Synthesis, characterization, DNA interaction, thermal and in vitro biological activity investigation of some Ni(II)-Isatin bishydrazone complexes

Article abstract of DOI:10.1007/s13738-013-0383-5

Complexes of the type [Ni (L) (H₂O)] Cl₂.nH ₂O, where L = [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetyl pyridine)-3-isatin]-bishydrazone (apish) and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bp

Full text of DOI:10.1007/s13738-013-0383-5

J IRAN CHEM SOC
DOI 10.1007/s13738-013-0383-5
ORIGINAL PAPER
Synthesis, characterization, DNA interaction, thermal and in vitro
biological activity investigation of some Ni(II)-Isatin bishydrazone
complexes
Mostafa K. Rabia
Nabawia M. Ismail
•
Ahmad Desoky M. Mohamad
Ali Abdo Mahmoud
•
•
Received: 28 August 2013 / Accepted: 16 November 2013
Ó Iranian Chemical Society 2013
Abstract Complexes of the type [Ni (L) (H O)] Cl .nH O,
2
Keywords Isatin-bishydrazone ligands ꢀ Ni(II)
complexes ꢀ Formation constant ꢀ Antibacterial ꢀ
Antifungal ꢀ DNA-interaction
2
2
where L = [(pyridine-2-carboxaldhyde)-3-isatin]-bishyd-
razone (cpish), [(2-acetyl pyridine)-3-isatin]-bishydrazone
(
(
apish) and [(2-benzoyl pyridine)-3-isatin]-bishydrazone
bpish) have been synthesized and characterized on the bases
Introduction
of elemental analysis, molar conductance, IR, NMR, elec-
tronic spectra and thermal analysis (TGA and DTA).
Moreover, the stoichiometry and the formation constants of
these complexes have been determined spectrophotometri-
cally. Kinetics and thermodynamic parameters of the ther-
mal decomposition have been computed from the thermal
data using Coats and Redfern method, which confirm first-
order kinetics. The bioefficacy of the ligands and their
complexes have been examinedfor their in vitro antibacterial
and antifungal activity against many types of bacteria and
anti fungal cultures, which are common contaminants of the
environment in Egypt, and the results indicate that the
ligands and their metal complexes possess notable antimi-
crobial activity. Investigation of their interaction with CT-
DNA under physiological conditions, using spectroscopic
The study of the interaction of exogenous small molecules
with DNA has been the subject of intensive investigation for
decades. It provides insight into the screening design of new
and more efficient multifarious drugs targeting to DNA for
the prevention of diseases and the improvement of the
medicinal efficiency. It is evident from the biochemical
structure of DNA macromolecule that it has variety of sites
where ligands/pro-drug candidates may interact. However,
most drugs binding to DNA do not involve covalent bond
formation and are thus dependent on intermolecular inter-
actional forces [1]. Hence interactional binding is mostly
non-covalent and equilibrated process. There are three key
modes of non-covalent drug–DNA interactions: Groove
binding, hydrophobic intercalation and non-specific elec-
trostatic surface binding. Nucleic acids are common targets
for antiviral, anticancer and antibiotic drugs [2–4]. A con-
crete knowledge of drugs–nucleic acid interaction, including
sequence recognition, structural details, kinetics and ther-
modynamics of binding [5] is prerequisite for the optimiza-
tion of drug effectiveness as well as to discover new drugs.
The binding interactions of small molecules and their com-
plexes with DNA have attained utmost importance for both
therapeutic and scientific reasons [6]. These interactions may
also be used for conformational recognition to find new
structures of DNA and sequence-specific differences along
the helix of DNA molecule [7–9].
(
UV–visible) and hydrodynamic techniques (viscosity mea-
surements). Binding constant ‘‘K ’’ obtained from spectro-
b
scopic methods revealed significant binding of compounds
with DNA via intercalation, Furthermore, free energies of
compounds–DNA interactions indicated spontaneity of their
binding.
Electronic supplementary material The online version of this
article (doi:10.1007/s13738-013-0383-5) contains supplementary
material, which is available to authorized users.
M. K. Rabia ꢀ A. D. M. Mohamad ꢀ N. M. Ismail ꢀ
A. A. Mahmoud (&)
Chemistry Department, Faculty of Science, Sohag University,
Sohag 82534, Egypt
e-mail: aliabdo@science.sohag.edu.eg;
alyabdo8081@yahoo.com
The metal ions play key role in the biological pro-
cesses of life. It has been estimated that about 0.03 % by
123

J IRAN CHEM SOC
weight of human body consists of metals [10]. It was
found that concentration of metals like Cd, Cr, Ti, V, Ni,
Cu, Se and Zn were lower in cancerous parts of the
kidney than in non-cancerous parts [11]. As many
medicinal organic compounds do not have a pure organic
mode of action and traces of metal ions are required
directly or indirectly for their activation. Metal com-
plexes are well known to accelerate the drug action and
the efficiency of a therapeutic agent can often be
enhanced upon coordination with metal ions [12]. The
pharmacological activity has also been found to be
highly dependent on the nature of the metal ion and the
donor sequence of the ligands as different ligands exhibit
different biological properties [13]. Therefore, the
chemistry of metal-based drugs (metallopharmaceutical)
has a broader role. As a consequence, the investigation
of the biological properties of the individual bioactive
metal complex drug candidate is of an utmost impor-
tance. The identification of metal complex–DNA inter-
action is of fundamental importance to the understanding
of the molecular basis of therapeutic activity.
The structures of the prepared ligands and their Ni(II)
complexes in this investigation are shown in Scheme (1).
Experimental
Chemicals
All chemicals were used as received without further puri-
fication. Isatin, 2-acetyl pyridine, 2-benzoyl pyridine and
pyridine-2-carboxaldhyde were obtained from Sigma-
Aldrich Company Ltd. Hydrazine hydrate and hydrated
Nickel chloride (NiCl 6H O) was obtained from BDH
2
ꢀ
2
Company. All other reagents and solvents (methanol, eth-
anol and DMF) were purchased from commercial sources
and were of analytical grade.
Synthesis of the ligands and there Ni(II)-complexes
Synthesis of the ligands
Isatin-bishydrazone ligands, namely [(pyridine-2-Carbox-
aldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetyl pyri-
dine)-3-isatin]-bishydrazone (apish) and [(2-benzoyl
pyridine)-3-isatin]-bishydrazone (bpish) were prepared in
two steps: the first step is the synthesis of Isatin-mono-
hydrazone, followed by condensation with the 2-pyridyl,
giving the Isatin-bishydrazone Ligands.
Among the metal complexes the influence of metal
Isatin-hydrazones, especially transition metal Isatin-
hydrazones and their derivatives, has received consider-
able attention owing to their synthetic and effective wide
range of biological activity [14–18]. Metal Isatin-hydra-
zones based drugs have evoked keen interest in the
development of coordination chemistry, resulting in an
enormous number of publications ranging from pure
synthetic work to physiochemical and biochemical rele-
vant studies [19, 20].
Synthesis of Isatin-monohydrazone Isatin (1.47 g,
10 mmol) was dissolved in methanol (40 mL) and was
added to a solution of hydrazine hydrate (0.05 g, 10 mmol)
dissolved in hot methanol (5 mL). The resulting mixture
was refluxed for 3 h on a water bath. On cooling, the
formed yellow compound was filtered, washed with cold
methanol, dried and recrystallized from methanol [22].
One strategy for the development of drugs and che-
motherapeutic agents involves medicinal candidates
which interact reversibly with DNA through non-cova-
lent interactions. Therefore, the design of new metal
Isatin-hydrazones with the ability to bind specifically and
bring about DNA cleavage is important to develop new
chemotherapeutic agents [21]. Thus, the aim of present
work is to design and characterize novel Ni(II) com-
plexes with newly synthesized Isatin-bishydrazones
ligands. Testing the in vitro antibacterial and antifungal
activity of the free ligands and their complexes against
many types of bacteria and anti fungal cultures, which
are common contaminants of the environment in Egypt,
in order to assess the antimicrobial activity of the syn-
thesized compounds. Make an attempt to investigate the
interaction of the Ni(II) Isatin-bishydrazone complexes
with (CT-DNA) using UV–visible spectroscopy, and
hydrodynamic technique under physiological conditions
Synthesis of Isatin-bishydrazone ligands A (1.0 mmol of
2-pyridyl (2-acetyl pyridine or 2-benzoyl pyridine or Pyr-
idine-2-carboxaldhyde) was added drop wise to a hot
methanolic solution of Isatin-monohydrazone (1.0 mmol),
the resulting mixture was refluxed for 1 h with constant
stirring and then 2–3 drops of glacial acetic acid was
added, with continued refluxing for 4 h under constant
magnetic stirring. On cooling, the formed ligand was fil-
tered, washed with cold methanol, dried, and finally
recrystallized from methanol.
Synthesis of Ni(II) complexes
[
at stomach (4.7) and blood (7.4) pH and at body tem-
A solution of the metal salt in minimum amount of water
[NiCl .6H O, 1.0 mmol] was added drop wise to a hot
perature (37 °C)].
2
2
1
23

