SYNTHESIS, CHARACTERIZATION, MAGNETIC … · SYNTHESIS, CHARACTERIZATION, ... A series of homo and...
Transcript of SYNTHESIS, CHARACTERIZATION, MAGNETIC … · SYNTHESIS, CHARACTERIZATION, ... A series of homo and...
International Journal of Pharmaceutical
Biological and Chemical Sciences
ISSN: 2278-5191
International Journal of Pharmaceutical, Biological and Chemical Sciences (IJPBCS)
| Apr-Jun 2016 | VOLUME 5 | ISSUE 2 |11-22 www.ijpbcs.net or www.ijpbcs.com
Original Research Article
Pag
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SYNTHESIS, CHARACTERIZATION, MAGNETIC INTERACTIONS
AND BIOLOGICAL APPLICATIONS OF HOMO
AND HETERO BINUCLEAR SCHIFF BASE COMPLEXES
R.PA. Bhoopathy1, M. Malathy
1, R. Jayalakshmi
1 and R. Rajavel
1*
Department of Chemistry, Periyar University, Salem- 636011, Tamilnadu, India.
*Corresponding Author Email: [email protected]
INTRODUCTION
The interaction of organic / inorganic ligands with the
metal centers is one of the most active research areas
in inorganic chemistry. Coordination chemistry
includes different types of coordination complexes
applicable in a wide diversity of fields such as,
catalysis, bioinorganic chemistry, medicine, ceramics,
material science and toxicology. Inclusion of a variety
of ligands in complexes has enabled their applications
such as chemical analysis, catalytic activity and
biological applications including antimicrobial,
insecticidal, anti-HIV, antitumor and in vitro -
cytotoxic activities as well as DNA binders [1, 2]. Due
to their easy formation and strong metal-binding
ability of Schiff base, various metal complexes were
easily synthesized. Schiff bases form stable chelates
with metal ions when an additional donor closes to the
azomethine nitrogen. However, many side-effects
such as nephrotoxicity, neurotoxicity, inherited or
acquired resistance phenomena limited its
comprehensive applications in the therapy of cancers.
These problems had prompted chemists to research
more optimal strategies based on different metals and
ligands, with the wide range of coordination numbers
and geometries, available redox states, thermodynamic
and kinetic characteristics, and intrinsic properties of
the metal ions. In this field, copper complexes were
definitely considered as alternative metal-based
anticancer drugs [3, 4].
As copper is an essential element for most aerobic
organisms, an assumption that this endogenous metal
may be less toxic for normal cells than cancer cells is
raised. It is reported that the metabolism and cell
response to copper between normal and tumor cells are
generally different, which ground the basis of copper
complexes endowed with antineoplastic
characteristics. Scientists found that the concentration
of copper in numerous ex-vivo cancerous tissues (e.g.,
breast, prostate, lung, and brain) was exceeded than
that of in normal tissues. Actually, control of tumor
ABSTRACT:
A series of homo and hetero binuclear Schiff base metal complexes, derived from mononuclear Schiff base complex which
behaves as a ligand using transition metal ions such as Cu(II), and Ni(II) with the title ligand has been prepared. The
ligand and its binuclear metal complexes were characterized by FT-IR, UV-VIS, 1HNMR, EPR spectroscopy, Cyclic
voltammetry and Thermal analyses method. Antimicrobial activities of the homo and hetero binuclear complexes were also
evaluated. Based on the spectroscopic results, tentative structures of the metal complexes have been proposed. Hence,
from the obtained results, though all the complexes exhibited excellent biological activity, the hetero binuclear complex
has effective protection and enhanced bioactivity.
KEYWORDS: Homo and hetero binuclear metal complexes, Spectral studies, Thermal analysis, Antibacterial activity.
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growth and metastasis could be attained by chelating
the excess of copper with several small molecules. At
present, many researches are focusing on the
synthesis, DNA cleavage activity and anticancer
mechanism of copper-based complexes [5,6]. The
redox behaviour of the Schiff base metal complexes
were performed by using electrochemical techniques
[7-9].
However, significant increasing drug resistance has
limited the clinical applications of metal compounds.
