Synthesis of hexadecylamine capped nanoparticles using group 12 complexes of N-alkyl-N-phenyl dithiocarbamate as single-source precursors

Article abstract of DOI:10.1016/j.poly.2010.10.023

Metal complexes of the type ML¹L² [M = Zn, Cd, Hg; L¹ = N-methyl-N-phenyldithiocarbamato and L² = N-ethyl-N-phenyldithiocarbamato] have been synthesized and characterized by elemental analyses, FT-IR and NMR spectroscopy. The complexes are formulated as four coordinate species with the dithiocarbamates acting as bidentate chelating ligands. The complexes were thermolysed and used as single-source precursors for the synthesis of HDA-capped MS (M = Zn, Cd, Hg) nanoparticles. The HgS nanoparticles show a narrow size distribution from their TEM images, while the CdS nanoparticles gave crystalline particles with a sharp band absorption edge and a narrow PL band. The ZnS nanoparticles gave crystalline particles with a stacking arrangement.

Full text of DOI:10.1016/j.poly.2010.10.023

Polyhedron 30 (2011) 246–252
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis of hexadecylamine capped nanoparticles using group 12 complexes
of N-alkyl-N-phenyl dithiocarbamate as single-source precursors
a
b
Peter A. Ajibade a, , Damian C. Onwudiwe , Makwena J. Moloto
⇑
a Department of Chemistry, University of Fort Hare, Private Bag X1314, Alice, South Africa
b Department of Chemical Technology, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, South Africa
a r t i c l e i n f o
a b s t r a c t
Metal complexes of the type ML1L2 [M = Zn, Cd, Hg; L1 = N-methyl-N-phenyldithiocarbamato and L2 = N-
ethyl-N-phenyldithiocarbamato] have been synthesized and characterized by elemental analyses, FT-IR
and NMR spectroscopy. The complexes are formulated as four coordinate species with the dithiocarba-
mates acting as bidentate chelating ligands. The complexes were thermolysed and used as single-source
precursors for the synthesis of HDA-capped MS (M = Zn, Cd, Hg) nanoparticles. The HgS nanoparticles
show a narrow size distribution from their TEM images, while the CdS nanoparticles gave crystalline par-
ticles with a sharp band absorption edge and a narrow PL band. The ZnS nanoparticles gave crystalline
particles with a stacking arrangement.
Article history:
Received 12 August 2010
Accepted 19 October 2010
Available online 9 November 2010
Keywords:
Metal complex
Dithiocarbamates
HgS
CdS and ZnS nanoparticles
Precursors
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
route to high-quality nanoparticles [13]. Since the introduction of a
single source precursor as an alternative and most convenient
Coordination compounds containing ligands with sulfur atoms
as donors have received much attention [1]. Among thesꢀe sulfur
containing ligands, the dithiocarbamate species (RR0NCS ) form
an important family of classical anionic ligands [2] and are very
relevant to the chemistry of disulfides. These anions, derived
from secondary amines, are versatile chelating agents. The strong
chelating property is utilized in their extensive use as separating
agents in gas chromatography [3] and liquid–liquid extraction
[4], in purification [5], as fungicides in agriculture [6] and anti-
dotes to fight metal poisoning [7]. The anions are three-electron
donors [8] and have a small bite angle (ꢁ2.8–2.9 Å) [9]. Hence,
they are able to delocalize the positive charge from the metal to-
ward the periphery of the complex and this stabilizes the metal
ions [8,10]. These ligands, apart from their vast technological
applications, are of interest as a potential source of novel struc-
tures [11]. Dithiocarbamate complexes of group 12 represent a
large and interesting class of inorganic compounds [12] and they
have been widely studied in recent years. Some of the studies of
these d10 complexes have been made to understand the interac-
tions which exist between the metal ion and the ligands [11],
and for their use as single-source precursors for semiconductor
nanoparticles.
