdendron hybrids, composed of linear hydrophilic polyethyleneglycol (PEG) block and a hydrophobic enzymeresponsive dendron.1 Herein, we applied this platform to prepare a set of hybrids with highly precise structuralchanges, in order to examine how small changes in the length of the hydrophobic dendritic end-groups would
affect the self-assembly and enzymatic degradation of the formed polymeric micelles. Taking advantage of this
modular and well-defined system, we were able to demonstrate that small changes in the hydrophobic dendron
block, can lead to dramatic changes on the rate of disassembly of the nanoparticle. Moreover, to further
examine the selectivity of the enzymatic hydrolysis to the structural changes, we prepared a mixture of hybrids
with two lengths of hydrophobic end-groups. The mixture gave a remarkable demonstration of the effect of the
minor changes between the mixed hybrids on their enzymatic degradation. This detailed molecular study
enhanced our fundamental understanding of enzyme-responsive platforms, which can potentially be applied to
create smart drug delivery platforms with controllable degradation rates using minimal structural
modifications.2
(1) Rosenbaum, I.; Harnoy, A. J.; Tirosh, E.; Buzhor, M.; Segal, M.; Frid, L.; Shaharabani, R.; Avinery, R.;
Beck, R.; Amir, R. J. J. Am. Chem. Soc. 2015, 137 (6), 2276–2284.
(2) Segal, M.; Avinery R.; Buzhor M.; Shaharabani R.;Harnoy A. J.; Tirosh E.; Beck R.; Amir R. J.
submitted.2016.
55
PB-55
Isotopic Study of Sodium Borohydride Reduction Mechanisms Catalyzed by
Metal-Nanoparticles
Alina Sermiagin, Tomer Zidki
Chemical Sciences Department, Ariel University, Ariel, Israel
Nowadays, metals are widely used in the chemical industry. In particular, noble metals are extensively
employed in industry, agriculture, jewelry and in the medicinal world. A wide range of industrial catalytic
reactions involve extensive usage of metals especially in solid state catalysis. Often, poisoning of metal
surfaces occurs during catalytic reactions under extreme conditions results in a widespread impact on the
environmental pollution.1
One of the most studied resolutions for this environmental problem is catalysis based on nanoparticles (NPs)
and in particular on metal NPs in liquid phase. NPs are known for their high catalytic efficiency in mild
conditions and they are extensively investigated due to their surface to volume ratio properties.2
Reduction is among important industrial catalytic reactions. Thus, we have chosen to study reduction reactions
and in particular water reduction. There are many studies engaged in catalytic water reduction by sodium
borohydride but the mechanism of these reactions is still not known.
We are investigating the catalytic reduction by borohydride on metal NPs catalysts (silver, gold and platinum
NPs) using sodium borodeuteride (NaBD4) as an isotopic marker. We are using GC, MS and TEM to analyze
the reactions` products and the catalysts properties. The data obtained especially by the MS, will give an insight
on the reduction mechanisms and the kinetics of the system investigated.
(1) Somorjai, G. A.; Rioux, R. M. High Technology Catalysts towards 100% Selectivity: Fabrication,
Characterization and Reaction Studies. Catal. Today 2005, 100 (3–4), 201–215.
(2) Zidki, T.; Cohen, H.; Meyerstein, D. Reactions of Alkyl-Radicals with Gold and Silver Nanoparticles in
Aqueous Solutions. Phys. Chem. Chem. Phys. 2006, 8 (30), 3552–3556.
56
PB-56
Tuning Optical Activity of IV−VI Colloidal Quantum Dots in the Short-Wave
Infrared (SWIR) Spectral Regime
Arthur Shapiro, Youngjin Jang, Efrat Lifshitz
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
The achievement of tunable optical properties across a wide spectral range, along with an efficient surface
passivation of lead chalcogenide (PbSe) colloidal quantum dots (CQDs), has significant importance for
scientific research and for technological applications. This paper describes two comprehensive pathways to tune
optical activities of PbSe CQDs in the near-infrared (NIR, 0.75-1.4 μm) and the short-wave infrared (SWIR,
1.4-3 μm) ranges. A one-pot procedure enabled the growth of relatively large PbSe CQDs (with average sizes
up to 14 nm) exploiting programmable temperature control during the growth process. These CQDs showed
optical activity up to 3.2 μm. In addition, PbSe/PbS core/shell CQDs prepared by an orderly injection rate led to
an energy red-shift of the absorption edge with the increase of the shell thickness, while a post-annealing
treatment further extended the band-edge energy toward the SWIR regime. A better chemical stability of the
CQDs with respect to that of PbSe core CQDs was attained by shelling of PbSe by epitaxial layers of PbS, but
limited to a short duration ( 1 day). However, air stability of the relatively large PbSe as well as the PbSe/PbS
CQDs over a prolonged period of time (weeks) was achieved after a post-synthesis chlorination treatment.
57
PB-57
Self-Assembling Micellar Clusters: Modification Strategies for New Functional
Materials Creation
Aleksei Solomonov1,2, Yuriy Marfin2, Evgeniy Rumyantsev2, Natalia Bumagina3,
Elena Antina3, Irek Musabirov4, Sergey Ostakhov5
1
Materials and Interfaces Department, Weizmann Institute of Science, Rehovot, Israel
2
Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology,
Ivanovo, Russia
3
Laboratory of Macroheterocyclic Compounds, G.A. Krestov Institute of Solution Chemistry of
the Russian Academy of Sciences, Ivanovo, Russia
4
EM Unit, Institute for Metals Superplasticity Problems of the Russian Academy of Sciences,
Ufa, Russia
5
Chamical Physics Department, Ufa Institute of Chemistry of the Russian Academy of
Sciences, Ivanovo, Russia
Poor aqueous solubility is usually a major obstacle in the development of therapeutic agents, drug delivery,
sensing or during investigation of properties of materials. There many approaches commonly used to enhance
the solubility of poorly soluble drugs are exist. Micellar solubilization is one of a widely used methods for the
dissolution of poorly soluble drugs. However, not always using of pure micellar aqueous solutions is suitable
for solubilization. Previously, it was shown, that concept of micellar conjugation followed by clusters formation
showed a great potential in the aspect of hydrophobic compounds solubilisation beyond their solubilization
limit. With the aim to extend the application fields of micellar clusters, we developed new schemes for micellar
clusterization which based on sequential self-assembly of nonionic detergent micelles followed by
encapsulation of various substances. Proposed strategies allowed us to sufficiently increase solubility not
always of “ordinary hydrophobic compounds” but several fluorescent dyes in aqueous media, which even serve
as micellar clusterization agents. Hydrophobic fluorescent compounds-loaded micellar complexes demonstrates
good optical response in aqueous media without crystallization. We also showed that clusters are also very
tunable and can be modified by various nanoparticles of noble metals or magnet nanoparticles. Therefore, the
conception of micellar clusters modifying allowed to obtain various nanosystems, such as fluoromagnetic
clusters, or drug-loaded composites that open a new horizons for new advanced functional materials creation.
The work was supported by the Grant of the President of the Russian Federation No. МК- 8835.2016.3 and
RFBR grants No. 16-03-01028, 15-33-20002 and 15-43-03214.
58
PB-58
Sensitive Detection of DNA Immobilization and Hybridization on
Polyelectrolyte-Modified Surfaces
Aleksei Solomonov1, Alexander Novoselsky2, Alexander Vaskevich1, Israel Rubinstein1
1
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
Accurate identification and quantification of nucleic acid targets has been a major issue in biological sciences,
as such targets reflect, in many cases, the state of the biological system. Specific and predictable
immobilization of oligonucleotides and their hybridization with respective counterparts play a fundamental role
in design of new oligonucleotide microarrays for DNA biosensing. However, signal interpretation generated by
a microarray has often been challenging in terms of the surface chemistry involved, as various details of the
DNA organization on surface haven’t been well understood.
Immobilization of oligo-DNA on surfaces using the polyelectrolyte layer-by-layer (LbL) method provides a
simple and convenient approach to DNA application in sensing schemes. Here we demonstrate DNA strands
immobilization on glass substrates and on gold nano-island films prepared by evaporation on glass and
annealing, using the polyelectrolyte LbL approach. The Au nano-island films serve as localized surface
plasmon resonance (LSPR) transducers, enabling optical detection of DNA binding. Use of DNA strands
labeled with chromophores allows quantification of DNA immobilization and surface hybridization with
complimentary or mismatched strands. Hence, each surface modification step (polyelecrolyte adsorption,
immobilization of labeled ssDNA probe, hybridization with target DNA) can be monitored by spectroscopic
detection of the Au LSPR response and by the chromophore UV-Vis absorbance.
Quantification of the DNA immobilization on the surface and subsequent hybridization, performed as described
above, was verified by fluorescence measurements, carried out using the fluorescent properties of the same
chromophore-derivatized DNA strands.
We show that optical signal associated with DNA sensing is sensitive to various experimental conditions
(polyelectrolyte organization, DNA immobilization conditions, additional compounds or counter ions),
allowing the development of a strategy for optimized DNA detection on polyelectrolyte-modified surfaces.
59
PB-59
Rigidity of Polymer Micelles Affects Interactions with Tumor Cells
Tal Stern1, Inon Kaner1, Hila Shoval1, Neta Lester2, Liraz Chai2, Ofra Benny1
1
The School of Pharmacy, The Institute for Drug Research,
The Hebrew University of Jerusalem, Jerusalem, Israel
2
The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
One of the main challenges in cancer therapy is the capability of drug penetration to the core of the tumor mass
in order to achieve substantial efficacy. Di-block polymer micelles are used as a drug delivery system with
markedly benefits including small dimension, ease of preparation, controlled drug release, drug targeting and
reduction of side effects. However polymer micelles are generally limited by the degradation time dictated by
the polymers in use, making it usable for short term after preparations. Moreover the ability of polymer
micelles to penetrate tissues is relatively low. We addressed that issue and developed a novel form of
lyophilized micelles i.e Solidified Polymer Micelle (SPM). The SPMs can be loaded with a variety of small
molecule drugs and importantly can endocytose rapidly into cancer cells. Interestingly we found that the SPMs
also exocytose from the cells and penetrate into multi-layer cellular cultures (spheroids). The combination of
endocytosis and exocytosis, termed transcytosis, can provide a mechanism for drug carrier penetration into
tumors, in addition to extra-cellular transport. By that, we hypothesize that SPM can reach deeper to the inner
parts of the tumor, enhancing the exposure of the core to the chemotherapy. We present here detailed
measurements of the SPM including examinations of particle size, stability, drug release kinetics and cell
transcytosis. We conclude that SPM can potentially be used as an improved drug vehicle with elevated tumor
penetration ability and that further studying of SPM is a promising field.
60
PB-60
Spatial Confinement of Light onto a Flat Metallic Surface using Hybridization
between Two Cavities
Adam Weissman1, Matan Galanty1, David Gachet2, Elad Segal1, Omer Shavit1, Adi Salomon1
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Senior Application Specialist, Attolight AG, Lusanne, Switzerland
Controlling the optical field down to the nanometer scale is a key step in optoelectronic applications and light
matter interaction at the nanoscale. Bowtie structures, rods and sharp tapers are commonly used to realize such
optical properties, but their fabrication is challenging. In this context, the complementary structures, namely
holes and cavities, are less explored. Herein a simple system of two metallic nano-cavities milled in thin silver
film is used to confine the electromagnetic (EM) field to an area of ~60nm. The field is confined onto a flat
surface area and is either enhanced or suppressed by the polarization state of incident light. The energy of this
spatially confined mode is determined by the distance between the two cavities and thus any color (wavelength)
at the optical regime can be achieved. As a consequence, a dynamically controlled wavlength is generated on a
pixel size smaller than one micron square. If molecules are deposited onto those ‘hot spots’, they should
experience a very strong EM field that may shape their potential energies and thus open a new pathway for
controlling photochemical processes on surfaces. Those results are supported both by transmission spectra and
a Cathodoluminescence study.
61
PB-61
Dispersing Perylene Diimide/SWCNT Hybrids: Structural Insights at the
Molecular Level and Fabricating Advanced Materials
Haim Weissman1, Yael Tsarfati1, Volker Strauss3, Susanne Kuhri3, Elisha Krieg1,
Eyal Shimoni2, Jonthan Baram1, Dirk M. Guldi3, Boris Rybtchinski1
1
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
3
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials,
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
The unique properties of carbon nanotubes (CNT) are advantageous for emerging applications. Yet, the CNT
insolubility hampers their potential. Approaches based on covalent and noncovalent methodologies have been
tested to realize stable dispersions of CNTs. Noncovalent approaches are of particular interest as they preserve
the CNT’s structures and properties. We report on hybrids, in which perylene diimide (PDI) amphiphiles are
noncovalently immobilized onto single wall carbon nanotubes (SWCNT).[1]
The resulting hybrids were dispersed and exfoliated both in water (Figure 1) and organic solvents in the
presence of two different PDI derivatives, PP2b and PP3a. The dispersions were investigated using cryogenic
transmission electron microscopy, providing unique structural insights into the exfoliation. A helical
arrangement of PP2b assemblies on SWCNTs dominates in aqueous dispersions, while a single layer of PP2b
and PP3a was found on SWCNTs in organic dispersions. Spectroscopic probing of the dispersions revealed
appreciable charge redistribution in the ground state, and an efficient electron transfer from SWCNTs to PDIs
in the excited state. We also fabricated hybrid materials from the PP2b/SWCNT dispersions. A supramolecular
membrane was prepared from aqueous dispersions and used for size-selective separation of gold nanoparticles.
Hybrid buckypaper films were prepared from the organic dispersions. In the latter, high conductivity results
from enhanced electronic communication and favorable morphology within the hybrid material. Our findings
shed light onto SWCNT/dispersant molecular interactions, and introduce a versatile approach toward universal
solution processing of SWCNT based materials.
[1] Y. Tsarfati, V. Strauss, S. Kuhri, E. Krieg, H. Weissman, E. Shimoni, J. Baram, D. M. Guldi and B.
Rybtchinski, J. Am. Chem. Soc., 137, 7429 (2015).