Nickel (II) complexes containing nitrogen and oxygen
donor ligands are highly important. In this line,
analogues Nickel complexes are found to be potent in
various therapeutic applications. Nickel is a lighter
congener of platinum and several Nickel complexes
have been found to be potent in various therapeutic
applications [10-13]. Based on that new Ni(II)
complex has been screened for their antibacterial
activity against various pathogenic bacteria. These
types of new therapeutic approach are rapidly
emerging and further research may go to designing
more specific chelates. Moreover, this complex is
going to be a member of new larger family of complex
with Nickel (II) ion [14- 20].
In the present study, we have synthesized some homo
and hetero binuclear Schiff base complexes with the
titled ligand(6,6’-((1,2-
phenylenebis(azanylylidene))bis(ethan-1-yl-1-
ylidene))bis(2,4-dichlorophenol)) and reported to the
characterization and biological properties. The
bimetallic complexes have been isolated in multi-step
reactions. The reaction of two mononuclear complex
units with homo or hetero metal ions has been
interacted in the first step. The resulting binuclear
complexes contain nitrogen and oxygen groups in
close locality are encapsulated by in mononuclear the
step resulting in the formation of binuclear complexes.
The antibacterial activity of ligand, mono and
binuclear complexes was tested against some
bacteria’s and it was proved that the inhibition zones
were improved on increasing the concentration.
EXPERIMENTAL SECTION
Materials
The chemicals, 3, 5-dichloro-2-hydroxy acetophenone
and O- Phenylene diamine were purchased from sigma
Aldrich and used as recceived. The metal salts used
were of reagent grade and used without further
purification. The solvents were commercially
available, purchased from Merck.
General methods
Elemental analyses (C, H, N and S) were carried out
on a Vario EL III CHNS analyzer at SAIF-Cochin,
India. Physical measurements, Magnetization of a
sample powder of Cu-Ni-L was measured between 2
and 300 K with an applied magnetic field H = 10 k Oe
using a Cryogenic S600 SQUID magnetometer. The
effective magnetic moments were calculated by the
equation μeff. = 2.828 (Vm/T) ½
, where Vm is the
molar magnetic susceptibility was set equal to Mm/H.
FT-IR spectra were recorded as KBr pellets using a
FT-IR 1650 Shimadzu Spectrometer in the range
4000-400 cm-1
. Electronic spectra have been obtained
on a Schimadzu UV–3101PC UV-VIS NIR scanning
spectrophotometer at room temperature. 1H-NMR
spectra was carried out at room temperature on a 500
MHz Bruker advanced DPX spectrophotometers using
CDCl3 as a solvent and TMS as an internal reference.
The Molar conductance was of 10-3
M solutions of the
solid complexes in DMF were measured using
Corning conductivity meter NY 14831 model 441.
Thermal analyses (TGA/DTA) of the complexes were
carried out under nitrogen atmosphere in the
temperature from 40ºC to 900ºC using Shimadzu
DTG-60, heating rate of 20° C/min. EPR spectra of the
complexes were carried out using Bruker EMX Plus
with Microwave Frequency, 9.865832 GHz at room
temperature. Antibacterial activity was studied by disc
diffusion method.
Synthetic procedure for ligand (HL)
A solution of O-Phenylene diamine (0.1081g;1 mmol)
in 20 mL ethanol was added drop wise to a solution of
3, 5-dichloro-2-hydroxy acetophenone (0.4101g;2 m
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mol) in an ethanol (20 mL). The mixture was gently
heated under reflux for 3 h, which resulted in a rapid
change of color from brown to orange yellow crystals.
After refluxing, the resulting solution was filtered and
the filtrate was left unperturbed for the slow
evaporation of the solvent. After four days orange
yellow colored crystals were obtained [21].
Characterization data:
Yield: 70% (0.34 mg); color: yellowish orange; MP:
120–125°C; micro analytical data: C22H14Cl5N2O2
required: C, 54.87; H, 2.90; N, 5.82. Found: C, 53.12;
H, 2.45; N, 5.60; IR (KBr pellet, cm−1) 3426 ν(–OH);
1637 ν(C=N); 1438 ν(C–O), 1442 ν{Ph(P–Ph)}; UV-
vis (EtOH), λmax (nm): 203,345. 1HNMR (500 MHz,
CDCl3, ppm): δ=1.5 (s, 6H, –CH3); 7.6 (s,2H, –
CH=N); 10.8 (s, 2H, –OH); 6.5–7.3 (m, 8H, Ar).
