Physico-chemical and biological studies of Cu(II), Co(II) and Ni(II) complexes of an N4 coordinating ligand derived from the Schiff base of diacetyl with ethylenediamine and benzoic acid

Article abstract of DOI:10.2298/JSC110412148S

Mononuclear metal complexes of the type [ML1]Cl2 (where, M = = Cu(II), Co(II) or Ni(II) and L1 = ligand) were synthesized by the reaction of a new N4 coordinating ligand, N,N'-{(1,2-dimethylethanediylidene)bis[nitrilo( 2,1-ethanediyl)]}bis[benzamide] derived from the Schiff base of diacetyl with ethylenediamine and benzoic acid, and the corresponding hydrated metal chloride salts. The metal complexes were characterized by elemental analysis, melting point determination, molar conductance and magnetic moment measurements, IR, UV-Vis, 1H- and 13C-NMR, and ESR spectroscopy. The ligand and all the metal complexes were stable in the solid state at room temperature. From the analytical and spectroscopic investigations, the stoichiometry of the complexes was found to be 1:1 (metal:ligand). Based on the electronic spectra and magnetic moment data, the metal complexes had a square planar geometry. The molar conductance values show the 1:2 electrolytic nature of the metal complexes. A cyclic voltammetric study of the Cu(II) metal complex has also performed, which showed one electron quasi-reversible reduction around -0.92 to -1.10 V. In vitro biological activities of the ligand and metal complexes was checked against two bacteria Bacillus subtilis and Escherichia coli and two fungi Aspirgillus niger and A. flavus which showed the antibacterial and antifungal properties of the ligand and its metal complexes. 2012 Copyright (CC) SCS.

Full text of DOI:10.2298/JSC110412148S

J. Serb. Chem. Soc. 77 (5) 627–637 (2012)
JSCS–4296
UDC 546.562’732’742:547+57–
188:615.281/.282
Original scientific paper
Physico-chemical and biological studies of Cu(II), Co(II) and
Ni(II) complexes of an N4 coordinating ligand derived from the
Schiff base of diacetyl with ethylenediamine and benzoic acid
*
NETRA PAL SINGH and ABHAY NANDA SRIVASTAVA
Department of Chemistry, Meerut College, Meerut-250001, India
(Received 12 April, revised 28 August 2011)
Abstract: Mononuclear metal complexes of the type [ML1]Cl2 (where, M =
= Cu(II), Co(II) or Ni(II) and L1 = ligand) were synthesized by the reaction of a
new N4 coordinating ligand, N,N’-{(1,2-dimethylethanediylidene)bis[nit-
rilo(2,1-ethanediyl)]}bis[benzamide] derived from the Schiff base of diacetyl
with ethylenediamine and benzoic acid, and the corresponding hydrated metal
chloride salts. The metal complexes were characterized by elemental analysis,
melting point determination, molar conductance and magnetic moment
1
measurements, IR, UV–Vis, H- and 13C-NMR, and ESR spectroscopy. The
ligand and all the metal complexes were stable in the solid state at room
temperature. From the analytical and spectroscopic investigations, the stoichio-
metry of the complexes was found to be 1:1 (metal:ligand). Based on the elec-
tronic spectra and magnetic moment data, the metal complexes had a square
planar geometry. The molar conductance values show the 1:2 electrolytic
nature of the metal complexes. A cyclic voltammetric study of the Cu(II) metal
complex has also performed, which showed one electron quasi-reversible re-
duction around –0.92 to –1.10 V. In vitro biological activities of the ligand and
metal complexes was checked against two bacteria Bacillus subtilis and Es-
cherichia coli and two fungi Aspirgillus niger and A. flavus which showed the
antibacterial and antifungal properties of the ligand and its metal complexes.
Keywords: mononuclear Cu(II), Co(II) and Ni(II) complexes; square planar
geometry; antibacterial and antifungal properties.