approach to the synthesis of semiconductor nanoparticles, the
compounds that have found the greatest dissemination as precur-
sors for II–VI semiconductors are the dithiocarbamate complexes
[14]. Dialkyldithiocarbamato complexes [M(S2CNR2)2] (M = Zn(II),
Cd(II),R = alkyl) have been used as single-source precursors to
prepare nanoparticles and to deposit ZnS or CdS thin films by
metal–organic chemical vapour deposition (MOCVD) [15]. O’Brien
et al. have developed a series of Zn and Cd complexes of dithiocar-
bamates as precursors to prepare II–VI chalcogenides which
yielded high-quality nanocrystals organically capped with tri-n-
octylphosphine oxide (TOPO) [16–18], and also carried out in
depth studies on the effect of side groups on the deposition tem-
perature and decomposition mechanisms [19]. Asymmetrical four
coordinate dithiocarbamates M(E2CNR1R2)2 have proved relatively
better than the symmetrical dithiocarbamates for the synthesis of
nanoparticles and growth of chalcogenide films because they are
sufficiently more volatile. Hence, the relative use of dithiocarba-
mates as single-source precursors depends on both the nature of
the alkyl substituent and the dithiocarbamate groups. There are
relatively few reports on dithiocarbamates as a single source
precursor for mercury chalcogenides. Green et al. [20] have
reported the synthesis of mercury (II) N,N0-methyl-phenyl ethyl
dithiocarbamates and their use as a precursor for the room tem-
perature deposition of a HgS thin film. In this paper we report
the synthesis and characterization of some N-alkyl-N-phenyl
dithiocarbamates complexes of Zn(II), Cd(II) and Hg(II) and their
use as single molecular precursors for nanoparticles.
The use of single-source molecular precursors in which a me-
tal–chalcogenide bond is available has proven to be a very efficient
⇑
Corresponding author. Tel.: +27 40 602 2055; fax: +27 40 6022094.
E-mail address: pajibade@ufh.ac.za (P.A. Ajibade).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.10.023

P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
247
(C6H5–N(Me)), 54.67 (CH2–(Et)), 46.26 (CH3–N(Me)), 12.09 (CH3–
(Et)). Selected IR,
(cmꢀ1): 1456 (C@N), 1278 (C2–N), 939 (C@S).
2. Experimental
m
Anal. Calc. for C17H18N2S4Cd (490.99): C, 41.59; H, 3.70; N, 5.71;
2.1. Chemicals
S, 26.12. Found: C, 42.01; H, 3.92; N, 5.79; S, 26.09%.
Hexadecylamine (HDA) and trinoctylphosphine (TOP), toluene
and absolute methanol were purchased from Aldrich. Toluene
was dry and stored over molecular sieves (4.0 Å) before use. All
other solvents and metal salts were of analytical grade obtained
from Aldrich and were used without further purification. The li-
gands sodium N-methyl-N-phenyldithiocarbamate and sodium
N-ethyl-N-phenyl dithiocarbamate were prepared by a modified
procedure given in the literature [21].
2.3.3. HgL1L2
The complex was obtained as a greenish ash colour. Yield:
0.520 g, (72%), m.p. 218 °C. 1H NMR (CDCl3) d = 7.42–7.33 (m,
C6H5–N(Et)), 7.28–7.24 (m, C6H5–N(Me)), 4.16 (q, CH2–N(Et)),
1.53 (s, CH3–N(Me)), 1.26 (t, CH3–(Et)). 13C NMR (CDCl3)
d
206.43, 205.84 (CS2), 147.47, 145.26 (C6H5–N(Et)), 129.66,
128.80, 126.43, 125.34 (C6H5–N(Me)), 55.86 (CH2–(Et)), 48.93
(CH3–N(Me)), 12.26 (CH3–(Et)). Selected IR, m
(cmꢀ1): 1459 (C@N),
1280 (C2–N), 966 (C@S). Anal. Calc. for C17H18N2S4Hg (579.17): C,
35.25; H, 3.13; N, 4.84; S, 22.14. Found: C, 35.39; H, 3.24; N,
4.68; S, 21.96%.
2.2. Physical measurements
Infrared spectra were recorded from KBr pellets in the range
4000–400 cmꢀ1 on
a Perkin–Elmer 2000 FT-IR spectrometer.
