Synthesis, Chemical Characterization, DNA Interaction and Antioxidant, Studies of New Nitrosubstituted Thioureas and Their Copper Complexes

Article abstract of DOI:10.1002/jccs.201500169

In the present work new nitro substituted thioureas, and their copper complexes have been synthesized and characterized by FTIR and multinuclear NMR techniques. Some of the compounds namely 1-benzoyl-3-(4-chloro-3-nitrophenyl) thiourea (A-1), 1-benzoyl-3-(4-chloro-3-nitrophenyl) thiourea (A-2) and 1-benzoyl-3-(2-methoxy-4-nitrophenyl) thiourea (A-2) have also been characterized by single crystal XRD. All the synthesized compounds have been screened for DNA binding potencies (using cyclic voltametry, UV-vis spectroscopy) and free radical scavanging activities.

Full text of DOI:10.1002/jccs.201500169

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Synthesis, Chemical Characterization, DNA Interaction and Antioxidant, Studies of
New Nitrosubstituted Thioureas and Their Copper Complexes
Jahangeer Patujo,a Amin Badshah,a* Raja Azadar Hussain,a Muhammad Nawaz Tahir,b
Shaista Tahira and Muhammad Khawar Raufa
aCoordination Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, 45320, Islamabad, Pakistan
bDepartment of Physics, University of Sargodha, Punjab, Pakistan
(Received: May 7, 2015; Accepted: Sept. 21, 2015; Published Online: Oct. 30, 2015; DOI: 10.1002/jccs.201500169)
In the present work new nitro substituted thioureas, and their copper complexes have been synthesized
and characterized by FTIR and multinuclear NMR techniques. Some of the compounds namely
1-benzoyl-3-(4-chloro-3-nitrophenyl) thiourea (A-1), 1-benzoyl-3-(4-chloro-3-nitrophenyl) thiourea
(A-2) and 1-benzoyl-3-(2-methoxy-4-nitrophenyl) thiourea (A-2) have also been characterized by single
crystal XRD. All the synthesized compounds have been screened for DNAbinding potencies (using cyclic
voltametry, UV-vis spectroscopy) and free radical scavanging activities.
Keywords: Thiourea copper complexes; Cyclic voltammetry; DNA binding studies.
INTRODUCTION
Thioureaes are the diamides of thiocarbonic acids and
RESULTS AND DISCUSSION
IR-analysis
find their applications in pharmaceutical industry, as an
antifungal1 antimicrobial2-4 antituberculosis,5 antimalerial6
anticancer,7 anti-HIV,8 carbonic anhydrases inhibitor,9 b3-
adrenergic recepter agonists9 and appetite suppressants.10
For the investigation of anti-bacterial properties, carbonyl
thiourea derivatives have been synthesized by Yusof and
co-workers in 2009.11 It was found that presence of nitro,
bromo and chloro groups as a substituent on the carbonyl
thiourea increases the activities of compound towards
methicillin-resistant Staphylococus aureus (MRSA). More-
over N-methyl-N-(2-thiazolyl)-N-alkyl substituted thio-
ureas have shown plant regularity activity and inhibition of
stem elongation of rice and kidney bean plants without
phytotoxicity.12 In another attempt N-[2-(2-oxo-1-imida-
zolidinyl)ethyl]-N’-phenylurea, in the tobacco callus bio-
assay have shown cytokinin activity13 and have also caused
cellular defences in a number of plant species against
ozone damage.14 These applications of thiourea menifest
that further new thiourea derivatives should be synthesized
and should be evaluated for their further useful biological
applications. In this article we have reported the synthesis
of some new nitrosubstituted thioureas with complete char-
acterization, complexation, electrochemical properties,
DNA binding studies and antioxidant activities with a spe-
cial empahsis on the comparison of the activities before and
after the complexation.