J IRAN CHEM SOC
Scheme 1 Schematic diagram
of the Isatin-bishydrazone
ligands and their Ni(II)
complexes
R
H N
NH2
2
O
N
O
NH
NH2
NH
+
N
O
O
Isatin
2-Pyridyl
Isatin mono hydrazone
Ligand
Abbrev.
Metal
Complex
Empirical formla
Nicpish [Ni(cpish)(H
Niapish [Ni(apish)(H
2 2 2
Nibpish [Ni(bpish)(H O)]Cl .nH O
Reflux 4-5 h HCl
R
H
CH
ph
Abbrev.
cpish
apish
bpish
2
O)]Cl
O)]Cl
2
.nH
.nH
2
O
O
II
Ni
R
3
2
2
2
N
N
N
N
H
O
R
N
N
NiCl2 . 6 H O
2
NH
Cl . 2H O
2
2
(
1:1)
Ni
O
N
H O
2
methanolic solution of the ligand [cpish or apish or bpish,
Biological activity
In Vitro antibacterial and anti-fungi screening
1.0 mmol]. The resulting mixture was refluxed at 70 °C for
10 h under constant stirring. By evaporation overnight, the
resulted solid product was filtered, washed with water–
methanol solvent, dried and finally recrystallized from
water–methanol mixed solvent.
The antimicrobial activity of all the synthesized Isatin-
bishydrazone ligands and their corresponding Ni(II) com-
plexes were tested against six bacterial (three gram positive
bacteria and three gram negative bacteria) and six fungal
strains. These strains are common contaminants of the
environment in Egypt, some of which are involved in
human and animal diseases (Trichophyton rubrum, Can-
dida albicans, Geotrichum candidum, Scopulariopsis
brevicaulis, Aspergillus flavus and Staphylococcus aureus
(?ve)) or in plant diseases (Fusarium oxysporum) or fre-
quently reported from contaminated soil, water and food
substances [Escherichia coli (-ve), Bacillus cereus (?ve),
Pseudomonas aeruginosa (-ve), Serratia marcescens (-ve)
and Micrococcus luteus (?ve)]. To prepare inocula for
bioassay, bacterial strains were individually cultured for
48 h in 100-ml conical flasks containing 30 ml nutrient
broth medium. Fungi were grown for 7 days in 100-ml
conical flasks containing 30 ml Sabouraud’s dextrose
broth. Bioassay was done in 10-cm sterile plastic Petri
plates in which microbial suspension (1 ml/plate) and
15 ml of appropriate agar medium (15 ml/plate) were
poured. Nutrient agar and Sabouraud’s dextrose agar were,
respectively, used for bacteria and fungi. After
Analyses of the complexes
The stoichiometric analysis (C, H and N) of the new
compounds was performed using elemental analyzer
Perkin-Elmer model 40c, at the Micro-analytical Centre
at Cairo-University, Egypt. The molar conductance of
-
3
1
0
molar dilution was measured by JENWAY con-
ductivity-meter model 4320 at 298 K at wide range of
different solvents to verify the complex structure. The IR
spectra were recorded on Shimadzu FTIR model 8101 in
-
1
the region 4,000–400 cm
using dry KBr discs. The
electronic spectra of the new compounds in methanol
were recorded in the region of 200–800 nm using a
1
0-mm matched quartz cells on Jasco UV–Visible
1
13
spectrophotometer model V-530. H NMR and C NMR
spectra were recorded in DMSO-d6 solvent (solvent
peak = 3.8 ppm) on a Bruker Advance 400 instrument.
Rigaku model 8150 thermo-analyzer was used for
simultaneous recording of TG–DTA curves at a heating
-
1
rate of 10 min
.
123

J IRAN CHEM SOC
solidification of the media, 5-mm diameter cavities were
cut in the solidified agar (3 cavities/plate) using sterile cork
borer. Chemical compounds dissolved in dimethyl sulfux-
ide (DMSO) at 100 ppm were pipetted in the cavities (20
ul/cavity). Cultures were then incubated at 28 °C for 48 h
in case of bacteria and up to 7 days in case of fungi.
Results were read as the diameter (in mm) of inhibition
zone around cavities.
DNA from 8 lM up to 35 lM in the sample cell by stan-
dard addition method. In order to achieve the equilibrium
between the compound and DNA for the formation of
compound–DNA adduct, solutions were allowed to stay for
5 min at 37 °C before each measurement was made.
Viscosity measurements
Initially viscosity of DNA solution (g ) was determined at
o
Determination of minimum inhibitory concentration (MIC)
value
pH; 7.4, 4.7, and at 37 °C. Then specific viscosity contri-
bution (g) due to the DNA (8 lM) in the presence of
increasing concentration of the investigated compound was
determined. Viscosity measurements were carried out
using an Ostwald type viscometer, thermostated at
37 ± 1 °C. The flow times of the samples were repeatedly
measured with an accuracy of ± 0.2 with a digital stop-
watch operated timer for different concentrations of the
complex (2–20 lM), maintaining the concentration of
DNA constant (8 lM).
To determine the minimum inhibitory concentrations
(
MICs), chemical compounds giving positive results were
diluted with DMSO to prepare a series of descending
concentrations down to 5 ppm. Diluted chemicals were
similarly assayed as mentioned before and the least con-
centration (below which no activity) was recorded as the
MIC.
Determination of the Activity Index (%) for the complexes
Results and discussion
The antibacterial and antifungal activities of a common
standard antibiotic Chloramphenicol as antibacterial stan-
dard and Clotrimazole as antifungal standard were also
recorded maintaining the same protocol as above at the
same concentrations and solvent. The antibacterial and
antifungal results of the compounds were compared with
the standard and % Activity Index for the complexes was
calculated using the formula as under [23]:
Identification of the prepared compounds
Microanalysis and molar conductance measurements
The results of the microanalysis of the prepared Isatin-
bishydrazone ligands and their Ni(II) complexes in addi-
tion to the molar conductance measurements (Table 1),
suggested that the subject ligands act as neutral tridentate
and form complexes in 1:1 molar ratio (metal to ligand),
with 1:2 electrolytic nature of all the complexes [26, 27].
Thus, the general formula of the prepared complexes is
suggested to be [Ni(L)(H O)]Cl .nH O according to the
Zone of inhibition by test compound ðdiamterÞ
%
Active index ¼
Zone of inhibition by compound ðdiamterÞ
100
ꢁ
2
2
2
Interaction with Calf Thymus DNA (CT-DNA)
following reaction:
NiCl2:6H2O þ L ! ½NiðLÞðH2OÞꢂCl2:2H2O;
Spectroscopic titrations
where L is the Isatin-bishydrazone ligand. The satisfactory
results of analytical data (Table 1) and spectral studies
revealed that the ligands and their complexes were of good
purity.
The purity of DNA was tested spectrophotometrically; CT-
DNA solution at pH 7.4 gave a ratio of UV absorbance at
260 and 280 nm of about[1.86:1, indicating that the DNA
was sufficiently free from protein contamination [24, 25]
and fit for use. Concentration of DNA determined spec-
-
Spectroscopic studies
1
trophotometerically at 260 nm (using e = 6,600 mol
2
60
2
-4
cm ) was found to be 1.056 9 10 M. The stock solution
was stored at 4 °C and used within only 1 day. Spectro-
photometric titrations as optical probes were carried out at
stomach pH (4.7) and blood pH (7.4), and at body tem-
perature 37 °C, using 0.1 M acetate and 0.1 M phosphate
buffers, respectively. The UV–Vis. absorption spectra were
recorded by keeping the concentration of each compound
constant (10 lM), while varying the concentration of CT-
Spectra and mode of bonding In the absence of a pow-
erful technique such as single X-ray crystallography,
infrared spectra has proven to be the most suitable tech-
nique to give enough information to elucidate the nature of
bonding of the subject ligands to the metal ion. Thus a
detailed interpretation of IR spectra of the free ligands and
the effect of binding of Ni(II) of the vibration frequencies
of the free ligands are discussed to determine the
1
23