NMR spectra were recorded on a Bruker NMR spectrometer
(400.1 MHz for 1H, 100.6 MHz for 13C). Microanalysis was carried
out on a Fisons elemental analyzer. The optical measurements
were carried out using an Analytikjena Specord 50 UV–Vis spectro-
photometer. The samples were placed in glass cuvettes (1 cm path
length) using toluene and methanol as a reference solvents for the
nanoparticles. A Perkin–Elmer LS 45 Fluorimeter was used to mea-
sure the photoluminescence of the nanoparticles by dissolving
them in toluene and placing the samples in glass cuvettes (1 cm
path length) for analysis. The X-ray diffraction patterns were re-
corded by a Phillip’s X’Pert materials research diffractometer at
2.4. Synthesis of HDA-capped nanoparticles
The metal sulfide nanoparticles were prepared from their
respective metal complexes. In a typical synthesis, the metal com-
plexes (0.50 g) were each dissolved in TOP (10 mL) and injected
into hot HDA (7 g) at 120 °C. An initial decrease in temperature
(by about 20–30 °C) was observed. The solution was stabilized
and the reaction was continued for 1 h at 120 °C. After completion,
the reaction mixture was allowed to cool to 70 °C and methanol
was added to precipitate the nanoparticles. The solid was sepa-
rated by centrifugation and washed three times with methanol.
The resulting solid precipitates of HDA-capped MS nanoparticles
were dispersed in toluene for further analysis.
40 kV/50 mA using secondary graphite monochromated Cu K
a
radiation (k = 1.5406 Å). Measurements were taken at a high angle
2h range of 20–90° with a scan speed of 0.01°. The TEM images
were obtained using a Philips CM 200 compustage electron micro-
scope operated at 200 kV. The samples were prepared by placing a
drop of a dilute solution of the sample in toluene on a copper grid
(400 mesh, agar).
3. Results and discussion
3.1. Synthesis
Sodium salts of the ligands were obtained by the reaction of the
secondary amines with CS2 and sodium hydroxide in aqueous
medium at low temperature. The white solids obtained were stable
at room temperature. The metal complexes were conveniently ob-
tained in high yield at room temperature by the substitution reac-
tion of NaL1, NaL2 and the respective metal salts in equimolar
ratios in water, following Scheme 1. These complexes are air-stable
and the Zn(II) and Hg(II) complexes are soluble in dichloromethane
and chloroform. The poor solubility of the cadmium complex in
both organic and inorganic solvents could be attributed to the
possibility of the complex existing in the polymeric form. The
2.3. Synthesis of the complexes
The same synthetic procedure was used for all the complexes: a
solution of sodium N-methyl-N-phenyldithiocarbamate, L1
(0.256 g, 1.25 mmol) and sodium N-ethyl-N-phenyldithiocarba-
mate, L2 (0.274 g, 1.25 mmol) in 20 mL of water at room tempera-
ture was added to (1.25 mmol) Zn(OOCCH3)2ꢂ2H2O (0.274 g),
CdCl2ꢂ2.5H2O (0.230), HgCl2 (0.340) in 20 mL of water to obtain
an immediate precipitation. After stirring for 1 h, the precipitate
was filtered off, rinsed thoroughly with water and dried in vacuo.
2.3.1. ZnL1L2
H3C
H3CH2C
The complex was obtained as a white solid. Yield: 0.435 g,
(78.52%), m.p. 212–214 °C. 1H NMR (CDCl3) d = 7.44–7.34 (m,
C6H5–N(Et)), 7.30–7.22 (m, C6H5–N(Me)), 4.18 (q, CH2–N(Et)),
S
S
N
C
N
C
+
MX2
+
S
Na
S
Na
1.53 (s, CH3–N(Me)), 1.28 (t, CH3–(Et)). 13C NMR (CDCl3)
d
207.29, 206.44 (CS2), 146.10, 144.07 (C6H5–N(Et)), 129.61,
128.65, 128.56, 126.70 (C6H5–N(Me)), 53.97 (CH2–(Et)), 46.89
(CH3–N(Me)), 12.38 (CH3–(Et)). Selected IR, m
(cmꢀ1): 1458 (C@N),
1276 (C2–N), 939 (C@S). Anal. Calc. for C17H18N2S4Zn (443.96): C,
45.99; H, 4.09; N, 6.31; S, 28.89. Found: C, 46.33; H, 4.19; N,
6.32; S, 28.92%.