INTRODUCTION
Metallo-drugs became an interesting research area after the discovery of cis-
1
platin. Since then, many complexes have been synthesized and tested on a num-
ber of biological systems. New areas of research, which mainly focused on the
specific synthesis of highly functional metal-based drug complexes have drawn
considerable attention. Some transition metals are essential for the normal func-
*Corresponding author. E-mail: netrapal_chem@yahoo.com
doi: 10.2298/JSC110412148S
627
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SINGH and SRIVASTAVA
tion of living organisms. Schiff bases and their complexes have a variety of ap-
2,3
plications in biological, clinical, analytical and pharmacological areas. When
ligands coordinate to transition metals, it is believed that the selectivity towards
4–7
certain biological systems is improved.
The enormous interest in the field of
coordination chemistry of transition metal ions with Schiff bases is due to use of
8,9
these compounds as biological models, as oxygen carriers and as drugs. Re-
cently synthesized Cu(II), Ni(II), Co(II), Zn(II) and Fe(III) complexes show the
current interest of researchers in the field of coordination chemistry of these
10,11
metal ions.
N-Coordinating ligands and their transition metal complexes have
12–14
been found to possess important catalytic as well as biological activity.
Some
other transition metal complexes have also been synthesized recently which show
good biological activities viz. antibacterial, antifungal, toxicity, DNA interaction
15–21
and antitumour.
In view of the importance of metal complexes, herein the
preparation and characterization of Cu(II), Ni(II) and Co(II) metal complexes of
a new N coordinating ligand derived from the Schiff base of diacetyl with
4
ethylenediamine and benzoic acid are reported. The synthesized compounds were
characterized by various analytical and spectral studies, such as elemental anal-
ysis, magnetic moment and molar conductance measurements, and IR, UV–Vis,
NMR and ESR spectroscopy. In vitro antibacterial and antifungal activities of the
synthesized compounds against some specific bacteria (viz. Bacillus subtilis and
Escherichia coli) and fungi (viz. Aspirgillus niger and A. flavus) were also
studied.
EXPERIMENTAL
All chemicals were of A.R. grade. MeOH, EtOH, n-BuOH, diethyl ether and the metal
salts were purchased from Qualigens. Diacetyl was purchased from Aldrich. Ethylenediamine
and benzoic acid were purchased from CDH. All chemicals were used as obtained without
further purification. Elemental analysis (C, H, N) was performed using a Carlo Erba 1106
elemental analyzer. Metals and chlorides were determined volumetrically22 and gravimetri-
cally,23 respectively. The IR spectra were recorded using KBr discs (4000–400 cm-1) on a
Shimadzu 8300 IR spectrophotometer. The electronic absorption spectra in the 200–900 nm
range were obtained in dimethylformamide (DMF) (1.0×10-4 M) on a Systronic UV–Vis spec-
trophotometer. The molar conductance measurements were performed in dimethyl sulphoxide
(DMSO) (≈10-3 M) at room temperature using a Jenway Model 4070 conductivity meter. The
magnetic moment measurements were realized by the Gouy method using Hg[Co(SCN)4] as
the calibrant. The 1H- and 13C-NMR spectra were recorded at room temperature in DMSO-d6
(≈1.0×10-3 M) on a Bruker AC 700L NMR spectrometer with reference to TMS (tetramethyl-
silane). Chemical shifts are reported on the δ scale. The electrochemical behaviour of the
Cu(II) complex was investigated in acetonitrile solution on a CH620A electrochemical ana-
lyzer using a platinum electrode. Tetraethylammonium perchlorate (0.4 M) was used as the
supporting electrolyte and the potentials are referenced to the saturated calomel electrode
(SCE) without junction correction. The cyclic voltammogram was recorded at a scan rate of
50 mV s-1 with iR compensation. The ESR spectrum of the Cu(II) complex was recorded in
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BIOLOGICAL PROPERTIES OF METAL COMPLEXES OF AN ORGANIC MOIETY
629
acetonitrile solution at room temperature on an E-112 ESR spectrophotometer employing 2,2-
diphenyl-1-picrylhydrazyl (DPPH) as the g-marker.