All the compounds have been synthesized and puri-
fied from impurities i.e byproduct (KCl, amide, carboxylic
acid and unreacted material) on the basis of difference of
their solubilities in organic solvents and obtained in form
of yellow, red and light yellow crystals. In all the com-
pounds there was a strong absorption above 1650 cm-1 due
to stretching vibrations of the C=O group; there is a broad
signal above 3200 cm-1 for the -NH stretching vibrations
because of the intramolecular hydrogen bond between the
hydrogen atom of the NH and oxygen of the carbonyl
group whereas a medium band above 1200 cm-1 is attrib-
uted to the C=S. No absorption band was observed in the
range 2600-2500 cm-1 for the S-H group further conform-
ing that compound do not exist in the thioenol form. This
can also be taken as an evidence for the synthesized ligands
exist in the thioketone form. Peak above 400 cm-1 (Cu-O)
appears for their copper complexes.
H1 NMR analysis
In the H1 NMR spectra of all the synthesized com-
pounds, singlet above 12 ppm can be attributed to NH pro-
ton that is in between C=S and substituted aryl group; is
maximum deshielded because of the electron withdrawing
effect of the aryl group and its involvement in intramole-
cular hydrogen bond with the oxygen of the carbonyl
group. Singlet above 10 ppm is attributed to the proton of
the other NH moiety present in the compounds between
* Corresponding author. Email: aminbadshah@yahoo.com
Supporting information for this article is available on the www under http://dx.doi.org/10.1002/jccs.201500169
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Copper Thiourea Complexes as DNA Binders
C=S and C=O. 8 protons of the two aromatic rings appear
as multiplet in the region 9.0–6.9 ppm. In 13C NMR spec-
trum signal above 180 ppm is attributed to the carbon of the
C=S and signal above 165 ppm is attributed to the carbon of
the carbonyl group. Two aromatic rings give their signals
between 145–119 ppm. The complexes in which Cu was in
+1 oxidation state were scanned with 1H-NMR and the ab-
sence of one peak out of the two –NH confirms the forma-
tion of complexes.
A-1. However A-3 exists as a monomer and there are two
molecules per unit cell (Figure 1c). Intermolecular as well
as intramolecular hydrogen bonding stabilize the crystal
lattice as shown in Figure 1c1. This intramolecular hydro-
gen bonding between the oxygen of carbonyl and the NH
which was present between the phenyl ring and C=S was
also evident in the proton NMR. Because of this hydrogen
bonding, this NH is comparatively downfield then the other
NH which is present between the carbonyl group and C=S
in proton NMR of all the thioureas presented in this manu-
script.
X-ray crystallography
Basic crystal data and crystal refinement parameters
have been given in Table 1 whereas important bond lengths
and bond angles have been presented in Table 2 for all the
three crystals A1-A3. ORTEP diagram of A-1 has been pre-
sented in Figure 1a which shows that this molecule exists in
a dimeric form and is stablized by the intermolecular as
well as intramolecular hydrogen bonding. Two such dimers
per unit cell exist and are extended in the lattice in a zigzag
manner (Figure 1a1). ORTEP diagram of A-2 has been
given in Figure 1b which also exists as a dimer and has very
similar type of hydrogen bonding and extended lattice to
DNA BINDING STUDIES
Cyclic voltammetry
Changes in the peak potentials and peak currents in
CV provide very useful information about the interaction