Fig. 1: Material fabrication from hybrids of PP2b/SWCNT dispersions in aqueous and organic media
This work was supported by the Minerva Foundation, Gerhardt M.J. Schmidt Minerva Center of
Supramolecular Architectures, and the Helen and Martin Kimmel Center for Molecular Design. The work at
Friedrich-Alexander-Universität
Erlangen-Nürnberg
was
also
supported
by
the
Deutsche
Forschungsgemeinschaft. The TEM studies were conducted at the Irving and Cherna Moskowitz Center for
Nano and Bio-Nano Imaging (Weizmann Institute).
62
PB-62
3D Nanostructured Electrodes for High Energy Density Li-ion Batteries
Valeria Yarmiayev, Yana Miroshnikov, David Zitoun
Department of Chemistry, Bar-Ilan Institute of Technology and Advanced Materials (BINA),
Bar-Ilan University, Ramat-Gan, Israel
Recent efforts for the design of new negative electrode materials for Li-ion batteries have led to the screening
of binary compounds MPx exhibiting high gravimetric and volumetric capacities. Among them, Cu3P has been
recently investigated both experimentally and by first-principles calculations. According to this study, the
electrochemical mechanism for Cu3P during the first discharge is characterized by the conversion to a
composite electrode consisting of metallic nano-sized particles embedded in a Li3P matrix.1,2 The reaction can
be described as follows:
Cu3P + 3Li ® Li3P + Cu
3D metal porous structure can stand as an attractive electrode material since it facilitates new electron
pathways, allows simple access of the electrolyte to the active material and promotes charge transfer between
them during battery cycling. Moreover, 3D electrode can accommodate for the volume changes occurring in the
active material upon lithium insertion and avoids the use of a current collector.
In this work, we demonstrate a simple method to synthesize Cu3P 3D structure directly on a Cu porous
membrane. Cu3P grows perpendicular to the surface and exhibits disk like morphology. The Cu3P 3D
electrodes show outstanding cycling performance and high coulombic efficiency.
1] S. Boyanov, M. Womes, L. Monconduit, and D. Zitoun, Chem. Mater., 2009, 21, 3684–3692.
2] S. Boyanov, D. Zitoun, M. Me, I. Charles, and G. M. C. Agre, 2009, 21441–21452.
63
PB-63
Development of Catalytic Microreactors by Non-aqueous Microencapsulation
Method
Ahmad Zarour, Raed Abu-Reziq
Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Despite the greater selectivity and reactivity in homogeneous catalysis compared to heterogeneous catalysis,
processes performed by heterogeneous catalysis are more desirable, owing to facile recovery and low costs. The
latent monumental potential in the bridging of both types of catalysis has encouraged the development of
numerous methods for heterogenization of homogeneous catalysts. As a valuable emerging term, the
homogeneous-heterogeneous principle is regarded as the best possible conjunction of both catalytic routes,
where green processes with low economic cost and highly desired efficiency can be manifested.
Recently, we developed a new heterogenization method based on non-aqueous microencapsulation.. In this
method, the catalyst is encapsulated within silica or polyurea microcapsules by applying either non-aqueous
sol-gel processes or interfacial polymerization principles. Both preceded by the preparation of oil-in-oil (O/O)
emulsion by dispersing a polar organic phase such as polyethylene glycol (PEG) in a non-polar organic solvent
containing a proper surfactant. The catalyst is dissolved in the polyethylene glycol phase. At the end of this
process, microreactors of silica or polyurea containing in the core the a solubilized catalyst are obtained. The
characterization of these microreactors and their catalytic activity in different organic transformations will be
presented.
64
PB-64
Single DNA Molecular Rectifier Enabled by Structure Modification
Cunlan Guo1, Kun Wang1, Elinor Zerah-Harush2,3, Joseph Hamill1, Bin Wang1,
Yonatan Dubi2,3, Bingqian Xu1
1
Single Molecule Study Laboratory, University of Georgia, Athens, Georgia
2
Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
3
Department of Chemistry & Ilse-Katz Institute for Nanoscale Science and Technology,
Ben-Gurion University of the Negev, Beer-Sheva, Israel
The predictability, diversity and programmability of DNA make it a leading candidate for the design of
functional electronic devices that use single molecules, yet its electron transport properties have not been fully
elucidated. This is primarily because of a poor understanding of how the structure of DNA determines its
electron transport. Here, DNA-based molecular rectifier is demostrated constructed by site-specific
intercalation of small molecules (coralyne) into a custom-designed 11-base-pair DNA duplex. Measured
current–voltage curves of the DNA–coralyne molecular junction show unexpectedly large rectification with a
rectification ratio of about 15 at 1.1 V, a counter-intuitive finding considering the seemingly symmetrical
molecular structure of the junction. A non-equilibrium Green’s function-based model— parameterized by
density functional theory calculations—revealed that the coralyne-induced spatial asymmetry in the electron
state distribution caused the observed rectification. This inherent asymmetry leads to changes in the coupling of
the molecular HOMO−1 level to the electrodes when an external voltage is applied, resulting in an asymmetric
change in transmission.
Cunlan Guo, Kun Wang, Elinor Zerah-Harush, Joseph Hamill, Bin Wang, Yonatan Dubi, Bingqian Xu.
Molecular rectifier composed of DNA with high rectification ratio enabled by intercalation. Nature Chemistry
8, 484–490 (2016).
65
PB-65
Novel Chiral Nano-Sized Supports for Asymmetric Heterogeneous Catalysis
Amani Zoabi, Raed Abu-Reziq, Dmitri Gelman
Chemistry, The Hebrew University of Jerusalem, Jersualem, Israel
Over the past few decades, asymmetric transition metal catalysis has become the domain of very intense
research activity and greatly expanded the scope of catalytic asymmetric transformations that can be performed
with high efficiency. Consequently, large libraries consisting of hundreds of (expensive) chiral ligands and
thousands of the corresponding transition metal complexes have been developed for various homogeneously
catalyzed organic transformations. However, despite this spectacular progress, only a limited number of
asymmetric catalysts found industrial large-scale applications due to the high cost of the metal and of the chiral
ligands (both are unrecoverable).
Over the past few decades, a number of strategies have been developed for heterogenizing homogenous
(molecular) transition metal catalysts. Roughly, stationary supports may be organic macromolecules (e.g.
linear/cross-linked polymers or dendrimers), inorganic or hybrid materials (e.g. graphite, activated carbon,
amorphous silica/alumina, zeolites, mesoporous silica/alumina, periodic mesoporous organosilica, metal
organic frameworks, etc.). Noteworthy, in all these cases, enantioselection originates from the chiral pocket
provided by the chiral ligand, while supports are generally inert and play no active role over the course of the
catalytic cycle.
Our group is interested to design efficient heterogeneous asymmetric catalytic systems based on robust achiral
transition metal particles incorporated into novel chiral non-racemic porous network and, thus, to establish a
new approach to the development of practical heterogeneous asymmetric catalysts for industrial and laboratory
applications.
66
PB-66
An Ultrasensitive Method for Protein and DNA Detection at the Single
Molecule Level
Haya Dachlika Ben Shimol
Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
We demonstrate a general single molecule method for ultrasensitive detection of macromolecules such as DNA,
proteins and biomarkers. The method is based on conjugation of two nanoparticles to target macromolecules
followed by imaging of the specific dimeric structures formed using electron microscopy.
Detection of macromolecular biomarkers such as disease-specific DNA and proteins provides essential
information that allows early diagnosis, prognosis and management of diseases. Today biomarkers detection is
limited in sensitivity and therefore detection often comes at a late disease stage. Therefore new techniques are
required to enable rapid and immediate diagnosis from physiological samples. Critically, such a system must be
capable of detecting very low levels of biomarkers, as many of them are present at minute concentrations
during early disease phases. These methods should be generic for a wide range of macromolecules and based on
affordable detection tools.
The proposed method presents ultrasensitive detection of macromolecules at the single molecule level using
NPs. The method is based on conjugation of two different ligands, which bind the target macromolecule at two
different binding sites, to two NPs with different sizes. The formed complex, in which each macromolecule is
flanked by two easily recognizable NPs (a dimer), is then detected and characterized using EM. The surface
concentration of the dimers can be calibrated to the concentration of the macromolecule in the sample.
We will use model systems to validate the general proposed concept of dimer formation and highly sensitive
detection. The first model system will be a target DNA, which is detected using two single NPs each bearing a
complementary ssDNA. The second model system will be a target protein, which is detected using two NPs
covered with conjugated peptides that bind specifically to two different sites in the protein. Following the
implementation of those model systems, we will utilize the proposed method for various macromolecules and
biomarkers detection.
67
PB-67
Responsive Self-Assembled Nanotransporters as Multi Faceted Controlled
Release Systems
1
Gilad Golden1, Roi Rutenberg1, Elena Poverenov2
Department of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
2
Food Quality and Safety, The Volcani Center, ARO, Rishon LeZion, Israel
A series of modified biopolymers was designed to self-assemble into nanotransporter aggregates, which may be
implemented as responsive multi faceted controlled release systems. For this end, antimicrobial aliphatic
aldehydes were coupled to the antimicrobial biopolymer chitosan via a reversible dynamic covalent N-imine
Schiff base linkage. The conjugated aldehydes’ introduced hydrophobicity, along with chitosan’s hydrophilic
nature, yielded amphiphilic block copolymers. These modified biopolymers undergo self-assembly into nano
sized aggregates that successfully envelope both hydrophobic and hydrophilic active payloads as either micelles
or vesicles, respectively. Active payloads can then be released in a measured and controlled fashion as a
response to an external pH stimulus. Upon acidic hydrolysis, the systems’ aggregate structure immediately
breaks down to their original constituents, which until then have been dormant in terms of bioactivity. This
novel approach allows for a controlled multi facet attack not only by the active payload, but also by all of the
system’s other components individually.
68
PB-68
Cu0.89Zn0.11O as a Peroxidase-Mimicking Nanozyme with High Sensitivity
for Glucose and Antioxidant Detection
Anjani P. Nagvenkar, Aharon Gedanken
Department of Chemistry and Institute for Nanotechnology and Advanced Materials,
Bar-Ilan University, Ramat-Gan, Israel
Nanomaterial-based enzyme mimetics (nanozymes) is an emerging field of research that promises to produce
alternatives to natural enzymes for a variety of applications.1The search for the most cost-effective and efficient
inorganic nanomaterials, such as metal oxides, cannot be won by pristine CuO.2 However, unlike CuO, the Zndoped CuO (Zn-CuO) nanoparticles reported in this paper reveal superior peroxidase-like enzyme activity. This
places Zn-CuO in a good position to participate in a range of activities aimed at developing diverse enzyme
applications.3 The peroxidase-like activity was tested and confirmed against various chromogenic substrates in
the presence of H2O2 and obeyed the Michaelis–Menten enzymatic pathway. The mechanism of enhanced
enzymatic activity was proved by employing terephthalic acid as a fluorescence probe and by electron spin
resonance. The nanozyme, when tested for the detection of glucose, showed a substantial enhancement in the
detection selectivity. The limit of detection (LOD) was also decreased reaching a limit as low as 0.27 ppm.
Such a low LOD has not been reported so far for the metal oxides without any surface modifications. Moreover,
the nanozyme (Zn-CuO) was utilized to detect the three antioxidants tannic acid, tartaric acid, and ascorbic acid
and the relative strength of their antioxidant capacity was compared.
References:
1. H. Wei and E. Wang, Chem. Soc. Rev., 2013, 42, 6060-6093.
2. W. Chen, J. Chen, A. L. Liu, L. M. Wang, G. W. Li and X. H. Lin, ChemCatChem., 2011, 3, 1151 – 1154.
3. K. M. Koeller, C. H. Wong, Nature 2001, 409, 232-240.
69
PB-69
Highly Efficient Core Shell (Sn@Pt and Sn@PtPdSn) Catalyst for Direct
Dimethyl Ether Fuel Cells
Diwakar Kashyap, Hanan Teller, Alex Schechter
Department of Chemical Sciences, Ariel University, Ariel, Israel
Dimethyl ether (DME) has been considered as a promising alternative fuel for direct-feed fuel cells. It has a
number of advantages over other prominent fuels, including high energy density, easier storage with respect to
hydrogen, lower toxicity and crossover when compared to methanol, and more facile complete oxidation as
compared to ethanol. However, electro-oxidation mechanism of the dimethyl ether is poorly understood,
hindering development of efficient catalysts. The commonly studied binary PtRu catalyst shows much lower
activity in DME than methanol oxidation. Sluggish DME adsorption and high activation barrier for the C-O
bond cleavage may be responsible for the slow kinetics. Since palladium is known to facilitate the C-O bond
cleavage of ethers, the addition of Pd may enhance the electro-oxidation of DME. In this work, core-shell
catalysts (Sn@Pt, Sn@PtSn, and Sn@PtPdSn) were prepared by galvanic replacement reaction, which shows
much higher activity, both in aqueous and polymer electrolyte fuel cell, than the state-of-the-art binary
(Pt50Ru50/C) and ternary catalyst (Pt46Ru44Pd10/C). Moreover, the onset potential for DME oxidation also
shifted 100 mV lower then Pt50Ru50/C. The X-ray diffraction pattern confirmed formation of intermetallic
nanoparticles.