Synthesis of the ligand (L1)
A diacetyl (0.44 ml, 5 mmol) solution in 20 ml of n-BuOH was added to ethylene-
diamine (0.67 ml, 10 mmol) and stirred for ≈2.5 h. The formed white solid (N,N’-(1,2-dime-
thylethanediylidene)bis[1,2-ethanediamine] (L)) was filtered off, washed with water and
diethyl ether and dried in a vacuum desiccator. A solution of L (0.85 g, 5 mmol) in 30 ml of
EtOH was added to a benzoic acid (1.22 g, 10 mmol) solution in 20 ml of EtOH and stirred at
35 °C for ≈8 h and cooled to room temperature. The precipitated ligand N,N’-{(1,2-dime-
thylethanediylidene)bis[nitrilo(2,1-ethanediyl)]}bis[benzamide] (L1) was filtered, washed with
diethyl ether and dried in a vacuum desiccator over anhydrous calcium chloride (Scheme 1).
Yield: 76 %; m.p. 104 °C; colour: yellow. Anal. Calcd. for C22H26N4O2 (FW: 378.45):
C, 69.85; H, 6.92; N, 14.80 %. Found: C, 69.80; H, 6.94; N, 14.85 %.
Step I:
H3C
H3C
O
O
N
N
NH2
NH2
H3C
H3C
+
2
n-BuOH, Stirring (~ 2.5 h)
NH2
NH2
-2H2O
(L)
Step II:
O
N
N
NH2
NH2
H3C
N
N
NH
NH
C
H3C
HOOC
EtOH, Stirring
(35 °C, ~ 8 h)
+
2
-2H2O
H3C
H3C
C
O
(L1)
Scheme 1. Synthesis of the ligand L1.
Synthesis of the metal complexes
A solution of 1.0 mmol of hydrated metal chloride salt (CuCl2·2H2O (0.17 g),
NiCl2·6H2O (0.23 g) and CoCl2·6H2O (0.23 g)) in 15 ml EtOH was added to an ethanolic
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SINGH and SRIVASTAVA
solution of L1 (0.38 g, 1.0 mmol) and stirred at 50 °C for ≈10 h and cooled in refrigerator
overnight. Coloured products of the metal complexes were obtained which were filtered off,
washed with methanol, ethanol and diethyl ether and dried in a vacuum desiccator over
anhydrous calcium chloride (Scheme 2).
O
N
N
NH
NH
C
H3C
H3C
EtOH, Stirring(50 °C, ~ 10 h)
+
MCl2 .nH2O
-nH2O
C
O
O
N
N
NH
NH
C
H3C
H3C
Cl2
M
C
O
Scheme 2. Synthesis of the metal complexes [ML1]Cl2.
In vitro antibacterial and antifungal studies
The antibacterial and antifungal study of the newly synthesized ligand (L1) and all the
metal complexes were realised in vitro by reported methods.24 A stock solution (1 mg ml-1) of
the test chemical was prepared by dissolving 10 mg of the test chemical in 10 ml of DMSO.
The stock solution was suitably diluted with sterilized distilled water to obtain 500 and 100 µg
ml-1 solutions. A control for each dilution was prepared by diluting 10 ml of solvent instead of
stock solution with sterilized distilled water. All compounds were evaluated for their in vitro
antibacterial activity against Bacillus subtilis and Escherichia coli and antifungal activity
against Aspirgillus niger and A. flavus by the agar-well diffusion method. The bacteria were
inoculated into Nutrient Broth (Difco) and incubated for 30 h and the studied fungi were
incubated in Malt Extract Broth (Difco) for 54 h. In the agar-well diffusion method, Müller
Hinton Agar (Oxoid) for the bacteria and Malt Extract Broth (Difco) for the fungi, sterilized in
a flask and cooled to ≈48 °C, were distributed (20 ml) in sterilized petri dishes after injecting
0.01 ml of a culture of a bacterium or fungus, prepared as mentioned above, and allowed to
solidify. The dilution plate method was used to enumerate the microorganism (105 bacteria
per ml and fungi 103–104 per ml) for 24 h. Wells were dug in the culture plates using a
sterilized cork borer (7 mm diameter). The compounds dissolved in DMSO were added (0.2
µl) to these wells. The Petri dishes were left at 4 °C for 2 h and then the plates were incubated
at 30 °C for the bacteria (24–28 h) or at 25 °C for the fungi (78 h). Subsequently, the dia-
meters of the inhibition zones formed on the medium were evaluated in millimetres. The bio-
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BIOLOGICAL PROPERTIES OF METAL COMPLEXES OF AN ORGANIC MOIETY
631
logical activity data of all the compounds are expressed as the % inhibition over the control.
