Supporting Information
Controlling the Spatial Organization of Liquid Crystalline
Nanoparticles by Composition of the Organic Grafting Layer
Michał M. Wjcik,* Magdalena Olesińska, Michał Sawczyk, Jzef Mieczkowski, and
Ewa Grecka*[a]
chem_201406262_sm_miscellaneous_information.pdf
Experimental procedures
The small angle X-ray diffraction patterns were obtained by Bruker Nanostar system with an area detector VANTEC 2000
and CuKα radiation. The temperature of the sample was controlled with precision 0.1 degree. The signal intensities vs.
wave vector q were obtained through integration of the pattern over azimuthal angle. The nanoparticle samples were
aligned by shearing of small amount of material placed on the Kapton tape at temperature ~80 °C or ~130 °C. Gold clusters
size was also evaluated from broadening of the x-ray signals from gold crystal lattice using Debye-Schererr model and
from TEM images. TEM observations were performed on a JEM 1400 (JEOL Co., Japan 2008) electron microscope. The
optical birefringence was measured using setup built with photoelastic modulator (PEM-90), He-Ne laser photodiode (PIN20) and lock-in amplifier (EG&G 7265), the same setup was used previously for precise measurements of birefringence in
liquid crystalline phase. All reactions were carried out under a nitrogen (N 2) atmosphere in dried glassware with efficient
magnetic stirring. Purification of reaction products was carried out by column chromatography using silica gel 60 (230-400
mesh). Analytical thin-layer chromatography (TLC) was performed using Silica Gel 60Å F254 (Merck) pre-coated glass
plates (0.25 mm thickness) and visualized using iodine vapor and/or UV lamp (254 nm). The solvents used:
trichloromethane, dichloromethane, toluene and tetrahydrofuran were of p.a. quality. Unless otherwise specified,
substrates were obtained from Sigma-Aldrich and used without further purification. Yields refer to chromatographically and
spectroscopically (1H NMR) homogeneous materials. Vario EL III (Heraeus) was used for determination of C, H, N and S
contents. The method was based on the catalytic combustion at 1150 oC in helium/oxygen atmosphere. The resulting
products were separated using special adsorption columns and measured using the thermal conductance detector (TCD).
Synthesis of mesogenic ligands
General procedure for the synthesis of intermediates of rod – like mesogenic ligands has been described previously compound Ii and compound IIii. Only difference is a synthesis of final thiol molecules where the following procedure with
the respective stoichiometry was applied.
Synthesis of branched mesogenic molecule I - N, N – dioctyl – 4 – [(4’ – (11- mercaptoundecyloxy)biphenyl – 4 –
ylo)xymethyl] benzamide
O
(H 17 C8 ) 2 N
HMDST
O
O
(H 17 C8 ) 2 N
O(CH 2 ) 11 Br
O
O(CH 2 ) 11 SH
TBAF
I-Bromide
I
To a cooled solution of 4.4g (5.8 mmol) of [3] (Scheme 1, main text) in dry tetrahydrofuran under argon atmosphere 1.30
mL (6.09 mmol) of HMDST was added quickly. After 5 minutes 6.38 mL (1M solution in tetrahydrofuran) of TBAF was
added. The reaction mixture was stirred at room temperature for 1h. Then to the reaction mixture 80 mL of CH 2Cl2was
added and washed with saturated water solution of NH4Cl (three times using 40 mL). Afterwards mixture was dried under
MgSO4and the solvent was evaporated. The crude product was purified by column chromatography (eluent: CHCl 3) to get
3.12g (75 %) of the compound I.
1
H NMR (500 MHz; CDCl3): 7.48 (2H; d; J = 8.5 Hz); 7.45 (4H; m); 7.37 (2H; d, J=8.0Hz); 7.01 (2H, d, J=8.8Hz; 6.94 (2H;
d, J=8.8Hz); 5.12 (2H; s); 3.98 (2H; t; 7.4Hz); 3.32 (4H; br); 2.52 (2H, m); 1.92 – 1.72 (6H, m); 1.68-1.16 (34H; m); 0.90
(6H; m); MS (TOF MS ES+): m/z 753.5 [M+Na+].
