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DOI:10.1002/ejic.201301008
Phase-Controlled Deposition of Copper Sulfide Thin Films
by Using Single-Molecular Precursors
Saba Ashraf,[a] Aamer Saeed,[a] Mohammad Azad Malik,[b]
Ulrich Flörke,[c] Michael Bolte,[d] Naghmah Haider,[e] and
Javeed Akhtar*[f]
Keywords: Copper sulfide / Thin films / Chemical vapor deposition / Acyl thiourea
Herein, we describe the synthesis and characterization of
new ligands, N,N-diethyl-N⬘-(1-naphthoyl)thiourea (1a) and
N,N-dipropyl-N⬘-(1-naphthoyl)thiourea (1b), and their complexes with copper, bis[N,N-diethyl-N⬘-(1-naphthoyl)thioureato]CuII (2a) and bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]CuII (2b). All four compounds (i.e., 1a, 1b, 2a, and 2b)
were characterized by elemental analysis, 1H NMR and 13C
NMR spectroscopy, and FTIR spectroscopy. The structures of
compounds 1a, 1b, and 2b were determined by single-crystal
X-ray diffraction analysis. Thermogravimetric analysis of 2a
and 2b showed that both compounds decompose between
190 and 370 °C. Compounds 2a and 2b were then used as
single-molecular precursors for the deposition of copper sulfide thin films through aerosol-assisted chemical vapor deposition. The phase and purity of the as-deposited thin films
were confirmed by powdered X-ray diffraction, which
showed that the as-grown films were composed of the orthorhombic (Cu7S4) phase only. Morphological studies of the asdeposited films were performed by using field-emission
scanning electron microscopy. The elemental composition of
the thin films was determined by energy-dispersive X-ray
spectroscopy.
Introduction
explore new and improved reaction pathways.[3] The DSR
involves the use of toxic and pyrophoric reagents, and the
synthesis is performed in multiple steps; this often results
in lower yields. Moreover, the quality of the as-prepared
nanomaterials is not good, and it was shown that methods
used to grow nanomaterials have a significant influence on
crystallinity, composition, and size.
These parameters subsequently control the properties of
the as-prepared nanomaterials. The single-molecular precursor route (SMPR) has recently gained considerable attention for the deposition of thin films and nanomaterials
of metal sulfides, selenides, tellurides, and oxides.[4] Interestingly, by the careful design of an organic ligand, we can
incorporate a metal atom to produce what is commonly
known as a single-source precursor (SSP) or a single-molecular precursor (SMP). Depending on the nature and
number of metal-coordinating centers in the ligand, more
than one similar or dissimilar metal atom can be incorporated to deposit binary- or ternary-phase thin films/nanomaterials. The SMP approach is a very attractive route to
prepare thin films and nanomaterials owing to the choice
of a wide variety of precursor reagents, mild reaction conditions, and thermal/photostability of the as-prepared SMP.[5]
Nanomaterials and thin films of copper sulfide have been
the focus of significant interest for applications in optical
filters, nanoswitches, thermoelectric and photoelectric
transformers, and gas sensors.[6] Copper sulfide has a bulk
indirect band gap of approximately 1.2 eV and occurs in a
variety of crystallographic phases for which the stoichio-
Synthetic chemistry has emerged as an indispensable tool
to prepare size- and shape-controlled nanomaterials/thin
films of semiconductors for functional devices.[1] Soon after
the first report on the deposition of thin films of gallium
arsenide by Manasevit who used the metal–organic chemical vapor deposition (MOCVD) technique, many attempts
were made to develop and extend MOCVD processes to
