Synthesis, characterization, cytotoxicity and antimicrobial studies on Bi(III) dithiocarbamate complexes containing furfuryl group and their use for the preparation of Bi2O3nanoparticles

Article abstract of DOI:10.1016/j.poly.2016.09.038

Bismuth(III) dithiocarbamate complexes, tris(N-furfuryl-N-propyldithiocarbamato-S,S')bismuth(III) (1), tris(N-furfuryl-N-butyldithiocarbamato-S,S')bismuth(III) (2) and tris(N-furfuryl-N-benzyldithiocarbamato-S,S')bismuth(III) (3), have been prepared and characterized by microanalysis, and spectroscopy (IR and NMR). Structure of 3 has been obtained by single crystal X-ray diffraction. This complex contains distorted pentagonal pyramidal Bi(III) centres which attain an overall distorted pentagonal bipyramidal coordination via long range intermolecular Bi?S interactions. DFT quantum mechanical studies of 3 were carried out, supporting the partial double bond character of C–N (thioureide) and C–S bonds in dithiocarbamate ligands. All the compounds have been screened against a panel of microbes viz. Vibrio cholerae, Bacillus subtilis, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Aspergillus niger and Candida albicans. Complexes 1 and 3 were found to have better activity against K. pneumoniae, V. cholerae, A. niger and C. albicans than the complex 2. Complexes 1–3 have been evaluated for their in vitro cytotoxic activity against KB cells. Complexes 1 and 3 showed higher activity than 2. Bi₂O₃obtained from thermal decomposition of 3 has been characterized by PXRD, HRTEM, EDAX, UV–Vis and Fluorescence spectroscopy. PXRD study showed that the sample is composed of monoclinic phase of α-Bi₂O₃. Photocatalytic activity of as-prepared α-Bi₂O₃was determined by decolourization of rhodamine-B in aqueous solution under ultra violet irradiation.

Full text of DOI:10.1016/j.poly.2016.09.038

Accepted Manuscript
Synthesis, characterization, cytotoxicity and antimicrobial studies on Bi(III) di-
thiocarbamate complexes containing furfuryl group and their use for the prep-
aration of Bi O nanoparticles
2
3
Sundaramoorthy Tamilvanan, Govindasamy Gurumoorthy, Subbiah
Thirumaran, samuele Ciattini
PII:
S0277-5387(16)30468-5
DOI:
http://dx.doi.org/10.1016/j.poly.2016.09.038
POLY 12226
Reference:
To appear in:
Polyhedron
Received Date:
Revised Date:
Accepted Date:
18 May 2016
15 September 2016
21 September 2016
Please cite this article as: S. Tamilvanan, G. Gurumoorthy, S. Thirumaran, s. Ciattini, Synthesis, characterization,
cytotoxicity and antimicrobial studies on Bi(III) dithiocarbamate complexes containing furfuryl group and their use
for the preparation of Bi O nanoparticles, Polyhedron (2016), doi: http://dx.doi.org/10.1016/j.poly.2016.09.038
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Synthesis, characterization, cytotoxicity and antimicrobial studies on Bi(III)
dithiocarbamate complexes containing furfuryl group and their use for the preparation
of Bi O nanoparticles
2 3
a
b
b
Sundaramoorthy Tamilvanan , Govindasamy Gurumoorthy , Subbiah Thirumaran *
and samuele Ciattinic
a
Chemistry section [FEAT], Annamalai University, Annamalainagar, Tamilnadu 608002, India
Department of Chemistry, Annamalai University, Annamalainagar, Tamilnadu 608002, India
b
c
Centro di Cristallografia strutturale, Polo Scientifio di Sesto Fiorentino, Via della Lastruccia No.3, 50019 Sesto
Fiorentino, Firenze, Italy
*Corresponding author
Dr. S. Thirumaran
Department of Chemistry
Annamalai University
Annamalainagar 608 002
Tamil Nadu, INDIA
Tel: +91 9842897597
E-mail: sthirumaran@yahoo.com