J IRAN CHEM SOC
coordination sites which may involve in chelation. The
significant infrared bands of the subject ligands and their
metal complexes are given in Table 2. The observed bands
may be classified into those originating from the ligands
and those arising from the bonds formed between metal
ions and the coordinating sites. The IR spectrum of the
Isatin-bishydrazone ligands exhibited characteristic band
due to (-NH) and lactonyl carbon m(C=O) at
-
1
-1
&
3,180–3,200 cm and &1,722 cm [28], respectively.
-1
In addition, the strong band at &1,460 cm and a char-
-
1
acteristic high-intensity band at &1,621 cm in the IR
spectrum of the Isatin-bishydrazone ligands are assigned to
m(C=N) and m(HC=N), respectively. In comparison with
the spectra of the Isatin-bishydrazone ligands, all the Ni(II)
complexes exhibited the band of m(HC=N) in the region
-
1
&
numbers indicating that the azomethine nitrogen is coor-
1,590 cm ; showing the shift of the band to lower wave
dinated to the metal ion [29, 30]. The band of m(C=O) in
-
1
the region 1,670–1,680 cm
in the metal complexes
showing the shift to lower wave numbers confirms that the
carbonyl oxygen is coordinated to the metal ion [31, 32].
The unaltered position of a band due to m(NH) and m(C=N)
in all the metal complexes indicates that these groups are
not involved in coordination. The new bands in the region
-
1
of 500–510 and 630–650 cm in the spectra of the com-
plexes are assigned to stretching frequencies of (M–N) and
(M–O) bonds, respectively [33]. Thus the IR spectral
results provide strong evidences for the complexation of
Isatin-bishydrazone ligands with metal ion in tridentate
mode via Isatin-carbonyl(C=O), azomethine-N(C=N), and
pyridine-N (C=N).
NMR spectra The NMR spectra data provide valuable
information regarding the structure of Isatin-hydrazone
1 13
ligands. The H-NMR and C-NMR spectra of the Isatin-
bishydrazone ligands (in DMSO-d ) were recorded using
6
tetramethylsilane as the internal standard.
1
1
H-NMR and spectra The H-NMR spectrums of the
1
ligands are summarized in Table 3. In H-NMR, the singlet
signal at &10.8–11.0 ppm corresponds to the -NH proton
of Isatin. The azomethine proton appeared as singlet peak
at &8.98 ppm in the case of cpish-ligand and disappeared
in the other ligands (apish and bpish) due to substitution of
the azomethine proton by methyl or phenyl group in apish
and bpish ligands, respectively. Also, all the eight aromatic
protons (Isatin ring and pyridine ring) appeared as a mul-
tiplet in the range &7.80–8.20 ppm. Protons of the methyl
group in the case of apish ligand appeared at &2.37 ppm
as singlet. Also the five aromatic protons of the substituted
phenyl ring appeared as multiplet in the range
&
7.80–8.20 ppm in the case of bpish-ligand.
123

J IRAN CHEM SOC
-
Table 2 The infrared absorption frequencies (cm ) and electronic spectra of the investigated Isatin-hydrazone ligands and their metal
1
complexes
No Compound
t
t (N–
H)
t
(C=O)
t
(HC=N)
t
(C=N)
t (M–
O)
t (M–
N)
Electronic spectra
a
b
c
d
e
(OH)
k
nm
max
,
e
max
(dm mol cm )
Assignment
3
-1
-1
*
1
2
3
cpish
3421.2 3276.5
3430.8 3287.1
3393.2 3180.0
1721.7
1685.0
1721.7
1613.7
1611.7
1618.5
1460.3
1409.0
1458.4
–
–
237
1744.05
865.49
320.12
293.02
538.30
580.97
339.05
723.22
256.57
1096.47
882.56
653.87
268.80
295.95
p–p
*
3
24
627 nm
76 nm
254
n–p
Ni- cpish
apish
656.8
–
510.2
–
d–d band
d–d band
6
*
p–p
*
2
3
74
25
p–p
*
n–p
4
5
Ni- apish
bpish
3357.5 3159.8
3424.0 3181.0
1672.5
1721.7
1592.4
1607.9
1463.2
1452.6
637.6
–
504.4
–
625 nm
80 nm
252
d–d band
d–d band
6
*
p–p
*
2
3
71
27
p–p
*
n–p
6
Ni- bpish
3359.4 3160.7
1671.5
1594.4
1463.2
636.6
503.5
636 nm
82 nm
d–d band
d–d band
6
a
b
c
d
e
Vibrations of the water molecules
Vibrations of the Indol ring (N–H)
Vibrations of the Lactonyl group (C=O)
Vibrations of the azomethine group (C=N)
Vibrations of group from the b-hydrazone of Isatin (C=N)
1
3
13
The C-NMR spectrum of the
C NMR spectra
at 298 K. The absorption maxima bands are listed in
Table 2 and the spectra are given in Fig. 1. The UV–Vis
spectrum of the Isatin-bishydrazone ligand shows
important strong bands at &388 and &230 nm due to
p–p and n–p transitions [34], respectively. These bands
are altered to a greater extent on complexation. The
spectrum of Ni(II)-complexes shows characteristic band
at kmax = 670–680 nm due to d–d transition band.
1
3
Ligands and its DEPT- C-NMR are summarized in
1
3
Table 3. In C-NMR; the azomethine carbon appears as
singlet peak at &149–154 ppm in all the ligands, and still
as it is in the DEPT-NMR in the case of cpish-ligand and
disappeared in the DEPT-NMR of the apish, bpish ligands
due to substitution of methyl and phenyl groups in the
apish, bpish ligands respectively.
*
*
Electronic spectra Electronic spectra are a valuable
tool for coordination chemists to draw important infor-
mation about the structural aspects of the complexes.
The ligands, which are organic compounds, have
absorption bands in the ultraviolet region and in some
cases these bands extend to higher wavelength region
due to conjugation. Upon complexation with metal ions,
changes will take place in the electronic properties of the
system. New bands in the visible region due to d–d
absorption and charge transfer spectra from metal to
ligand (M ? L) or ligand to metal (L ? M) can be
observed and these data can be processed to obtain
information regarding the structure and geometry of the
complexes. The Electronic spectra of the Isatin-bishyd-
razone ligands and its Ni(II)-complexes were recorded in
Stoichiometry and stability of the complexes
Determination of the stoichiometry of the complexes
The stoichiometry of the various Ni(II) Isatin-bishydrazone
complexes was determined by applying the spectrophoto-
metric molar ratio [35–37] and continuous variation [38,
39] methods, which suggested the possible formation of 1:1
complexes. The curves of continuous variation method
(Fig. 2) displayed maximum absorbance at mole frac-
tion 9 ligand = 0.5, indicating the formation of the com-
plex between the metal ion and the ligands in 1:1
(metal:ligand) molar ratio as presented in Scheme 1.
Moreover, the data resulted from applying the mole ratio
method support the same metal ion to ligand ratio of the
prepared complexes (cf. Fig. 3).
-
3
3
MeOH (&1 9 10 mol/dm ) in the range 200–800 nm
1
23