realize the commercial production of thin films.[2] Traditionally, a dual source route (DSR) is used to synthesize
thin films and nanomaterials of tailored morphologies;
however, the risks and hazardous effects associated with
DSR methodology have motivated chemists to design and
[a] Department of Chemistry, Quaid-I-Azam University,
Islamabad 45320, Pakistan
[b] School of chemistry, The University of Manchester,
Oxford Road Manchester, M13 9PL, UK
[c] Department of Chemistry, University of Paderborn,
33098 Paderborn, Germany
[d] Department of Inorganic Chemistry, Goethe University
Frankfurt,
60438 Frankfurt Main, Germany
[e] Geoscience Advance Research Laboratories, Geological Survey
of Pakistan,
Islamabad
[f] Department of Physics, Nanoscience & Materials Synthesis
Lab, COMSATS, Institute of Information Technology,
Chak Shahzad Islamabad, Pakistan
E-mail: [email protected]
Homepage: www.javeedakhtar.com
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201301008
Eur. J. Inorg. Chem. 0000, 0–0
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FULL PAPER
δ = 180.3 and 166.0 ppm, respectively. The representative
resonance patterns in the 1H NMR (δ = 10.2 ppm, N–H; δ
= 8.26–8.01 ppm, m, aromatic; δ = 0.88 ppm, –CH3 protons) and 13C NMR spectra (δ = 181.0 ppm, C=S; δ =
166.2 ppm, C=O) also confirmed the formation of 1b. Complexes 2a and 2b were prepared from 1a and 1b in ethanol
at room temperature with an aqueous solution of copper(II)
metric composition varies from copper-rich chalcocite
(Cu2S) to copper-poor villamaninite (CuS2).[7] The stoichiometry composition of as-prepared copper sulfide materials
determines the band gap as well as the electrical properties.
Thin films with an excess amount of copper are classified
as p-type and are good materials for photovoltaic devices
that exhibit enhanced short-circuit currents (Isc).[8] Thus,
the composition, stoichiometry, and phase of the copper
sulfide nanomaterials need to be precisely controlled for the
fabrication of a functional device.
Thin films of copper sulfide have been deposited by using
complexes of copper(II) including, dithiocarbamates,[9] thiophosphinates[10] and dithiobiurets;[6] through aerosol-assisted chemical vapor deposition (AACVD), however, the
deposited films were not of good quality, were nonadhesive
to the substrate, and/or were composed of a mixture of cubic and hexagonal phases.[2b,6] For AACVD, the volatility
of the precursor is a prerequisite, and most of the used compounds are less volatile and decompose at higher temperature.[2b] Acyl-substituted thioureas are potential precursors
for the preparation of nanoparticles.[6,11] They are easy to
prepare and are stable under ambient conditions. In the
pursuit of the synthesis of new precursors, the symmetrical
ligands N,N-diethyl-N⬘-(1-napthoyl)thiourea (1a) and N,Ndipropyl-N⬘-(1-naphthoyl)thiourea (1b) and their complexes with copper(II), bis[N,N-diethyl-N⬘-(1-naphthoyl)thioureato]CuII (2a) and bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]CuII (2b), were synthesized and used to deposit copper sulfide thin films by AACVD. As-prepared ligands 1a and 1b and copper complexes 2a and 2b were
obtained in high yields by using less-toxic materials and can
be scaled up to deposit copper sulfide thin films. The asdeposited thin films of copper sulfide obtained by using 2a
and 2b exhibited very good adhesion to the glass substrates
(confirmed by the scotch-tape test). They all consisted of a
single phase of copper sulfide, anilite.
Figure 1. Single-crystal structure of (a) N,N-diethyl-N⬘-(1-naphthoyl)thiourea (1a) and (b) N,N-dipropyl-N⬘-(1-naphthoyl)thiourea
(1b).