The percent inhibition was calculated using the formula:
Inhibition level = 100(C – T) / C
where C is the diameter of the microbial colony in the control plate and T is the diameter of
the microbial colony in the tested plate after same incubation period.
RESULTS AND DISCUSSION
The newly synthesized ligand and its metal complexes are stable at room
temperature in the solid state. The ligand is soluble in common organic solvents
whereas the metal complexes are soluble in DMF and DMSO.
Condensation of N,N’-(1,2-dimethylethanediylidene)bis[1,2-ethanediamine]
and benzoic acid readily gives the corresponding ligand L , which is easily iden-
1
1
13
tified by its IR, H-NMR and C-NMR spectra. The metal complexes of general
formula [ML ]Cl of Cu(II), Co(II) and Ni(II) were prepared by stirring a mix-
1
2
ture of corresponding hydrated metal chloride with the title ligand at a ratio of
1:1. Square planar geometry is proposed for all complexes.
Analytical data for the complexes
[CuL ]Cl (1). Yield: 64 %; m.p. 222 °C. Colour: brown. Anal. Calcd. for
1
2
C H Cl CuN O (FW 512.90): C, 50.51; H, 5.11; N, 10.92; Cu, 12.39; Cl,
22 26
2
4 2
13.82 %. Found: C, 51.48; H, 5.07; N, 10.90; Cu, 12.37; Cl, 13.80 %.
[CoL ]Cl (2). Yield: 61 %; m.p. 212 °C. Colour: light brown. Anal. Calcd.
1
2
for C H Cl CoN O (FW 508.30): C, 51.98; H, 5.15; N, 11.02; Co, 11.60; Cl,
22 26
2
4 2
13.95 %. Found: C, 51.96; H, 5.12; N, 11.08; Co, 11.58; Cl, 13.92 %.
[NiL1]Cl2 (3). Yield: 67 %; m.p. 198 °C. Colour: reddish brown. Anal.
Calcd. for C H Cl N NiO (FW 508.07): C, 51.00; H, 5.16; N, 11.03; Cu,
22 26
2
4
2
11.56; Cl, 13.94 %. Found: C, 51.05; H, 5.12; N, 11.08; Cu, 11.54; Cl, 13.91 %.
The analytical data are in good agreement with the proposed stoichiometry
of the complexes.
IR spectra
The IR spectral data of ligand and metal complexes are given in Table I. The
–1
IR spectrum of the ligand shows a sharp band at 1576 cm , which shows the
23
presence of ν(C=N) vibrations. There is no peak of free –NH groups in the IR
2
spectrum of ligand, which indicates the formation of the proposed ligand. In the
IR spectra of metal complexes, the ν(C=N) band is shifted to 1598–1626 cm ,
which shows the coordination of (C=N).
the range 460–466 cm may be assigned ν(M–N) vibrations. A band in the
range of 1762 cm in the spectra of the ligand and all the metal complexes show
–1
25–29
The new band which appeared in
–1
30
–1
that the C=O group did not participate in the coordination. In the IR spectra of
–1
L , the sharp medium band at 3300 cm is assigned to ν(N–H) stretching vib-
1
rations. This band is shifted to lower wave numbers in the spectra of Cu(II),
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SINGH and SRIVASTAVA
–1
Co(II) and Ni(II), i.e., to 3208, 3200 and 3196 cm , respectively, which in-
31,32
dicates the coordination of the (–N–H) nitrogen.