J IRAN CHEM SOC
Table 3 NMR Spectroscopic data of the Isatin-hydrazone ligands
1
13
13
DEPT C-NMR
Compound
H-NMR spectra
C-NMR spectra
Chemical
Shift (d, ppm)
Assignment
Chemical
Shift (d, ppm)
Assignment
Chemical
Shift (d, ppm)
cpish (C14
H
10
N
4
O)
164.5
157.4
153.6
152.3
C=O
–
1
8
6
1.25
(S, 1H, NH-group)
(S, 1H, CH-azomethine)
(m, 8H, Aromatic)
b-hydrazone of Isatin (C=N).
C=N Pyridine ring
–CH=N azomethine
=C–NH
–
.85
–
.80–8.20
–
1
1
48.5
152.3
10–146
8-CH aromatic
C=O
110–146
apish (C15
H
12
N
4
O)
162.3
155. 5
150.2
149.3
147.5
–
1
–
6
1
0.70
(S, 1H, NH-group)
(S, 1H, CH-azomethine)
(m, 8H, Aromatic)
(s, 3H, methyl)
b-hydrazone of Isatin (C=N).
C=N Pyridine ring
–C=N azomethine
=C–NH
–
–
.70–8.50
.85
–
–
1
1
10–146
8.9
8-CH aromatic
110–146
–CH
3
group
18.9
bpish (C20
H
14
N
4
O)
165.1
156.3
155.5
153.7
150.5
C=O
–
(
S, 1H, NH-group)
b-hydrazone of Isatin (C=N).
C=N Pyridine ring
–C=N azomethine
=C–NH
–
1
–
6
1.15
(S, 1H, CH-azomethine)
(m, 13H, Aromatic)
–
–
.75–8.40
–
1
10–149
13-CH aromatic
110–149
Evaluation of the apparent formation constants
of the synthesized complexes
biological activities. Therefore, they are widely subjected
to investigation by thermal analysis and other physico-
chemical methods, and also for perfect deduction of the
complex structure, by determining the number of
hydrated and coordinated water molecules. Thermal data
of the complexes are given in Table 5. The Ni (II)
complexes of the Isatin-bishydrazone ligands exhibited
thermal stability in the range &25–50 °C and then
degraded in three steps (Fig. 4a, b, c). The first degra-
dation step in the temperature range &350–360 K may
account for the loss of the hydrated water molecules
The formation constants (K ) of the studied Ni(II) Isatin-
f
bishydrzone complexes formed in solution were obtained
from the spectrophotometric measurements by applying the
continuous variation method according to the following
relations [40]:
A
=
A
m
Kf ¼¼ ꢀ
ꢁ
;
2
A
1
ꢃ =
C
Am
(two water molecules). The second degradation step in
where A is the absorbance at the maximum formation of the
m
the temperature range &470–540 K may be attributable
to the loss of the coordinated water molecule (one water
molecule) and the third step of decomposition occurs
within the temperature range &730–790 K, correspond-
ing to the loss of organic moiety leaving NiCl2 as
metallic residue.
complex, A is the actual absorbance of the complex and C is
the initial concentration of the metal. As mentioned in
Table 4, the obtained K values indicate the high stability of
f
the prepared complexes. The values of K for the studied
f
complexes increase in the following order: Ni-bpish[ Ni-
apish [ Ni-cpish.
Thermal investigation of the prepared Isatin-
bishydrazone complexes
Kinetics of thermal decomposition of the complexes
T. G, Dr. T. G analysis of the prepared Isatin-bishydrazone
complexes
The kinetic analysis parameters such as activation energy
*
*
(DE ), enthalpy of activation (DH ), entropy of activation
*
*
(
DS ), and free energy change of decomposition (DG )
were evaluated graphically by employing the Coats–Red-
The importance of this study on the Ni(II) complexes of
the Isatin-bishydrazone ligands stems from their possible
fern relation [41]:
123

J IRAN CHEM SOC
Fig. 1 UV–Vis. Spectrum of
the Ni(II) Isatin-hydrazone
complexes
[Ni(bpish)(H O)]Cl .2H O Complex
bpish-Ligand
2
2
2
5
4
3
2
1
0
2
1
0
600
700
800
Wave Length [nm]
2
00
300
400
500
600
700
800
Wave Length [nm]
Abs. of [Ni(cpish)(H O)]Cl .2H O
Abs. of [Ni(cpish)(H O)]Cl .2H O Complex
2 2 2
2
2
2
Abs. of [Ni(apish)(H O)]Cl .2H O
1.6
Abs. of [Ni(apish)(H
Abs. of [Ni(bpish)(H O)]Cl .2H O Complex
2 2 2
O)]Cl .2H O Complex
2
2
2
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
Abs. of [Ni(bpish)(H O)]Cl .2H O
2
2
2
2
2
2
1
1
1
1
1
1
.5
.4
.3
.2
.1
.0
0.0
0.5
1.0
1.5
2.0
2.5
0
.0
0.2
0.4
0.6
0.8
1.0
Wave Length [nm]
[L] / ([M]+[L])
Fig. 3 Molar ratio plot of Ni(II)-Isatin-bishydrazone complexes
Fig. 2 Continuous variation plot of Ni(II)-Isatin-bishydrazone
complexes
calculated and A (Arrhenius constant) was determined from
the intercept. Figure 5 represents the linear plot in case of
Ni(II) complexes. The Coats and Redfern linearization
plots confirmed first-order kinetics for the decomposition
ꢂ
ꢃ
ꢂ
ꢄ
ꢅꢃ
ꢃLnð1=ð1 ꢃ aÞ
AR
2RT
1 ꢃ Eꢄ
Log
¼ Log
2
ꢄ
*
T
bE
process. The activation entropy (DS ), the activation
ꢄ
E
*
*
enthalpy (DH ), and the free energy of activation (DG )
can be calculated using the following equations [42, 43]:
ꢃ 2
;
:303RT
where a is the fraction of sample decomposed at
temperature T, R the gas constant, E* the activation
ꢂꢄ
ꢅꢃ
Ah
ꢄ
DS ¼ 2:303 R log
;
-
1
KBTs
energy in J mol , b the linear heating rate and (1 - 2RT/
E*) = 1. A plot of left-hand side of Coats–Redfern
equation against 1/T gives a slope from which E* was
ꢄ
DH ¼ E ꢃ RT
a
S
ꢄ
ꢄ
ꢄ
DG ¼ DH ꢃ TDS
1
23