70
PB-70
Microspheres of P2-type Na0.67Mn0.65Fe0.20Ni0.15O2as Cathode Material with
Enhanced Na-ion Battery Performance
Brij Kishore1, Venkatesh Gopal2, Viswanatha Ramarao1, Doron Aurbach3,
Munichandraiah Nookala1
1
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru,
India
2
Department of Instrumentation and Applied Physics, Indian Institute of Science, Bengaluru,
India
3
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Research activities on Na-ion battery materials have gained importance in recent years as this battery is
considered as an economical substitute for the Li-ion batteries in future. Sodium manganese oxide is reported as
a high capacity positive electrode material of Na-ion battery. In the present work, P2-type
Na0.67Mn0.65Fe0.20Ni0.15O2 is synthesized in microspherical morphology and characterized for physicochemical
and electrochemical properties. Microspheres of FeCO3 are first prepared and used as the template to synthesize
Mn0.65Fe0.20Ni0.15CO3, followed by its thermal decomposition to the corresponding oxide and finally the thermal
fusion of the oxide and Na2CO3. The desired sodiated mixed metal oxide formed in microspherical morphology
is pure crystalline phase with a wide mesopore size distributed at 29 nm. Cyclic voltammograms are
characterized by well-defined two pairs of current peaks corresponding to the oxidation and reduction processes
in two different stages. The sodiated oxide provides an initial discharge capacity of about 220 mAh g-1 at C/15
rate cycling with an excellent stability. The rate of decay in discharged capacity is about 0.3 % per cycle at
C/15 rate, but it increases to 0.9 % per cycle over 100 continuous charge-discharge cycles at higher rates. The
rate capability is also high and the discharge capacity is about 100 mAh g -1 at 2C rate. The high discharge
capacity and high rate capability are attributed to porous microspherical morphology.
References:
1. S. W. Kim, D. H. Seo, X. Ma, G. Ceder, and K. Kang, Adv. Energy Mater., 2, 710 (2012).
2. V. Palomares, P. Serras, I. Villaluenga, K. B. Hueso, J. C. Gonzalez, and T. Rojo Energy Environ. Sci., 5,
5884 (2012).
3. D. Yuan, X. Hu, J, Qian, F. Pei, F. Wu, R. Mao, X. Ai, H. Yang and Y. Cao, Electrochimica Acta, 116, 300
(2014).
71
PB-71
Stable Ti Based Support for Polymer Electrolyte Membrane Fuel Cell
Olga Krichevski, Hanan Teller, Palaniappan Subramanian, Alex Schechter
Chemical Science, Ariel University, Ariel, Israel
New conductive and stable TiH2 particles intended for application in Polymer Electrolyte Membrane Fuel Cell
cathodes were prepared by sonication method in Hexane solution. TiH2 particles were characterized by
Scanning electron microscope (SEM), X-ray diffraction, Dynamic Light Scattering (DLS) and BrunauerEmmett-Teller (BET) techniques. After sonication process the BET surface area increased from 0.2 g/m 2 to 0.7
g/m2. Good thermal stability of this material at high temperatures in Oxygen atmosphere was shown by
Thermal Gravimetric Analysis. The electrochemical stability was studied by cyclic voltammetry (CV), Linear
Sweep voltammetry (LSV) in acid solutions at different gas atmospheres. The sonicated TiH 2 was found to
catalyze oxygen reduction reaction in acid solutions possible due to the formation of surface oxide defects. The
durability measurements show the sonicated TiH2 acting as Pt support exhibited superior stability than Vulcan
XC-72. High corrosion resistance, thermal stability is identified as properties that have rendered better
structural stability for sonicated TiH2 particles at elevated temperatures.
72
PB-72
Highly Active, Corrosion-Resistant Cathode for Fuel Cells, Based on Platinum
and Molybdenum Carbide
Oran Lori, Shmuel Gonen, Lior Elbaz
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Considering the need for alternative and efficient energy sources, fuel cells might possibly be a viable and costeffective solution. One of the more acute setbacks in the commercial distribution and utilization of this
technology is the lifetime of the fuel cell which is limited by the stability of the electrode. In this regard,
carbon-based materials are not suitable as an electrode material.
Consequently, nano-crystallites of Mo2C were synthesized via modified polymer-assisted deposition (mPAD)
and utilized as support material for the deposition of Pt catalyst in order to be studied as a durable, corrosionresistant ceramic-based system for the oxygen reduction reaction (ORR). The synthesized ceramic compound
was found to include no free amorphous carbon, making it potentially compatible for fuel cell electrode
material. The molybdenum carbide appeared to improve both the electro-catalytic activity of Pt catalyst,
showing an increase in both the mass activity, three times higher at 0.9 V vs. RHE, and in the half-wave
potential by 70 mV, when compared to commercial Pt/C catalyst. As anticipated, the durability was also
increased, showing 40% more resistance to chemical and physical corrosion than standard commercial Pt/C
catalyst/support system.
73
PB-73
Maximyzing the Potential of Layered Compounds for Hydrogen Production
Oren Meiron1, Lothar Houben2, Maya Bar Sadan1
1
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
2
Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
Layered transition metal dichalcogenides (TMDs) gained much attention in recent years. Layer edges were
identified as the catalytic sites, making edge oriented morphologies a desired design. In addition, first principle
calculations showed that doping and alloying of TMDs can be used to modify their electronic properties. To
date, TMD alloying is primeraly performed at high temperature, solid state reactions, such as chemical vapor
deposition (CVD) or chemical vapor transport (CVT) which limit morphology and composition control. We
used low temperature, controllable colloidal synthesis to produce nanoflower alloyed TMDs. Specifically
Mo(SxSe1-x)2 nanoflowers with edge oriented nanostructures. A range of alloy compositions were prepared. The
Materials were analyzed using TEM, XRD, UV-Vis, ICP-MS spectroscopy and electron tomography. We found
that the produced nanoflowers were molybdenum rich, in agreement with previous reports. The composition
closely follows the feed ratio enabling the production of precisely controlled compositions. XRD and UV-Vis
spectra results suggests the formation of a homogeneous solid solution rather than two separate phases of MoS 2
and MoSe2. Tunable bandgap was achieved as a function of alloying degree, as measured by UV-Vis. Time
series analysis results support a growth mechanism of fast-precipitating amorphous material, followed by
crystallization of a few layers of small sheets, which curl and tangle around themselves. We have demonstrated
the synthesis of improved edge oriented alloys using simple colloidal technique. By controlling the alloying
degrees, the electronic properties of the TMDs can be optimized for a variety of applications such as photo
catalysis, optoelectronics, transistors and many others.
74
PB-74
Electrocatalytic Activity of Post Pyrolysis Plasma treated BPC FeGly for the
Oxygen Reduction Reaction
Roopathy Mohan, Alex Schechter
Department of Chemical Sciences, Ariel University, Ariel, Israel
The design and fabrication of electrocatalysts for oxygen reduction reaction (ORR) with high performance at
low cost remains a crucial challenge for the commercialization of fuel cells. In order to replace the Pt and Pt
alloy based electrocatalysts, metal nitrides and Metal Carbon Nitrogen (MNC), metal free heteroatom doped
carbon material and plasma treated material were found to have interesting ORR properties. The enhanced
active site formation, O2 adsorption of the catalyst, electrical conductivity of the surface modified carbon based
(MNC) catalysts have shown promising activity that closely matches the oxygen reduction activity of Pt in
acidic and alkaline media.In order to improve ORR activity in acidic medium, we prepared MNC based ORR
electrocatalysts by coupling of simple mechanomilling method and post pyrolysis plasma treatment of BPC
FeGly catalysts. The plasma treatment for BPC-Fe-Gly is an added approach leads to increase in number of
oxygen adsorption sites of the catalyst and improve the electrical conductivity by N doping and defects
generation by surface modification. The electrochemical properties of as prepared material was studied by
cyclic voltammetric measurements which show that the untreated BPC- FeGly has an ORR onset potential of
0.73 V vs RHE whereas BPC- FeGly after treatment in N2 cold plasma showed 0.79 V vs RHE. Based on our
previous reported results, we attribute the increase in activity largely to the formation of highly active nitrogen
sites and to the promotion of electron transport in the ORR process by these dopants. Accordingly, N2 plasma
treated BPC FeGly exhibits enhanced ORR performance with only 70 mV shift in half wave potential when
compared to 20% Pt-C in 0.5 M H2SO4. The structural properties of these materials were evaluated by XRD
analysis and the catalysts morphology was characterized by SEM and EDS.
75
PB-75
Molecular Catalysts - for Urea Electrooxidation
Kalaiyarasi Rajavelu, Alex Schechter, Michael Montag
Department of Chemical Sciences, Ariel University, Ariel, Israel
In order to meet the growing global demands for energy in the age of environmental awareness, alternative
clean energy sources must be explored. Hydrogen gas is such a source of energy, with water being the only
byproduct in its energy conversion process. Urea electrolysis is a promising new technology that has the
capacity to produce high-purity hydrogen from sustainable sources, such as wastewater. Urea is a highly
attractive hydrogen carrier, because it is abundant, stable, non-toxic and non-flammable, and can be stored and
transported conveniently, since it is solid under ambient conditions.
Different solid-state electrocatalysts, particularly nickel- based materials, have been studied extensively for urea
conversion, providing relatively high current densities and low over potentials for its oxidation to CO2 and N2.
However, solid state catalysts are difficult to control, manipulate and study at the atomic level. In order to
improve urea conversion, we aim to develop molecular catalysts that can be fine-tuned relatively easily at the
atomic level and studied in great detail using methods that are common for such molecular systems, such as
NMR spectroscopy and single-crystal X-ray crystallography.
To the best of our knowledge, no molecular system has thus far been reported to promote the electrochemical
conversion of urea. Herein, we describe our efforts to investigate molecular catalysts of different transition
metal complexes (e.g.; Co, Ni, Mn, Cu) as molecular catalyst for urea conversion, using various ligands set
ranging from such as phenol-imines to macrocyclic amine complexes.
76
PB-76
Silicon-Nanowire-based 3D Anodes for High-Capacity Lithium-Ion Batteries
Dan Schneier1, Emanuel Peled1, Fernando Patolsky1, Diana Golodnitsky1,2,
Kathrin Freedman1, Guy Davidi1
1
School of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
Applied Materials Research Center, Tel Aviv University, Tel Aviv, Israel
We report on the scalable synthesis and characterization of novel-architecture three-dimensional high-capacity
amorphous SiNW-based anodes, with focus on the study of their electrochemical-degradation mechanisms. We
achieved an unprecedented combination of remarkable performance characteristics: high loadings of 3-25
mAh/cm2, a very low irreversible capacity (10% for the 3-4mAh/cm2 anodes), current efficiency greater than
99.5%, cycle stability both in half cells and in a LiFePO4 battery and fast charge–discharge rates (up to 2.7C at
20mA/cm2). These SiNW-based binder-free 3D anodes have been cycled for over 500 cycles, exhibiting a
stable cycle life. Notably, it was found that the increase in the continuous SEI layer thickness, and the
concomitant increase in resistivity, represents the major cause of the observed capacity loss of the SiNW-based
anodes, as we demonstrated by cleaning and reusing cycled anodes. We also demonstrate the effects of different
types of coatings on the SEI and on cycling stability of the cell. Our data reveal that NW-based anodes of novel
architecture are expected to meet the requirements of lithium-ion batteries for both portable and electric-vehicle
applications.
77
PB-77
EQCM-D as an Effective Tool for Tracking Morphological and Mechanical
Changes in Energy Storage and Conversion Electrodes
Netanel Shpigel, Sergey Sigalov, Vadim Dargel, Micheal Levi, Doron Aurbach
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Electrodes for energy storage and conversion applications are tending to undergo mechanical and
morphological changes during ions insertion / adsorption processes. During long time operation or repeated
cycling, these changes are accumulated and result in electrode`s degradation and failure.
EQCM-D (electrochemical quartz crystal with dissipation monitoring) can play and important role in tracking
and understating of such processes.
Correlating between the electrochemical processes and changes in resonance frequency and energy dumping
(dissipation) for different overtone orders (odd numbers from 3rd to 13th) provide unique information about the
volumetric and mechanic electrochemical-induced changes.
Applying EQCM-D measurements on Ti3C2 electrodes allow us to demonstrate for the first time in-situ
quantitative analysis of intercalation-induced viscoelastic changes. The obtained results revealed stiffening of
the MXene electrodes during Li intercalation and softening on Li extraction.
This information provides excellent opportunity for theresearches in the energy storage field of mechanical
characterization of battery and supercapacitor electrodes, and for the development of QCM-D method as an
effective analytical tool for such applications.
78
Co
III
PB-78
Corrole as a Potential Catalyst for Oxygen Reduction in Fuel Cells
Jennifer Shulamit Shpilman, Lior Elbaz, Dan Thomas Major
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
The projected limited supply of energy is one of the biggest problems of this century. In recent years, with an
increase in global population density, we see a surge in pollution and a concomitant damage to the natural
environment.1 Without a doubt, an alternative way to produce energy must be developed. One of the most
promising renewable energy technologies today is fuel cells.2 Fuel cells are devices that convert chemical
energy to electrical energy by redox reactions that occur at the anode and cathode. Currently, the most efficient
and popular catalyst in fuel cells is Pt, which is a scarce and expensive metal.
In order to design alternative fuel cell cathodes, the current research examines potential bio-inspired oxygen
reduction catalysts for fuel cells. Specifically, we focus on metallocorrole derivatives that modulate the extent
of catalytic activity.3 In the current work we studied CoIII corroles containing meso substituents with different
electronegativity (Figure 1).4 We investigate the corroles by performing electrochemical measurements, as well
as atomistic density functional theory calculations to estimate their stability and electronic structure. We
identify factors that affect the catalytic activity and in particular the role of substituents with different
electronegativity.
Figure 1. A metallocorrole with its substituents- C6F5 as meso, X as β and L as an axial ligand.
References
[1] Adrian Cho Science, 2010, 329 (5993), 786-787.
[2] Yun Wang, Ken S Chen, Jeffrey Mishler, Sung Chan Cho and Xavier Cordobes Adroher Appl. Energy,
2011, 88 (4), 981-1007.
[3] (a) Naomi Levy, Atif Mahammed, Ariel Friedman, Bar Gavriel, Zeev Gross and Lior Elbaz ChemCatChem,
2016, 8, 2832-2837. (b) Naomi Levy, Atif Mahammed, Monica Kosa, Dan T Major, Zeev Gross and Lior Elbaz
Angew. Chem. Int. Ed. 2015, 2015, 54 (47), 14080-14084. (c) Atif Mahammed, Biswajit Mondal, Atanu Rana,
Abhishek Dey and Zeev Gross Chem. Commun., 2014, 50 (21), 2725-2727.
[4] Iris Aviv and Zeev Gross Chem. Commun., 2007, (20), 1987-1999.