H3C
S
S
S
S
N
C
M
N
C
2.3.2. CdL1L2
CH2CH3
The complex was obtained as a white solid. Yield: 0.48 g
(78.37%), m.p. 248–250 °C. 1H NMR (CDCl3) d = 7.43–7.38 (m,
C6H5–N(Et)), 7.31–7.22 (m, C6H5–N(Me)), 4.12 (t, CH2–N(Et)),
1.15 (t, CH3–(Et)). 13C NMR (CDCl3) d = 208.27, 207.55 (CS2),
148.10, 146.00 (C6H5–N(Et)), 129.15, 127.57, 126.84, 125.80
M = Zn, Cd, Hg
X = Cl - , CH3COO-
Scheme 1. The preparation of N,N-methyl phenyl-N,N-ethyl phenyl dithiocarbam-
ato complexes.

248
P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
Fig. 1. Absorption (a) and emission (b) spectra of HDA-capped CdS nanoparticles prepared from the cadmium complex.
3
(a)
3
2
2
1
1
0
300
400
500
600
700
Wavelength (nm)
(b)100
75
50
25
0
300
400
500
600
700
Wavelength (nm)
Fig. 2. Absorption (a) and emission (b) spectra of HDA-capped HgS nanoparticles prepared from the mercury complex.

P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
249
4.3
4.0
3.8
3.5
3.3
3.0
2.8
2.5
2.3
2.0
1.8
(a)
300
400
500
600
700
Wavelength (nm)
900
(b)
800
700
600
500
400
300
200
100
0
300
400
500
600
700
Wavelength (nm)
Fig. 3. Absorption (a) and emission (b) spectra of HDA-capped ZnS nanoparticles prepared from the zinc complex.
formation of polymers might be due to the fact that dithioacid
complexes of the ML2 type are coordinatively unsaturated, thus
leading to the formation of a higher coordination number either
by the addition of one or two molecules of a Lewis base or by poly-
merization of ML2 [22].
for the complexes. An established criterion for the bonding modes
in dithiocarbamates uses the number of bands observed in the re-
gion 1000 50 cmꢀ1 to determine the coordination mode of the
dithiocarbamate ligand to the metal ion [27,28]. In the above re-
gion, a single sharp band implies a symmetrical bidentate coordi-
nation, while the splitting of this band into a doublet may
indicate a monodentate unsymmetrical coordination of the dithio-
carbamato group. All the compounds show a single peak within
this region which implies the presence of symmetrically bonded
bidentate dithiocarbamates. Peaks in the region 2930–2960 cmꢀ1
3.2. Infrared spectral studies
Infrared spectra of the ligands and the complexes were com-
pared and assigned on careful comparison. In both ligands, the
strong peaks were observed around 3335 and 3174 cmꢀ1 due to
can be assigned to m(C–H) of the alkyl groups. The m(M–S) peaks
are characteristically found in the far infrared region, typically be-
tween 300 and 400 cmꢀ1. This peak usually depends on the nature
of the organic substituent attached to the nitrogen atom [29].
symmetrical and asymmetrical m(O–H) vibrations of water mole-
cules in the sodium salt of the dithiocarbamates [23]. These peaks
were completely absent in all the complexes, indicating the loss of
the water molecules upon coordination to the metal ions. An ob-
served feature of the spectra of the three compounds is the CN
bond observed at 1458, 1458 and 1459 cmꢀ1 for the Zn, Cd and
3.3. 1H and 13C NMR
Hg complexes, respectively. These
m
(C–N) bands are shifted to
In the 1H NMR spectra, all the chemical shifts were found in the
expected regions, only subtle differences were observed from one
complex to another. The electronic and magnetic influence of the
alkyl substituent’s (–CH3 and –C2H5) are evidenced in the reso-
nance spectra observed in the upfield region. All the spectra
contain a set of quartets around 4.15 ppm, assigned to the methy-
lene protons, and a sharp singlet at about 1.53 ppm, associated
with the methyl group bound to an electronegative nitrogen atom.
This peak is differentiated from the –CH3 of the ethyl substituent,
which was observed around 1.20 ppm, since the magnitude of
the deshielding decreases with the increase in distance from the
metal centre or the thioureide bond [30]. The protons of the
higher energy relative to the ligands (ca. 1453 cmꢀ1). The shift is
a reflection of increased bond strength. This strengthening of the
CN bond is ascribed to the increase in the double bond character,
which is observed upon coordination to the metal centre [24,25].