J IRAN CHEM SOC
where h, K and T are Planck constant, Boltzmann constant
B
by measuring the diameter (in mm) of the inhibition zone
around cavities. The antimicrobial activity data of all
synthesized Isatin-bishydrazone ligands and there Ni(II)
complexes are summarized in Tables 7 and 8 and show that
the newly synthesized ligands and their Ni(II) complexes
possess notable biological activity. The antibacterial
screening results exhibited marked enhancement in activity
on coordination with the metal ions against most the testing
bacterial strains (cf. Figs. 6, 7). This enhancement in the
activity can be rationalized to the basis of the structures of
the ligands by possessing an additional azomethine (C=N)
linkage which is important in elucidating the mechanism of
transamination and resamination reaction in biological
system [45]. It has also been suggested that the ligands with
nitrogen and oxygen donor systems might inhibit enzyme
production [46], since the enzymes which require these
groups for their activity appear to be especially more sus-
ceptible to deactivation by the metal ions upon chelation
[47]. The polarity of the metal ion is reduced by chelation
[48] and this mainly because of the partial sharing of its
positive charge with the donor groups and possibly with the
delocalized p-electrons within the whole chelation ring,
which is formed because of the coordination. This process
of chelation increases the lipophilic nature of the central
metal atom, which in turn favors its permeation through the
lipoid layer of the membrane [49]. This is also responsible
for the increasing of the hydrophobic character and lipo-
solubility of the molecules in crossing the cell membrane
of the microorganism and hence enhances the biological
utilization ratio and activity of the testing drug/compound.
The results are quite promising. It is evident from the
results that the biological activity of the metal complexes is
higher than the corresponding ligands. This enhancement
in the activity of the metal complexes can be explained on
the basis of chelation theory [50]. It is, however, known
that the chelating tends to make the Schiff base act as more
powerful and potent bactereostatic agents, thus inhibiting
the growth of bacteria and fungi more than the parent
s
and the peak temperature obtained from the DTA curve,
*
*
*
*
respectively. The calculated values of E , DS , DH and DG
for the decomposition steps are given in Table 6. According
to the kinetic data obtained from the TG curves, all the
complexes have negative entropy, which indicate that the
complexes are formed spontaneously. The negative entropy
also indicates a more ordered activated state that may
be possible through the decomposition of other products.
The negative values of the entropies of activation are
compensated by the values of the enthalpies of activation,
leading to almost the same values for the free energies of
activation [44]. The high values of the activation energies
reflected the thermal stability of the complexes. The positive
#
values of DH reflected the endothermic nature of thermal
=
decomposition. Furthermore, the negative values of DS in
the studied complexes indicate that the reaction rates were
=
slower than normal and the positive values of DG indicated
the non-spontaneous nature of the process. The data clearly
indicates similarity in the thermal degradation of the
complexes.
Biological activity (anti-bacteria and antifungal
activity)
The susceptibilities of certain strains of bacteria and fungal
cultures to Isatin-bishydrazone complexes were evaluated
f
Table 4 The formation constant (K ), stability constant (pK) and
=
Gibbs free energy (DG ) values of the prepared complexes in
aqueous-methanol at 298 K
=
Complex
Type of the Formation Stability DG
complex constant
constant (KJ/mol)
(Log K
(K
f
)
f
)
9
4.09 9 10 9.61
9
4.47 9 10 9.65
9
5.43 9 10 9.73
Ni-cpish complex 1:1
Ni-apish complex 1:1
Ni-bpish complex 1:1
-54.8212
-55.0321
-55.5348
Table 5 Thermo analytical data. (TG, DTG)
Complex
Step
TGrange (°C)
DTAmax (°C)
Thermal effect
Mass loss: Obs.
(
Assignment
Metallic
residue
Calc.) (%)
Ni-cpish complex
I
53.11–106.55
106.55–426.69
426.69–600.53
54.07–219.16
219.16–389.07
389.07– 497.8
56.07–210.55
210.55–404.91
404.91–580.93
78.38
209.42
506.16
78.71
Endo
Endo
Endo
Endo
Endo
Endo
Endo
Endo
Endo
8.98 (8.30)
5.13 (4.14)
2H
1H
2
O (hydrated)
NiCl
NiCl
NiCl
2
2
2
II
III
I
2
O (coordinated)
58.10 (57.68)
8.55 (8.03)
5.22 (4.02)
75.11 (72.86)
7.35 (7.06)
4.05 (3.53)
65.78 (63.99)
Organic moiety
Ni-apish complex
Ni-bpish complex
2H
1H
2
O (hydrated)
II
III
I
196.61
460.33
87.68
2
O (coordinated)
Organic moiety
2H
1H
2
O (hydrated)
II
III
265.57
519.39
2
O (coordinated)
Organic moiety
123

J IRAN CHEM SOC
⎡
− L n (1 /(1 − α ) ⎤
L o g
⎢
2
⎥
⎣
T
⎦
-
8.00
8.05
8.10
8.15
8.20
8.25
8.30
8.35
-
-
-
-
-
-
-
0
.00292 0.00294 0.00296 0.00298 0.00300 0.00302 0.00304 0.00306
1
/T
Fig. 5 Coats–Redfern linear plot for [Ni (cpish)(H2O)]Cl2.2H2O
complex
hypochromic (red shift) or hyperchromic effect (blue shift)
are observed in the absorption spectra of small molecules if
they intercalate with DNA [55]. Spectrophotometric stud-
ies of Isatin-bishydrazone complexes were carried out
under physiological pH 4.7(stomach) and 7.4 (blood) and
body temperature 37 °C. No significant change in the
wave-lengths was observed at both pHs, which may indi-
cate non-interactive behavior of these compounds with
buffer solutions. UV–Vis. spectra of Isatin-bishydrazone
complexes were recorded separately after addition of DNA
and the effect of the varying concentrations of DNA on
optimized concentrations (10 lM) of all the compounds in
stomach (Fig. 8a, b, c) and blood pH (Fig. 9a, b, c) under
body temperature. Peak intensity in the absorption spectra
of Isatin-bishydrazone complexes (Ni-cpish, Ni-apish and
Ni-bpish complexes) increased with a pronounced red shift
of 5.0, 4.0 and 6.0 nm, respectively, at stomach pH,
(
Fig. 8a, b, c), and increased with a pronounced blue shift
of magnitude 7.0, 9.0 and 8.0 nm, respectively, at blood pH
Fig. 9a, b, c), by the addition of DNA. Percent decrease in
(
the peak intensities of Isatin-bishydrazone complexes in
the presence of DNA was calculated as 28.8, 37.17 and
23.37 %, respectively, at stomach pH, while percent
increase was calculated as 62.33, 39.08 and 23.55 %,
respectively, at blood pH, using the following equation:
Fig. 4 Thermal decomposition of a Ni-cpish, b Ni-apish and c Ni-
bpish
Afree ꢃ Abound
H% ¼
ꢁ 100
Afree
ligand [51–53], and also noticed that the activity of Ni(II)
complexes were more than the parent ligands.
A peculiar hypochromism, (Fig. 8a, b, c) and hyper-
chromism (Fig. 9a, b, c) indicate the interaction of elec-
tronic states of intercalating chromophores of the
compounds and those of the stacked base pairs of CT-DNA
[56]. A red shift can be directly linked with p*-orbital of
DNA binding study by UV–Vis. spectroscopy
The binding of complex to DNA has been characterized
classically through absorption titrations [54]. Generally,
1
23