of a particular aimed drug with DNA. Drug-DNA binding
constant is calculated by a change in the peak current of a
drug-DNAadduct relative to the free drug (when CV is per-
formed without DNA of a certain compound) by using the
following equation:
Table 1. Crystal data and structure refinement parameters for A-1, A-2 and A-3
Identification code
A-1
A-2
A-3
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a/Å
b/Å
c/Å
a/°
b/°
C14H10ClN3O3S
335.76
C14H10ClN3O3S
335.76
C16H12N2O5S
344.34
296(2)
Triclinic
P-1
8.6253(9)
9.1232(13)
11.6163(14)
107.112(6)
92.335(4)
118.144(4)
752.65(16)
2
296(2)
Triclinic
P-1
10.8443(7)
12.1972(7)
13.0054(13)
111.505(4)
108.815(5)
100.085(3)
1428.4(2)
296(2)
Triclinic
P-1
7.0785(4)
13.9627(8)
16.1038(10)
66.478(3)
86.944(3)
84.800(3)
g/°
Volume/Å3
Z
1453.10(15)
4
4
rcalcg/cm3
m/mm-1
1.561
0.429
1.535
0.422
1.519
0.246
F(000)
688.0
688.0
356.0
Crystal size/mm3
Radiation
Index ranges
0.38 ´ 0.26 ´ 0.24
MoKa (l = 0.71073)
-13 £ h £ 13, -15 £ k £ 15,
-16 £ l £ 16
22490
0.4 ´ 0.28 ´ 0.26
MoKa (l = 0.71073)
-9 £ h £ 7, -18 £ k £ 16,
-20 £ l £ 20
23578
0.4 ´ 0.32 ´ 0.3
MoKa (l = 0.71073)
-11 £ h £ 10, -11 £ k £ 11,
-15 £ l £ 15
10760
Reflections collected
Independent reflections
6309 [Rint = 0.0283,
Rsigma = 0.0309]
6309/0/397
1.038
6665 [Rint = 0.0299,
Rsigma = 0.0363]
6665/0/397
1.029
3426 [Rint = 0.0280,
Rsigma = 0.0271]
3426/0/209
1.085
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [all data]
Largest diff. peak/hole/e Å-3
R1 = 0.0669, wR2 = 0.1168 R1 = 0.0705, wR2 = 0.1068 R1 = 0.1207, wR2 = 0.2572
0.66/-0.54 0.27/-0.25 0.90/-1.22
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Patujo et al.
Table 2. Bond lengths and bond angles for A-1, A-2 and A-3
Ligands (Drug) Do (cm2s-1)
K (M-1)
Complexes (Drug)
Do (cm2s-1)
K (M-1)
A-1
A-1-DNA
A-2
A-2-DNA
A-3
A-3-DNA
A-4
A-4-DNA
A-5
A-5-DNA
A-7
4.30 ´ 10-6 9.84 ´ 103
6.02 ´ 10-8
Cu(A-1)2
Cu(A-1)2-DNA
Cu(A-2)2
Cu(A-2)2-DNA
Cu(A-3)2
Cu(A-3)2-DNA
Cu(A-4)2
Cu(A-4)2-DNA
Cu(A-5)2
Cu(A-5)2-DNA
Cu(A-7)2
6.31 ´ 10-6
9.00 ´ 10-8
1.1 ´ 104
8.86 ´ 10-6 9.57 ´ 103
2.08 ´ 10-8
1.93 ´ 10-6 1.23 ´ 104
2.16 ´ 10-8
3.30 ´ 10-7 4.38 ´ 103
1.33 ´ 10-9
1.59 ´ 10-5 1.03 ´ 104
1.31 ´ 10-7
6.70 ´ 10-5 2.06 ´ 103
1.99 ´ 10-7
7.37 ´ 10-6 1.62 ´ 104
1.41 ´ 10-7
2.84 ´ 10-6 6.08 ´ 103
1.74 ´ 10-8
9.49 ´ 10-6 1.12 ´ 104
1.82 ´ 10-7
6.00 ´ 103
7.20 ´ 10-6 6.83 ´ 103
4.75 ´ 10-8
A-7-DNA
Cu(A-7)2-DNA
Fig. 1. ORTEPs and crystal diagrams for A-1 (a, a1), A-2 (b, b1) and A-3 (c, c1).
log(1/[DNA]) = logK + log(I/Io-I)
Eq 1
surface area of electrode in cm2, C is the concentration of
the drug in molcm-3, n is the number of electrons involved,
D is the diffusion coefficient in cm2s-1 and u is the scan rate.
CV of a representative complex Cu(A-7)2 has been
presented in Figure 2 for DNA binding studies. This com-
pound provides two oxidation and two reduction peaks in
the region between -1.5 to 0.6 V in a quasi reversible elec-
trochemical process. The peaks in the negative potential re-
gions are for the nitrogroup available in the structure of the
ligand whereas the peaks in the positive potential region
are for the oxidation and reduction of Cu (I). Quasi revers-
where, K is the binding constant, Io is the peak current of
free drug and I is the peak current of drug-DNA adduct.
Formation of drug-DNA adduct in case of all the
ligands and complexes was proved by the lower value of
diffusion coefficient of drug-DNA adduct realtive to the
free drug (synthesized ligand/complex) according to Eq 2.