Results and Discussion
N,N-Diethyl-N⬘-(1-naphthoyl)thiourea (1a) and N,N-dipropyl-N⬘-(1-naphthoyl)thiourea (1b) were prepared by a
one-pot synthesis. A mixture of potassium thiocyanate, 1naphthoyl chloride, and a dialkylamine [R1R2-NH, R1 =
R2 ethyl (1a) R1 = R2 propyl (1b)] in acetone was heated at
reflux for 30 min according to the scheme outlined in Figure S1 (Supporting Information). After purification, ligands 1a and 1b were recrystallized from ethanol at room
temperature by slow evaporation. The FTIR spectrum of
1a shows characteristic absorption bands at 3269, 1681, and
1525 cm–1 for N–H, C=O, and C=C, respectively. The
FTIR spectrum of 1b exhibits characteristic bands at 3259,
1688, and 1545 cm–1 for N–H, C=O, and C=C, respectively.
The 1H NMR spectrum of 1a shows a singlet resonance at
δ = 10.79 ppm for the –NH proton, characteristic aromatic
signals at δ = 8.26–8.01 ppm (multiplet), and a triplet at δ
= 1.27 ppm for the –CH3 protons. The 13C NMR spectrum
of 1a shows distinctive resonances for C=S and C=O at
Eur. J. Inorg. Chem. 0000, 0–0
Figure 2. Molecular structure of bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]copper(II), only molecule A is shown.
2
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Table 1. Crystal refinement parameters for compounds 1a, 1b, and 2b.
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
γ [°]
Volume [Å3]
Z
Dcalcd. [Mg m–3]
Absorption coefficient [mm–1]
F(000)
Crystal size [mm3]
θ range for data collection [°]
Index ranges
Reflections collected
Data/restraints/parameters
Goodness-of-fit on F2
R1 [I ⬎ 2σ(I)]
wR2 [I ⬎ 2σ(I)]
R1 (all data)
wR2 (all data)
1a
1b
2b
C16H18N2OS
286.38
173(2)
0.71073
triclinic
P1̄
7.6122(10)
9.9206(13)
10.8964(13)
105.263(10)
107.804(10)
94.483(11)
744.47(16)
4
1.278
0.215
304
0.50 ⫻ 0.30 ⫻ 0.10
3.27 to 25.69
–9 ⱕ h ⱕ 9
–12 ⱕ k ⱕ 11
–13 ⱕ l ⱕ 13
15520
2804/9/184
1.069
0.0590
0.1300
0.0706
0.1348
C18H22N2OS
314.45
173(2)
0.71073
triclinic
P1̄
7.8863(8)
12.6146(11)
17.4353(16)
95.619(8)
101.931(8)
96.547(8)
1672.9(3)
4
1.248
0.197
672
0.42 ⫻ 0.35 ⫻ 0.28
3.24 to 25.86
–9 ⱕ h ⱕ 9
–15 ⱕ k ⱕ 15
–21 ⱕ l ⱕ 21
29050
6313/0/410
1.048
0.0633
0.1599
0.0756
0.1671
C36H42CuN4O2S2
690.40
130(2)
0.71073
triclinic
P1̄
14.205(3)
15.700(3)
18.518(4)
101.962(4)
103.897(4)
113.057(4)
3472.3(12)
4
1.321
0.78
1452
0.25 ⫻ 0.10 ⫻ 0.06
1.20 to 27.88
–18 ⱕ h ⱕ 18
–20 ⱕ k ⱕ 20
–23 ⱕ l ⱕ 24
32900
16477/0/811
0.594
0.0483
0.0744
0.1793
0.1120
sulfate as depicted in the scheme outlined in Figure S1
(Supporting Information). The FTIR spectrum of 2a shows
distinguishing bands at 2958, 460, and 783 cm–1 for C–H,
Cu–O, and Cu–S. Similarly, in the FTIR spectrum of 2b,
bands at 465 cm–1 show the Cu–O stretching vibration,
whereas the band for Cu–S bending appears at 778 cm–1.