Synthesis, characterization, cytotoxicity and antimicrobial studies on Bi(III)
dithiocarbamate complexes containing furfuryl group and their use for the preparation
of Bi O nanoparticles
2 3
a
b
b
Sundaramoorthy Tamilvanan , Govindasamy Gurumoorthy , Subbiah Thirumaran *
and samuele Ciattini c
a
Chemistry section [FEAT], Annamalai University, Annamalainagar, Tamilnadu 608002, India
Department of Chemistry, Annamalai University, Annamalainagar, Tamilnadu 608002, India
b
c
Centro di Cristallografia strutturale, Polo Scientifio di Sesto Fiorentino, Via della Lastruccia No.3, 50019 Sesto
Fiorentino, Firenze, Italy.
Correspondence e-mail: sthirumaran@yahoo.com
Abstract
Bismuth(III) dithiocarbamate complexes, tris(N-furfuryl-N-propyldithiocarbamato-
S,S’)bismuth(III) (1), tris(N-furfuryl-N-butyldithiocarbamato-S,S’)bismuth(III) (2) and
tris(N-furfuryl-N-benzyldithiocarbamato-S,S’)bismuth(III) (3), have been prepared and
characterized by microanalysis, and spectroscopy (IR and NMR). Structure of 3 has been
obtained by single crystal X-ray diffraction. This complex contains distorted pentagonal
pyramidal Bi(III) centres which attain an overall distorted pentagonal bipyramidal
coordination via long range intermolecular Bi···S interactions. DFT quantum mechanical
studies of 3 were carried out, supporting the partial double bond character of C–N
(
thioureide) and C–S bonds in dithiocarbamate ligands. All the compounds have been
screened against a panel of microbes viz. Vibrio cholerae, Bacillus subtilis, Klebsiella
pneumoniae, Escherichia coli, Staphylococcus aureus, Aspergillus niger and Candida
albicans. Complexes 1 and 3 were found to have better activity against K. pneumoniae, V.
cholerae, A. niger and C. albicans than the complex 2. Complexes 1-3 have been evaluated
for their in vitro cytotoxic activity against KB cells. Complexes 1 and 3 showed higher
activity than 2. Bi
PXRD, HRTEM, EDAX, UV-Vis and Fluorescence spectroscopy. PXRD study showed that
the sample is composed of monoclinic phase of ꢀ-Bi . Photocatalytic activity of as-
prepared ꢀ-Bi was determined by decolourization of rhodamine-B in aqueous solution
2 3
O obtained from thermal decomposition of 3 has been characterized by
2
O
3
2
O
3
under ultra violet irradiation.
Keywords : Bismuth(III) dithiocarbamates; antimicrobial; cytotoxicity; bismuth oxide
nanoparticles; photodegradation.

1
.
Introduction
A growing interest in dithiocarbamate chemistry is due to their structural diversity and
a wide range of applications in industries as rubber vulcanization accelerators, flotation
agents in metallurgy, heavy metal scavengers from waste and as effective antidotes for
cadmium detoxication [1-4]. The chemistry of bismuth dithiocarbamates of the general
2 2 3
formula Bi(S CNR ) is a subject of increasing interest during the last decades considering
their utility for the preparation of bismuth sulfide nanoparticles [5-6]. The coordination
chemistry of Bi(III) with dithiocarbamates is dominated by intermolecular interactions which
lead to polymeric structures [7]. The supramolecular aggregation is determined by steric bulk
of ligand bound R substituents. The presence of bulky R substituents often precludes
supramolecular aggregation via secondary M···S interactions whereas smaller R groups allow
for the formation of such interactions [8]. A review by Buac et al [9]. shows
dithiocarbamate complexes with various metals as a new type of potent proteasomes
inhibitors in human cancer cells. Proteasome inhibition has emerged recently as a novel
approach to cancer therapy with first-in-class proteasome inhibitor bortezomib. Bortezomib
is used for treatment of multiple Myeloma in the clinic from 2003 [10]. Nagy et al. review
promising results of recent research in anticancer activity of dithiocarbamate complexes with
noble metals (such as platinum, palladium, copper, ruthenium and gold) and their mechanism
of action [11]. Metal dithiocarbamate (M=Pt(IV) , Pd(II) ,Sn(IV) ,Ru(I), Au(III)) complexes
have also been investigated for their anti-cancer potential [12]. Recently the Bismuth
dithiocarbamate complexes were shown to be potent in vitro cytotoxicity against various
human cancer cell lines [13,14]. Synthesis and study of physical properties of semiconducting
nanoparticles have been the subject of active research during the past decade [15,16].
Bismuth oxide nanoparticles have been used as a material for optical coatings, photovoltaics
and microwave integrated circuits superconductor [17-19]. The aim of this work is to prepare