Ipa = 2.99 ´ 105n(an)1/2 AC*o1/2Do1/2u1/2 Eq 2
where, Ipa is the anodic peak current in amperes, A is the
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Copper Thiourea Complexes as DNA Binders
ibility of the process was confirmed by observing three
phenomena, i) slight change in the peak potential with scan
rate, ii) deviation of the peak current (oxidation and reduc-
tion) ratios from 1 and iii) more than 60 mV potential dif-
ference between the oxidation and reduction peaks (Figure
2a).17,18 Decrease in the peak current of drug-DNA adduct
relative to the free drug confirms the lower diffusion of the
drug-DNA adduct in the solution which decreases its rate
of approach towards the electrode (Figure 2b). Lower dif-
fusion coefficient of the drug-DNA adduct relative to the
free drug (synthesized ligand/complex) also confirms the
formation of the adduct (Figure 2c). If we compare the peak
positions in Figure 2b of the free drug and drug-DNA
adduct two things are obvious. First is the prominent de-
crease of the current for both the oxidation and reduction
peaks and second are the shifts in the peak potentials. Gen-
erally electrostatic interactions provide the electrons to the
free drugs (synthesized ligand/complex) which ease the ox-
idation process and hence provide the negative shift in the
peak potential however intercalation mode gives positive
shifts in the peak potentials. Cu(A-7)2 provides a mixed
mode of interaction because peaks of copper ion exhibit a
negative shift in the peak potential of drug-DNA adduct
relative to the free drug (complex) but for nitro group there
is a positive shift in the peak potential in the same CV.
Negative shift in the peak potential may be because of the
surface electrostatic interaction of copper cation (within
the complex) with negatively charged phosphate backbone
of the DNA. Because of the presence of negatively charged
oxygens in the nitro group it can not be oriented towards
negatively charged phosphate backbone of the DNA so
there may be an orientation of Cu(A-7)2 relative to the
DNA double helix that intercalates the nitro group to pro-
vide the positive shift in the peak potential. Data for all the
other compounds presented in this article have been pre-
sented in Table 3. If we look at the binding constant values,
it is evident that copper complexes have almost 2-8 times
higher binding potency with the DNA as compared to the
ligands, and these binding constant values are comparable
to that of the cisplatin19 and its derivatives. Moreover cop-
per complexes have been found to be effective for their
cytotoxic action on the tumor cells.20 Due to this reason
screening of these complexes for further biological activies
might show better results against cancer.
CV results were equally supported by UV-vis spec-
troscopy as well. UV data for the DNA binding studies of
Cu(A-7)2 have been displayed in Figure 3. In UV-vis spec-
trum Cu(A-7)2 provides two peaks which are under the in-
fluence of hyperchromism after the formation of drug-
Table 3. DNA binding parameters of the ligands and their
complexes
Bond type
Bond angle (°) Bond type Bond length (Å)
A-1
C(7)-N(1)-C(8)
C(8)-N(2)-C(9)
N(1)-C(7)-C(1)
N(1)-C(8)-S(1)
N(2)-C(8)-S(1)
128.30(18)
129.33(17)
116.75(18)
118.67(15)
126.71(15)
S(1)-C(8)
O(1)-C(7)
1.655(2)
1.222(3)
A-2
C(7)-N(1)-C(8)
C(8)-N(2)-C(9)
N(1)-C(7)-C(1)
N(1)-C(8)-S(1)
N(2)-C(8)-S(1)
128.78(17)
130.78(17)
117.38(18)
118.59(14)
126.85(15)
C(8)-S(1)
C(7)-O(1)
1.650(4)
1.214(4)
Fig. 2. a) CV of Cu(A-7)2 at different scan rates using
DMSO as a solvent and 1 mL of 1.5 M KCl as
supporting electrolyte. b) CV of Cu(A-7)2 in
the presence and absence of increasing DNA
concentrations where 1DNA = 6 mM. c) Plot of
current vs. square root of scan rate for diffusion
coefficient calculation of free and DNA bound
drug. d) Plot of log1/[DNA] vs. log I/Io-I for the
calculation of drug-DNA binding constant.