The difference in the electron releasing ability of the organic
groups affects the electron density on the sulfur atom via the
p
-system and therefore influences the double bond character of
the C@N bond [24]. These peaks observed for the complexes fall
within the stretching frequencies of
(C–N) 1250–1350 cmꢀ1 and
(C@N) 1640–1690 cmꢀ1 [26]. The close similarities in the posi-
tions of the bands strongly suggest similar coordination modes
m
m

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P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
aromatic unit appear in two groups as complex multiplets between
7.44 and 7.22 ppm.
The 13C NMR spectra of all the compounds exhibit a low field
resonance associated with the backbone carbon of the dithiocarba-
mate [31]. Two distinct peaks were observed at ca. 207.00 and
206.00 ppm. Each of these signals is said to indicate the contribu-
tion of the double bond character to a formally single N–C bond in
the dithiocarbamate group, i.e., the admixture of the sp2 hybridized
state to the sp3 orbitals of the nitrogen atom, thus a considerable d+
surplus charge is localized on the nitrogen atom, while a dꢀ charge
is delocalized through the four-membered metallochelate ring –
CS2M [32]. The occurrence of two NCS2 peaks is attributed to the
influence of the different organic substituents on their magnetic
equivalence. The ligating group (dithiocarbamate) with the greater
electronic density has a more shielded –CS2 carbon [33]. The meth-
ylene carbon of the ethyl group resonates around 54.00 ppm, while
the N–CH3 appears at around 47.00 ppm. It experiences a more
deshielding effect than the –CH3 of the ethyl group, which
resonates around 12.20 ppm, due to the influence of the electro-
Fig. 4. TEM image of HDA-capped CdS nanoparticles from the cadmium complex.
negative nitrogen and the thioureide
p-system [30,34]. In the
aromatic region, two sets of signals were observed; two peaks of
low intensity between 148.00 and 144.00 ppm, which are assigned
to the aromatic carbons of the N-ethyl unit. The second set of
aromatic peak occurred as four peaks of relatively high intensity
between 129.00 and 125.00 ppm, which is due to the N-methyl
unit. The occurrence of these peaks in different environments indi-
cates the magnetic unequivalence of the aromatic groups [35].
3.4. Synthesis and characterization of nanoparticles
The complexes of mercury, cadmium and zinc used for the
nanoparticles synthesis were synthesized from aqueous media at
room temperature. The complexes crystallize into yellow to white
precipitates in relatively good yields. Variation of the alkyl groups
on the dithiocarbate ligand always gave particles with non-spher-
ical morphologies [36,37], and in this work a mixture of short alkyl
and phenyl groups are investigated for their effect on the nature of
the particles produced. A lot of factors contribute towards the sizes
and shapes of particles, and hence influence the absorption and
emission features. Therefore the optical and morphological proper-
ties will be discussed next.
3.4.1. Optical properties of CdS, HgS and ZnS nanoparticles
Fig. 5. TEM image of HDA-capped HgS nanoparticles (a) from its corresponding
complex with HRTEM images for the spherical particles (b).
All the semiconductor nanoparticles CdS, HgS and ZnS, prepared
from their respective complexes, showed a blue shift in their
absorption band edges (Figs. 1–3). CdS (469 nm and emission at
484 nm – kexc at 450 nm), HgS (excitonic feature at 335 nm with
typical tailing of the absorption band and emission maximum at
425 nm) and ZnS nanoparticles (with an excitonic feature at
337 nm tailing and emission maximum at 424 nm). The tailing of
the absorption features from ZnS and HgS results from the particle
sizes ranging from significantly small to larger and growth of par-
ticles in the form of layers of concentric circles. CdS nanoparticles
showed a sharp band edge, and narrow emission bands were ob-
served for CdS and HgS nanoparticles with the width typical of
small particles size range and that of ZnS gave a wider band gap
of about 320 nm. All gave emission maxima which are red shifted
to the absorption band edges, ranging from 21 to 79 nm. CdS nano-
particles from heterocyclic dithiocarbamate complexes were re-
ported to produce rods, tripods and tetrapods, depending on the
concentration and temperature [34,35] with absorption features
similar to the CdS nanoparticles obtained in this work.