new Bi(III) dithiocarbamate complexes, and to study their application. In this paper, we
report synthesis, spectral, antimicrobial and cytotoxicity studies on three Bi(III)
dithiocarbamate complexes 1-3. Crystal structure of 3 is reported. In addition, preparation of
bismuth oxide nanobars from complex 3 and its photocatalytic activity is also presented.
2. Experimental
2
.1. Materials and physical measurements
All materials and solvents were analytical grade and used without further purification.
Melting points were determined by thermal melting point apparatus and used with open
capillary tubes and are uncorrected. Elemental analysis for carbon, hydrogen and nitrogen
were carried out with varioMICRO V2.2.0 elemental analyser. The IR spectra were recorded
–
1
on a SHIMADZU FT-IR spectrophotometer in the frequency range 4000–400 cm as KBr
1
13
pellets of the complexes. H and C NMR spectra were recorded with a Bruker 400 MHz
NMR instruments at room temperature using CDCl as a solvent and TMS as an internal
3
reference. TECNAI T2 G2 make-FEI instrument was used to record HRTEM images and
Powder X-Ray diffraction patterns were recorded using XPERT-PRO. Fluorescence and UV-
vis absorption spectra were recorded on Perkin Elmer L555 and SHIMADZU UV-1650 PC,
respectively. EDAX are performed by SUPRA 55VP CARL.
2
.2. X-ray crystallography
Suitable single crystals were obtained by the slow evaporation of complex 3 from
acetone at room temperature. The crystal diffraction data of complex 3 were collected on an
Xcalibur, Sapphire3 diffractometer equipped with a graphite monochromated MoK
ꢀ
radiation (ꢀ = 0.71073) at ambient temperature. The structure was solved and refined by
direct method using SHELXL-2014/7 (Sheldrick, 2014) [20]. All the non-hydrogen atoms

were refined anisotropically and the hydrogen atoms were refined isotropically. Details of the
crystal data and structure refinement parameters for 3 are summarized in Table 1.
2
.3 Computational methods
DFT studies were performed with GAUSSIAN-09 program package with the aid of
the Gauss View visualization program [21]. Molecular geometry was optimized with DFT
using basic set of LANL2DZ and calculation method of B3LYP.
2
2
.4. Synthesis of complexes
.4.1. Preparation of amines
N-furfuryl-N-propylamine , N-furfuryl-N-butylamine and N-furfuryl-N-benzylamine
were prepared by general methods reported as earlier [22].
2
.4.2. Preparation of complex 1
N-furfuryl-N-propylamine (0.88 g, 6.0 mmol,) and carbon disulfide (0.36 mL, 6.0
mmol) were dissolved in ethanol (20 ml) and stirred for 30 min under ice cold condition.
Bi(NO .5H O (0.96g, 2mmol) was dissolved in 50 ml of water and added to the solution.
A pale yellow solids were obtained by filtration. The product was recrystallised in acetone
3
)
3
2
-
1
1
(
Scheme 1). Yield: 78%; m.p. 115-117°C; IR (KBr (ν/cm ): 1478 (νC-N); 1012 (νC-S); H
NMR (CDCl ); δ = 0.92 (t, 9H, N–CH –CH –CH ); 1.76 (m, 6H, N–CH –CH –CH ); 3.76(t,
H, N–CH –CH –CH ); 5.07 (s, 6H, CH furfuryl); 6.43 (d, 3H, H–3 (furyl); 6.36 (dd, 3H,
H–4 (furyl); 7.38 (d, 3H, H–5 (furyl); C NMR (CDCl
CH -CH -CH ); 49.6 (CH -CH -CH ); 55.3 (CH furfuryl); 110.3, 142.4, 148.9 (furyl
ring carbons); 203.1 (NCS ). Anal, Calc. for C27 (%) : C, 38.06; H, 4.26; N,
.93. Found: C, 37.94; H, 4.11; N, 4.89.
3
2
2
3
2
2
3
6
2
2
3
2
1
3
3
); δ = 11.3 (CH
2
-CH
2
-CH ); 20.1
3
(
2
2
3
2
2
3
2
2
H
36BiN
3
O
3 6
S
4

2
.4.3 Preparation of complex 2
A method similar to that described for the synthesis of 1 was adopted; However N-
furfuryl-N-butylamine was used instead of N-furfuryl-N-propylamine. Yield: 84%; m.p. 116-
-
1
1
1
18°C; IR (KBr (ν/cm ): 1478 (νC-N); 1011 (ν(C-S); H NMR (CDCl
CH –CH –CH –CH ); 1.34 (m, 6H, N–CH –CH –CH –CH ); 1.71 (m, 6H, N–CH
CH –CH ); 3.79 (t, 6H, N–CH –CH –CH –CH ); 5.06 (s, 6H, CH furfuryl); 6.43 (d, 3H, H–3
furyl); 6.37 (dd, 3H, H–4 (furyl); 7.39 (d, 3H, H–5 (furyl). C NMR (CDCl
CH -CH -CH ); 20.1 (CH -CH -CH -CH ), 28.6 (CH -CH -CH -CH ); 49.5 (CH
CH -CH ); 53.6 (CH furfuryl); 110.4, 142.5, 148.8 (furyl ring carbons); 202.7 (NCS
(%): C, 40.30; H, 4.74; N, 4.70. Found: C, 40.12; H, 4.68;
3
); δ = 0.94 (t, 9H, N–
2
2
2
3
2
2
2
3
2 2
–CH –
2
3
2
2
2
3
2
1
3
(
3
); δ = 13.7 (CH
2
-
2
2
3
2
2
2
3
2
2
2
3
2
-CH
2
-
2
3
2
2
).
Anal, Calc. for C30
N, 4.72.
H
42BiN
3
O
S
3 6
2
.4.4 Preparation of complex 3
A method similar to that described for the synthesis of 1 was adopted; However
N-furfuryl-N-benzylamine was used instead of N-furfuryl-N-propylamine. Yield: 67%;
-
1
1
m.p.127-129°C; IR (KBr (ν/cm ): 1465 (νC-N); 1012 (νC-S); H NMR (CDCl
s, N-CH -C ); 5.19 ( 6H, s, CH furfuryl) ; 6.35-7.39 (aromatic protons);
CDCl ); δ= 48.0 (CH -C ); 55.9 (CH furfuryl), 110.4,110.6,142.6, 148.6 (furyl ring
carbons); 128.0, 128.1, 128.8, 134.9 (phenyl ring carbons); 204.7 (NCS ). Anal, Calc. for
(%): C, 47.03; H, 3.64; N, 4.22. Found: C, 46.90; H, 3.65; N, 4.18.
3
); δ= 5.00(6H,
1
3
2
6
H
5
2
C NMR
(
3
2
6
H
5
2
2
39 3 3 6
C H36BiN O S
2
.4.5 Preparation of bismuth oxide nanoparticles
The bismuth oxide nanoparticles were prepared by thermal decomposition of complex
3
. 1.5 g of complex 3 was placed in muffle-furnace at 500°C for 30 min in the presence air
atmosphere. The final residue analyzed to ꢁ-Bi
2
3
O .