A-3
C(7)-O(1)
C(8)-S(1)
1.214(4)
1.650(4)
N(1)-C(8)-S(1)
N(2)-C(8)-S(1)
N(2)-C(8)-N(1)
117.7(3)
127.0(3)
115.2(3)
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DNA adducts by keeping the dilution same before and after
the addition of five different concentration of the DNA.
Binding constant K can be obtained by Benesi-Hildebrand
equation.
scavanging were evaluated for IC50 values with the help of
UV-vis spectroscopy (Figure 5). IC50 value of A-1 is 125
mM, A-2 is 250 mM, A-4 is 254 mM, A-5 is 112 mM and A-7
is 239 mM. Structure to activity relationship for IC50 values
is difficult to determine because there are two NH groups
and both of them can interact with the free radical (DPPH)29
however, chloro substituted derivatives are more active
than the methoxy substituted derivatives. Antioxident
strength of these compouds (ligands) have been shown
relative to that of the antioxident activity of the ascorbic
acid33 which was used as positive control (Figure 4). Their
corresponding complexes have not been evaluated for IC50
values because their response to DPPH was too poor to be
evaluated for further investigation and this weak response
might be attributed to the absence of easily available proton
(that has been removed during complex formation).
Eq 3
where, K is binding constant, Ao denotes absorbance of the
free-Drug (ligand/complex), A stands for Drug-DNA (li-
gand/complex + DNA) adduct, eG and eH-G are absorption
coefficients of the free drug and Drug-DNA adduct respec-
tively.
Plot of Relative absorbance (Ao/A-Ao) vs DNA con-
centration gives a straight line from which slope to inter-
cept ratio yields the DNA binding constant of 1.32 ´ 103
M-1 which is in close agreement with the values determined
from CV (6.83 ´ 103).15,21-29 Values of the DNA binding
constants of these thioureas and their complexes are in very
close agreement with recently reported transition metal
complexes,30 i.e thioureas derivatives coupled with fer-
rocene31 selenoureas coupled with ferrocene15,21-27 and
ferrocene incorporated antimoney derivatives32 which
shows their importance in the near future as anticancer
agents under study.
Antioxidant activity
All the ligands show DPPH scavanging activity that
may be mainly because of the presence of NH protons how-
ever during complex formation one of these protons is re-
moved and the other one is not easily available that’s why
their corresponding complexes show negligible antioxi-
dant activity. Figure 4 shows the total percentage scavang-
ing of DPPH by using 1000 mM solution of the all the
ligands. All those ligands which showed more than 50%
Fig. 4. DPPH scavenging activity of 1000 mM ligands
(A-1-A-7).
Fig. 3. a) Plot of absorbance vs. wavelength of Cu(A-7)2
before and after the addition of different DNA
concentrations. b) Plot of Ao/A-Ao vs, 1/[DNA]
for the calculation of DNA binding constant.
Fig. 5. Representative plot of absorbance vs. wave-
length for IC50 value of A-2.
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Copper Thiourea Complexes as DNA Binders
EXPERIMENTAL
General Procedure used for the synthesis of ligands (N,
N’-disubstituted thioureas): In 30 ml acetone (10 mmol) potas-
sium thiocyanate was dissolved in two neck round bottom flask.
In resulting solution acid chloride (10 mmol) was added and
stirred for 1 hour. Equimolar amount of neat nitro substituted ani-
line was added to the resulting reaction mixture and were set on
stirring for 4-5 hours to produce the thioureas (Scheme 1).16
Materials and methods: 3-chlorobenzoyl chloride, 3-
nitroaniline, 4-nitroaniline, 2-chloro-4-nitroaniline, 4-chloro-
3-nitroaniline, 2-methoxy-4-nitroaniline, 2-methyl-4-nitroani-
line, 2-methoxy-5-nitroaniline, potassium thiocyanate, and cop-
per (II) acetate monohydrate were purchased from Sigma Ald-
rich. Melting points were determined in glass capillary tubes, us-
ing electro thermal melting point apparatus-model MP-D Riken
Kogyo Japan. FT-IR spectra were recorded using Thermo Scien-
tific Nicolet-6700 FT-IR spectrophotometer in the spectral range
of 4000-350 cm-1. Bruker Advanced Digital 300 MHz NMR spec-
trometer (Switzerland) was used for 1H and 13C NMR. Si(CH3)4
was used as an internal reference in case of ligands as well as
complexes. Chemical shifts were indicated in ppm and spectra
were recorded in the range between 0-12 ppm and 0-220 ppm for
1H and 13C NMR respectively.