J IRAN CHEM SOC
Table 6 Thermodynamic activation parameters for the thermoanalysis of the investigated Isatin-hydrazone complexes
*
E (KJ mol
-1
)
-1
-1
-1
*
-1
*
-1
)
Complex
Order
1
Step
A (S
)
DS* (JK mol
)
DH (KJ mol
)
DG (J mol
Ni-cpish complex
I
49.255
8.386
494,185.73
124,409.39
127,856.08
496,722.47
53,371.46
390,861.98
53,708.27
11,163.51
13,620.96
-137.29
-151.40
-155.15
-137.26
-158.21
-145.36
-155.967
-172.363
-173.920
46.333
4.375
94.576
77.414
II
III
I
12.859
51.593
43.955
136.150
40.780
40.254
61.315
6.381
127.275
96.945
Ni-apish complex
Ni-bpish complex
1
1
48.669
40.051
130.053
37.782
35.776
54.727
II
III
I
114.350
236.652
94.036
II
III
128.606
192.539
Table 7 Antibacterial activity of the synthesized Isatin-hydrazone ligands and their metal complexes
Compound conc. Diameter of inhibition zone in mm, minimum inhibition concentration (MIC) and Activity Index (%) for some bacteria
(
ppm)
Gram-positive bacteria
Gram-negative bacteria
Staphylococcus
aureus
Micrococcus
luteus
(?ve)
Bacillus cereus
(?ve)
Escherichia coli Pseudomonas
(-ve)
Serratia
marcescens
(-ve)
aeruginosa
(-ve)
(
?ve)
mm MIC
%
mm MIC
%
mm MIC
%
Mm MIC
%
mm MIC
%
mm MIC
%
cpish
100
100
100
100
100
100
6
45
40
50
20
25
25
40
5
50
45
40
15
20
25
35.7
10
9
40
55
45
20
20
15
45.4
9
50
45
45
25
25
20
45
5
45
50
50
20
15
25
25
7
50
55
50
30
25
25
38.8
50
apish
4
5
26.7
33.3
6
7
42.8
50
40.9
36.4
8
7
40
35
7
8
35
40
9
6
bpish
8
33.3
66.7
66.7
55.6
Ni-cpish
Ni-apish
Ni-bpish
13
12
11
86.7 10
80 11
73.3 10
100 14
71.4 17
78.6 14
71.4 15
77.3 16
63.6 15
68.2 16
80 17
75 15
80 15
100 20
85 12
75 12
75 10
100 18
Chloramphenicol 15
as antibacterial
standard
100
22
100
20
100
mm, diameter of inhibition zone in mm; MIC, minimum inhibition concentration (ppm); %, Activity Index
Table 8 Anti-fungi activity of the synthesized Isatin-hydrazone ligands and their metal complexes
Compound
conc. (ppm)
Diameter of inhibition zone in mm, minimum inhibition concentration (MIC) and Activity Index (%) for some fungi
Candida albicans
Geotrichum
candidum
Trichophyton
rubrum
Fusarium
oxysporum
Scopulariopsis
brevicaulis
Aspergillus flavus
mm MIC
%
mm MIC
%
mm MIC
%
Mm MIC
%
mm MIC
%
mm MIC
%
cpish
apish
bpish
100
6
40
50
55
30
25
25
42.8
6
55
45
30
10
9
40
30
35
20
20
25
33.3
30
8
30
35
40
30
25
20
44.4
11
9
40
50
45
20
20
25
45.8
37.5
12
9
45
55
40
100
100
5
5
35.7
35.7
5
7
25
35
7
5
38.9
27.8
30
50
25
30
25
9
30
7
29.2
75
8
40
30
20
15
26. 7
63.3
66. 7
73.3
100
Ni-cpish 100 11
Ni-apish 100 10
Ni-bpish 100 11
78.6 13
71.4 13
78.6 14
65 20
65 19
70 21
100 30
66.7 15
63.3 16
83.3 18
88.9 19
77.8 18
19
79.2 20
70
14
18
75
22
30
Clotrimazole
14
100
20
100
100
24
100
as antifungal
standard
mm, diameter of inhibition zone in mm, MIC, minimum inhibition concentration (ppm), %, Activity Index
123

J IRAN CHEM SOC
Fig. 6 Antibacterial activity of the synthesized Isatin-hydrazone ligands and their Ni(II) complexes
Fig. 7 Antifungal activity of the synthesized Isatin-hydrazone ligands and their Ni(II) complexes
intercalated compound couples with the p-orbital of the
base pairs, thus decreasing p–p* transition energy. On the
other hand, the coupling p-orbital is partially filled by
electrons, thus decreasing transition probabilities and
concomitantly resulting in hypochromism [57]. A blue shift
may also be attributed to improper coupling (due to con-
formational changes) of p*-orbital of intercalated ligand
with the p-orbital of the base pairs. This unstacking of base
pairs (distortion in the p-orbital of the base pairs and p*-
orbital of intercalated ligand) infatuate slight blue shift
(hypsochromic effect). Similarly reduction of face to face
base stacking (exposed electrons) induces enhancement of
absorption intensity (hyperchromism) [58–62]. Further-
more, the spectral changes both at stomach and blood pH
4.7, 7.4 were characterized by one isosbestic point for the
complexes on titration with DNA; hence the presence of
species other than free and the intercalated complexes
could be ruled out. The presence of isosbestic point indi-
cates that there is equilibrium between bound DNA and
free form of the metal complexes [63–65].
1
23

J IRAN CHEM SOC
Fig. 9 UV-spectra for A Ni-cpish, B Ni-apish and C Ni-bpish
(10 9 10 lM) in the absence (a) and presence of 8 lM (b), 11 l M
Fig. 8 UV-spectra for A Ni-cpish, B Ni-apish and C Ni-bpish
-6
-6
(10 9 10 lM) in the absence (a) and presence of 8 lM (b), 11 l M
(c), 14 lM (d), 17 lM (e), 20 lM (f), 23 lM (g), 26 lM (h), 29l M
(i), 32 lM (j), and 35 lM (k) DNA at pH 4.7 and 37 °C. The arrow
(
(
c), 14 lM (d), 17 lM (e), 20 lM (f), 23 lM (g), 26 lM (h), 29l M
i), 32 lM (j), and 35 lM (k) DNA at pH 7.4 and 37 °C. The arrow
direction indicates increasing concentrations of DNA
direction indicates increasing concentrations of DNA
123

J IRAN CHEM SOC
absorbance in UV–Vis. spectra. The binding constant val-
ues were evaluated for these compounds at both pH i.e., 4.7
and 7.4 and at body temperature using Benesi–Hildebrand
equation [66–68]:
A0
eG
eG
1
¼
þ
;
A ꢃ A0
where A and A are the absorbances of free compound
eHꢃG ꢃ eG eHꢃG ꢃ eG Kb½DNAꢂ
o
and DNA bound complex, respectively, eG and eH-G the
molar extinction coefficients of free compound and DNA
bound complex, respectively. From the plot of A /(A -
o
Ao) to 1/[DNA], the ratio of the intercept to the slope
gave the value of binding constant ‘‘K ’’, (Fig. 10a, b).
b
The binding constant values of all the compounds were
calculated and given in Table 9. Kb values for all the
4
3
compounds were in the range of 10 –10
-1
M . The
overall binding constant values are comparable to that of
3
typical intercalators such as isoxazocucu-mine (6.3 9 10
-
1
4
-1
M ) [69, 70] and
M
) and lumazine (1.74 9 10
revealed stronger interaction of investigated compounds
with DNA via intercalation at both pH values. UV–Vis.
spectral changes (hypochromic effect with bathochromic
shift and hyperchromic effect with hypsochromic shift)
also lend support the possibility of intercalative binding
mode of interaction.
From the values of binding constant, K , and free energy
b
‘‘DG’’ of compound–DNA complex was calculated, using
DG ¼ ꢃRT ln Kb
Binding constants are measures of compound–DNA
complex stability while free energy indicates the
spontaneity/non-spontaneity of compound–DNA binding.
Free energies of all the compounds at both pHs were
evaluated as negative values showing the spontaneity of
compounds–DNA interaction (Table 9).
Fig. 10 Plot of Ao/A/Ao vs. 1/[DNA] for the application of Benesi–
Hildebrand equation for calculation Ni-cpish, Ni-apish and Ni-bpish –
DNA binding constant of at pH a 4.7 and b 7.4 (37 °C)
Determination of binding constants and free energies
by UV–vis. spectroscopy
Viscosity measurements
Since absorbance is varied after addition of CT-DNA, the
binding constant ‘‘K ’’ of the investigated compounds–
b
Viscosity measurement is a comprehensive method to
understand the interactional mode between small
DNA complexes can be determined from the variation in
Table 9 Spectral parameters for DNA interaction with the prepared complexes: Binding constants and free energy values for compound–DNA
complexes from UV–spectrophotometric data at pH 4.7 and 7.4 and at body temperature (37 °C)
k
(
max free
nm)
kmax bound
(nm)
Dk
chromism
(%)
Type of
cheomism
Binding
constant K
Free energy
-1
DG (KJ mol )
-
1
)
b
(M
At pH 4.7
Ni-cpish
4
627
76
625
80
636
82
632
629
642
5.0
4.0
6.0
28.8
Hypo
Hypo
Hypo
1.14 9 10
1.2 9 10
1.87 9 10
-24.08
-24.23
-25.36
6
4
Ni-apish
Ni-bpish
37.17
23.37
6
4
6
1
23