3
3
. Biological assays
.1 Antimicrobial assay
The cultures of microorganism were spreaded on the incubated test plates (Mueller
Hinton Agar) [23]. The sterile antibiotic discs (diameter of 6 mm) loaded with required
concentrations (400 and 800 ꢂg/ml) of complexes 1, 2 and 3 were placed on the plates. The
plates were incubated for 24 h at 37ºC. After that, the zones of inhibition were examined and
read the diameter as the activity against the tested microorganism.
3
.2 Cytotoxicity assay
The cytotoxic activity of complexes 1-3 in KB cells was determined by the MTT
6
assay [24]. The KB Cells (1 × 10 cells/ml) were seeded into a 96 well plate and incubated at
7°C in 5% CO atmosphere for 24 hours. Then the KB cells were treated with different
concentrations (0-1000 ꢂg/ml) of complexes 1, 2 and 3. After 24 h incubation with
complexes , the cells were further incubated at 5% CO at 37°C for 24 h. 0.5 mg/ml MTT dye
3
2
2
was added. Then color was allowed to develop for additional 4 h incubation. An equal
amount of DMSO was added to stop the reaction and to solublize the formazan crystals.
Absorbance was measured colorimetrically at 570 nm. The percentage of cytotoxic activity
was calculated as follows:
%
Cytotoxicty = Test optical density / Control optical density X 100
4
. Photocatalytic experiments
HEBER Multi Lamp Photo Reactor was used for photo catalytic experiment. The
photocatalytic performance of the bismuth oxide was evaluated through the photocatalytic
degradation of rhodamine-B. Double distilled water was used to prepare all solutions. In a
2 3
typical photocatalytic experiments, 0.1 g of as-prepared ꢁ-Bi O was added to 250 ml of
aqueous solution of rhodamine-B in the concentration of 0.01 M. The suspensions were
magnetically stirred under darkness for 1 h to reach the adsorption–desorption equilibrium.

The suspension was irradiated by UV light from mercury vapour lamp in a photocatalytic
instrument with water cooling device. At certain time intervals, 3 ml of suspension was
centrifuged to remove the photocatalyst and analysed by UV-visible spectrophotometer at a
wavelength of 554 nm. The measurements were carried out upto 180 min [25].
5
. Results and discussion
5
.1. Infrared spectral studies
Infrared spectra of complexes 1-3 are shown in Fig. S1-S3. The infrared absorption
spectra of the metal dithiocarbamate complexes have proven to be an important tool in the
analysis of the coordination mode (monodentate or bidentate) of the dithiocarbamate ligands
-1
[
26]. In the present study, the ꢃC-S band is observed at 1012 cm for all complexes. The
values of the ꢃC-S indicate a bidentate chelating mode of the ligand towards the metal cation
-
1
[
27]. In all the spectra, a strong band appeared in the range of 1445-1480 cm is assigned to
the C–N (thioureide) stretching mode. This band is characteristic of C–N (thioureide) bond
which lies between the single and double bond energies, indicating the partial double bond
character [27,28].
1
13
5
.2 H and C NMR spectral studies
1
13
H and C NMR spectra of complexes 1- 3 are given in Fig. S4-S9. Proton NMR
spectra were characteristic of each ligand type. Thus N-furfuryl-N-propyldithiocarbamate
complex 1 showed three signals (0.92, 1.76 and 3.76 ppm) associated with the methylene
and methyl group of propyl that bound to nitrogen appearing at relatively lowfield, together
with a sharp singlet (5.07 ppm) assigned to the methylene of furfuryl moiety. For complex 2,
signals observed at 5.06 and 3.79 ppm are due to methylene protons of furfuryl and NCH
butyl) protons, respectively. The remaining signals in the aliphatic region are assigned to the
other methylene protons and methyl protons of butyl groups. Two singlets observed in the
2
(