Synthetic procedure for mono nuclear Copper (II)
complex [Cu-L]
A solution of Copper (II) acetate (0.1816g;1mmol) in
20 mL ethanol was added drop wise to a solution of
ligand (0.4811g;1mmol) in an ethanol(20 mL). The
mixture was gently heated under reflux for 3 h [22],
which resulted in a rapid change of color from brown
to yellowish brown crystals. After refluxing, the
resulting solution was filtered and the filtrate was left
unperturbed for the slow evaporation of the solvent.
After four days orange yellow colored crystals were
obtained.
Characterization data:
Yield: 75% v (0.50 mg); color: yellowish brown; MP:
142–146°C; micro analytical data: CuC22H12Cl5N2O2
required: C, 48.64; H, 2.21; N, 5.16;Cu, 11.71. Found:
C, 46.78; H, 2.05; N, 5.01; IR (KBr pellet, cm−1)
1604 ν(C=N); 1425 ν(C–O), 548 (νM-O); 450(νM-N)
UV-vis (EtOH), λmax (nm): 206,375,647; Conductance
(ohm-1
cm2 mol
-110
-6): Λm=11
Synthesis of homobinuclear Copper (II) complex
[Cu2-L]
The homo binuclear Copper (II) complex was
synthesized by slow addition of 20ml ethanolic
solution of CuCl2 (0.1345g;1 mmol) to 20ml ethanolic
solution of Cu-L(0.5427g;mmol). The resulting
mixture was heated under reflux for 4 hrs [22]. After
refluxing, the resulting solution was filtered and the
filtrate was left undisturbed for the slow evaporation
of the solvent. After five days brown colored crystals
were obtained.
Characterization data:
Yield: 65%(0.46mg); color: brown; MP: 152–157°C;
micro analytical data: Cu2C22H12Cl7N2O2 required: C,
38.98; H,1.77; N, 4.13;Cu, 18.76. Found: C, 37.41.78;
H, 1.24; N, 3..98; IR (KBr pellet, cm−1) 1619 ν(C=N);
1428 ν(C–O), 519 (νM-O); 464 (νM-N) UV-vis (EtOH),
λmax (nm): 209, 378, 591; Conductance (ohm-1
cm2
mol-1
10-6
): Λm=20
Synthesis of heterobinuclear copper (II) and Nickel
(II) complex [Cu-Ni-L]
30 mL solution of NiCl2(0.1296g;1mmol) in ethanol
was added drop by drop to 30mL hot solution of
mono nuclear Copper(II) complex(0.5427g;1mmol) in
ethanol and the resulting mixture was heated under
reflux for 5 h by refluxing the contents for 3 hrs [22].
After refluxing, the resulting solution was filtered,
washed with ethanol and the filtrate was left
undisturbed for the slow evaporation of the solvent.
After five days brown colored crystals were obtained.
Characterization data:
Yield: 60%(0.41mg); color: brown; MP: 160–164°C;
micro analytical data: CuNiC22H12Cl7N2O2 required:
C, 39.26; H,1.78; N, 4.16;Cu, 9.45;Ni,8.73. Found: C,
37.24; H, 1.32; N, 3..78; IR (KBr pellet, cm−1) 1630
ν(C=N); 1427 ν(C–O), 612 (νM-O); 460 (νM-N) UV-vis
(EtOH), λmax (nm): 210, 370, 505; Conductance
(ohm-1
cm2 mol
-110
-6): Λm=24
RESULTS AND DISCUSSION
Synthesis and characterization
A new series of homo and hetero binuclear complexes
of the type [ML, M2L, M-M’-L-X2] (M = Cu (II), M’ –
Ni (II), L = ligand and X = Cl) were synthesized as
shown in Scheme 1. All the complexes are soluble in
ethanol but insoluble in water.
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Scheme- I
Scheme- II
The molar conductance values are in the range 10-24
Ω-1
cm2 mol
-1 which is perfectly near to non-
electrolytes values (20-30 Ω-1
cm2 mol
-1) in 10
-3 M
DMF solution were shown in Table 1. The neutrality
of the complexes can be related by the deprotonated
nature of the ligand with most complexes.