Ligands 1a and 1b and copper complexes 2a and 2b are
stable under ambient conditions. Complexes 2a and 2b
showed good solubility in most organic solvents, including
toluene and THF. The crystal structures of 1a, 1b, and 2b
were determined by single-crystal X-ray crystallography
and are shown in Figures 1 and 2. Crystal refinement parameters are given in Table 1, whereas selected bond lengths
and bond angles are given in Table S1 (Supporting Information).
terized by N–H···S intermolecular hydrogen-bonded dimers
[N(2)H(2)···S(1)#1: d(D–H), d(H···A), d(D···A), ⬍(DHA),
0.82(3), 2.63(3), 3.442(2), 175(3)]. Symmetry transformations used to generate equivalent atoms are #1: –x + 2, –y
+ 1, –z + 1.
Single-Crystal Structure of N,N-Dipropyl-N⬘-(1-naphthoyl)thiourea (1b)
There are two crystallographically independent but
chemically equivalent molecules per asymmetric unit in
N,N-dipropyl-N⬘-(1-naphthoyl)thiourea (1b). The main difference between the two molecules is the conformation of
the propyl chains. In one molecule, one of the propyl chains
is disordered over two positions with a site occupation factor of 0.8 for the major occupied site. The naphthyl residue
is almost perpendicular to the thiourea moiety (dihedral angle 75.2 and 80.6° for the two molecules in the asymmetric
unit). Compound 1b has a triclinic crystal system, and the
characteristic features are shown in Table 1. The bond
lengths and bond angles are in close agreement with earlier
reports (Table 1) and intermolecular hydrogen bonds (N–
H···S) are present between two units.
Single-Crystal Structure of N,N-Diethyl-N⬘-(1-naphthoyl)thiourea (1a)
N,N-Diethyl-N⬘-(1-napthoyl)thiourea (1a) crystallized
with one molecule in the asymmetric unit in space group
P1̄ in the triclinic crystal system. The naphthyl residue is
almost perpendicular to the thiourea moiety (dihedral angle
77.8°). Acyl thiourea based organic compounds have been
used as polydentate ligands owing to the simultaneous presence of S, N, and O electron-donor atoms.[12] In most acyl
thioureas, intramolecular hydrogen bonds between the
carbonyl oxygen atom and a hydrogen atom on N⬘– are
common.[12] However, in 1a, the crystal packing is characEur. J. Inorg. Chem. 0000, 0–0
Single-Crystal Structure of Bis[N,N-dipropyl-N⬘-(1naphthoyl)thioureato]copper(II) (2b)
In this compound, there are two crystallographically independent but chemically equivalent molecules A and B per
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asymmetric unit. The molecular structure for A (Figure 2)
shows that the copper atom is cis coordinated by two sulfur
atoms and two oxygen atoms from two chelating N,N-dipropyl-N⬘-(1-naphthoyl)thiourea ligands with a distorted
square-planar geometry. The Cu atom lies 0.114(1)/
0.133(1) Å (molecule A/B) from the S2O2 best plane. The
two naphthyl planes make dihedral angles of 76.16(8)/
59.63(7)° (molecule A/B). In general, there are no unexpected geometric parameters if this structure is compared to
similar thiourea compounds, for example, bis[2,2-diphenylN-(di-n-propylcarbamothioyl)acetamido]copper(II)[13] and
bis[4-bromo-N-(di-n-butylcarbamothioyl)benzamido]copper(II).[13] The S-parameter (Goof, goodness of fit) normally lies in the 0.7–1.0 range. In some cases, however, for
example, owing to weak intensities, the Goof may well be
less (as in our case) although the refinement is correct.
FULL PAPER
Figure 3. Powdered X-ray diffraction (PXRD) of copper sulfide
thin films deposited at 450 °C by AACVD by using (a) bis[N,Ndiethyl-N⬘-(1-naphthoyl)thioureato]copper(II) and (b) bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]copper(II).