aliphatic region are due to the methylene protons of furfuryl and benzyl groups. In all the
complexes, methylene protons adjacent to nitrogen atom are deshielded to a large extent on
complexation compared to the free amines.
1
3
The N CS carbon signals are appeared in the expected region (around 200 ppm) for
2
main group metal dithiocarbamate complexes [29]. In complexes 1-3, these signals are
observed around 203 ppm, indicating contribution of double-bond character to a formally
single N–C bond in the dithiocarbamate. For complexes 1-3, the signals for methylene
carbons adjacent to nitrogen atoms are observed in the region 48.0-55.9 ppm. The other two
and three signals appeared in the aliphatic region for complexes 1 and 2, respectively are
assigned to the remaining carbons of propyl and butyl groups.
5
.3 Single crystal X-ray diffraction analysis of 3
ORTEP diagram of complex 3 is shown in Fig. 1. Selected parameters of bond
distances and angles are listed in Table 2. Complex 3 was crystallised from acetone
to give yellow crystals. The central bismuth is six coordinated. Bi has bonded to
six crystallographically independent sulfur atoms with Bi–S distances ranging
from 2.5876(12) Å to 2.9055(13) Å (Table 2) forming a distorted pentagonal pyramid
coordination sphere with the shortest distance (Bi–S4 = 2.5876(12) Å) to the S4 atom at the
apex. Five sulfur atoms (S2-S6) in the equatorial plane and the central atom (Bi) are not
coplanar. S2 atom shows maximum deviation (–0.415 (1) Å) from the mean plane of the
atoms S2-S6 and Bi. Furthermore, due to the constraint of the chelate, the angle S1-Bi-S2
being axial is 65.65(3)°, which deviate from the angle 90°. From this, the Bi atom of this
complex is in the distorted pentagonal pyramidal configuration.

The short C–N (thioureide) bond distances [C1–N1 = 1.327(6) Å, C14–N2 = 1.357(6)
Å and C27–N3 = 1.324(6) Å] indicates that the ꢁ-electron density is delocalized over NCS
2
.
The C–S bond distances [mean: 1.7188(5) Å] are lower than C–S single bond length of 1.81
Å and longer than C–S double bond distance of 1.69 Å. The observed values indicate partial
double bond character.
A long BiꢄꢄꢄS and C–HꢄꢄꢄO contacts of 3.340 Å and 2.967 Å, respectively leads to the
dimeric association of molecules in the crystal structure as shown in Fig. 2. In the crystal
structure, neighbouring molecules linked by C–Hꢄꢄꢄꢁ (chelate) and pairs of C–Hꢄꢄꢄꢁ [C11–
H11ꢄꢄꢄCg1 (O3, C29–C32) = 2.790 Å and C5–H5ꢄꢄꢄCg2 (O2, C16–C19) = 2.671 Å] contacts,
thus generating supramolecular network (Fig. 3). A weak intramolecular interaction C–Hꢄꢄꢄꢁ
(
chelate ring, (Bi, S1, S2, C1)) is also found in this complex (Fig. S10). Various
intramolecular C–HꢄꢄꢄO and C–HꢄꢄꢄS hydrogen bonds are observed (Figs. S11 and S12).
5
.4 DFT calculations of complex 3.
Optimized structure of complex 3 is given in Fig. S13. Optimized geometrical
parameters are compared with experimental geometrical parameters (Table 3). Theoretically
calculated Bi–S bond lengths are greater than those of the experimental data. This may be
due to the free isolated molecule is optimized, so the intermolecular interactions are not
included which is obvious in solid. The optimized energy and dipolemoment of the complex
are -1963.52 a.u. and 3.92 Debye. The C–N(thioureide) and C–S distances are almost equal
in both the cases. This observation also supports the delocalization of ꢁ-electron density over
2
S CN moiety [30].