3.4.2. Structural characterization of CdS, HgS and ZnS nanoparticles
Generally, complexes such as cadmium, mercury and zinc with
the ligand alkylphenyldithiocarbamate produce metal sulfides due
Fig. 6. TEM image of HDA-capped ZnS nanoparticles from its corresponding
complex.

P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
251
Fig. 7. XRD patterns of HDA-capped CdS nanoparticles prepared from its complex.
Fig. 8. XRD patterns of HDA-capped HgS nanoparticles prepared from its complex (* – peaks due to HDA).
Fig. 9. XRD patterns of HDA-capped ZnS nanoparticles prepared from the zinc complex. (* – peaks due to the presence of hexadecylamine).
to the nature of bonding between the metal and the ligand through
sulfur (M–S bond). The nanoparticles were prepared in a hot boil-
ing solvent of hexadecylamine at a temperature of 120 °C, with
HDA used for stabilizing nanoparticles. The complexes are gener-
ally air and thermally stable, such that their decomposition to yield
metal sulfides took place at a temperature of 120 °C. Figs. 4–6 show
the TEM images of the HDA-capped CdS, HgS and ZnS nanoparti-
cles, prepared from their corresponding complexes. HgS nanoparti-
cles, under the synthetic conditions, produced spherical and oval
shapes, with some intercalated, with sizes ranging from 8 to
25 nm and with a good uniform size distribution throughout the
sample (Fig. 5). A single particle shows good crystalline features

252
P.A. Ajibade et al. / Polyhedron 30 (2011) 246–252
with perfect alignment of the atoms. The zinc complex produced
stacks of concentric ZnS particles, which are highly crystalline with
concentric lattice planes (Fig. 6) and with particle sizes in the range
63–91 nm and d-lattice spacings of 2.27 nm. The powder X-ray dif-
fraction patterns for the nanoparticles prepared from the com-
plexes are shown in Figs. 7–9. ZnS nanoparticles show the
predominant 1 1 1 plane of the cubic phase on their XRD pattern.
The cadmium complex produced growth of particles in the hexag-
onal phase with XRD patterns indexed to 1 1 1, 2 0 0, 2 2 0, 3 1 1
and 4 0 0 for the peaks with 2h values of 25.9, 29.5, 43.1 and
51.1, respectively. The peaks are broad, indicative of nanoscale par-
ticles. HgS nanoparticles gave crystalline particles with predomi-
nant peaks at 25.9, 29.5, 43.1 and 51.1 indexed to 1 1 1, 2 0 0,
2 2 0 and 3 1 1, respectively.
The complexes used to prepare these nanoparticles have similar
ligand features, such as the alkyl group used – ethyl and methyl,
and the corresponding phenyl substituent which influences the
formation of needle-like, oval and concentric particles for the cad-
mium and mercury and the zinc complexes, respectively. Memon
et al. [34] reported the synthesis of ZnS and CdS using bis(dode-
cyl)dithiocarbamate cadmium and zinc complexes, which pro-
duced rods and tetrapods at higher temperatures than 120 °C
used in this work, while the morphologies are similar with differ-
ent particles sizes.
XRD, TEM and HRTEM images from the CSIR, NCNSM, 1-Meiring
Naude, Brummeria, 0001.
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4. Conclusion
Zn(II), Cd(II) and Hg(II) complexes of N,N-methyl phenyl-N,N-
ethyl phenyl dithiocarbamate complexes have been prepared and
characterized by elemental analyses and spectroscopic techniques.
Four coordinate geometries are proposed for the complexes. The
complexes were used as a single source precursor to synthesise
ZnS, CdS and HgS semiconductor nanoparticles. The nanoparticles
showed a blue shift in their absorption band edges, and emissions
which are red shifted. The alkyl and phenyl substituents appear to
influence the overall shape of the particles. The mercury complex
was effective as a precursor to produce particles of uniform size
that are highly crystalline, hexagonal and cubic phases with one
predominant 1 1 1 plane, driven by hexadecylamine.
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The authors are grateful to GMRDC, University of Fort Hare,
South Africa for financial support and the University of Witwaters-
rand for providing space for the preparation of the nanoparticles.
Special mention goes to Mr. Siya Mpelane who helped with the