Thermal Studies of Precursors 2a and 2b
The thermal properties of as-prepared precursors 2a and
2b were studied by thermogravimetric analysis (TGA). Both
precursors were subjected to thermal decomposition in the
temperature range from 40 to 600 °C at a heating rate of
10 °C min–1 under a nitrogen atmosphere. Figure S2 (Supporting Information) shows the typical thermograph obtained for 2a and 2b. The decomposition of precursor 2a
begins at 190 °C and is complete at 410 °C in a single step.
A minor shoulder between 250 and 310 °C is also present
in the thermograph, as shown in Figure S2 (Supporting Information). The inset in Figure S2 (Supporting Information) shows the thermograph of precursor 2b in which
decomposition of the precursor begins at 170 °C and stops
at 400 °C.
The morphology of the as-deposited thin films of copper
sulfide was studied by field-emission scanning electron microscopy (FE-SEM). Thin films obtained by decomposition
of precursor 2a by AACVD are composed of spherically
shape crystallites, as shown in Figure 4. The average size of
these crystallites estimated from SEM is (4.4 ⫾ 11) μm.
Thin-Film Deposition
Thin films of copper sulfide were deposited through the
AACVD technique with the use of copper complexes 2a
and 2b as SMPs. Deposition experiments were performed
from 350 to 450 °C to find out the optimum temperature
for the best deposition of the films. At 350 and 400 °C, very
thin deposition was observed onto the glass substrates.
However, at 450 °C a uniform, black, shiny, and well-adhered material was deposited.
PXRD studies of as-deposited thin films by using precursors 2a and 2b showed that they were polycrystalline and
composed of a single pure phase, anilite (Cu7S4), having an
orthorhombic system (ICDD: 01-072-0617). Figure 3 shows
the typical PXRD patterns of as-deposited thin films. The
films deposited from precursor 2a show diffraction peaks
at 2θ = 72, 50, 43, 42, 28, and 26°. These peaks corresponds
to (206), (141), (304), (232), (302), and (131) crystal plans.
In the PXRD patterns of the thin films deposited by using
2b, diffraction peaks at 28 and 26° are not prominent as a
result of the lower intensity; however, all other peaks are
present.
Eur. J. Inorg. Chem. 0000, 0–0
Figure 4. FE-SEM images of thin films of copper sulfide deposited
at 450 °C by AACVD by using (a) bis[N,N-diethyl-N⬘-(1-naphthoyl)thioureato]copper(II) and (b) bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]copper(II).
The high-resolution image shown in the inset in Figure 4
(b) reveals that the crystallites are sea urchin like structures
having numerous spikes on their surface. Thin films deposited by using SMP 2b have flakelike structures (Figure 4,
c and d). The average estimated size of these flakes is
(3 ⫾ 20) μm. The elemental compositions of the as-grown
thin films were determined by energy-dispersive X-ray
(EDX) spectroscopy. An EDX scanning profile of the whole
area of the sample showed that they are composed of copper and sulfur, as depicted in Figure S3 (Supporting Information). Elemental analysis of the thin films showed the
presence of copper (ca. 76 %) and sulfur (ca. 24 %).
4
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Conclusions
FULL PAPER
clearly derived from difference Fourier maps and refined on idealized positions with Uiso = 1.2Ueq(C) or 1.5Ueq(Cmethyl), C–H distances of 0.95–0.99 Å. The H atoms bonded to N were freely refined with the N–H distances restrained to 0.90(1) Å.
In this work, we reported the synthesis of the new acyl
thiourea based ligands N,N-diethyl-N⬘-(1-naphthoyl)thiourea (1a) and N,N-dipropyl-N⬘-(1-naphthoyl)thiourea (1b)
and their complexes with copper metal, bis[N,N-diethyl-N⬘(1-naphthoyl)thioureato]copper(II) (2a) and bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]copper(II) (2b). The asprepared ligands and complexes were characterized by elemental analysis and FTIR and NMR (1H, 13C) spectroscopy. The single-crystal molecular structures of 1a, 1b,
and 2b were also determined. Complexes 2a and 2b were
used as SMPs to deposit copper sulfide thin films on glass
substrates by AACVD at 450 °C. The as-deposited thin
films were characterized by PXRD, FE-SEM, and EDX.