5
.5 Frontier molecular orbital analysis
Frontier molecular orbital densities can be used to describe the reactivity of a
particular atom in the molecule. According to frontier electron reactivity theory, the chemical
reaction takes place at a position where overlap of the HOMO and LUMO are the maximum.
In the case of donor and acceptor molecule, the HOMO density and LUMO density
respectively are important. The HOMO and LUMO energies are directly related to the
ionization potential and electron affinity, respectively. The 3D plots of the HOMO and
LUMO energy levels and energy gaps for the complex 3 are shown in Fig. 4. These reveal
that sulfur atoms have the ability to donate electron and Bi, C and N atoms act as electron
acceptor. HOMO-LUMO orbital studies imply that the electron density from the N is
transferred to S in the complex. The energy gap between the HOMO and LUMO is 3.7496
eV. The large energy gap reveals that the complex is stable. The hardness of the complex is
1
.8748 eV [31].
5
.6 Molecular Electrostatic Potential
Molecular electrostatic potential is related to the electronic density and is useful to
determine the sites for electrophilic and nucleophilic reactions. The MEP surface and
electrostatic potential contour maps are shown in Fig. 5. The MEP surface shows the
negative region(red) of the MEP related to electrophilic reactivity and the positive regions
(
blue) of the MEP related to nucleophilic reactivity. Electrostatic potential surface energies
−1
are in the range from −396.54 (red) to +396.54 (blue) kJmol [32]. Calculated electrostatic
potential surfaces are generated at an isodensity of 0.02 a.u. MEP surface diagram shows that
the complex has possible site for electrophilic attack (red region on S) and a site for
nucleophilic attack (blue region on N).

5
.7 Antimicrobial studies
The antibacterial study was conducted against Vibrio cholerae, Bacillus subtilis,
Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus, using the disc diffusion
method. Ciprofloxacin was used as the reference drug. The results of the complexes are
shown in Fig. 6. The antibacterial study exhibited that all the complexes have no effect
towards B.substils and S.aureus. All the complexes demonstrated lower activity against
E.coli. Complexes 1 and 3 showed better activity towards K.pneumoniae and V.cholerae
than complex 2. The antifungal studies revealed that the complexes 1 and 3 have higher
activity against all tested fungi than the complex 2. Generally, the antimicrobial studies
~
indicated that the activity of the complexes follows the order: 1 3 >2.
5
.8 In vitro cytotoxicity
The cytoxic activity of bismuth(III) dithiocarbamates 1-3 was evaluated. Microscopic
images of control and apoptic morphological changes in KB (oral) cell line treated with
complexes 1-3 are shown in Fig. S14. The graph for the cytotoxic effect against KB(oral)
cells after 24 h treatment using all three complexes 1-3 are presented in Fig. 7. Figure 7
showed that complexes 1 and 2 were able to effectively kill about 70% of the cell population,
whereas complex 3 kills 98% of the cell population at the concentration 500 µg/ml.
Complexes 1 and 3 display the in vitro cytotoxic activity against KB(oral) cells with IC50
values of 44 and 40 µg/ml, respectively, while the complex 2 has low activity (IC50 = 85
µg/ml). Apparently, the ligands especially N-bound organic moieties play an important role
in the antiproliferative action of the complexes.

5
.9 Characterization of Bismuth oxide nanoparticles
The powder X-ray diffraction pattern for ꢁ-Bi
the diffraction pattern is characteristics of the monoclinic phase of ꢁ-Bi
good agreement with the reported pattern (JCPDS file No: 76-1730) [33, 34]. The observed
narrow peak at (1 2 0) for ꢁ-Bi reveals that the particles are elongated towards the c-axis
which is characteristic of the bar shaped nanoparticles.
2
O
3
is shown in Fig. 8. The peaks in
2
O
3
, which are in
2
O
3
HRTEM images (Fig. 9a and 9b) of as-prepared ꢁ-Bi
products are nanobars. The width and length of the nanobars are in the range 24-40 nm and
5-200 nm. The d spacing calculated from high magnification HRTEM was found to be 2.48
Å corresponding to the (1 2 0) plane for ꢁ-Bi and also supports the XRD analysis.
SAED pattern of Bi confirms that the obtained products are in crystalline nature. The
elemental composition of the as-prepared ꢁ-Bi was studied by EDS analysis. The energy
dispersive X-ray spectrum is given in Fig. S15.
2 3
O display that the obtained
7
2
O
3
2
O
3
2
O
3
EDS confirms the obtained products are Bi
This confirms that no bismuth sulfide is formed by thermal decomposition of 3. The
formation of Bi is further supported by the fact that Bi was obtained as a final residue
in the thermal decomposition of Bi(III) dithiocarbamate complexes in air atmosphere [35 ].
2
O
3
. A peak due to sulfur is not observed.
2
O
3
2
O
3
UV-Vis absorption and photoluminescence spectra of as-prepared ꢁ-Bi
in Fig. 10. An absorption band appeared at 253 nm (4.90 eV) is attributed to the first exciton
absorption of ꢁ-Bi nanobars. The blue shift of the absorption band of the as-prepared ꢁ-
Bi compared to bulk Bi (435 nm, 2.85 eV) displays the quantum confinement effect
of ꢁ-Bi nanobars [36]. The observed peak at 369 nm in the photoluminescence spectrum
of Bi is commonly attributed to the excitonic or band edge emission. The
2 3
O are shown
2
O
3
2
O
3
2 3
O
2
O
3
2
O
3