Synthesis of nitrosubstituted thioureas and
their copper complexes.
Scheme 1
For DNA binding studies; commercial Solman DNA was
dissolved in doubly distilled water to prepare a stock solution of
2.6 ´ 10-4 M. Working solutions of different DNA concentration
were prepared from this stock solution. Concentration of the stock
solution was measured by UV absorbance at 260 nm having epsi-
lon value 6600 M-1cm-1. DNA was free of protein because A260/
A280 was ~1. For DNA binding studies working solutions were
prepared by our previous reported method.15 UV-visible spectro-
scopic data was collected on Shimadzu 1800 spectrophotometer.
Quartz cells with 1 cm path length were used for running samples.
First the spectra of pure compound solution were recorded in the
range from 200-800 nm in the absence of DNA and then equal
amount of different DNA concentrations were added to both sam-
ple and reference cells in order to avoid its interference. Cyclic
voltammetry (CV) of synthesized compounds was performed, us-
ing software EC-Lab Express 5.40, Japan with three electrode
systems i.e. platinum disc (working electrode having surface area
of 0.071 cm2), Pt-wire as counter and SCE/3M as reference elec-
trode. Working electrode was polished each time with alumina
powder before getting every reading and rinsed with distilled wa-
ter. Potassium Chloride of analytical grade quality was used as
supporting electrolyte and interference of oxygen was avoided by
purging N2 gas (99.9%) through the mixture. For X-ray examina-
tion crystals were obtained from acetone solution by slow evapo-
ration and mounted on glass fiber and intensity data were col-
lected on Bruker Kappa APEXII CCD diffractometer having
graphite monochromatic Mo-Ka radiation source (l = 0.71073
Å). Structure of crystals were solved via direct method, and the fi-
nal structure was refined by full-matrix least square method
against F2 of data by using SHELX97 (Sheldrick, 273 2008) pro-
gram.
Synthesis of 1-benzoyl-3-(4-chloro-3-nitrophenyl) Thio-
urea (A-1): Quantities used: KSCN = (0.001 mol, 0.1 g),
C6H5COCl = (0.001 mol, 0.115 ml), 4-Chlor-3-nitroaniline,
(0.001 mol) (0.17 g) Yield: 77%, Melting point: 169-170 °C FTIR
(u cm-1): NH (3337, broad), C-Har (3054), C=O (1683), C=S
(1223). 1HNMR (300 MHz, Acetone-d6): d 12.66, (s, 1H, CSNH),
d 11.82 (s, 1H, CONH), 9.19-7.52 (m, 8H, C6H4, C6H5) ppm.
13CNMR (300 MHz, Acetone-d6): d 180.51, 168.11, 148.21,
144.31,136.51, 133.69, 132.43, 130.22, 127.43, 126.55, 121.33,
121.10 ppm. Synthesis of 1-benzoyl-3-(2-chloro-4-nitroph-
enyl) Thiourea (A-2): Quantities used: KSCN = (0.001 mol, 0.1
g), C6H5COCl = (0.001 mol, 0.115 ml), 2-Chloro-4-nitroaniline
(0.001 mol, 0.17 g). Yield 72%, Melting Point: 168-170 °C, FTIR
(u cm-1): NH (3326), C-Har (3055), C=O (1673), C=S (1250).