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Table 1: Analytical and physical data of Schiff base ligand and its metal complexes
Table 2: IR and UV Spectral data of the ligand and its metal complexes
Compounds υ (O-H) cm-1
υ (C=N) cm-1
υ (C-O) cm-1
υ (M-O) cm-1
υ (M-N) cm-1
λmax nm
L 3426 1637 1438 - - 203,345
CuL - 1604 1425 548 450 206,375,647
Cu2L - 1619 1428 519 464 209,378,591
Cu-Ni-L - 1630 1427 612 460 210,350,505
Table 3: Cyclic voltammetric data of homo and hetero binuclear metal complexes
Complexes
Reduction Oxidation
Epc(V) Epa(V) E1/2(V) ΔEp
(mV) Epc(V) Epa(V) E1/2(V)
ΔEp
(mV)
[Cu-CuL] -1.8 -1.6 -1.7 200 0.9 1.3 1.1 400
[Cu-NiL] -1.2 -0.9 -1.05 300 0.3 0.65 0.475 350
Table 4.Thermo Analytical data of the metal complexes
Complexes Temperature range of
decomposition(ºC) % of weight loss Remarks
CuL
235-450 6.7 Loss of chloride ion from complex
450-540 34.5 Partial decomposition of organic part of ligand
590-735 50.3 Complete decomposition with the formation of
mixed metal oxide
Cu2L
170-290 16 Loss of chloride ion
300-450 39.33 Partial decomposition of organic part of ligand
550-740 77 Complete decomposition with the formation of
mixed metal oxide
Cu-Ni-L
145-340 25 Loss of chloride ion
400-575 62 Partial decomposition of organic part of ligand
610-690 87 Complete decomposition with the formation of
mixed metal oxide
FT-IR Spectra
The FT-IR analysis of Ligand (HL), mono nuclear
(Cu-L) and binuclear complexes (Cu2-L and Cu-Ni-L)
was carried out and the corresponding spectra are
shown in Fig. 1(a-d) and Table 2. In the IR spectrum
of the ligand, the –O-H stretching vibration band was
observed at 3427 cm -1
, as well as the C-N band at
1438 cm−1
, the C=N sharp band at 1637 cm−1
, and the
C-O band at 1243 cm−1
. Fig. 1(b) shows IR spectra of
the mono nuclear complex (Cu-L), similar to that of
Compounds Molecular
formula
Color
Found (calcd) % Λm
ohm-1
cm2
mol-1
10-6
C H N M
Cu Ni
L C22H14Cl5N2O2 Yellowish
Orange
53.12
(54.87)
2.45
(2.9)
5.60
(5.82)
- - -
CuL CuC22H12Cl5N2O2 Yellowish
brown
46.78
(48.64)
2.05
(2.21)
5.01
(5.16)
11.56
(11.71)
- 11
Cu2L Cu2C22H12Cl7N2O2 Brown 37.41
(38.98)
1.24
(1.77)
3.98
(4.13)
18.59
(18.76) - 20
Cu-Ni-L CuNiC22H12Cl7N2O2 Brown 37.24
(39.26)
1.32
(1.78)
3.78
(4.16)
9.36
(9.45)
8.61
(8.73) 24
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the ligand but with a slight change in the wave
numbers. The spectrum of mono nuclear complex (Cu-
L) shows the C=N sharp band, the C-N and the C-O
band at 1625 cm-1
, 1425 cm−1
, and 1224 cm−1
respectively. Fig. 1(c) and 1(d) shows IR spectra of
homo and hetero binuclear complexes respectively
which represent the characteristic peaks corresponding
to the mono nuclear complex but with slight change in
the wave number. In the IR spectra of these complexes
(-OH) stretching vibrations disappeared which shows
coordination of oxygen to the metal. The band
assigned to ν(C-O) shifted to lower frequency i.e.19
cm−1
upon coordination in the complexes. The band
assigned to ν(C-N) shows a shift of 13 cm−1
towards a
lower frequency [23-25]. IR data confirm the copper
(II) metal atom binding together with both O and N
donor groups of the Schiff base ligand and support the
tentative structure of the complexes. The stronger
bands appearing at 450 - 460 cm-1
were assigned to M
- N and M - O stretching frequencies for all the
complexes respectively [26-28].
Fig. 1: FT-IR spectra of (a) Ligand (HL) (b) mono nuclear complex (Cu-L) (c) homo binuclear complex
(Cu2-L) (d) hetero binuclear complex (Cu-Ni-L).