photoluminescence peak position of band edge emission of nanomaterials is strongly size
dependent.
5
2 3
.10 Dye degradation by UV light irradiated as-prepared Bi O .
The use of metal oxides and metal sulfides for decomposition of pollutants such as
dyes has received considerable recent attention. Particularly, Bi is considered as a good
photocatalyst used for degradation of dyes under UV irradiation . The photocatalytic activity
of Bi prepared here are therefore of interest. The absorptions of UV light irradiated sample
aqueous solution of rhodamine-B and as-prepared Bi ) at various time intervals (30, 60,
0, 120, 150 and 180 min) were recorded to study the photocatalytic activities of as-prepared
. The percentage of dye degradation was defined by the following formula:
2
O
3
2
O
3
(
2 3
O
9
2 3
Bi O
A
0
- A
t
%
of degradation =
X 100
A
0
0 t
Where A is the initial absorbance of dye; A is the absorbance of dye at time t.
Aqueous solution of rhodamine-B without catalyst shows small degradation when irradiated
with UV light. Fig. 11 shows time-dependent UV-Vis absorption spectra of rhodamine-B
during photoirradiation with as-prepared Bi
decolorization efficiency of Bi is 92 %.
2
3
O under ultra violet light. The percentage of
2
O
3
6
. Conclusions
Complexes 1-3 have been prepared and characterized. Bismuth atom in the
mononuclear complex exists within an S donor set that defines a distorted pentagonal
pyramidal geometry. Computational studies on complex 3 were carried out. IR spectral,
structural and DFT studies confirm the partial ꢁ-conjugation over the NCS group. All the
6
2

complexes were screened for in vitro antibacterial and antifungal activities. These results
exhibited that complexes 1 and 3 showed good antimicrobial activity against selected
bacterial strains and fungal strains than 2. The cytotoxicity of complexes 1-3 against KB cells
have been evaluated. Complexes 1 and 3 (IC50 = 44 and 40 µg/ml, respectively) revealed
higher activity than 2 (IC50 = 85 µg/ml). This study show that the modification of N-bound
organic moiety in dithiocarbamate ligands may increase the antimicrobial and cytotoxic
activities. ꢀ-Bi
characterized.
confinement effect. The as-prepared ꢀ-Bi
rhodamine-B.
2
O
3
nanoparticles were obtained from the thermal decomposition of 3 and
UV-Vis spectral studies on ꢀ-Bi established pronounced quantum
functions as photocatalyst for the degradation of
2
O
3
2
O
3
7
. Supplementary data
CCDC 1479695 contains the supplementary crystallographic data for 3. This data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(
+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.

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1
Scheme and Figure captions
Scheme 1.
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Preparation of the complexes 1-3
ORTEP diagram of complex 3 at 40% probability
The dimeric structure of 3 predicted by BiꢄꢄꢄS and C-HꢄꢄꢄO interactions
Intermolecular C–Hꢄꢄꢄꢁ (chelate) and C–Hꢄꢄꢄꢁ interactions in complex 3
Frontier molecular orbital diagram of complex 3
(a) Electrostatic potential surface and (b) Contour map of electrostatic
Potential of complex 3
Figure 6.
Figure 7.
Figure 8.
Antimicrobial activity of complexes 1-3 against tested organisms
Percentage of cell viability at different concentrations of complexes 1-3
X-ray diff raction pattern of the as-synthesized bismuth oxide NPs
Figure 9.
HR-TEM images of bismuth sulfide NPs, scale bars (a) 200 nm, (b) 100 nm,
(
c) 10 nm and (d) Selected area electron diffraction (SAED) pattern of the as-
synthesized bismuth oxide NPs
Figure 10. (a) UV-Vis spectra and (b) Photoluminescence spectra of the as-synthesized
bismuth oxide nanoparticles
Figure 11. Time-dependent UV-Vis absorption spectra for decolorization of
2 3
rhodamine- B using as-prepared Bi O

Table 1 Crystal data, data collection and refinement parameters for complex 3
Empirical formula
39 3 3 6
C H36 Bi N O S
FW
996.05
Crystal dimensions (mm)
0.3 × 0.282 × 0.25
Crystal system
monoclinic
Space group
1
P 2 /n
a/Å
b/Å
c/Å
α/°
β/°
γ/°
10.5715(3)
11.7179(3)
32.0535(9)
90.00
96.744(3)
90.00
3
V/Å
3943.18(19)
4
Z
–
3
Dc/g cm
1.678
–
1
µ/cm
4.831
F(000)
1976
λ/Å
MoK
α
(0.71073)
4.2460 – 31.1350
θ Range/°
Index ranges
−16 ≤ h ≤ 15, −16 ≤ k ≤ 14,
43 ≤ l ≤ 48
−
Reflections collected
13195
9769
Observed reflections [I > 2σ(I)]
Weighting scheme
2
2
2
Calc.W=1/[σ (F
where P = (F
o
)+(0.0493P) + 6.6827P]
2
2
o
+2F
c
)/3
Number of parameters refined
469
2
2
2
R[F > 2σ(F )], wR(F )
0.0777, 0.1188
0.961
GOOF