13
C NMR (125MHz, CDCl3) 172.85, 160.24, 160.21, 138.70, 136.14, 133.46, 129.33, 128.72, 127.97, 126.37, 116.25,
115.62, 70.96, 69.66, 45.61, 31.73, 29.15, 29.04, 28.80, 28.69, 27.75, 27.64, 26.58, 14,00. Elemental analysis. Calculated:
C(77.31%), H(9.80%), N(1.92%) Found: C(77.41%), H(9.78%), N (1.98%)
Synthesis of kinked-tail
yl]oxymethyl]benzoate
mesogenic
molecule
O
H3 C(H 2 C) 7 HC=HC(H 2 C) 8 O
II
HMDST
O
(oleyl-4-[4'-(11
mercaptoundecyloxy)
O
H3 C(H 2 C) 7 HC=HC(H 2 C) 8 O
O(CH 2 ) 11 Br
biphenyl-4-
O
O(CH 2 ) 11 SH
TBAF
II-Bromide
II
The reaction was performed in a Schlenk flask with argon/vacuum connection. To a 50 mL flask oleyl- 4-[4'(bromoundecyloxy)biphenyl-4-yloxymethyl]benzoate [4] (1000 mg, 1.24 mmol, 1 eq.) and anhydrous THF (5 mL) were
added. The mixture was stirred under N2 at room temperature for 10 minutes. Precipitate was dissolved. The resulting
solution was cooled to –10 oC and HMDST (hexamethyldisilthiane) (243 mg, 1.36 mmol, 1.1 eq.) was injected using
syringe. After 5 minutes TBAF (tetra-n-butylammonium fluoride) (3.94 mg, 1.30 mmol, 1.05 eq in 2ml of THF) was added
under vigorous stirring. After 40 minutes the reaction mixture was allowed to warm gradually to room temperature and
stirred over 30 minutes. To a slightly green solution 70 mL of CH2Cl2 was added and then washed with saturated solution
of NH4Cl (2x40 mL) and with pure water (1x40 mL). Afterwards mixture was dried (MgSO 4). The solvent was evaporated
and the crude compound was purified by column chromatography (eluent: toluene/hexane 1:1) to afford 700 mg of
compound II as white solid (71%).
H NMR (CDCl3, 200MHz) δ8.07 (2H, d, J=8.9Hz); 7.54- 7.41 (6H, m); 7.04-6.89 (4H, m); 5.44-5.30 (2H, m); 5.16 (2H,s);
4.32 (2H, t, J=6.7); 3.98 (2H, t, J=6.6Hz); 2.52 (2H, m);2.08-1.94 (4H, m); 1.89-1.68 (8H, m); 1.52-1.22 (34H, m); 0.89 (3H,
t,J=6.8);
1
C NMR (125 MHz, CDCl3) δ, 166.41;158.34; 157.54; 142.16; 134.09; 133.09; 130.45; 130.25; 130.08; 129.98;
129.85; 129.79; 127.76; 127.69; 126.93; 115.10; 114.76; 69.46; 68.07; 65.17; 39.19; 34.03; 32.60; 32.57; 31.92; 31.90;
29.76; 29.72; 29.69; 29.65; 29.60; 29.51; 29.49; 29.42; 29.31; 29.35; 29.31; 29.29; 29.26; 29.21; 29.17; 29.04; 28.72;
28.51; 28.35; 27.21; 27.18; 26.03; 24.64; 22.67; 14.10;
13
Plot 1. Percent of carbon, sulfur, nitrogen and gold atoms content in the hybrid material versus number of attached
secondary mesogenic ligands LN (I) used for estimation of average secondary ligands population in hybrids H-1 to H-5
Plot 2. Percent of carbon, sulfur and gold atoms content in the hybrid material versus number of attached secondary
mesogenic ligands used for estimation of average secondary ligands population in hybrids H-6 and H-7
Figure 1 . The x-ray pattern of oriented sample II-bromide, the absence of high angle signal along direction
perpendicular to the layer normal evidences presence of hexaticSmF phase
Figure 2. The x-ray pattern of oriented sample II-bromide, the presence of high angle signal along direction
perpendicular to the layer normal evidences presence of hexatic SmI phase.
Figure 3. The x-ray pattern of oriented sample II-bromide in SmC phase, the diffused signal at high angle evidences
presence of liquid like order inside the layer
Figure 4. 1H NMR spectra of primary gold nanoparticles covered with hexane thiol (C 6H13SH)
Figure 5. 1H NMR spectra of I2-decomposed gold nanoparticles H2.
Figure 6. 1H NMR spectra of I2-decomposed gold nanoparticles H3
Figure 7. 1H NMR spectra of I2-decomposed gold nanoparticles H4.
Figure 8. 1H NMR spectra of I2-decomposed gold nanoparticles H5.