2b: Data were collected at 130(2) K with a Bruker AXS SMART
APEX CCD diffractometer by using Mo-Kα radiation. The structure was solved[12] by direct methods and refined[12] on F2 by fullmatrix least-squares with 811 parameters and 16477 unique intensities. All non-hydrogen atoms were refined anisotropically. All H
atom positions were clearly derived from difference Fourier maps
and refined on idealized positions with Uiso = 1.2Ueq(C) or
1.5Ueq(Cmethyl), C–H distances of 0.95–0.99 Å. The methyl H
atoms were allowed to rotate but not to the tip.[15]
Synthesis of Compounds: The preparation of ligands 1a and 1b was
performed by using a modified literature procedure.[5c] Briefly, a
solution of 1-naphthoyl chloride (2.7 g, 24 mmol) in acetone
(30 mL) was added to a solution of KSCN (3.6 g, 24 mmol) in acetone (30 mL) at room temperature in a 250 mL, two-necked flask
under an atmosphere of nitrogen. The contents of the flask
changed their color from white to yellowish-brown. The mixture
was stirred for 35 min at reflux temperature to ensure completion
of the reaction. The addition of a solution of the dialkylamine
(3.7 mL, 24 mmol) in acetone (10 mL) to the mixture resulted in a
color change from yellowish-brown to bright yellow after another
30 min of stirring at reflux temperature. The progress of the reaction was monitored by thin-layer chromatography. Upon completion of the reaction, the reaction mixture was poured into crushed
ice. The thiourea formed precipitated as a solid, which was then
filtered off, washed well with cold distilled water, dried, and recrystallized from ethanol to give yellow crystals of 1a and 1b.
Experimental Section
General Methods: All synthetic preparations were performed under
reflux. All reagents were purchased from Sigma–Aldrich and used
as received. Solvents were distilled and dried prior to use as necessary. 1H NMR spectra were obtained by using an Avance series
300 MHz NMR spectrometer. IR spectra were obtained with a
Nicolet 6700 ATR instrument (4000–400 cm–1). Thin films of copper sulfide were deposited by using a home-built AACVD reactor.[14] X-ray powder diffraction patterns were obtained by using a
PANalytical X⬘PRO diffractometer (using Cu-Kα radiation). The
samples were scanned between 20 and 80°. Thin films were carbon
coated by using an Edwards E-306A coating system before performing SEM and EDX analysis. SEM was performed by using a
Jeol model JSM 6610LV, and EDX analysis was performed by
using an Oxford model x-Max 20 mm 2 (square). AACVD was
performed in a home-built setup that was composed of a Carbolite
furnace (21-101847, type MTS10/15/130) and a Deurer living LB44
humidifier equipped with an ultrasonic system. Microscope glass
slides were cut in 1 ⫻ 3 cm dimension and used to grow thin films.
Prior to film deposition, these substrates were placed in a mixture
of nitric acid and sulfuric acid for 24 h. They were then removed
and washed with distilled water two times and sonicated for 30 min.
Finally, they were washed with acetone and dried in an oven at
100 °C.
N,N-Diethyl-N⬘-(1-naphthoyl)thiourea
(1a):
Yield
76 %.