79
PB-79
Electrochemical Investigation of Urea Electro-oxidation on Ni, α and β Phases
of Ni(OH)2: A Comparative Study
Ramesh Kumar Singh, Alex Schechter
Department of Chemical Sciences, Ariel University, Ariel, Israel
In the work, the electro-activity of carbon-supported Ni, α and β phases of Ni(OH)2 is investigated for urea
oxidation reaction. A comparative analysis is carried out to understand the mechanism of urea oxidation on
different surfaces of Ni(OH)2. The α and β phases of Ni(OH)2 is characterized by X-ray diffraction (XRD),
Raman spectroscopy and inductively coupled plasma-optical emission spectrometer (ICP-OES). These catalysts
are electrochemically studied by cyclic voltammetry (CV), chronoamperometry, and electrochemical
impedance spectroscopy (EIS) in standard three electrode configuration. Highest activity towards urea
oxidation is observed with Ni/C with an onset potential of 0.35 V vs. Ag/AgCl. Effect of alkali and urea
concentration is systematically varied on Ni, α and β-Ni(OH)2/C and the order of reaction with respect to alkali
and KOH is deduced. The chronoamperometric plots suggest catalysts are stable in 1 hour in oxidizing urea in
1M KOH. The scan rate dependent analysis carried out to understand the urea oxidation mechanism. Impedance
analysis suggest the sluggish kinetics of Ni(OH)2 towards urea oxidation reaction is caused by high charge
transfer resistance and it is in the order of β-Ni(OH)2/Cα-Ni(OH)2Ni/C. A mechanistic study on these catalysts
suggests that the urea oxidation is on Ni-based catalysts is governed by NiOOH hydroxide intermediate in an
electrochemical-chemical (EC) mechanism in support with previous reports.
Key Words: Urea oxidation, α and β Ni(OH)2, electrochemical impedance spectroscopy, direct urea fuel cells
80
PB-80
Investigation of Bimetallic Ni-Cr Catalyst for Urea Oxidation in Alkaline
Solution
Ramesh Kumar Singh, Alex Schechter
Department of Chemical Sciences, Ariel University, Ariel, Israel
Urea oxidation reaction is the major barrier for widespread commercialization of direct urea fuel cells because
of its very sluggish reaction kinetics. In this work, Ni-Cr/C is reported for enhanced performance towards urea
oxidation. They are characterized by X-ray diffraction (XRD), inductively coupled plasma-optical emission
spectrometer (ICP-OES) and Fourier transform infrared spectroscopy (FTIR). The electrochemical properties
towards urea oxidation are evaluated by cyclic voltammetry and electrochemical impedance spectroscopy
(EIS). The amount of the Cr is optimized in the catalysts and it was found that Ni 60-Cr40/C exhibits highest urea
oxidation activity of 87 mA cmgeo.-2 @0.55 V with an onset potential of 0.33 V vs. Ag/AgCl. The
chronoamperometric plots suggest catalysts are stable in presence of urea even after 2000 s. The charge transfer
resistance with Ni60-Cr40/C is lowest at various bias potential relevant to urea oxidation reaction which is
indicative of enhanced conductivity observed from EIS measurements.
Keywords: Ni-Cr/C, urea oxidation, electrochemical impedance spectroscopy, borohydride reduction
81
PB-81
Oxygen Reduction on Tip Guided Platinum Particle Deposits using
Electrochemical Atomic Force Microscopic
Kolagatla Srikanth, Palaniappan Subramanian, Schechter Alex
Department of Chemical Sciences, Ariel University, Ariel, Israel
Oxygen reduction reaction (ORR) is traditionally studied on electrodes of large surface covered with a layer of
catalysts. However it is important to understand the oxygen reduction reaction occurring on separated catalytic
metal particles of different morphology, size and also to probe the hydrogen peroxide byproduct, if any,
generated during the reduction process. Therefore, it is necessary to produce metal particles under controlled
electrochemical conditions that will allow concomitant high resolution imaging. Herein, we have used a
relatively less explored technique- ‘Electrochemical Atomic Force Microscopy (EC-AFM)’ to do controlled
electrodeposition and subsequently image the catalytic platinum particles deposited on conductive carbon
substrates on a nanometric scale. AFM tip electrodes were used to direct the deposition of platinum particles
while simultaneously scanning the substrate. We have presented the effect of deposition parameters including
tip scan rate, platinum salt concentration and electrodeposition time on the nature of platinum deposits and
oxygen reduction activity of these deposits.
82
PB-82
Highly Insensitive and Thermostable Energetic Coordination Nanomaterials
based on Functionalized Graphene Oxides
Adva Ziv Cohen1, Qi Long Yan1, Natan Petrutik1, Avital Shlomovich1, Larisa Burstein1,
Si-Ping Pang2, Michael Gozin1
1
Department of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
Department of Chemistry, BIT, Beijing, China
In this research, a group of new energetic coordination nanomaterials (CNMs) based on functionalized
graphene oxide sheets (FGS) have been designed and characterized. GO was first functionalized with N-rich
energetic ligands such as triaminoguanidine (TAG), and then the resulting FGS was coordinated with metal
ions to prepare energetic CNMs with high thermostability and insensitivity to mechanical stimuli. The density
of GO–TAG–Cu(smallII/small)/Cu(smallI/small) is as high as 3.14 g cmsmall−3/small, while it has a
Tsmallp/small of 495 °C and VoD of 7723 m ssmall−1/small by using 40 wt% ammonium perchlorate as the
oxidant. These insensitive (Ismallm/small 81 J) and highly thermostable energetic CNMs in combination with
oxidizers are good candidate ingredients of low-vulnerability solid propellants and charges of deep-well
perforating guns.
83
PB-83
Quantitative Prediction of Optical Absorption in Molecular Solids using an
Optimally Tuned Screened Range-Separated Hybrid Functional
Arun K. Manna1, Sivan Refaely-Abramson1,2, Anthony M. Reilly3, Alexandre Tkatchenko4,
Jeffrey B. Neaton2, Leeor Kronik1
1
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
2
Department of Physics, University of California, Berkeley, California, USA
3
., The Cambridge Crystallographic Data Center, Cambridge, UK
4
Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg,
Luxembourg
Quantitative prediction of optical absorption in the solid-state using density functional theory (DFT) is a longstanding challenge. In principle, this should be possible with time-dependent DFT (TDDFT). In practice, the
results depend very strongly on the approximate exchange-correlation functional and standard approximations
usually fail qualitatively in the solid state.
We show that such prediction is possible, using the recently-developed time-dependent optimally-tuned
screened range-separated hybrid (OT-SRSH) [1]. In this method the molecular electronic structure is
determined by optimal tuning of the range-separation parameter in a range-separated hybrid functional.
Screening and polarization in the solid-state are taken into account by adding long-range dielectric screening to
the functional form.
We provide a comprehensive benchmark for the accuracy of this approach, by considering the X23 benchmark
set of molecular solids [2]. The results are in good agreement with many-body perturbation theory in the GWBSE approximation [3]. We discuss strengths and weaknesses of the approach. We believe that it could be used
for studies of molecular solids typically outside the reach of computationally more intensive methods.
1. S. Refaely-Abramson, M. Jain, S. Sharifzadeh, J. B. Neaton, L. Kronik, “Solid-state optical absorption from
optimally tuned time-dependent range-separated hybrid density functional theory”, Phys. Rev. B (Rapid Comm.)
92, 081204(R) (2015).
2. A. M. Reilly and A. Tkatchenko, “Understanding the role of vibrations, exact exchange, and many-body van
der Waals interactions in the cohesive properties of molecular crystals”, J. Chem. Phys. 139, 024705 (2013).
3. A. K. Manna, S. Refaely-Abramson, A. M. Reilly, A. Tkatchenko, J. B. Neaton, and L. Kronik, “Quantitative
prediction of optical absorption in molecular solids using an optimally tuned screened range-separated hybrid
functional” (manuscript in preparation).
84
PB-84
C-H Bond Activation Process in Alkyl-Titanium Complex: Over the Barrier or
Tunnel through the Barrier?
Ashim Nandi, Sebastian Kozuch
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Recently, an Alkyl-Titanium complex, [Cp2TiCH2CHMe(SiMe3)]+(I) which exists in equilibrium between its βagostic and γ-agostic isomer was synthesized. EXSY studies show that the β-H atom of (I) undergoes facile
exchange with the three hydrogen atoms of the β-methyl group (β-H/γ-H exchange) but not with the α-H atom.
This exchange process is very different from that involving deuterium atom redistribution suggesting a
significantly high kinetic isotope effect (KIE) because it is completely shut down when
[Cp2TiCH2CH(CD3)(SiMe3)]+ is used. On the basis of such a large kinetic isotope effect, it is proposed that
quantum mechanical proton tunnelling is involved during the β-H/γ-H exchange and possibly via allylic CH
bond activation. In this study, we employed DFT calculation to obtain the electronic structural properties of the
reaction. Additionally, in order to obtain a better insight of the tunnelling effect we carried out quantum
tunnelling calculations.
85
PB-85
Computational Design of Biofuels from Isoprenoids
Efrat Pahima, Dan T. Mayor
Department of Chemistry, Bar-llan University, Ramat-Gan, Israel
Biofuels present a very promising direction for sustainable and renewable energy materials. A particular class
of compounds that show great potential as biofuels are terpenoids. These abundant organics compose ca. 60 %
of all natural compounds, and to date 60,000 natural terpenoids are known. In this project we suggest a novel
pathway for rational design of new biofuels. To this end we propose a multiscale computational approach,
wherein we perform a systematic study of the inherent thermodynamic properties of some promising highenergy terpene molecules that show high compatibility with petroleum fuels criteria, including their heats of
combustion and formation. In particular we employ density functional theory and ab-initio quantum chemistry
methods as well as classical molecular dynamics simulations. By using these quantum chemistry calculations,
the initial design phase of the compatibility of potential fuel replacements by experimental trial and error can be
skipped, saving time and money, and with no contribution to environmental pollution.
86
PB-86
Adsorption of CO on Thin Layers of Pt on Sn
Itay Pitussi1, Alex Schechter1, Amir Natan2, Haya Korenwitz1
1
Chemical Sciences, Ariel University, Ariel, Israel
2
Physical Electronics, Tel Aviv University, Tel Aviv, Israel
Fuel cells are electrochemical devices which convert chemical energy to electrical energy in a much more
efficient and clean manner compared combustion engines. Typically, these devices utilize pure hydrogen and
air that reacts on Pt based catalyst in the anode and the cathode respectively. Never the less the cost of Pt and its
poisoning by CO in the ppm level in hydrogen prevents their commercialization market. Highly dispersed very
thin layers of Pt on metallic Sn is being studied in our group. This approach may provide high utilization of Pt
as well co-catalysis of adsorbed CO removal from Pt surface via a well-known Pt-Sn bi-functionality
mechanism1,2.
PtSn alloys and their CO adsorption have been reported before. However, this research deals with tin coated by
Pt and not with an alloy. The effect of various number of Pt(111) slabs on a well-defined core of Sn was
studied. The effect of Pt layer number on the adsorption energy of CO was studied in comparison to the
adsorption energy of CO over pure Pt.
The approach in this research was mainly computational. The calculations have been carried out using the
Vienna Ab initio Simulation Program (VASP) using periodic boundaries, PAW PBE pseudopotentials and
default cut off energies were used. According to the computational result, the coated Pt on a tin core changes
the adsorption energy of CO on selected sites and geometrical configurations. Correlation between the number
of Pt slabs and the adsorb CO adoption energy was found. Reducing the adsorption energy was demonstrated
on a single atomic layer slab.
Reference
(1) Wang, K.; Gasteiger, H. a.; Markovic, N. M.; Ross, P. N. On the Reaction Pathway for Methanol and
Carbon Monoxide Electrooxidation on Pt-Sn Alloy versus Pt-Ru Alloy Surfaces. Electrochim. Acta 1996, 41
(16), 2587–2593.
(2) Mukerjee, S.; Urian, R. C. Bifunctionality in Pt Alloy Nanocluster Electrocatalysts for Enhanced Methanol
Oxidation and CO Tolerance in PEM Fuel Cells: Electrochemical and in Situ Synchrotron Spectroscopy.
87
PB-87
Spin-State Energetics of Fe Complexes from an Optimally-Tuned
Range-Separated Hybrid Functional
Georgia Prokopiou, Leeor Kronik
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
We assess whether the optimally-tuned range separated hybrid (OT-RSH) functional approach can predict the
correct ground-state electronic configuration and spin-state energetics of complexes that can potentially exhibit
multiple spin configurations. To that end, we investigate eight iron complexes: Four spin-crossover complexes,
for which reference data from other approximate density functionals are available, and four smaller complexes,
for which reference ab initio data are available.
We show that the spin-state energetics are mostly governed by the percentage of short-range exact exchange
and are only weakly influenced by the choice of range-separation parameter. However, the electronic structure,
especially the HOMO-LUMO gap, is much more sensitive to the range-separation parameter. We find that use
of OT-RSH improves the electronic structure, as compared with that obtained from semi-local or global hybrid
density functionals. However, as with global hybrid functionals, correct prediction of the ground-state in the
spin-crossover compounds requires a reduction in the amount of short-range exact exchange, possibly owing to
a larger role of static correlation.
88
PB-88
Improved Sugar Puckering Profiles for Nicotinamide Ribonucleoside for
Hybrid QM/MM Simulations in Gas Phase, Explicit Water and DHFR
Enzyme Environments
Yaron Pshetitsky, Reuven Eitan, Anil Mhashal, Dan Thomas Major
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
The coenzyme nicotinamide adenine dinucleotide (NAD+) and its reduced form (NADH), and their
phosphorylated counterparts NADPH/NADP+, participate in several redox hydride transfer reaction in nature1.
Several reports on enzymes containing NADH/NAD+ utilize the QM/MM hybrid method with the
implementation of the low cost semiempirical (SE) methods to treat the QM region. The ribose sugar ring of
NADH/NAD+ may influence the electronic configuration during the reaction, and therefore should be included
in the QM region. Recent work2-7 suggests that SE methods do not adequately describe the ring puckering in
sugar molecules. In this work8 we corrected the SE Hamiltonian by adding a correction potential. This potential
is the difference between an accurate DFT potential energy surface (PES) and the SE PES of the ribose sugar of
NAD+/NADH obtained from the gas phase calculations. We found that the population distributions obtained
from the free energy QM(corrected SE)/MM molecular dynamics simulations are in good agreement with DFT
and experimental results. This modified Hamiltonian is further used to investigate the free energy profiles of
NADH/NAD+ puckering in the enzymatic environment of Dihydrofolate Reductase (DHFR).