UV-Visible Spectra
The UV spectral analysis of Ligand (HL), mono
nuclear complex (Cu-L) and binuclear complexes
((Cu2-L) & (Cu-Ni-L)) was carried out and shown in
Fig. 2(A-D). Fig.2 (A), the absorption spectral data for
Schiff base ligand shows the peaks around 203 nm and
345 nm were assigned to ligand-centred (LC) π→π*
and n→π* transitions. Fig.2 (B) shows the absorption
spectrum of complex 1 in alcohol solution at room
temperature exhibits a band at 647 nm, due to d–d
transition. This type of absorption band has been
previously assigned to copper (II) complex with
square–planar geometry. Bands below 400 nm are due
to intraligand transitions. Fig.2 (C) and Fig. 2(d) show
the absorption spectrum of homo and hetero binuclear
complexes respectively. The broad band at 591 nm
and 505 nm regions, which are attributed to the d-d
transition bands of d9 (Cu(II)) and spin-paired d
8
(Ni(II)) with a square-planar structure [29].
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Fig. 2: UV-VIS spectra of (A) Ligand (HL) (B) mono nuclear complex (Cu-L) (C) hetero binuclear
complex (Cu2-L) (D) hetero binuclear complex (Cu-Ni-L).
1H NMR spectra
The 1H NMR spectrum of the ligand (HL) in CDCl3
(Fig. 3) shows the phenyl multiplet at δ= 6.5–7.3 ppm
and the azomethine proton at δ= 7.6 ppm (singlet).
The peak at δ= 10.8 ppm is attributed to the phenolic -
OH group present in the ligand and an additional peak
at δ=1.5 ppm is attributed to the -CH3 protons of the
ligand (HL).
Thermal Analyses (TGA/DTA)
Thermo gravimetric analyses of the Schiff base metal
complexes were investigated using TGA and DTA
analysis (Fig. 4(a-c)). The thermal analyses (TGA)
were performed in a nitrogen atmosphere with a
heating rate of 20oC/min over a temperature range of
20–800oC/min. The mono and binuclear copper
complexes have a different decomposition process.
The high thermal stability investigated complexes may
correspond to whether any solvent/water molecules
were inner/outer coordination sphere of the central
metal ion. The TG weight loss of the first stage,
exhibit decomposition between 335 and 420oC/min,
correspond to loss of chloride ion from complexes.
The second stage indicates (450oC) the partial
decomposition of organic part of ligand and the final
stage possess to complete decomposition together with
the formation of mixed metal oxide as final product
[30]. The differential thermal analysis (DTA) curves
of the mono and binuclear copper complexes shows
endothermic peak in the temperature range 180–
200oC/min assigned to loss of coordinated chloride
ion. The DTA curves that contained one sharp
exothermic peak falling in the temperature range of
350–415oC/min and conclude the formation of metal
oxides [31]. From the results, it is well evident that the
hetero binuclear complex decomposes at higher
temperature than compared to mononuclear and homo
binuclear complexes.
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Figure 3: 1H NMR spectra of ligand
EPR spectra
The X-band EPR spectra of mono nuclear complex
(Cu-L) as well as homo binuclear complex (Cu2-L)
were recorded at room temperature using DPPH as a
reference standard and the corresponding spectra are
shown in Fig. 5 (a-b). EPR spectra of homobinuclear
Complex (Fig. 5(b)), the hyperfine lines could not be
resolved which indicate the exchange interaction and
strong dipolar between copper (II) ions in the
complex. The reported complexes gave g‖ and g+
values in the regions 2.15–2.28 and 2.05–2.11
respectively. The exchange interaction between copper
centers, which measures by g values are related by the
expression G = (g‖ 2)/ (g+
2). The calculated G values
for these complexes appeared the parameters in the
range 2.18–3.00 which predicts the weak exchange
interaction. The g|| value is an important function for
indicating covalent character of M-L bonds [33]. For
ionic character, g‖ > 2.30 while for covalent character
g‖ < 2.30. In the present compounds, the g‖ < 2.30
indicating appreciable covalent character for Cu-L
bond. Such a spectrum is expected in complexes with
square planar geometry.
Cyclic voltammetry:
The electro chemical behavior of metal complexes was
studied by using cyclic voltammetry in DMSO
containing TBAP as supporting electrolyte beyond the
range of 2.0 to -2.0 V. The obtained electrochemical
data of the metal complexes were shown in Fig. 6 (a-
b) and summarized in Table 3. The cyclic
voltammogram of the Cu-CuL complex showed a
quasi-reversible reduction peak and the E1/2 values
indicate that each couple corresponds two step one
electron transfer process. Likewise oxidation process
as well quasireversible in nature [32]. So, the
processes were designated as follows.