1HNMR (300 MHz, Acetone-d6): d 13.43, (s, 1H, CSNH), d 10.76
(s, 1H, CONH), 9.03-6.97 (m, 8H, C6H4, C6H5) ppm. 13CNMR
(300 MHz, Acetone-d6): d 180.4, 168.5, 144.3, 143.1, 137.2,
130.6, 129.4, 129.2, 127.4, 126.5, 122.3, 121.5 ppm. Synthesis of
1-benzoyl-3-(2-methoxy-4-nitrophenyl) Thiourea (A-3): Qu-
antities used: KSCN = (0.001 m, 0.1 g), C6H5COCl = (0.001 mol,
0.115 ml), 2-Methoxy-4-nitroaniline (0.001 m, 0.17 g). Yield
79%, Melting Point: 201-203 °C, FTIR (u cm-1): NH (3242),
1
C-Har (3058), C=O (1657), C=S (1236). HNMR (300 MHz,
Acetone-d6): d 12.64, (s, 1H, CSNH), d 10.50 (s, 1H, CONH),
9.37-6.97 (m, 8H, C6H4, C6H5) ppm. 13CNMR (300 MHz, Ace-
tone-d6): d 181.0, 168.2, 148.2, 144.4, 134.9, 132.6, 130.9, 130.4,
129.2, 128.9, 123.3, 121.4 ppm. Synthesis of 1-benzoyl-3-(3-
nitrophenyl) thiourea (A-4): Quantities used: KSCN = (0.001
J. Chin. Chem. Soc. 2015, 62, 1020-1027
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Article
Patujo et al.
mol, 0.1 g), C6H5COCl = (0.001 mol, 0.115 ml), 3-nitroaniline
(0.001 mol, 0.13 g). Yield 73%, Melting point: 160-162 °C, FTIR
(u cm-1): NH (3250), C-Har (3052), C=O (1651), C=S (1232).
1HNMR (300 MHz, Acetone-d6): d 12.66, (s, 1H, CSNH), d 10.33
(s, 1H, CONH), 9.21-7.62 (m, 9H, C6H4, C6H5) ppm, 13CNMR
(300 MHz, Acetone-d6): d 181.3, 168.2, 147.3, 144.0, 136.5,
131.6, 132.4, 130.2, 129.4, 126.4, 121.3, 121.1 ppm. Synthesis of
1-benzoyl-3-(4-nitrophenyl) Thiourea (A-5): Quantities used:
KSCN = (0.001 mol, 0.1 g), C6H5COCl = (0.001 mol, 0.115 ml),
4-nitroanilne (0.001 mol, 0.13 g). Yield 78%, Melting Point:
169-170 °C, FTIR (u cm-1): NH (3250), C-Har (3058), C=O
(1658), C=S (1229). 1HNMR (300 MHz, Acetone-d6): d 12.82, (s,
1H, CSNH), d 11.00 (s, 1H, CONH), 9.21-7.52 (m, 9H, C6H4,
C6H5), ppm. 13CNMR (300 MHz, Acetone-d6): d 180.3, 168.2,
147.2, 144.2, 137.9, 132.6, 131.91, 130.4, 129.2, 128.9, 122.3,
121.24 ppm. Synthesis of 1-benzoyl-3-(2-methoxy-5-nitro-
phenyl) Thiourea (A-6): Quantities used: KSCN = (0.001 mol,
0.1 g), C6H5COCl = (0.001 m, 0.115 ml), 2-methoxy-5-nitro-
aniline (0.001 mol, 0.17 g). Yield 71%, Melting Point: 172-174
°C FTIR (u cm-1): NH (3334), C-Har (3058), C=O (1652), C=S
C6H4, C6H5) ppm. Synthesis of Cu(A-3)2: Yield 64%, Decompo-
sition point: 233-234 °C. Color: Brown. FTIR (u cm-1): C-Har
(3058), C=S (1141), Cu-O (422), 1HNMR (300 MHz, DMSO): d
11.210 (NH), 9.031-6.972 (m, 8H, C6H4, C6H5), 4.122 (3H,
OCH3) ppm. Synthesis of Cu(A-4)2: Yield 79%, Decomposition
point 184-185 °C. Color Dark Green. FTIR (u cm-1): C-Har
(3065), NH (3339), C=S (1157), Cu-O (416). 1HNMR (300 MHz,
DMSO): d 11.78, (NH), 8.09-7.74 (m, 9H, C6H4, C6H5) ppm. Syn-
thesis of Cu(A-5)2: Yield 66%, Decomposition point: 188-189
°C. Color Dark Green. FTIR (u cm-1): C-Har (3054), NH (3359),
C=S (1156), Cu-O (439). Synthesis of Cu(A-6)2: Yield 65%, De-
composition point: 228-229 °C. Color: Dark green. FTIR (u
cm-1): C-Har (3055), C=S (1167), Cu-O (439). Synthesis of
Cu(A-7)2: Yield 64%, Decomposition point: 151-152 °C. Color:
Dark green. FTIR (u cm-1): C-Har (3054), C=S (1167), Cu-O
(439), 1HNMR (300 MHz, DMSO): d 11.210 (NH), 9.031-6.972
(m, 8H, C6H4, C6H5). ((Indication of figures/schemes/tables; will
be inserted by the editorial staff.))