1} Alberts, B.; Bray, D.; Lewis, J.; Raff, M.; Roberts, K.; Watson, J. D., Molecular Biology of the Cell.
2 ed.; Garland Publishing: New York, 1989.
2] McNamara, J. P.; Muslim, A.-M.; Abdel-Aal, H.; Wang, H.; Mohr, M.; Hillier, I. H.; Bryce, R. A.,
Towards a quantum mechanical force field for carbohydrates: a reparametrized semi-empirical MO
approach. Chem. Phys. Lett. 2004, 394 (4), 429-436.
3] Barnett, C. B.; Naidoo, K. J., Stereoelectronic and Solvation Effects Determine Hydroxymethyl
Conformational Preferences in Monosaccharides. J. Phys. Chem. B 2008, 112 (48), 15450-15459.
4] Islam, S. M.; Roy, P.-N., Performance of the SCC-DFTB Model for Description of Five-Membered
Ring Carbohydrate Conformations: Comparison to Force Fields, High-Level Electronic Structure
Methods, and Experiment. J. Chem. Theory Comput. 2012, 8 (7), 2412-2423.
5] Govender, K.; Gao, J.; Naidoo, K. J., AM1/d-CB1: A Semiempirical Model for QM/MM Simulations
of Chemical Glycobiology Systems. J Chem Theory Comput 2014, 10, 4694-4707.
6] Govender, K. K.; Naidoo, K. J., Evaluating AM1/d-CB1 for Chemical Glycobiology QM/MM
Simulations. J. Chem. Theory Comput. 2014, 10 (10), 4708-4717.
7] Huang, M.; Giese, T. J.; Lee, T. S.; York, D. M., Improvement of DNA and RNA Sugar Pucker
Profiles from Semiempirical Quantum Methods. J Chem Theory Comput 2014, 10 (4), 1538-1545.
8] Pshetitsky, Y.; Eitan, R.; Verner, G.; Kohen, A.; Major, D. T., Improved Sugar Puckering Profiles for
Nicotinamide Ribonucleoside for Hybrid QM/MM Simulations. J. Chem. Theory Comput. 2016.
89
PB-89
Enhanced Magnetoresistance in Molecular Junctions by Geometrical
Optimization of Spin-Selective Orbital Hybridization
Soumyajit Sarkar1, David Rakhmilevitch2, Ora Bitton3, Leeor Kronik1, Oren Tal2
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
3
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
1
Molecular junctions based on ferromagnetic electrodes allow the study of electronic spin transport near the
limit of spintronics miniaturization. However, these junctions reveal moderate magnetoresistance that is
sensitive to the orbital structure at their magnetic tip - molecule interfaces. The key structural parameters that
should be controlled in order to gain high magnetoresistance have not been established, despite their importance
for efficient manipulation of spin transport at the nanoscale. Here, we show that single-molecule junctions
based on nickel electrodes and benzene molecules can yield a significant anisotropic magnetoresistance of up to
∼200% near the conductance quantum G0. The measured magnetoresistance is mechanically tuned by changing
the distance between the electrodes, revealing a nonmonotonic response to junction elongation. These findings
are ascribed with the aid of first-principles calculations to variations in the metal–molecule orientation that can
be adjusted to obtain highly spin-selective orbital hybridization. Our results demonstrate the important role of
geometrical considerations in determining the spin transport properties of metal–molecule interfaces.
citeNano Lett./cite, 16, 1741–1745, (2016)
90
PB-90
Ping-Pong Reactions by Heavy Atom Tunneling
Adam Sucher, Sebastian Kozuch
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Quantum mechanical tunneling (QMT) is a known effect that has the potential to significantly accelerate the
kinetics of chemical reactions even at extremely low temperatures, where classical, “over the barrier” thermal
reactions are virtually impossible. Since this effect is dependent on the mass of the shifting atoms, QMT has
been widely studied for hydrogen transfer. However, a slowly growing body of evidence has shown that
“heavy” (i.e. non-hydrogen) atom tunneling is indeed possible, as long as the barrier height is low and, more
important, the barrier width is markedly narrow. In this computational research degenerate rearrangement
reactions of the “Ping-Pong” style have been studied, where a heavy atom (fluoride or boron) jumps from one
conformation to another over an anthracene or similar scaffold. These reactions possess a double-well potential
energy surface where the atomic trajectory to pass from one minimum to another is extremely short, and the
barrier height is too high to be traversed via a classical thermal pathway at low temperatures, thus making these
reactions ideal for QMT.
91
PB-91
Toward a W4-F12 Approach: Can Explicitly Correlated and Orbital-Based ab
initio CCSD(T) Limits be Reconciled?
Nitai Sylvetsky1, Kirk A. Peterson2, Amir Karton3, Jan M. L. Martin1
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
2
Department of Chemistry, Washington State University, Washington, Pullman, USA
3
School of Chemistry and Biochemistry, The University of Western Australia, Perth, Australia
1
In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and
doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set
convergence problem, followed by the (T) component. In the present study, we make a detailed comparison, for
an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based
CCSD/AV{5,6}Z+d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations
with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H–He, B–Ne, and Al–
Ar, is shown to be very close to the basis set limit. Apparent differerences (which can reach 0.35 kcal/mol for
systems like CCl4) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with
additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations
reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital
calculations have significant BSSE even with AV(6+d)Z basis sets, leading to non-negligible differences
between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching
to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous
reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to
different CCSD(T) limits than “valence limit+CV correction” approaches like Feller-Peterson-Dixon and
Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets.
For (T) corrections, conventional CCSD(T)/AV{Q,5}Z+d calculations are found to be superior to scaled or
extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the
Hartree-Fock and valence CCSD components from CCSD-F12b/cc-pV{Q,5}Z-F12 calculations, but the (T)
component from conventional CCSD(T)/aug’-cc-pV{Q,5}Z+d calculations using Schwenke’s extrapolation;
post-CCSD(T), core-valence, and relativistic corrections are to be obtained as in the original W4 theory. W4F12 is found to agree slightly better than W4 with ATcT (active thermochemical tables) data, at a substantial
saving in computation time and especially I/O overhead.
92
PB-92
Thin films with Switchable Conductivity: About the Production of Vanadium
Oxide thin Films Applying CVD Technique
Anita Pilipody Best1, Artur Meling2, Bastian Krueger2, Tim Schaefer2, Vladimir Tsionsky3,
Sergey Cheskis1, Alec M. Wodtke2,4, Igor Rahinov3
1
School of Chemistry, Tel Aviv University, Tel Aviv, Israel
2
Institute of Physical Chemistry, Georg-August University of Goettingen, Goettingen,
Germany
3
Department of Natural Sciences, The Open University of Israel, Raanana, Israel
4
Max Planck Institute, Max Planck Institute, Goettingen, Germany
Oxides of vanadium are widely used in catalytic protocols for pollution abatement
[1, 2] synthetic fuel production [3, 4] and heterogeneous catalysis in general. In addition, Vanadium dioxide has
some peculiar properties: Vanadium dioxides exhibits a phase transition from semi-conductor to a metal at 68
°C. This process is called Mott transition [5] and occurs due to change in the unit cell structure from monoclinic
structure to tetragonal rutile structure. These unusual properties could be used as thermo-electric switches,
optical switches, thermal windows and super-capacitors. Vanadium dioxides films were grown in hot wall,
horizontal, low pressure MOCVD apparatus. The CVD fabrication of 1-3 µm thick VO2 films employed
sublimation of Vanadyl acetylacetonate (VO(acac)2) at ~150-190oC and its subsequent reaction with O2 at CVD
chamber. Annealing of VO2 films under oxidizing environment will result in V2O5 films [6]. The dependence of
film morphology and resistance properties on CVD reactor temperature, precursor sublimation temperature and
the substrate position along the reaction axis was tested. Scanning Electron Microscopy (SEM) analysis reveals
grain sizes in the range of 0.5-2 µm. Four probe resistance measurements indicate resistance drop of 3-4 orders
of magnitude across the insulator-to-metal transition. Scattering experiments are a method to explore the energy
conversion of excited molecules on surfaces. These processes are essential for the understanding of
macroscopic catalytic reactions.Scattering of gas molecules from insulator and from metal surface are well
established [7]. The motivation of this project is to perform scattering experiments from surfaces with
switchable conductivity and work function. Here presented preliminary results of NO molecule scattering from
the resulting VO2 thin films.
References:
1] F. Gilardoni and J. Weber, A.B., International Journal of Quantum Chemistry, 1997. 61.
2] H. Randall, R.D., A. Renken, Applied Catalysis B: Environmental, 1998. 17.
3] L. C. Caero, E.H., F. Pedraza, F. Murrieta, Catalysis Today, 2005. 107-108.
4] K. Otsuka, A.M., S. Takenaka, I. Yamanaka, International Journal of Hydrogen Energy, 2001. 26.
5] Mott, A.Z.a.N.F., Phys. Rev. B, 1975. 11.
6] A. Pan, H. B. Wu, L. Yu, and X. Wen (David) Lou, Template-Free Synthesis of VO2 Hollow
Microspheres with Various Interiors and Their Conversion into V2O5 for Lithium-Ion Batteries,
Angew. Chem., 2013, 125.
7] Y.Huang, C.T.R., Daniel J. Auerbach, Alec M. Wodtke, Vibrational Promotion of Electron Transfer.
SCIENCE, 2000. 290(6).
93
PB-93
Directed Microstructures Formation by Standing Surface Acoustic Waves
Silvia Piperno, Haim Sazan, Hagay Shpaisman
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Not available.
94
PB-94
Adsorption under Nano-Confinement: Predicting Remarkably Higher Levels
of Surface Coverage
Micha Polak, Leonid Rubinovich
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Remarkable Nano-Confinement Entropic effects on equilibrated Adsorption in a system consisting of small
numbers of molecules and adsorption-sites inside a nanoscale space are revealed for the first time by employing
statistical-mechanical principles in the combined framework of the ideal-gas and lattice-gas models. The novel
effect (termed NCEA) is reflected in computed adsorption isotherms exhibiting considerable positive deviations
from the classical Langmuir isotherm of macroscopic systems, namely a system-size dependent significant
increase of coverage (Fig.1). Likewise, nano-confined coverage variations with temperature at constant volume
exhibit heightened adsorption levels. In particular, the NCEA is found to induce selectivity enhancement for
H2O vs. CO as well as for CO2 vs. N2, when the respective two molecular species are co-physisorbed on Ndoped carbon materials. Similarly to nano-confinement effects on chemical-equilibrium reported by us
previously [1,2], the NCEA origin is associated with distinct intrinsic variations in mixing-entropy and pressure.
The present introduction of nano-confined adsorption phenomena indicates the emergence of a new
subdiscipline of nanoscience, which can be pertinent also to nanotechnological applications such as gas storage
and gas-mixture separation.
[1] "Nanochemical equilibrium involving a small number of molecules: A prediction of a distinct confinement
effect" M. Polak, L. Rubinovich - Nano Letters 2008.
[2] "The intrinsic role of nanoconfinement in chemical equilibrium: Evidence from DNA hybridization" L.
Rubinovich, M. Polak - Nano Letters 2013.
Figure 1. Isotherms at 300 K for n molecules of H2 physisorbed on n Ti-sites in doped graphene under
nanoconfinement (varying volume V). Insets: illustration of the preadsorption and predesorption configurations
and pressures for the smallest system.
95
PB-95
Surface Patterning through Local Electrodeposition of Metals using
Liquid/Solid & Liquid/Liquid Interface
Sujoy Sarkar, Daniel Mandler
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Electrochemical scanning probe methods offer an alternative approach for the deposition of micrometer or submicrometer structures. Scanning electrochemical microscopy (SECM) is a new approach to deposit
micropatterns at the liquid/solid or liquid/liquid interface driven by electrochemistry. The feedback mode of
SECM has been applied to deposit the patterned palladium (Pd) sub-micron structures from Pd microelectrode
on a conducting and insulating substrates. The Pd patterns on the surface are further modified with electroless
copper plating solution to obtain copper microstructure on the flexible and transparent surface. A similar
approach, widely known as scanning ion conductance microscopy (SICM) has also been introduced here for the
localized electrochemical deposition of Pd using a pulled micropipette as a tip. In contrast to the other scanning
probe microscopy technique, SICM is still under development, especially in terms of local electrodeposition.
Herein, the micropipette is filled with palladium salt and Ag/AgCl reference is inserted in the pipette as well as
in the bath solution. The application of negative potential to the electrode in the micropipette causes negatively
charged ions, PdCl42-, to leave the pipette. This flux can be further reduced on a bias ITO or pretreated PET
substrate. The surfaces are subsequently treated with copper electroless plating formulation. SICM has huge
potential over SECM in micro/nano electronics and device fabrication.
96
PB-96
Directed Assembly of Nanoparticles Using Standing Surface Acoustic Waves
Haim Sazan1, Silvia Piperno1, Michael Layani2, Shlomo Magdassi2, Hagay Shpaisman1
1
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Casali Institute for Applied Chemistry, Institute of Chemistry,
The Hebrew University of Jerusalem, Jerusalem, Israel
In our lab, we develop different methods which direct materials to form patterns and micro-structures. This
project deals with standing surface acoustic waves (SSAWs). We want to study how these waves affect the
formation of structures from suspended nanoparticle solutions. Under the exposure of SSAWs, nanoparticles in
a microfluidic channel would be forced towards pressure nodes (for particles with a positive acoustic contrast
factor in the medium) forming new microstructures. While previous work of SSAWs focused on ordering,
sorting and separation of particles, the novelty of our work is that we use them to form new materials. We use
suspended silver nanoparticles that can be sintered at room temperature with exposure to chloride ions.