TABLE I. IR spectral data (ν / cm-1) of the ligand and its metal complexes. All spectra were
recorded using KBr discs in the range 4000–400 cm-1
Compound
ν(–N–H)
ν(C=O)
ν(C=N)
ν(M–N)
L1
3300
3208
3200
3196
1762
1765
1763
1765
1576
1598
1626
1610
–
[CuL1]Cl2
[CoL1]Cl2
[NiL1]Cl2
460
462
466
Electronic absorption spectra
The electronic absorption data of the metal complexes were obtained in
DMF. The absorption region and band assignments of the complexes are given in
Table II. The UV–Vis spectra of the Cu(II) complex showed an absorption band
2
2
at 487 nm, which was assigned to the B g → A g transition characteristic of
1
1
square planar Cu(II) complexes. The Co(II) complex exhibited an absorption
band at 510 nm, which was assigned to the A g → B g transition characteristic
of square planar Co(II) complexes. The Ni(II) complex showed absorption bands
at 512 nm and 633 nm, which were assigned to A g → A g and A g → B g
transitions, respectively, characteristics of square planar Ni(II) complexes. These
obtained spectral values are comparable with those of many similar reported me-
1
1
1
1
1
1
1
1
1
2
1
1
33–36
tal complexes.
TABLE II. Electronic spectral data and magnetic moment values of the metal complexes. All
electronic absorption spectra were measured in DMF (≈1.0×10-4 M) and magnetic moment
values were measured at room temperature using Hg[Co(SCN)4] as the calibrant
Compound
[CuL1]Cl2
λ
max / nm
Assignments
μ
eff / μB
1.76
240
380
487
242
378
510
238
370
512
633
INCT
INCT
2B1g → 2A1g
INCT
[CoL1]Cl2
[NiL1]Cl2
3.62
INCT
1A1g → 1B1g
INCT
Diamagnetic
INCT
1A1g → 1A2g
1A1g → 1B1g
1
13
H- and C-NMR spectra
1
13
The H- and C-NMR spectral data of the ligand and the Ni(II) complex
1
were obtained in DMSO-d and the results are given in Table III. In the H-NMR
6
spectrum of ligand, no signal corresponding to primary amine proton was ob-
1
served, which suggests the formation of the ligand. In the H-NMR spectrum of
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BIOLOGICAL PROPERTIES OF METAL COMPLEXES OF AN ORGANIC MOIETY
633
Ni(II) complex, the signal of the signal of (H3C–C=N) protons and (–N–H) pro-
ton shifted compared to the free ligand, suggesting coordination through azo-
31
methine and (–N–H) nitrogen atoms.
1
TABLE III. H- and 13C-NMR spectral data of the ligand and its Ni(II) complex. All spectra
were measured in DMSO-d6 (≈1.0×10-3 M) at room temperature with reference to TMS
(tetramethylsilane)
Compound
L1
1H-NMR (δ / ppm)
1.62 (6H, s, 2 =C–CH3), 3.58
13C-NMR (δ / ppm)
10.13 (C-9, C-11), 46.20 (C-6, C-13),
(4H, t, 2 =N–CH2), 3.84 (4H, 97.13 (C-7, C-12), 116.42 (C-4, C-15),
m, 2 –N–CH2), 7.16–7.35
(10H, m, Ar), 9.68 (2H, s,
br, 2 –NH)
1.11 (6H, s, 2 =C–CH3), 3.46
(4H, t, 2 =N–CH2), 3.83
117.63 (C-(2, 2'), C-(17, 17')), 119.82 (C-
(3, 3'), C-(16, 16')),122.07 (C-1, C-18),
160.40 (C-8, C-10), 165.28 (C-5, C-14)
10.06 (C-9, C-11), 44.60 (C-6, C-13),
96.94 (C-7, C-12), 116.41 (C-4, C-15),
[NiL1]Cl2
(4H, m, 2 –N–CH2), 7.06–7.25 117.61 (C-(2, 2'), C-(17, 17')), 119.81 [C-
(10H, m, Ar), 9.01 (2H, s,
br, 2 –NH)
(3, 3'), C-(16, 16')), 122.11 [C-1, C-18),
157.80 (C-8, C-10), 165.26 (C-5, C-14)
13
In the C NMR spectrum of Ni(II) complex, change in the chemical shift
values compared to the free ligand, show coordination through nitrogen atom of
azomethine and (–NH) group. On the other hand, no change in the chemical shift
value of carbon of carbonyl group moiety indicates that oxygen atom of this
1
13
group did not participate in the coordination. Thus, H and C NMR spectral
data support proposed structure (Fig. 1) of ligand and metal complex and as well
31
coordination behaviour of ligand.