J IRAN CHEM SOC
Table 9 continued
k
(
max free
nm)
kmax bound
(nm)
Dk
chromism
(%)
Type of
cheomism
Binding
constant K
Free energy
-1
DG (KJ mol )
-
1
)
b
(M
At pH 7.4
Ni-cpish
4
627
7
9
8
62.33
39.08
23.55
Hyper
Hyper
Hyper
1.59 9 10
7.89 9 10
1.69 9 10
-24.93
-23.13
-25.09
6
76
625
80
636
82
3
Ni-apish
Ni-bpish
616
628
6
4
6
Hypo hypochromism, Hyper hyperchromism
viscosity and is a prerequisite for classical intercalation
model [72–74]. Compound–DNA interactions investi-
gated by spectroscopic method in present studies were
further verified by viscommetric studies. The third root
of values of the relative specific viscosities (g/g for the
o)
1
/3
ligands and the complexes, i.e., (g/go)
were plotted
against r, where g and go are the specific viscosity
contributions of DNA in the presence and absence of
compounds under investigations and r = [Compound]/
[DNA] (Fig. 11a, b). Upon increasing ratio of the com-
pound to DNA, the viscosity of DNA is increasing,
which indicated that compound binds to DNA by inter-
calation of the aromatic rings into the base pairs of DNA
[
75, 76]. This increase in viscosity is not only the
indication of intercalative binding mode but also fore-
shadows the pronounced hyperchromism, hypochromism,
bathochromism and hypsochromism of the complex in
the presence of DNA [77].
Conclusion
In this paper, we synthesized and characterized new
Ni(II) isatin hydrazone complexes by studying their
antimicrobial effect against many types of bacteria and
anti fungal cultures, which are common contaminants of
the environment in Egypt. The results indicate that the
newly synthesized ligands and their Ni(II) complexes
possess notable biological activity and exhibited marked
enhancement in activity on coordination with the metal
ions against the testing bacterial strains. Also, studying
the interaction of the new complexes with CT-DNA at
physiological conditions. The binding constant values of
3
4
-1
all the compounds were in the range of 10 –10 M by
Fig. 11 Plot of relative specific viscosity vs. [Compound]/[DNA] for
Ni-cpish, Ni-apish and Ni-bpish at a pH 4.7; b 7.4 and at 37 °C
comparing to that of typical intercalators such as iso-
3
-1
xazocucu-mine
4
(1.74 9 10
(6.3 9 10
M
)
and
lumazine
-1
M ) revealed stronger interaction of
molecules and DNA [71]. Lengthening of DNA helix as
a consequence of base pair separation to accommodate
the binding molecule will lead to an increase in DNA
investigated compounds with DNA via intercalation at
both pH values.
123