Streaming the silver suspended nanoparticles with chloride ions solution under the SSAWs field could sinter
the particles in a micro-fiber shape.
97
PB-97
ODMR Measurements of CdSe\CdMnS Nanoplatelets
Rotem Strassberg, Yahel Barak, Efrat Lifshitz
Solid State Institute, Technion - Israel Institute of Technology, Haifa, Israel
The current study invastigates the magneto-optical properties of an ensemble colloidal Nanoplatelets (NPs),
doped with a few Mn+2 ions (1%). Replacing a single atom of a host semiconductor nanocrystal with a
functional dopant can introduce completely new properties potentially valuable for “solotronic” informationprocessing applications. The NPs consist of a CdSe core, covered by 8 monolayers (MLs) of CdMnS shell,
adjusted to an appropriat band-gap by the size, and tuned to a quasi-type-II electronic alignment by variation of
the core/shell-thickness ratio. The material design enables the appearance of the dopant excited states to lie
nearly in resonance with the conduction band levels of the host semiconductor in order to create strong sp-d
exchange interaction. The magneto-optical properties were investigated by probing the single exciton
recombination emission of these NPs, using micro-photoluminescence (μPL) spectroscopy, obtaining an
exchange split in the presence of an external magentic field (B0). Well-resolved optically detected magnetic
resonance (ODMR) peaks (Fiigure 2) are observed that can be related to the discrete spin projections of
individual Mn2+ ions. Further more, a spin flip (magentic polaron) is examined by monitoring the mPL intensity
under magnetic resonance conditions, m-PL magnetic resonance (mPL-MR) spectroscopy. These advanced
measurements are the only way to reach spectral resolution of a sub-meV and control over a spin flip, essential
for the detection of a spectroscopic fine structure generated by the exciton-Mn2+ interactions. The experimental
results is supported by a theoretical model, based on the effective mass approximation of the NPs electronic
states, perturbed by the relevant exchange interactions: electron-Mn+2, hole- Mn+2 and electron-hole, depending
on the heterostructure design. This allows a calculation of the Mn+2 g-factor together with the exciton-Mn+2
coupling.
98
PB-98
Direct Observation of Confinement-Induced Charge Inversion at a Metal
Surface
Ran Tivony, Dan Ben-Yaacov, Gilad Silbert, Jacob Klein
Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
Surface interactions across water are central to areas from nanomedicine to colloidal stability. They are
predominantly a combination of attractive but short-ranged dispersive (van der Waals) forces, and long-ranged
electrostatic forces between the charged surfaces. Using a surface force balance, we showed that electrostatic
forces between two surfaces across water, one at constant charge (a dielectric) while the other (a molecularlysmooth metal surface) is at constant potential of the same sign, may revert smoothly from repulsion to attraction
on progressive confinement of the aqueous intersurface gap. This remarkable effect, long predicted
theoretically in the classic Gouy-Chapman (Poisson-Boltzmann) model but never previously experimentally
observed, unambiguously demonstrates surface charge reversal at the metal-water surface.
Its experimental demonstration emphasizes the importance of taking such charge reversal – and the
accompanying cross-over from repulsion to attraction – into account, for interactions between dielectrics and
metal surfaces in aqueous media in similar circumstances. These include phenomena such as colloidal
interactions, adsorption of proteins, cells or nanoparticles on metal surfaces, imaging of metal surfaces by
ceramic AFM tips and tribology of dielectric-metal interfaces in aqueous surroundings.
99
PB-99
Oscillatory Discharging Behavior of a Pyridine-Based Polymer Blend Gel
Evgenia Vaganova, Faina Dubnikov
The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Our investigation of molecular binding in a unique, concentrated polymer solution has, to date, been unable to
adequately explain its remarkably flexible response to external perturbation.1,2 During the last two years, the
blend of poly(4-vinyl pyridine)/poly(4-vinyl pyridine – co – butylmethacrylate), gelled in pyridine, has been
shown to be supersensitive to both heat and IR-radiation1, with markedly different relaxation times3. However,
one fundamental question was indeed answered – the gel contains multiple forms of hydrogen bonding due to
the self-protonation of the pyridine side-chain.4 The suggested source of the bi-functional sensitivity is the
combination of ester-group oxygen / protonated side-chain and NH….N structural group complexes.
Here we present an additional aspect of gel functionality. Following poling of the gel to achieve saturation
resistance, electrical oscillations appear during gel discharging (Figure 1). The oscillations appear at three
different frequencies: 0.02Hz ; 0.3Hz; 0.7Hz. The amplitude of the slow and intermediate oscillations is
approximately 1.00 -1.25 V and that of the more rapid oscillations, approx. 0.12 V. Interestingly, this type of
behavior mimics that observed during charge transfer in neuronal axons. A possible explanation as well as its
significance will be discussed.
Figure 1. Voltage oscillations of the polymer blend, observed during discharging; insert – sketch of the
electrical scheme (RC of capacitor is about 0.1).
1..United States Patent Application No.14/004, 801 “Polymeric compositions and uses thereof” Our
Ref:2244875 RB/lid (2016).
2. E. Vaganova et al, “White light and heat Sensitivity in a Pyridine-Based Polymer Blend” J. Phys Chem. C
2012, 116, 25028-25033.
3. YouTube Evgenia Vaganova
4. E. Vaganova et al. “Photoinduced proton transfer in a pyridine Based Polymer Gel” J. Phys Chem B, 2010,
114, 10728-10733.
100
PB-100
NMR Investigations of the Structure and Dynamics of New KcsA inhibitors
Netanel Mendelman1, Ruiming Zhao2, Steve A. N. Goldstein2, Jordan H. Chill1
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Biochemistry, Brandeis University, Waltham, Massachusetts, USA
Peptide channel-inhibiting neurotoxins are commonly used for research and as therapeutic agents. Recently two
toxins, Hui1 and HmK, were found to inhibit KcsA, a prototypical bacterial potassium channel, at nanomolar
affinity. These toxins were isolated from a library of over one million toxins derived from ShK, a sea-anemone
toxin which does not bind KcsA. While HmK promiscuously binds both KcsA voltage-gated channels, Hui1 is
selective for KcsA. Having determined the Hui1 structure using standard 2D NMR spectra, we found that
structurally Hui1 and the parent ShK toxin are quite similar, and that changes in the electrostatic surface
potential of both toxins are the source for their different selectivity profiles [1]. In addition, dynamic
measurements, obtained from NMR relaxation dispersion experiments, showed that as ShK [2], Hui1 exhibits
millisecond motion in the toxin backbone which implies that it has a minor conformer which may have a role in
channel binding. We are currently refining the structure of HmK, and the comparison of its structure with those
of Hui1 and ShK will provide new insights into the recognition elements of the various toxins and channels.
Initial measurements of binding between Hui1 and KcsA were performed using nanodiscs as membrane mimic
environment [3] for KcsA. Addition of nanodisc-embedded KcsA to Hui1 led to chemical shift perturbations
indicating that a complex had been obtained. Labelling of specific amino acids in KcsA will enable us to obtain
distance constraints between specific toxin and channel residues, and these will eventually be used for docking
simulations for obtaining the Hui1-KcsA complex structure.
References
[1] Ruiming Zhao , et al. PNAS, 112, 7013-7021 (2015).
[2] Sher Inabal, et ak. ChemBioChem, 2402-2410 (2014).
[3] A. Nath, W. M. Atkins, and S. G. Sligar, Biochemistry, 46, 2059–2069 (2007).
101
PB-101
Effect of Asp122 Mutations on E. Coli DHFR: Structure and Dynamics
Anil Mhashal, Yaron Pshetitsky, Dan Thomas Major
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Dihydrofolate reductase (DHFR) catalyzes the reduction of dihydrofolate (DHF) to tetrahydrofolate (THF) in
the presence of NADPH as a hydride donor. The key steps in the reaction are accomplished by correlated
protein motions in the Michaelis-Menten (E:NADPH:DHF) complex. The present theoretical study employs
mutagenesis to examine the relation between structural and functional properties of the enzyme. We mutate
Asp122 in Escherichia coli DHFR, which is a highly conserved amino acid in the DHFR family.1 The
consequent effect of the mutation on the enzyme catalysis is examined both structurally and energetically.
Furthermore, we inspected the ribose sugar conformational behavior, which is expected to influence ligand
binding and hydride donor–acceptor dynamics during the chemical reaction. We employed a hybrid quantummechanical/molecular mechanical (QM/MM) approach with a recently developed semi-empirical AM1-SRP
Hamiltonian that provides accurate results for this reaction.2-5 Our investigations reveal that the structural and
dynamic perturbations caused by Asp122 mutations are along the reaction coordinate and lower the rate of
hydride transfer. Altered coupled motions in the enzyme suggest that the possible dynamic coupling is lost as a
result of the mutation. These effects are also reflected in the ribose sugar puckering profile which unveils that
the fine balance of interactions is perturbed by the mutations. The role of water during the catalysis is also
investigated suggesting networks of hydrogen bonded water molecules near the active site.
References:
1] Agarwal, P. K.; Billeter, S. R.; Rajagopalan, P. T. R.; Benkovic, S. J.; Hammes-Schiffer, S., Network
of coupled promoting motions in enzyme catalysis. Proc. Natl. Acad. Sci. U.S.A. 2002, 99 (5), 27942799.
2] Warshel, A.; Levitt, M., Theoretical studies of enzymic reactions - dielectric, electrostatic and steric
stabilization of carbonium-ion in reaction of lysozyme. J. Mol. Biol. 1976, 103 (2), 227-249.
3] Dewar, M. J. S., Applications of quantum-mechanical molecular-models to chemical problems .70.
Quantum-mechanical molecular-models. J. Phys. Chem. 1985, 89 (11), 2145-2150.
4] Rossi, I.; Truhlar, D. G., Parameterization of NDDO wavefunctions using genetic algorithms. An
evolutionary approach to parameterizing potential energy surfaces and direct dynamics calculations for
organic reactions. Chem. Phys. Lett. 1995, 233, 231-236.
5] Doron, D.; Major, D. T.; Kohen, A.; Thiel, W.; Wu, X., Hybrid Quantum and Classical Simulations
of the Dihydrofolate Reductase Catalyzed Hydride Transfer Reaction on an Accurate Semi-Empirical
Potential Energy Surface. J. Chem. Theory Comput. 2011, 7 (10), 3420-3437.
102
PB-102
Structural and Dynamics Characterization of the MerR Family
Metalloregulator, CueR, in the Repressed and Active States
Hila Sameach1, Aya Narunsky2, Salome Azoulay-Ginsburg1, Yoni Moskovitz1,
Lada Gevorkyan Airapetov1, Yonathan Zehavi3, Tamar Juven-Gershon3, Nir Ben-Tal2,
Sharon Ruthstein1
1
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Biochemistry and Molecular Biochemistry, Tel Aviv University, Tel Aviv, Israel
3
Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
Metalloregulators have evolved metal coordination sites that “sense” specific metal ion and upon coordination
either activate or inhibit DNA binding, thereby controlling the expression of genes that mediate the intracellular
metal concentration. Understanding the interactions among metal, DNA, and its sensor is very important for
deciphering the microorganism’s degree of survival in the host organism. In this study, we focused on the Cu(I)
E.coli metal sensor, CueR. We utilized electron paramagnetic resonance (EPR) spectroscopy and computation
to better understand how Cu(I)-DNA binding is harnessed to drive changes in the structure of CueR,
consequently inducing the transcription process. We found that CueR undergoes structural changes upon
binding DNA and Cu(I), indicating that CueR plays a significant role in initiating the transcription process.
CueR is an all-α, tail-to-tail, homodimer where each monomer is composed of an N-terminal domain (helices 1through-4) that interacts with DNA, and a C-terminal domain (helices 5-6) that mediates the interaction with
the other monomer. We show that the active state is formed when the α1 region approaches the α2-α3 region in
the DNA binding domain, and the two DNA binding domains of the CueR dimer are getting closer to each
other. Moreover, we indicate that CueR exists in solution both in DNA bound and unbound states. We also
discovered that mutations in the metal binding site destabilize the protein and imped dimerization. This research
provides a detailed structural mechanism underlying the transcription of metalloregulators.
103
PB-103
The Cellular Copper Uptake Mechanism
Yulia Shenberger, Ortal Marciano, Hugo Gottlieb, Sharon Ruthstein
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Copper is a nutrient essential metal, which is involved in many enzymatic and biological processes in the cell.
However, insufficient regulation of copper may lead to severe neurological diseases and disorders.
Today’s, it is known that Cu(II) is accumulated in the body through diet to the blood cycle, where human serum
albumin (HSA) transfers it to the extra cellular domain of the main copper transporter, CTR1. The first copper
binding sites is rich in methionine and histidne residues. In addition, it was suggested that at this site Cu(II) is
reduced to Cu(I) in the presence of ascorbate. Segments that are rich with methionine residues, (also called
Mets motifs) are found in many of the proteins that bind Cu(I) and are capable of binding Cu(I) and Ag(I) ions
with micromolar affinity.
Herein, we focus on gaining information on the copper uptake mechanism by the CTR1 protein using several
spectroscopic techniques such as EPR, CD, and NMR. We first explored the interaction between the blood
carrier protein, HSA, and the extracellular domain of CTR1. We then gained information on the binding of
Cu(I) and Ag(I) to a general Mets Motif. We used this information to identify the first Cu(II) and Cu(I) binding
sites in CTR1. Finally we explored the Cu(II) reduction mechanism on the CTR1 extracellular domain.
This study presents one step toward a complete understanding of the cellular copper uptake mechanism in the
human body.