CuII Cu
II ↔ Cu
II Cu
I ↔ Cu
I Cu
I
The representative cyclic voltammogram of the hetero
binuclear complex (Cu-NiL) was shown in Fig. 6 (b).
Based on these observations, both the E1/2 and ΔE
values suggest that the reduction process may involve
the two step one-electron transfer and quasireversible
and the processes were expressed as follows: CuII Ni
II
↔ CuII Ni
I ↔ Cu
I Ni
I
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Fig.4. TG/DTA of (a) mono nuclear complex (Cu-L) (b) homo binuclear complex (Cu2-L) (c) hetero
binuclear complex (Cu-Ni-L).
Fig.5. EPR spectra of (a) mono nuclear complex (Cu-L) and (b) homo binuclear complex (Cu2-L).
Magnetic properties
The magnetic susceptibility measurements (XM) and
its product with temperature (T) is shown in Fig. 7.
The variable temperature magnetic susceptibilities of
hetero binuclear complex were measured in the 2–300
K temperature range. The XM vs T value (1.26 cm3
mol-1 K) at room temperature slightly lower than the
spin-only value (1.38 cm3 mol-1 K) anticipated for the
uncoupled Cu(II)-Ni(II) unit. On cooling it decreases
smoothly and reaches a plateau below 40 K with XM
Vs T between 0.41 and 0.50 cm3 mol
-1 K. These
features are typical of Cu(II)-Ni(II) pairs with
antiferromagnetic intramolecular interaction. At low
temperature the plateaus below 40 K indicate that only
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the doublet ground state is thermally populated. It
decreases smoothly on cooling. These features are
typical of Cu (II)-Ni (II) pairs with antiferromagnetic
intramolecular interaction [34].
Figure 6 :( a) Cyclicvoltammogram of Cu2L; (b)Cyclicvoltammogram of Cu-Ni-L
Figure 7: Magnetic Susceptibility of hetero binuclear metal Complex.
Figure 8 (a): Antibacterial activity of Schiff base ligand and its metal complexes
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Figure 8(b): Antibacterial activity of Schiff base ligand and its metal complexes
Antibacterial activity
S. aureus, Bacillus (Gram-positive) and E. coli,
Proteus (Gram-negative) are the general bacterias that
are found in the contaminated wound. The synthesized
homo and hetero binuclear complexes were tested
against S. aureus, E. coli, Proteus and Bacillus stains
at different concentrations like 25, 50 and 75 (µg/mL)
which are compared with control (Fig.9(a-b)). From
the figure, it is well evident that heterobinuclear
complex has higher antibacterial activity versus both
the Gram-positive and Gram-negative bacteria stains.
Because of this, it is concluded that the substitution of
hetero atom to the binuclear complex can react with
the nuclear content of bacteria and destroy them
easily. Hence the hetero binuclear complex showed
excellent anti-bacterial activity. The variation in the
effectiveness of different compounds against different
organisms depends either on the impermeability of the
cells of the microbes or on divergence in ribosome of
microbial cells. In particular the complex showed
excellent activity against E. coli which is due to the
differences in the cell wall structure. The cell wall of
the gram-positive bacteria is made of a thick layer of
peptidoglycan, consisting of linear polysaccharide
chains leading to difficult penetration compared to the
gram-negative bacteria where the cell wall possesses
thinner layer of peptidoglycan. Therefore, changes in
the membrane structure of bacteria follows in the
increased anti-bacterial activity for the coatings
against E. coli. From the results it is well evident that
the binuclear complex not only retards the bacterial
adhesion, but also effectively kills the adhered bacteria
suggesting effective and long lasting antibacterial
activity against S. aureus, E. coli, Proteus and Bacillus
[35].
CONCLUSION
In this paper, we have shown the successful synthesis
of Schiff base ligand and its mononuclear, homo and
hetero binuclear complexes have been characterized
using spectroscopic methods, molar conductivity,
thermal analysis, cyclic voltammetry, EPR and
magnetic measurements. The square planar
environment of the metal complexes was confirmed by
electronic spectral data and magnetic moment values.
The cyclic voltammetry result supported that both the
mono and binuclear metal complexs exhibits with one
electron transfer and quasi-reversible nature. The
stability of metal complexes was ratified by using
thermal analyses. The EPR g|| values indicate high
energy d-d transition typical for planar CuN2O2
complexes. From the result of antibacterial activity
test, we concluded that the hetero binuclear complex
plays an effective role in improving the bioactivity.
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