12
13
O
11
H C
16
3
N
NH
C
15
4
17
18
14
10
16`
8
17`
3
5
NH
6
C
N
7
H C
3
2
1
9
O
3`
Fig. 1. Numbering of the C-atoms in the li-
gand (L1).
2`
Molar conductance measurements
The molar conductance (Λ ) values of all the metal complexes were mea-
M
–1
2
–1
sured in DMSO and the obtained values (8.4, 5.2 and 9.8 Ω cm mol for
complexes 1, 2 and 3, respectively) show their 1:2 electrolyte nature.
37
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SINGH and SRIVASTAVA
Magnetic moment measurements
Magnetic moments of metal complexes were measured at room temperature
and the effective magnetic (μ ) values of the complexes are given in Table II.
eff
The magnetic moment of Cu(II) complex is 1.76 μ , which corresponds to a
B
9
38
single unpaired electron of the d -system of square planar Cu(II). The magnetic
moment of the Co(II) complex is 3.62 μ , which corresponds to square planar
B
geometry of Co(II). The Ni(II) complex is diamagnetic.
ESR spectrum of the Cu(II) metal complex
The ESR spectrum of the Cu(II) complex shows four lines due to hyperfine
splitting with nuclear hyperfine 3/2. For Cu(II) complex, the observed g║ value
was 2.31 while the g┴ value was 2.02. The relation g║ > g┴ is typical for Cu(II)
39
having one unpaired electron in a d 2
The g value, calculated
x –y2 orbital.
av
according to the relation = 1/3 (g║ + 2g┴), was found to be 2.12. A <g> value less
40
than 2.3 indicates a square planer geometry around Cu(II).
Cyclic voltammetric study of the Cu(II) complex
The electrochemical properties of Cu(II) complex were studied by cyclic
voltammetry in acetonitrile solution vs. SCE. The cyclic voltammogram of Cu(II)
complex was recorded in the potential range 0 to –1.4 V. The voltammogram
shows one quasi-reversible reduction wave at a negative potential in the range
–0.90 to –1.04 V, which was assigned to Cu(II) to Cu(I) reduction.
In vitro antibacterial and antifungal activity
The in vitro antimicrobial activities of the newly synthesized ligand and me-
tal complexes were determined against the bacteria B. subtilis and E. coli and the
fungi A. niger and A. flavus and the results are summarized in Table IV. The va-
lues indicate that all complexes have higher antimicrobial activity than the free
ligand. Of the tested metal complexes, the Co(II) metal complex shows the high-
est biological activity against all microbes. Such increased activity of the metal
TABLE IV. In vitro antibacterial and antifungal activity data of the ligand and the metal
complexes (inhibition level, %). The agar well diffusion technique was used to evaluate the
antibacterial and antifungal activity of the synthesized compounds
B. subtilis
E. coli
A. niger
A. flavus
Compound
L1
c / μg ml-1
100
40
48
48
53
52
61
46
52
51
58
54
55
73
82
59
64
62
74
71
83
82
89
69
77
65
78
72
85
80
86
70
79
500
100
500
100
500
100
500
[CuL1]Cl2
[CoL1]Cl2
[NiL1]Cl2
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BIOLOGICAL PROPERTIES OF METAL COMPLEXES OF AN ORGANIC MOIETY
635
chelates can be explained based on chelation theory. On chelation, the polarity of
the metal ion will be reduced largely due to overlap of the ligand orbital and the
partial sharing of the positive charge of the metal ion with the donor groups. Fur-
thermore, it increases the delocalization of the π-electrons over the whole chelate
ring, which enhances the penetration of the complexes into the lipid membranes
and the blocking of the metal binding sites in the enzymes of the microorga-
nisms. These complexes also disturb the respiration process of the cell and thus
block the synthesis of proteins, which restricts further growth of microorga-
41
nisms.