104
PB-104
First Principles Model Calculations of the Biosynthetic Pathway in Selinadiene
Synthase
Susanta Das, Mudit Dixit, Dan Thomas Major
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Terpenes represent the largest class of natural products currently known. These natural compounds are derived
from a few linear precursors, such as geranyl diphosphate (GPP), farnesyl diphosphate (FPP) and
geranylgeranyl diphosphate (GGPP). Terpenes have diverse biological functions that are widespread across all
three domains of life. Terpene synthases (TPSs) naturally catalyze the synthesis of terpenes via cationic
mechanisms, which include numerous highly reactive intermediates. A common feature in all TPSs is highly
evolved active sites that can seclude and protect highly reactive carbocation intermediates. 1 In this study, we
present a detailed mechanistic investigation of the biosynthesis of Selinadien.2-4 We employ density functional
theory (DFT) to understand the exact pathways of the reaction in the gas-phase. Our investigation revealed that
during the formation of the product, Selina-4 (15), 7 (11) -diene, FPP folds into a conformation conducive to
several sequential cyclizations. We suggest that a required proton transfer cannot occur intramolecularly in the
gas phase due to a high free energy barrier, and that enzyme assistance is essential for this step. Hybrid
quantum mechanics-molecular mechanics (QM/MM) docking studies suggest that enzyme intervention could
be realized through electrostatic guidance.5 Initial free energy QM/MM simulations are also presented.
References:
[1] Roland D. Kersten, Jolene K. Diedrich, John R. Yates, Joseph P. Noel ACS Chem. Biol., 2015, 10, 25012511.
[2] Philipp Baer, Patrick Rabe, Katrin Fischer, Christian A. Citron, Tim A. Klapschinski, Michael Groll, Jeroen
S. Dickschat Angew. Chem. Int. Ed. 2014, 53, 7652-7656.
[3] Philipp Baer, Patrick Rabe, Christian A. Citron, Carina C. de Oliveira Mann, Norman Kaufmann, Michael
Groll, Jeroen S. Dickschat Chem. Bio. Chem, 2014, 15, 213-216.
[4] Susanta Das, Mudit Dixit, Dan T. Major. Bioorg. & Med. Chem. 2016, 24, 4867–4870
[5] Dan T. Major, Y. Freud, M. Weitman. Curr. Opin. Chem. Biol. 2014, 21, 25-33.
105
PB-105
Deciphering Molecular Pathways and Cellular Interactions Initiated by
Anticancer Ti(IV) Phenolato Complexes
Maya Miller1, Ori Braitbard2, Jacob Hochman2, Edit Y. Tshuva1
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
2
Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem,
Jerusalem, Israel
1
Metal containing compounds have entered the field of anticancer research with the introduction of cisplatin in
the early 70th, followed by titanium complexes a decade later. Unlike platinum, titanium is a biocompatable
metal providing a clear advantage for the use in therapy. The first class of titanium containing drugs introduced
suffered from rapid hydrolysis in biological environment, which hampered the identification of the active
species and the study of its molecular mechanism, thus ultimately resulting in failure in clinical trials. Later
titanium complexes based on phenolato ligands achieved enhanced resistance to hydrolysis; 1 these compounds
have shown high anti-tumor activity toward various cancer cell lines, selectivity to cancer tissue, durability in
aquatic solutions and effectiveness in in vivo models.
This work aims to promote our understanding of the molecular mechanism involved in the activity of Ti(IV)
phenolato complexes. A leading phenolato Ti(IV) compound influenced the cell cycle, causing G1 arrest.
Cytotoxicity measurements have shown significant decrease in cell viability only within 24 hours of incubation,
supporting a programmed rather than instant cell death. Additionally, upregulation of p53 and caspase9 proteins
imply on apoptotic pathways involved. Comparing cytotoxicity, cellular uptake, and protein levels in two cell
lines imply that different mechanisms are plausible.2 Additional experiments suggest that chromosomal DNA
and/or mitochondria may serve as cellular targets for this class of complexes. Preliminary results with chiral
complexes will also be presented. Altogether, the preliminary mechanistic insights gained should advance these
promising Ti(IV) phenolato complexes for the use in cancer treatment.
References:
1] Miller M; Tshuva E.Y.; Eur. J. Inorg. Chem. (2014) 9, 1485.
2] Miller M; Braitbard O.; Hochman J.; Tshuva E.Y.; J. Inorg. Biochem. (2016) 163, 250-257.
106
PB-106
Development of Novel Reagents for Generating Islets β-Cells and Enhancing
their Function Based on Clustered Nanoformulation of Neuroligin-2 Mimetics
Anna Munder1, Efrat Shtriker1, Olga Viskind1, Edward Korshin1, Steven D. Chessler2,
Arie Gruzman1
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Department of Medicine, University of California, Irvine, California, USA
Β-cell membrane and presynaptic zones of neurons have sites of similar protein complexes mediating secretion
of bioactive molecules. Synaptic proteins that mediate interactions between neurons and guide the formation
and functional maturation of synapses have been recently identified. These synapse-inducing proteins include
neuroligins and their binding partners: neurexins. It was found that insulin secretion and the proliferation rate of
β-cells increased when β-cells were co-cultured with cells overexpressing neuroligins. We propose that
neuroligin-derived molecules arranged in clusters can enhance β-cell functions by increasing insulin secretion,
functional maturity and protecting in stress conditions. Several peptides were derived from crystal structures of
different neuroligins and neurexins using molecular modeling method. Based on these results, we designed and
fabricated poly(amidoamine) dendrimer decorated by the peptide. The compound increased insulin secretion,
induced the formation of islets-like cellular structures, proliferation rate and protected β-cell line against
oxidative and ER stresses. Identical effect on the insulin secretion was also obtained in isolated mice islets.
Moreover, diabetic mice treated by our compound significantly reduced blood glucose level in comparison to
untreated mice.
In summary, we report about the development of a new class of potential antidiabetic compounds. Such systems
might support β-cell differentiation and viability in vitro, which will increase survival of further β-cell
transplants in vivo. Such approach of using the neuron secretion machinery presented in β-cells as a target for
antidiabetic drug design was never reported before.
107
PB-107
"Bitter Taste Signals Toxicity": Assessing the Paradigm using
Chemoinformatics
Ido Nissim, Ayana Dagan-Wiener, Masha Y. Niv
Institute of Biochemistry, Food Science and Nutrition, The Hebrew University of Jerusalem,
Rehovot, Israel
Bitter taste is one of the basic taste modalities and is commonly assumed to signal toxicity and alert animals
against consuming harmful substances, but no quantitative study has been conducted to validate this assumption
until this point. It is known that some toxic compounds are not bitter and many bitter compounds have
negligible toxicity while presenting profound health benefits. Furthermore, the receptors for bitter compounds,
Tas2Rs - a subfamily of G-protein-coupled receptors (GPCRs) - are expressed in extra-oral tissues. All this
suggests additional physiological roles that may not be related to food choices or toxicity. Building upon the
recently established database of bitter compounds – the BitterDB – and using several datasets of toxic
compounds, we set to quantify the bitterness-toxicity relationship. We found that the overlap between the bitter
and toxic compounds is only partial. Additionally, bitter acute oral LD50 values are much higher compared to
the toxic datasets. We therefore assess the similarity of the bitter and the toxic datasets and apply the newly
developed bitterness-prediction algorithm. While more than half of the bitter compounds have some toxicity,
only a third of the toxic compounds are expected to be bitter. The generalistic approach used allowed quantif
ication of the bitter and toxic chemical spaces and clarification of their relationship, suggesting that bitter taste
is not merely a gatekeeper for toxicity.
108
PB-108
Rational design of Polyglutamic acid delivering an optimized Combination of
Drugs Targeting Melanoma Brain Metastases
Evgeni Pisarevsky, Yana Epshtein, Dikla Ben-Shushan, Anat Eldar-Boock,
Ronit Satchi-Fainaro
Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv,
Israel
Targeted chemotherapy is an efficient approach to fight cancer, nonetheless it still shares some of the problems
associated with conventional chemotherapy such as limited therapeutic response. A more accurate and effective
method is required in order to target the drug to the tumor, aiming to facilitate its accumulation in cancer
tissues. Therefore, developing a novel targeted system is necessary, in which we can combine a number of
active entities to increase the treatment efficacy [1]. To meet these goals, we selected to exploit poly (α,Lglutamic acid) (PGA) polymer as a nanocarrier for selective delivery to the tumor. Excellent biocompatibility
and biodegradability in vivo make PGA an ideal biomedical material[2]. In addition, the carboxylic acid
sidechain can be modified for small drug conjugation for combined drug delivery. Here, we selected two drugs,
a MEK1/2 inhibitor (Selumetinib)[3] and a BRAF inhibitor (Dabrafenib)[4], that exhibited synergism in vitro.
The RAS/RAF/MEK/ERK pathway plays a role in normal organogenesis; however, it can lead to malignant
cellular proliferation, inhibition of apoptosis, and invasion when aberrantly activated. We report for the first
time the conjugation of these two drugs to PGA with controlled drug loading up to 30 wt. % and a diameter size
range of 5-15 nm. PGA-Selumetinib-Dabrafenib-di-ol inhibited the proliferation of melanoma cells at an IC50
of 80 nM (Dabrafenib-equivalent) and decreased their migratory ability. Comprehensive physico-chemical and
biological characterization was performed for better understanding of the structure-activity relationship of the
combined conjugate.
References
[1] Markovsky, E.; Baabur-Cohen, H.; Satchi-Fainaro, R., J. Controlled Release, (2014) 187, 145.
[2] Deming, T. J., Prog. Polym. Sci., (2007) 32, 858.
[3] Chapman, P. B et al., New England Journal of Medicine, (2011) 364, 2507.
[4] Falchook, G. S et al., The Lancet, 379, 1893.
109
PB-109
Highly Effective and Hydrolytically Stable Vanadium(V) Phenolato Antitumor
Agents: The Role of the Ligand in the Cytotoxic Pathway
Lilia Reytman, Edit Y. Tshuva
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Today numerous metal compounds are being investigated worldwide in order to resolve the limited activity
range and severe toxicity of the antitumor drug cisplatin. One of the most promising metals studied today is
vanadium. Vanadium compounds were found to exert favorable properties for use in therapy, but the
complicated aquatic chemistry of vanadium compounds impeded the potential of vanadium as an antitumor
agent. Therefore, the development of compounds with improved hydrolytic stability is essential for therapeutic
utilization. In previous work we developed a family of oxo-vanadium(V) complexes with pentadentate diamino
tris(phenolato) ligands, and no labile ligands, which therefore exhibited remarkable resistance towards
hydrolysis. Importantly, these compounds displayed exceptional cytotoxic activity, higher than that of cisplatin
by up to two orders of magnitude, which was preserved during incubation in DMSO for several weeks and in
aqueous medium for a few days. These complexes also displayed therapeutic potential through preliminary in
vivo results, in which a representative complex achieved promising anti-tumor effects with no sign of clinical
toxicity.1
However, 19F-NMR measurements of cells treated with a representative compound indicate that the complex
decomposes in the presence of cells and releases the free ligand, which also possesses cytotoxic activity. To
answer the question whether the free ligand might be the active species inside the cell mechanistic investigation
is being conducted. In addition, structural changes to the ligand are being applied to increase the stability of the
obtained complex. Preliminary results and insights regarding both objectives will be presented.
1] L. Reytman, O. Braitbard, J. Hochman, E. Y. Tshuva, Inorg. Chem. 2016, 55, 610–618.
110
PB-110
Neuroligin-2 Mimetics Positively Modulate Beta Cells Functions
Efrat Shtriker1, Guy Cohen1, Steven D. Chessler2, Gerardo Byk1, Arie Gruzman1
1
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Medicine, University of California, Irvine, USA
The β-cell membrane and the presynaptic active zones of neurons are the assembly sites of very similar protein
complexes mediating regulated secretion. Cell-surface, synaptic proteins that mediate interactions between
neurons and guide the formation and functional maturation of synapses have been recently identified. These
synapse-inducing proteins include the neuroligins and their binding partners: the neurexins. Like other synaptic
adhesion molecules, these participate in transcellular protein-protein interactions across the synaptic cleft. We
have shown that β-cells express neuroligins and neurexins on their plasma membrane, among them neuroligin-2
(NL-2) and neurexin-1 (NX-1). We also have found that insulin secretion and the proliferation rate of β-cells
increased when β -cells were co-cultured with cells overexpressing NL-2. Such co-cultured β-cells were also
less vulnerable to both oxidative and ER stress.
Based on these results, we aim to design and synthesize potent and effective NL-2 mimetics that might lead to
the development of a novel class of antidiabetic drugs. We created mimetic NL-2 (9-amino acid peptide derived
from the NL-4 crystal structure) covered by hydrogel nanoparticles. We hypothesized that this cluster may
enhance β-cell function, increasing glucose-stimulated insulin secretion and functional maturity and protecting
β-cells in stress conditions. Indeed, clustered peptide which was derived from NL-2 sequence increased β-cells
cell proliferation and protected them from oxidative stress. Furthermore, such cluster might support β-cells
differentiation from stem cells and their viability in vitro which might increase the survival of further β-cells
transplant. This application might be useful as a basis for development of novel antidiabetic treatment.
111
PB-111
Development of Novel Drug Candidate against Prostate Cancer
Moran Shubely1, Dhanoop Manikoth Ayyathan2, Michael Shokhen1, Michael Blank2,
Arie Gruzman1
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Faculty of Medicine, Bar-Ilan University, Safed, Israel
Among men, prostate cancer is the third leading cause for death out of all cancers. Despite remarkable progress
in premature diagnostics and treatment, prostate cancer stands as one of the most devastating human diseases.
The development of anti-prostate cancer drugs remains urgent.
Smurf2 is an E3 ubiquitin ligase sufficient in the regulation of protein homeostasis. Previous studies have
demonstrated that the distribution of Smurf2 is different in both normal and cancer tissues: nuclear Smurf2 is a
negative regulator of RNF20 that causes modifications in the epigenetic landscape, in particularly in
monoubiquitination of histone H2B. The H2B histone packs and orders the DNA and contributes in gene
expression regulation and DNA damage response. On the other hand, cytosolic Smurf2 has been reported to
reduce the steady-state of Axin and GSK3b (two negative regulator of Wnt/β-catenin signaling). The activation
of this signaling pathway leads to uncontrolled cell growth.