Table. 2
Selected bond distances (Å) and bond angles (°) for the complex 3.
3
S1-Bi1
S2-Bi1
S3-Bi1
S4-Bi1
S5-Bi1
S6-Bi1
2.5876(12)
2.8747(12)
2.8056(12)
2.9055(13)
2.8886(12)
2.7711(13)
C20-N2 1.469(6)
C15-N2 1.467(6)
S2-Bi1-S1
S6-Bi1-S1
S5-Bi1-S6
S5-Bi1-S4
S3-Bi1-S4
S3-Bi1-S2
65.65(3)
85.70(4)
63.02(3)
C1-N1-C2
S4-C14-S3
N2-C14-S3
122.2(4)
119.9(3)
120.0(3)
120.2(3)
121.7(4)
122.4(4)
C27-S6
C27-S5
1.722(5)
1.727(5)
158.24(3) N2-C14-S4
62.47(3) C14-N2-C15
C27-N3 1.324(6)
C33-N3 1.478(6)
136.46(4) C14-N2-C20
91.53(17) C15-N2-C20
83.30(17) S6-C27-S5
C1-S1
C1-N1
C1-S2
C7-N1
C2-N1
C14-S3
C14-S4
1.748(5)
1.327(6)
1.692(5)
1.471(6)
1.489(6)
1.719(5)
1.705(5)
C28-N3 1.467(6)
C1-S1-Bi1
C1-S2-Bi1
N1-C1-S1
N1-C1-S2
S1-C1-S2
C2-N1-C7
C7-N1-C1
115.4(4)
118.2(3)
121.4(3)
120.4(3)
123.1(4)
122.6(4)
113.9(4)
117.9(3)
122.6(3)
119.4(3)
113.7(4)
124.2(4)
N3-C27-S5
N3-C27-S6
C33-N3-C27
C28-N3-C27
C28-N3-C33
C14-N2 1.357(6)

Table 3 Selected bond parameters (theoretical and experimental) for 3
Bond
distances (Å)
DFT/
LAN2DZ
DFT/
LAN2DZ
XRD
Bond angle(°) XRD
65.65(3)
Bi1-S1
Bi1-S2
Bi1-S3
Bi1-S4
Bi1-S5
Bi1-S6
N1-C1
S1-C1
2.5876(12)
2.8747(12)
2.8056(12)
2.9055(13)
2.8886(12)
2.7711(13)
1.327(6)
2.9845
2.8364
3.0467
2.6737
2.9921
2.8536
1.3525
1.7803
1.8071
1.3550
1.7592
1.8291
1.3576
1.7833
1.8011
S2-Bi1-S1
S3-Bi1-S1
S4-Bi1-S3
S6-Bi1-S5
N1-C1-S1
N1-C1-S2
S1-C1-S2
N2-C14-S3
N2-C14-S4
S3-C14-S4
N3-C27-S5
N3-C27-S6
S5-C27-S6
64.03
81.53
88.59(4)
62.47(3)
63.02(3)
117.9(3)
122.6(3)
119.4(3)
120.0(3)
120.2(3)
119.9(3)
121.4(3)
120.4(3)
118.2(3)
64.96
63.59
121.46
119.68
118.85
123.31
117.93
118.75
121.38
120.01
118.60
1.748(5)
S2-C1
1.692(5)
N2-C14
S3-C14
S4-C14
N3-C27
S5-C27
S6-C27
1.357(6)
1.719(5)
1.705(5)
1.324(6)
1.727(5)
1.722(5)

Graphical abstract (synopsis)
Three new Bi(III) dithiocarbamates have been prepared and characterized. X-ray structure of 3
shows that Bi is in distorted pentagonal pyramidal environment. Cytotoxic activity against KB(cell) 1-
3
with IC50 = 44, 85 and 40 µg/ml, respectively. Thermal decomposition of 3 yielded ꢀ-Bi
2 3
O
nanobars. Optical, structural and photocatalytic properties of ꢀ-Bi were evaluated.
2
O
3

Graphical Abstract

Scheme 1.

Figure 1.

Figure 2.

Figure 3.

LUMO+1
LUMO
∆
E=3.7496 eV
∆E=4.6286 eV
Figure 5.
HOMO
HOMO-1
Figure 4.

-396.54 kJ/mol
+396.54 kJ/mol
(a)
(b)
Figure 5.