J IRAN CHEM SOC
References
39. R.M. Issa, A.A. Hassanein, I.M. El-Mehasseb, R.I. El-Abed
Wadoud, Spectrochimica Acta Part A 65, 206–214 (2006)
4
0. L.H. Abdel-Rahman, R.M. El-Khatib, L.A.E. Nassr, A.M. Abu-
Dief, J. Mol. Struct. 1040, 9–18 (2013)
1
. A. Serganov, D.J. Patel, The Royal Society of Chemistry, Cam-
bridge, 2006), pp. 233–252
4
4
1. A.W. Coats, J.P. Redfern, Nature 68, 201–202 (1964)
2. A.A. Abdel Aziz, A.N.M. Salem, M.A. Sayed, M.M. Aboaly, J.
Mol. Struct. 1010, 130–138 (2012)
2. M. Maiti, G.S. Kumar, J. Nucleic Acids 2010, 1–23 (2010)
3. M.J. Waring, Annu. Rev. Biochem. 50, 159–192 (1981)
4. L.H. Hurley, Biochem. Soc. Trans. 29, 692–696 (2001)
5. N. Arshad, U. Yunus, S. Razzque, M. Khan, S. Saleem, B. Mirza,
N. Rashid, Eur. J. Med. Chem. 47, 452–461 (2012)
4
4
4
4
4
4
4
5
5
3. A. Prakash, B.K. Singh, N. Bhojak, D. Adhikari, Spectrochimica
Acta Part A76, 356–362 (2010)
4. B.K. Singh, R.K. Sharma, B.S. Garg, J. Therm. Anal. Calorim.
4, 593–600 (2006)
5. N. Nishat, S. Hasnain, S.D. Asma, J. Coord. Chem. 63(21),
859–3870 (2010)
6. Z.H. Chohan, C.T. Supuran, A. Scozzafava, J. Enz. Inhib. Med.
Chem. 19, 79–84 (2004)
7. P.G. Avajia, C.H.V. Kumar, S.A. Patilc, K.N. Shivanandad, C.
Nagaraju, Eur. J. Med. Chem. 44(9), 3552–3559 (2009)
8. S.U. Rehman, Z.H. Chohan, F. Naz, C.T. Supuran, J. Enzy. Inhib.
Med. Chem. 20, 333–340 (2005)
9. Z.H. Chohan, M. Arif, Z. Shafiq, M. Yaqub, C.T. Supuran, J. Enz.
Inhib. Med. Chem. 21, 95–103 (2006)
0. K.N. Thimmaiah, W.D. Lloyd, G.T. Chandrappa, Inorg. Chim.
Acta. 106, 81 (1985)
1. A. Kulkarni, P.G. Avaji, G.B. Bagihalli, P.S. Badami, S.A. Patil,
J. Coord. Chem. 62(3), 481 (2009)
6
7
. L. Jia, P. Jiang, J. Xu, Z. Hao, X. Xu, L. Chen, J. Wu, N. Tang, Q.
Wang, J.J. Vittal, Inorg. Chim. Acta 363, 855–865 (2010)
. J.H. Griffin, P.B. Dervan, J. Am. Chem. Soc. 109, 6840–6842
8
3
(1987)
8. J.K. Barton, Science 233, 727–734 (1986)
9. E. Palecek, M. Fojta, Anal. Chem. 73, 74A–83A (2001)
1
1
1
1
0. S.K. Bharti, S.K. Singh, Int. J. Pharm. Tech. Res. 1, 1406–1420
(2009)
1. R.A. Sanchez-Delgado, K. Lazardi, L. Rincon, J.A. Urbina, A.J.
Hubert, A.N. Noels, J. Med. Chem. 36, 2041–2043 (1993)
2. V. Kumar, T. Ahamad, N. Nishat, Eur. J. Med. Chem. 44,
85–793 (2009)
3. V. Zelenak, K. Gyoryova, D. Mlynarcik, Met. Based Drugs 8,
69–274 (2002)
4. R.W. Daisley, V.K. Shah, J. Pharm. Sci. 73, 407 (1984)
5. S.N. Pandeya, D. Sriram, E. Declecq, C. Pannecouque, M.
Mitvrouw, Indian J. Pharm. Sci. 60, 207 (1999)
6. S.N. Pandeya, J.R. Dimmock, Pharmazie 48, 659 (1993)
7. R. Boon, Antiviral Chem. Chemother. 8, 5 (1997)
7
2
1
1
5
5
2. A.D. Kulkarni, S.A. Patil, P.S. Badami, J. Sulf. Chem., (2009)
3. Z.H. Chohan, H. Pervez, A. Rauf, K.M. Khan, C.T. Supuran, J.
Enz. Inhib. Med. Chem. 19, 417 (2004)
1
1
1
5
5
4. A.M. Pyle, J.P. Rehmann, R. Meshoyrer, C.V. Kumar, N.J. Turro,
J.K. Barton, J. Am. Chem. Soc. 111, 3051–3058 (1989)
5. Y. Sun, S. Bi, D. Song, C. Qiao, D. Mu, H. Zhang, Sens. Actuat.
B 129, 799–810 (2008)
8. S.N. Pandeya, D. Siram, G. Nath, E. Declercq, Eur. J. Pharm. Sci.
9
, 25 (1999)
9. N. Hadjiliadis, E. Sletten, in ed. by N. Hadjiliadis, E. Sletten
Eds.), (Blackwell Publishing Ltd., Oxford, 2009) pp. 1–511
0. Z.U. Rehman, A. Shah, N. Muhammad, S. Ali, R. Qureshi, A.
Meetsma, I.S. Butler, Eur. J. Med. Chem. 44, 3986–3993
1
2
(
56. X. Yang, G.L. Shen, R.Q. Yu, Microchem. J. 62, 394–404 (1999)
57. Z. Xu, G. Bai, C. Dong, Bioorg. Med. Chem. 13, 5694–5699 (2005)
58. R.F. Pasternack, E.J. Gibbs, J.J. Vilafranca, Biochemistry 22,
(2009)
2
406–2414 (1983)
9. S. Mahadevan, M. Palaniandavar, Inorg. Chem. 37, 693–700
1998)
2
2
1. R.C. Mehrotra, R. Bohra, Metal Carboxylates. (Academic Press
Inc., London, 1983)
2. A.D. Kulkarni, S.A. Patil, P.S. Badami, Int. J. Electrochem. Sci.
4
3. V.P. Singh, A. Katiyar, Pestic. Biochem. Physiol. 92, 8–14 (2008)
4. J. Murmur, J. Mol. Biol. 3, 208–218 (1961)
5. J. Murmur, J. Mol. Biol. 3, 208–218 (1961)
6. W.J. Geary, Coord. Chem. Rev. 7, 81 (1971)
7. H.G. olchoubian, O. Nazaria, B.K. ariuki, J. Chin. Chem. Soc.,
58(1), (2011)
8. S. Neena, H. Sunita, S. Jyoti, P. Vanita, B.V. Agarwala, Synth.
React. Inorg. Met.-Org. Chem. 22, 1283 (1992)
9. K. Nakamoto, Infrared spectra of inorganic and coordination
compounds (Wiley-Interscience, New York, 1970)
0. B. Murukan, S.K. Bhageerethi, M. Kochukittan, J. Coord. Chem.
0(15), 1607 (2007)
1. B. Murukan, S.K. Bhageerethi, M. Kochukittan, J. Coord. Chem.
0(15), 1607 (2007)
2. G. Cerchiaro, P.L. Saboya, A.M.C. Ferreira, D.M. Tomazela,
M.N. Eberlin, Tran. Met. Chem. 29, 495 (2004)
5
6
6
(
0. S. Kashanian, M.B. Gholvand, F. Ahmadi, A. Taravati, A.H.
Colagar, Spectrochim. Acta, Part A 67, 472–478 (2007)
1. A.J. Hobro, M. Rouhi, E.W. Blanch, G.L. Conn, Nucleic Acid
Res. 35, 1169–1177 (2007)
2. J.G. Thomas Jr, Biochim. Biophys. Acta 213, 417–423 (1970)
3. H.M. Torshizi, T.S. Srivastava, S.J. Chavan, M.P. Chitnis, J.
Inorg. Biochem. 48, 63–70 (1992)
4. A. Blake, A.R. Peacocke, Biopolymers 5, 871–875 (1967)
5. A.K. Paul, T.S. Srivastava, S.J. Chavan, M.P. Chitnis, S. Desai,
K.K. Rao, J. Inorg. Biochem. 61, 179–196 (1996)
, 717–729 (2009)
2
2
2
2
2
6
6
6
6
2
2
3
3
3
6
6. G.J. Yang, J.J. Xu, H.Y. Chen, Z.H. Leng, Chin. J. Chem. 22,
1
325–1329 (2004)
6
6
7. M.Y. Nie, Y. Wang, H.L. Li, Pol. J. Chem. 71, 816–822 (1997)
8. X.J. Dang, M.Y. Nie, J. Tong, H.L. Li, J. Electroanal. Chem. 448,
6
6
1–67 (1998)
6
6
7
9. N. Shahabadi, A. Fatahi, J. Mol. Struct. 970, 90–95 (2010)
0. M.S. Ibrahim, I.S. Shehata, A.A. Al-Nateli, Biomed. Anal. 28,
2
17–225 (2002)
3
3
3. A. Hatzidumitrious, C.A. Bolos, Polyhedron 17, 1779 (1998)
4. K. Nakamoto, Infrared spectra of inorganic and coordination
compounds (Wiley-Interscience, New York, 1970)
7
1. N.K. Janjua, A. Shaheen, A. Yaqub, F. Perveen, S. Sabahat, M.
Mumtaz, C. Jacob, L.A. Ba, H.A. Mohammad, Spectrochim.
Acta, Part A 79, 1600–1604 (2011)
3
3
3
3
5. J.H. Yoe, A.L. Jones, Ind. Eng. Chem. (Analyst. Ed.) 16,
7
7
2. N. Shahabadi, A. Fatahi, J. Mol. Struct. 970, 90–95 (2010)
3. N.K. Janjua, A. Shaheen, A. Yaqub, F. Perveen, S. Sabahat, M.
Mumtaz, C. Jacob, L.A. Ba, H.A. Mohammad, Spectrochim.
Acta, Part A 79, 1600–1604 (2011)
1
11–115 (1944)
6. R. El-Shiekh, M. Akl, A. Gouda, W. Ali, J. Am. Sci. 7(4),
97–807 (2011)
7. S.S. Shah, R.G. Parmar, Der Pharma Chemica 3(1), 318–321
2011)
8. P. Job, Ann. Chem. 9, 113–203 (1928)
7
7
4. J.B. Chaires, Energetics of drug–DNA interactions. Biopolymer
4
(
4, 201–215 (1997)
1
23

J IRAN CHEM SOC
7
5. N.K. Janjua, A. Shaheen, A. Yaqub, F. Perveen, S. Sabahat, M.
Mumtaz, C. Jacob, L.A. Ba, H.A. Mohammad, Spectrochim.
Acta, Part A 79, 1600–1604 (2011)
77. X.L. Wang, H. Chao, H. Li, X.L. Hong, Y.J. Liu, L.F. Tan, L.N.
Ji, J. Inorg. Biochem. 98, 1143–1193 (2004)
7
6. G. Zang, J. Guo, J. Pan, X. Chen, J. Wang, J. Mol. Struct. 923,
1
14–119 (2009)
123