Smurf2 is a member of HECT-type family of E3s. This family is characterized by a common modular
organization: an N-terminal C2 domain, two to four WW domains, and a C-terminal HECT domain. The HECT
domain is responsible for the attachment of ubiquitin moieties to target proteins. We hypothesized that targeting
of Smurf2 for inactivation might affect the ability of cancer cells to proliferate and/or withstand anticancer
treatments. Based on computational modeling several Smurf2 HECT domain specific binders (activators and
inhibitors) were designed and synthetized. Then, in vitro evaluation in prostate cancer models showed that two
novel peptidomimetic compounds were active at nM concentration range.
This novel approach for the possible treatment of prostate cancer which is based on the modulation of Smurf2
function has not been reported yet.
112
PB-112
Design and Synthesis of MRI-Based Molecular Biosensors for Monitoring Zn2+
Deva Nishanth Tirukoti, Alona Bar-On, Liat Avram Biton, Amnon Bar-Shir
Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
Zinc (Zn2+) is the second most abundant metal ion in the human body and it plays a pivotal role in various
cellular process in health and disease.1 Therefore it is very important to develop methodologies for longitudinal
visualization and quantification of labile Zn2+ levels from live intact subjects. The light signal source of
fluorescence Zn2+-sensors don’t allow their use in deep tissues of live subject and therefore molecular probes
for MRI applications should be considered. Several MRI-sensors for monitoring labile Zn2+ have been
suggested based on T1-contrast enhancement with Gd based contrast agent2,129Xe-NMR3,19F-CEST MRI4.
19
F-based sensors for MRI applications show several advantages over the MRI metal based contrast agents, due
to negligible amount of 19F in biological tissue and no background,100% natural isotope abundance of 19F. Here
we show that 19F-modified dipicolylamine derivatives have the potential to be used as 19F-CEST sensors for
Zn2+ monitoring with MRI. The synthesis of the library of the 19F-probes and their binding properties towards
Zn2+ ions is discussed. One compound showed the potentiality to be used as MRI-based probe for spatially
monitoring Zn2+ with MRI. The ability to amplify the 19F-signal through saturation transfer and thus monitoring
low concentrations of Zn2+ should allow us to proceed to biological models.
References:
1] Lippard, S. J et al. Annu. Rev. Biochem. 2011, 80, 333−355.
2] Sherry, AD. et al. PNAS. 2016. 113, 37, E5464-E5471.
3] Kotera, N. et al. Angew. chem. Int. Ed. 2012, 51, 4100-4103.
4] Bar-shir, A. et al. JACS. 2013, 135, 12164-12167.
113
PB-113
Design and Synthesis of Novel Peptidomimetic Inhibitors of TLR4 (Toll-like
receptor 4), as a Potential Cardio-Protective Agents
Lena Trifonov1, Vadim Nudelman2, Erez Matsree2, Edward Korshin1, Asher Shainberg3,
Edith Hochhauser2, Arie Gruzman1
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Felsenstein Medical Research Center, Tel Aviv University, Tel Aviv, Israel
3
Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
Myocardial ischemia (MI) is the leading cause of death in the USA and other developed countries. Similarly,
sepsis is one of the most common complications after surgery, and is the main cause of death in non-coronary
adult intensive care units. These conditions consist of two components: the first is a direct, depressive influence
on the cardiovascular system, and the second is the involvement of the systemic immune system in the heart as
a response to inflammation caused by sepsis or MI. The mechanism that leads to the release of proinflammatory cytokines also includes the activation of TLR4. This protein is a pattern recognition receptor that
specifically mediates cellular responses generated after binding to the receptor bacterial lipopolysaccharide
(LPS). TLR4 also responds to endogenous factors produced during different stress stimuli or with cell damage.
These responses support TLR4`s role in the inflammatory response to ischemic injury. The goal of presented
here research is to find a novel drug candidates which will be able to inhibit TLR4’s activity and as a result of
this to suppress the negative effects of sepsis and MI.
We used known peptide (IVFAEMOCG) which binds to the TIR domain of the receptor and inhibit the TLR4’s
activation. This peptide mimics a sequence of TLR4 downstream target (TRAM adaptor), binding to TRAM
and interrupts the physiological interaction between the TLR4 TIR domain and the adaptor molecule. Based on
sequence of the peptide, we synthesized its peptidomimetic derivatives.
Out of the first set of 7 peptidomimetics, LT51-54 exhibited a significant protective effect in cardiomyocytes.
Based on their structures, another 23 molecules were designed, synthesized, and tested in-vitro. The most active
compounds were: LT58, LT59, LT61, and LT62.
114
PB-114
Antitumor Ti(IV) Complexes Based on Salen Ligand: Fluorescence Properties
for Cell Imaging
Avia Tzubery, Edit Y. Tshuva
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Titanium(IV) complexes are highly attractive candidates for anticancer treatments due to their high antitumoral
features and low toxicity of their final hydrolysis product titanium dioxide. Accordingly, titanium complexes
titanocene dichloride and budotitane were the first to enter clinical trials after platinum complexes. These
compounds showed promising results but eventually failed due to their low hydrolytic stability in biological
environment that led to undefined aggregates with low solubility, hampering mechanistic investigations. We
have introduced Ti(IV) complexes with phenolato ligands that presented exceptional hydrolytic stability,
combined with high cytotoxicity. In particular, Ti(IV) complexes based on salen ligands showed promising
result with high activity and improved stability and solubility in relevant biological solvents. 1,2 Salen ligands,
salicylaldehyde based bis-shiff bases with different conjugated amine bridges, could be also functionalized by a
various electron accepting and donating subtituents, to present well tuned photophysial properties for various
applications.
Herein we present the design of Ti(IV) salen complexes that along with their high activity and stability, could
function as fluorophores for living cell imaging. The salen ligands can be modified to include different
subtituents on the phenolato and the anime moieties of the salen ligand, which could enhance their
fluorescence. Moreover, the salen ligands bind equatorially to the Ti(IV) center, enhancing the ligand planarity
and contributing to π-conjugation. This photophysial property of the salen Ti(IV) complexes may be utilized to
add new information on cellular integrations and biological target of the Ti(IV) complexes.
(1) Tzubery, A., and Tshuva, E. Y. Inorg. Chem. (2011) 50, 7946–7948.
(2) Tzubery, A., and Tshuva, E. Y. Inorg. Chem. (2012) 51, 1796–1804.
115
PB-115
Anti-Inflammatory Indoline Derivatives Mitigate Liver Damage in a Mouse
Model of Acute Liver Injury
Shani Zeeli1, Inessa Yanovsky1, Elinor Bardugo1, Abraham Nudelman1, Efrat Finkin-Groner2,
Shlomi Finkin3, Marta Weinstock2
1
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
2
Institute for Drug Research, Faculty of Medicine, The Hebrew University of Jerusalem,
Jerusalem, Israel
3
Institute for Medical Research Israel Canada, The Hebrew University of Jerusalem,
Jerusalem, Israel
Acute liver failure (ALF) is a severe life-threatening clinical syndrome caused by sudden and severe liver
injury.1 The underlying pathological cause for ALF is the extensive necrosis and apoptosis of hepatocytes that
can be induced by acute bacterial or viral infections, excessive alcohol intake, drug overdose, idiosyncratic drug
reactions and toxins.2-4
Exposure of mice to D-galactosamine (GalN) and lipopolysaccharides (LPS) induces acute liver failure through
elevation of the cytokine TNF-α, which causes liver damage resembling that in the human disease. The current
study evaluated in this model the effect of novel indoline derivatives (Figure), which display anti-inflammatory
and antioxidant effects in macrophages.
AN1284 is able to prevent lethality, apoptosis, cytokine production and oxidative stress in a mouse model of
acute liver failure induced by GalN/LPS at extremely low doses of 0.075-0.75 mg/kg. This remarkable potency
accords with its anti-inflammatory activity in isolated macrophages in the low nanomolar or picomolar range.
Moreover, in almost all measures of liver damage, AN1284 is at least as, if not more effective than
dexamethasone (3 mg/kg). Both indoline derivatives AN1284 and AN1297 produce their anti-apoptotic and
anti-inflammatory effects by preventing the phosphorylation of MAPK p38 and nuclear translocation of the
transcription factor, AP-1.
References
1] Bernal, et al., Lancet 2010, 376, 190–201
2] Khashab, et al., Gastroenterol. Rep. 2007, 9, 66-73
3] Lee, et al., Liver Dis. 2008, 28, 142–52
4] O’Grady, et al., Med. J, 2005, 81, 148–154
Acknowledgment – Supported by “The Ministry of Science, Technology and Space, Israel”
116
PB-116
Uridine-5`-O-α,α-Dithiophosphate Analogues: Synthesis and Chemical
Properties
Vadim Zelikman, Aviad Sela, Bilha Fischer
Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Replacement of a phosphate moiety by thiophosphate in nucleotides may be a useful tool for altering binding
properties of nucleotides with specific proteins with a view to studying those proteins or developing
biologically active molecules. Therefore, the presence of a di-thiophosphate moiety instead of a thiophosphate
group is expected to have a unique influence. In this study, a series of uridine-based nucleotides (1-4) were
synthesized via a dithiaphospholane intermediate (5). The synthesis was performed by coupling uridine-2’,3’methoxymethylidene with 3,1,2-dithiaphospholane, followed by phosphorus oxidation with S8 and finally,
opening of dithiaphospholane ring by DBU mediated nucleophilic attack by monophosphate, pyrophosphate, or
methylene-diphosphonate. The chemical stability of the analogues was evaluated by 31P-NMR regarding air
oxidation, as well, as acidic and basic conditions. Most of the analogues exhibited exceptional stability. For
instance, analogues 2-4 were stable more than one month under air-flow at RT and showed no disulfide bond
formation. Analogues 2 and 3 were highly stable at pH 1.6 for at least 1 week at RT. Analogue 3 exhibited
limited decomposition after 25 days at pH 12 (23% of decomposition). The ability of derivatives 1-4 to
coordinate physiologically relevant metal ions was studied. Specifically, we titrated analogues 2-4 with Zn2+
and Ca2+-ions. Analogues 2 and 4 bind Zn2+-ion via phosphates α and β and show selectivity toward Zn2+-ions
vs. Ca2+-ions, as determined by 31P-NMR. The unexpectedly stable uridine-dithiophosphate analogues may
prove useful tools for studying uridine-binding proteins, in particular Zn2+-containing proteins.
117
PB-117
Thermal and Catalytic Pyrolysis of High Density Polyethylene: Lessons
Learned on Solid Organic Waste Treatment
Hadas Raveh-Amit, Ofra Klein-Ben David, Gal Atlas, Nissim Banano, Gabriela Bar-Nes
Applied Chemistry, Nuclear Research Center Negev, Beer-Sheva, Israel
Organic waste is characterized by high volume to weight ratio and may pose a hazard due to radiolysis and
generation of combustible and explosive gases. Thus, minimizing waste volume and immobilization are of high
importance in the treatment of contaminated polymers. In the present study, polymer decomposition of the
commonly used thermoplastic polyolefin high density polyethylene (HDPE) was optimized. HDPE was
pyrolysed in a batch reactor at 450°C and atmospheric pressure with a range of aluminosilicate catalysts,
including Zeolite Y and ZSM-5. The impact of catalysts, their acid strength and catalyst to polymer ratio on
decomposition efficiency were evaluated. Product conversion into coke, liquid and gaseous products were
measured based on product yields, and gaseous product composition was measured by gas chromatography.
Higher conversions to gas were obtained for HDPE in the presence of ZSM-5 zeolites (~90%) than Zeolite Y
(~52%) or no catalyst (~20%). The highest impact of ZSM-5 was reached at a catalyst to polymer ratio of 1:10,
independent of the Si/Al ratio of the catalysts. Moreover, high fraction of gaseous light hydrocarbons (C1-C4)
was observed (~80%) and only minimal oil fractions were obtained (2-7%). Altogether, our data demonstrate
that catalytic pyrolysis of H---DPE over the ZSM-5 zeolite results in high decomposition efficiency and
supports its use for organic solid waste treatment. These results are especially encouraging due to the clear
benefits of pyrolysis over incineration techniques, including it being an environmentally friendly, easy to
control process.
118
PB-118
Conversion of Glycerol to 1,3-Propanediol via Fermentation by Saccharomyces
Cerevisiae
Betina Tabah1, Alexander Varvak2, Indra Neel Pulidindi1, Elizabeth Foran2, Ehud Banin2,
Aharon Gedanken1
1
Department of Chemistry and Institute for Nanotechnology and Advanced Materials (BINA),
Bar-Ilan University, Ramat-Gan, Israel
2
The Mina and Everard Goodman Faculty of Life Sciences and
Institute for Nanotechnology and Advanced Materials (BINA),
Bar-Ilan University, Ramat-Gan, Israel
The conversion of biorenewable feedstock for the production of valuable materials has become an important
research trend due to the depletion of non-renewable resources and increasing global energy demand. Once
considered a valuable by-product, crude glycerol is now becoming a ‘waste product’ due to the rapid growth of
biodiesel industry. It is, therefore, crucial to develop environmental-friendly solutions for glycerol waste and
facilitate the sustainability of the biofuel market. One of the most promising strategies for glycerol utilization is
the production of commercially-valuable propanediols through selective hydrogenolysis, providing a green and
economically-competitive route from a renewable carbon source rather than non-renewable petroleum. 1,3propanediol (1,3-PDO) is a high-value specialty chemical, usually produced by the reduction of glycerol and
used primarily in polyester fibers, films, and coatings. While the chemical and bacterial syntheses of 1,3-PDO
are well-known, we report for the first time the possibility of converting glycerol to 1,3-PDO by a fungal strain.
Synthesizing 1,3-PDO by biological means is extremely lucrative, and to the best of our knowledge, this is the
first study to develop an optimized process for the production of the value-added chemical 1,3-PDO from the
industrial waste glycerol via fermentation using the biocatalyst instant baker`s yeast (Saccharomyces
cerevisiae). Various glycerol fermentation types (aerobic, semi-aerobic, and anaerobic) were tested at different
reaction temperatures (25, 30, and 37 °C) to optimize the process. Under optimal conditions (anaerobic
fermentation at 25 °C), 42.3 wt% 1,3-PDO yield was achieved with 93.6 wt% glycerol conversion,
corresponding to ~60% of the theoretical 1,3-PDO yield.
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