CONCLUSIONS
1
(1230), C-N. HNMR (300 MHz, Acetone-d6): d 12.76, (s, 1H,
We have successfully reported the DNA binding abili-
ties of copper complexes synhtesized from nitrosubstitued
thiourea ligands and have characterized them with XRD sin-
gle crystal analysis (3 ligands), multinuclear NMR and FT-IR.
All the ligands and complexes show very good electrochemi-
cal behavior for DNA binding studies and the values of the
DNA binding constants are in a close agreement with the re-
cently reported transition metal compolexes, ferrocene deriv-
atives of thioureas and selenoureas. These electrostatic inter-
actions of the synthesized ligands and complexes indicate the
future use of these compounds as anticancer agents. Ligands
have also shown the free radical scavanging activities but the
complexes are inactive that might be because of the absence
of easily available NH protons.
CSNH), d 10.82 (s, 1H, CONH), 9.32-7.75 (m, 8H, C6H4, C6H5)
ppm, 13CNMR (300 MHz, Acetone-d6): d 180.2, 167.8, 148.2,
144.1, 138.5, 132.6, 130.4, 130.2, 127.4, 126.5, 121.3, 121.4
ppm. Synthesis of 1-benzoyl-3-(2-methyl-4-nitrophenyl) thio-
urea (A-7): Quantities used: KSCN = (0.001 mol, 0.1 g),
C6H5COCl = (0.001 mol, 0.115 ml), 2-Methyl-4-nitroaniline
(0.001 mol, 0.15 g). Yield 66%, Melting Point: 171-173 °C, FTIR
(u cm-1): NH (3335), C-Har (3054), C=O (1651), C=S (1244).
1HNMR (300 MHz, Acetone-d6): d 12.66, (s, 1H, CSNH), d 10.33
(s, 1H, CONH), 9.00-7.61 (m, 8H, C6H4, C6H5) ppm. 13CNMR
(300 MHz, Acetone-d6): d 181.0, 168.3, 146.2,144.1, 137.9,
132.5, 130.4, 130.5, 126.3, 126.5, 122.3, 121.32 ppm.
Synthesis of Copper Complexes: 0.1 mol of the synthe-
sized ligand (A-1 to A-7) were dissolved in dichloromethane un-
der constant magnetic stirring and mixed with 0.05 M solution of
copper (II) acetate monohydrate in methanol. Immediate change
in color was observed that indicated the progress of the reaction.
Resulting reaction mixture was stirred further for about 1 hour to
completion and precipitates of the complex were collected
(Scheme 1). Synthesis of Cu(A-1)2: Yield 66%, Decomposition
point: 197-198 °C. Color Dark red. FTIR (u cm-1): C-Har (3054),
C=S (1142), Cu-O (433), 1HNMR (300 MHz, DMSO): d 11.82,
(NH), 8.59-7.72 (m, 9H, C6H4, C6H5) ppm. Synthesis of
Cu(A-2)2: Yield 68%. Decomposition point: 194-196 °C. Color
Dark red. FTIR (u cm-1): C-Har (3061), C=S (1139), Cu-O (433),
1HNMR (300 MHz, DMSO): d 10.76, (NH), 9.03-6.97 (m, 8H,
ACKNOWLEDGEMENTS
We are thankful to the Higher Education Commis-
sion, Islamabad, Pakistan for financial support.
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