C16H18N2OS (286.38): calcd. C 67.1, H 6.3, N 9.7, S 11.2; found
C 66.8, H 5.9, N 9.4, S 10.7. FTIR: 3169 [υ(N-H) stretching], 2974
[υ(CH3) stretching], 1681 [υ(CO) stretching], 1525 [υ(C=C) skeletal
vibrations of aromatic ring], 1222 cm–1 [υ(C=S) stretching]; out-ofplane bending of ring C–H bonds of aromatic ring gives rise to
strong IR bands in the range between 910 and 650 cm–1. 1H NMR
[300 MHz, (CD3)2SO]: δ = 10.79 (s, 1 H, N-H), 8.28–7.55 (m, 7 H,
aromatic), 3.96 (q, 2 H, aliphatic), 3.68 (q, 2 H, aliphatic), 1.27 (t,
6 H, aliphatic) ppm. 13C NMR [75.5 MHz, (CD3)2SO]: δ = 180.38
(C=S), 166.55 (C=O), 133.62–125.35 (sp2-hybridized aromatic carbon atoms), 47.67, 47.02, 13.93, 11.62 ppm (four sp3 hybridized
aliphatic carbon atoms).
Single-Crystal X-ray Crystallography
1a: Data were collected at 173 K with a Stoe IPDS-II diffractometer by using Mo-Kα radiation. The structure was solved
by direct methods and refined on F2 by full-matrix least-squares
with 188 parameters and 2804 unique intensities. All non-hydrogen
atoms were refined anisotropically. All H atom positions were
clearly derived from difference Fourier maps and refined on idealized positions with Uiso = 1.2Ueq(C) or 1.5Ueq(Cmethyl), C–H distances of 0.95–0.98 Å. The H atom bonded to N was freely refined
with the N–H distance restrained to 0.90(1) Å. The methyl H atoms
were allowed to rotate but not to the tip. One ethyl group is disordered over two sites with a site occupation factor of 0.522(8) for
the major occupied site. Bond lengths and angles involving the disordered atoms were restrained to be equal.
N,N-Dipropyl-N⬘-(1-naphthoyl)thiourea
(1b):
Yield
78 %.
C18H22N2OS (314.45): calcd. C 68.7, H 7.0, N 8.9, S 10.2; found
C 68.3, H 6.6, N 8.5, S 9.7. FTIR: 3166 [υ(N-H) stretching], 2967
[υ(CH3) stretching], 1679 [υ(CO) stretching], 1597 [υ(C=C) skeletal
vibrations of aromatic ring], 1270 cm–1 [υ(C=S) stretching]; out-ofplane bending of ring C–H bonds of aromatic ring gives rise to
strong IR bands in the range between 910 and 650 cm–1. 1H NMR
[300 MHz, (CD3)2SO]: δ = 8.27 (s, 1 H, N-H), 8.26–7.56 (m, 7 H,
aromatic), 3.89 (t, 2 H, aliphatic), 3.58 (t, 2 H, aliphatic), 1.73 (m,
4 H, aliphatic), 0.95 (t, 3 H, aliphatic), 0.88 (t, 3 H, aliphatic) ppm.
13
C NMR [75.5 MHz, (CD3)2SO]: δ = 181.05 (C=S), 166.25 (C=O),
133.63–125.37 (sp2-hybridized aromatic carbon atoms), 54.75,
54.26, 48.80, 21.79, 19.59, 11.62 ppm (six sp3-hybridized aliphatic
carbon atoms).
1b: Data were collected at 173 K with a Stoe IPDS-II diffractometer by using Mo-Kα radiation. The structure was solved
by direct methods and refined on F2 by full-matrix least-squares
with 403 parameters and 6293 unique intensities. All non-hydrogen
atoms were refined anisotropically. All H atom positions were
Synthesis of Complexes: Heating of a solution of the ligand (1 g,
2.6 mmol) in ethanol (40 mL) with aqueous copper sulfate (0.43 g,
1.3 mmol) at reflux gave a colored (rust for 2a and dark green for
2b) precipitate of bis[N,N-dialkyl-N⬘-(1-naphthoyl)thioureato]copper(II).
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Received: August 5, 2013
Published Online: 䊏
Bis[N,N-diethyl-N⬘-(1-naphthoyl)thioureato]CuII (2a): Yield 83 %.