CONCLUSIONS
The newly synthesized N coordinating ligand was used to prepare Cu(II),
4
Co(II) and Ni(II) complexes. The ligand and all the metal complexes were cha-
racterized by various physico–chemical methods. The data obtained from these
studies were in good agreement with the proposed structure and composition of
the ligand and the metal complexes. Square planar geometry was confirmed for
the metal complexes by electronic absorption spectroscopy, ESR spectroscopy
[Cu(II)] and the magnetic moment values. Molar conductance values showed the
1:2 electrolyte nature of all the metal complexes. The electrochemical behaviour
of the Cu(II) complex was studied and the results showed a one electron quasi-
-reversible reduction of the Cu(II) to Cu(I). In vitro antibacterial and antifungal
studies showed that metal complexes were more biologically active than the free
ligand. The [CoL ]Cl complex showed the highest antibacterial and antifungal
1
2
activity against all the studied bacterial and fungal strains.
Acknowledgements. The authors are thankful to ACBR, Delhi for providing the spectral
data, IIT-Delhi for the NMR spectra, CDRI, Lucknow for providing the elemental analysis
data and SARC, Meerut for the biological activity results. The authors are also thankful to the
authorities of Meerut College, Meerut for providing the necessary research facilities.
И З В О Д
ФИЗИЧКО–ХЕМИЈСКА И БИОЛОШКА ИСПИТИВАЊА Cu(II), Co(II) И Ni(II)
КОМПЛЕКСА СА N4-ТИПОМ ЛИГАНАДА КОЈИ СУ ДОБИЈЕНИ ИЗ ШИФОВЕ БАЗЕ
ДИАЦЕТИЛА СА ЕТИЛЕНДИАМИНОМ И БЕНЗОЕВЕ КИСЕЛИНЕ
NETRA PAL SINGH и ABHAY NANDA SRIVASTAVA
Department of Chemistry, Meerut College, Meerut-250001, India
Полазећи од новог лиганда N4-типа N,N’-{(1,2-диметилетандиилиден)бис[нитрило(2,1-
-етандиил)]}бис[бензамида] који је изведен из шифове базе диацетила са етилендиамином у
и бензоеве киселине и хидратисане хлоридне соли јона метала синтетизовани су мононукле-
арни комплекси опште формуле [ML1]Cl2 (M = Cu(II), Co(II) или Ni(II); L1 = лиганд). Компле-
кси су окарактерисани помоћу елементалне микроанализе, одређивања њихових тачки топ-
љења, моларне проводљивости и магнетних момената, као и спектроскопских IR, UV–Vis,
1H- и 13C-NMR и ESR мерења. Лиганд и одговарајући комплекси су стабилни на собној тем-
ператури у чврстом стању. На основу аналитичких и спектроскопских резултата закључено
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636
SINGH and SRIVASTAVA
је да су у комплексима лиганд и јон метала координовани у 1:1 молском односу. На бази
електронских спектара и вредности магнетног момента закључено је да испитивани
комплекси имају квадратно-планарну геометрију. Вредности за моларну проводљивост по-
казују да су комплекси електролити типа 1:2. Циклично-волтаметријска испитивања за одго-
варајући Cu(II) комплекс показују једноелектронску квазиреверзибилну редукцију на –0,92
дo –1,10 V. Нађено је да лиганд и одговарајући комплекси показују одређену антибактериј-
ску и антифунгалну активност при in vitro испитивањима на две врсте бактерија, Bacillus
subtilis и Escherichia coli, и гљива Aspirgillus niger и A. flavus.
(Примљено 12. априла, ревидирано 28. августа 2011)
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