Figure 9. XPS survey spectra of H2. Bands of binding energy, EB, for the Au, N, O, S and C atoms are distinguished
Figure 10. XPS survey spectra of H4. Bands of binding energy, EB, for the Au, N, O, S and C atoms are distinguished
Figure 11. SAXS patter of oriented sample H-1 collected at 80 oC
Figure 12. SAXS patter of oriented sample H-3 collected at 81 oC
Figure 13. TEM image of hybrid material H-2, showing narrow size distribution of hybrid nanoparticles (core size ~2nm)
modified with mesogen I
Ligand exchange ration calculations
The ligand exchange reaction was performed in a Schlenk flask with argon/vacuum connection under following conditions:
Hybrid material GNP@C6H13SH
H-1
25 mg
H-2
25 mg
H-3
25 mg
H-4
25 mg
H-5
25 mg
H-6
25 mg
H-7
25 mg
Secondary Ligand (quantity)
I (3.2 mg)
I (5.32 mg)
I (10.7 mg)
I (21.4 mg)
I (53.0 mg)
II (5.1 mg)
II (23.3 mg)
Total Yield
71%
73%
65%
57%
59%
76%
61%
Table 1. Conditions of ligand exchange reaction (total volume of reaction mixture 6ml in toluene; re action time 72h). Total
yield decrease due to sustained purification procedure.
Sample
H2
H5
H2
H5
C peak area (a.u.)
6619
7740
C/RSF
21079.6
24649.9
S peak area (a.u.)
663.5
264.76
S/RFS
925.4
369.3
N peak area (a.u.)
207.49
268.79
N/RSF
415.2
538.7
Au peak area (a.u.)
28588.81
13672
Au/RSF
4201.4
2009.1
Table 2. Ratios between each elements in samples H2 and H4, where RSF are Relative Sensitivity Factors that are used
to scale the measured peak areas .The peak areas are representative of the amount of each element in the sample
surface.
In our recent investigations ligand exchange reactions of Au 309(SC6H13)91with hexanethiol (SHC6H13, further LX) and
mesogenic molecules ( I or II) as incoming ligands, produce nanoparticles having different, statistically determined, relative
populations of the two thiolate ligands (LX and I or II), i.e., Au309(LX)m(I)n, where m and n vary but always sum to 91. The
dynamics and mechanism of this reaction is well known and were probed by determining its kinetic order and final
equilibrium position relative to incoming and initial (RS) protecting thiolate ligands. The reactions can be characterized by
1
H NMR, IR, MALDI-MS, XPS, TGA or by simple elemental analysis (EA). Some authors mentioned the dispersity of placeexchange reaction products can be also preliminarily inspected by chromatography, where nanoparticles are degraded in
presence of iodine and mixture of organic molecules could be analyzed by LC-MS and 1H NMR. All those methods are
not completely ideal so should be correlated, where MALD-MS gives best results when nanoparticles are charged, IR is
not quantitative method and other tools are not accurate as should be. During our research we have chosen simple and
easily available elemental analysis (EA) and compare its results with 1H NMR investigations (both pure material and Iodidedecomposed). By choice of reactant concentrations, the exchange reaction can reach an equilibrium state and give mixed
population of primary and incoming ligands, which are easy to identify by EA because chosen incoming ligands (I) contains
nitrogen atoms, when primary ones do not. According to theoretical calculations, well known reported experimental data
and based on our research (SAXRD,HR-TEM) we assumed that nanoparticle consists of 309 gold atoms. That is why we
can estimate simple relation between the percentage of nitrogen (or other elements) atoms and number of incoming
ligands covering gold nanoparticles:
%𝑪 =
𝒏𝑴𝑪 𝟒𝟕 + (𝟗𝟏 − 𝒏)𝑴𝑪 𝟔
𝟑𝟎𝟗𝑴𝑨𝒖 + (𝟗𝟏 − 𝒏)𝑴𝑳𝑿 + 𝒏𝑴𝑰
Equation 1 where,
%C – percentage of carbon
n – number of incoming ligands I or II (from 1 to 91)
MC– molecular mass of carbon
MI– molecular mass of incoming ligands I (730.14 g/mol)
MII– molecular mass of incoming ligands II (757.16 g/mol)
MAu- molecular mass of gold atoms (196.96 g/mol)
MLX- molecular mass of primary ligands (118.24 g/mol)
Plot 3. TGA data recorded for samples H6 and H7 with their auxiliary samples (a1, a2, a3) having intermediate ligands (II)
concentration.
i
M.M. Wojcik, M. Gora, J. Mieczkowski, J. Romiszewski, E. Gorecka, D. Pociecha, Soft Matter, 2011, 7 (22) , 1056110564
ii
M. Wojcik, M. Kolpaczynska, D. Pociecha, J. Mieczkowski and E. Gorecka, Soft Matter, 2010, 6, 5397–5400