C32H34CuN4O2S2 (634.30): calcd. C 60.59, H 5.40, N 8.83, S 10.11;
found C 59.7, H 5.1, N 8.4, S 9.7. FTIR: 2978 [υ(CH3) stretching],
1540 [υ(C=C) skeletal vibrations of aromatic ring], 1137 [υ(C-O)
stretching], 460 [υ(Cu-O) stretching], 783 cm–1 [υ(Cu-S) stretching
vibrations].
(2b):
Yield
Bis[N,N-dipropyl-N⬘-(1-naphthoyl)thioureato]CuII
87 %.C36H42CuN4O2S2 (690.42): calcd. C 62.6, H 6.1, N 8.1, S 9.2;
found C 61.8, H 5.6, N 7.6, S 8.7. FTIR: 2961 [υ(CH3) stretching],
1507 [υ(C=C) skeletal vibrations of aromatic ring], 1124 [υ(CO)
stretching], 465 [υ(Cu-O) stretching], 778 cm–1 [υ(Cu-S) stretching
vibrations].
Deposition of Films by AACVD: The following typical procedure
was used to prepare solutions of SMPs 2a and 2b in toluene to
grow thin films by AACVD. First, the precursor (0.20 g, 0.8 mmol)
was dissolved in toluene (15 mL) in a two-necked, 100 mL roundbottom flask with a gas inlet that allowed the carrier gas (argon)
to pass into the solution and to help transport the aerosol. This
flask was connected to the reactor tube by a piece of reinforced
tubing. Six glass substrates (ca. 1 ⫻ 3 cm) were placed inside the
reactor tube and placed in a Carbolite furnace. The precursor solution in a round-bottomed flask was kept in a water bath above
the piezoelectric modulator of a humidifier Deurer living LB44,
equipped with an ultrasonic system. The generated aerosol droplets
of the precursor were transferred into the hot-wall zone of the reactor by a carrier gas where the precursor decomposed to deposit a
thin film.
Supporting Information (see footnote on the first page of this article): Selected bond lengths and angles for 1a, 1b, and 2b; synthetic
scheme for 1a, 1b, 2a, and 2b; TGA of 2a and 2b; EDX analysis
of thin films deposited at 450 °C by using 2a and 2b.
Acknowledgments
J. A. thanks the COMSATS Institute of Information Technology
(CIIT) Islamabad for funding the project “Phase and Composition
Controlled Deposition of Copper Sulfide Nanostructures”, grant
number 16-61/CRGP/CIIT/IBD/12/943 and also acknowledges financial assistance from the Higher Education Commission (HEC).
The authors are thankful to MPhil student Atta-ur-Rehman for
helping in AACVD deposition experiments. Special thanks go to
Dr. Ghulam Abbas (IRCBM, COMSAT, Lahore) for TGA analysis.
[1] a) M. A. Malik, M. Afzaal, P. O’Brien, Chem. Rev. 2010, 110,
4417–4446; b) M. Akhtar, J. Akhtar, M. A. Malik, F. Tuna, M.
Eur. J. Inorg. Chem. 0000, 0–0
FULL PAPER
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Date: 03-12-13 17:38:32
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FULL PAPER
Thin Films
Phase-controlled deposition of thin films of
copper sulfide on a glass substrate is
achieved for the first time by using singlemolecular precursors through aerosol-assisted chemical vapor deposition. The asdeposited thin films are characterized by
field-emission scanning electron microscopy, powdered X-ray diffraction, and
energy-dispersive X-ray spectroscopy.
S. Ashraf, A. Saeed, M. A. Malik,
U. Flörke, M. Bolte, N. Haider,
J. Akhtar* ......................................... 1–7
Phase-Controlled Deposition of Copper
Sulfide Thin Films by Using Single-Molecular Precursors
Keywords: Copper sulfide / Thin films /
Chemical vapor deposition / Acyl thiourea
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