Synthetic, spectral, structural and antimicrobial studies of some Schiff bases 3-d metal complexes

Article abstract of DOI:10.1134/S0036023611080195

The complexes of tailor made ligands with life essential metal ions may be an emerging area to answer the problems of multi-drug resistance (MDR). The coordination complexes of VO(II), Co(II), Ni(II) and Cu(II) with the Schiff bases derived from 3-bromobenzaldehyde/3-chlorobenzaldehyde with 2-aminophenol have been synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, ESR, FAB mass, thermal and magnetic susceptibility measurements, FAB mass and thermal data show degradation of complexes. Both the ligands behave as bidentate coordinating through O and N donor. The complexes exhibit coordination number 4, 5 or 6. X-ray powder diffraction data shows that four (2, 3, 6 and 7) complexes are crystallized in tetragonal system. The in vitro biological screening effects of the investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus and Streptococcus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by serial dilution method. A comparative study of the MIC values of the Schiff base and their Co(II) (6) and Cu(II) (8) complexes, indicates that the metal complexes exhibit higher or lower antimicrobial activity than the free ligand (L₂).

Full text of DOI:10.1134/S0036023611080195

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 11, pp. 1757–1764. © Pleiades Publishing, Ltd., 2011.
COORDINATION COMPOUNDS
Synthetic, Spectral, Structural and Antimicrobial Studies
of Some Schiff Bases 3ꢀd Metal Complexes1
A. P. Mishraa, R. K. Mishraa, and Mrituanjay D. Pandeyb
a BioꢀCoordination Laboratories, Department of Chemistry, Dr. H.S. Gour University Sagarꢀ470003 India
b Department of Chemistry, University of Allahabad, Allahabadꢀ211002, India
eꢀmail: apm19@rediffmail.com
Received November 24, 2009
Abstract—The complexes of tailor made ligands with life essential metal ions may be an emerging area to
answer the problems of multiꢀdrug resistance (MDR). The coordination complexes of VO(II), Co(II), Ni(II)
and Cu(II) with the Schiff bases derived from 3ꢀbromobenzaldehyde/3ꢀchlorobenzaldehyde with 2ꢀamiꢀ
nophenol have been synthesized and characterized by elemental analysis, molar conductance, electronic
spectra, FTꢀIR, ESR, FAB mass, thermal and magnetic susceptibility measurements, FAB mass and thermal
data show degradation of complexes. Both the ligands behave as bidentate coordinating through O and N
donor. The complexes exhibit coordination number 4, 5 or 6. Xꢀray powder diffraction data shows that four
(2, 3, 6 and 7) complexes are crystallized in tetragonal system. The in vitro biological screening effects of the
investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus and Streptoꢀ
coccus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by serial dilution
method. A comparative study of the MIC values of the Schiff base and their Co(II) (6) and Cu(II) (8) complexes,
indicates that the metal complexes exhibit higher or lower antimicrobial activity than the free ligand (L2).
DOI: 10.1134/S0036023611080195
1
In the recent years Schiff bases are widely used in and antidiabetic [12, 13]. The structure and functional
the metal coordination chemistry. The N and S atoms
of active sites of metallobiomolecules are very sensitive
to the coordination of metals [1]. The antibacterial,
anticancer, herbicidal and antifungal uses of Schiff
base make it as an extensively useful in various purꢀ
poses [2, 3]. The coordination complexes are useful in
the field of biocationic reactions in the biologically
important species. The biological activity of chelating
ligands having N, S and O as a donor atoms are
attracting attention due to their versatile nature of
metal binding mode. The metal ions may alter or
enhance the activity of biological active compounds
[4–6].
diversity of vanadium containing haloperoxidase and
nitrogenase have made a new platform to further
explore the coordination chemistry of vanadium [14].
The active site of haloperoxidase containing vanaꢀ
dium ions have been discovered by Xꢀray diffraction
technique. The structure of vanadateꢀcontaining
haloperoxidage revel a distorted trigonal pyramidal
geometry around the vanadate ion. The fifth coordinaꢀ
tion site of vanadate ion has been covalently satisfied by
the Nε of a histidine amino acid in the protein [15–17].
The Schiff base properties of nickel complex are
high in demand in bioinorganic chemistry as well as in
the redox enzyme reactions [17]. The cleavage of plasꢀ
mid DNA in the presence of iodosulbenzene or magꢀ
nesium mono peroxyphthalic acid (MPPA) by square
planner nickelꢀsalen [bisꢀ(salicylidene) ethylenediꢀ
amine] was observed by Morrow and Kolasa [18].
Numerous coordination complexes have been synꢀ
thesized and applied on the biological active systems.
The biomolecules containing copper in the field of
bioinorganic chemistry are very important due to their
wide applications in biochemical reactions [7], howꢀ
ever, the concentration of free metal ions of complex
should be lower than 10–15 M (calculated)/ 10–12
M
(observed) inside the cells. The concentration of free
metals higher than 10–9 M in the cytoplasm of cells
may be toxic [8, 9]. The multidentate ligands containꢀ
ing vanadium ions are now a day’s extensively used in
the industry and pharmaceuticals as a catalytic [9–11]
In this paper, we describe the synthesis, structural
and antimicrobial activity of VO(II), Co(II), Ni(II)
and Cu(II) complexes with some related Schiff base
ligands i.e. 3ꢀbromobenzylideneꢀ2ꢀamino phenol
(
BAP
)
and 3ꢀchlorobenzylideneꢀ2ꢀaminophenol
1
The article is published in the original.
(CAP).
1757

1758
MISHRA et al.
Table 1. Analytical and physical data of the metal complexes of BAP (L1) and CAP (L2) Schiff base ligands
Element analysis found
B.M.
μeff
Ω
cm2
%(Cal.)
Compound
Mol wt Colour
Yield
Metal
mol–1
C
H
N
(C13H10NOBr) (L1)
276.16 Dark black
653.3 Black
74.3
68.7
75.8
68.8
69.9
78.9
76.0
56.4
(56.48)
3.5
(3.62)
6.5
(5.06)
–
–
–
[VO(C13H9NOBr)2]
⋅
2H2O (
2H2O (
2H2O (
2H2O (
1
)
47.5
(47.56)
3.3
(3.36)
5.3
10.1
1.72
4.39
8.5
(4.28) (10.25)
[Co(C13H9NOBr)2]
[Ni(C13H9NOBr)2]
[Cu(C13H9NOBr)2]
(C13H10NOCl) (L2)
[VO(C13H9NOCl)2]
⋅
2)
645.2 Black
48.3
(48.35)
3.4
(3.40)
5.3
(4.33)
9.7
(9.12)
15.2
18.3
17.5
–
⋅
⋅
3
) 645.0 Brown
48.3
(48.37)
3.3
(3.41)
5.4
(4.34)
9.0 Dimag
(9.10)
4)
650 Brown
47.9
(48.00)
3.3
(3.38)
5.3
(4.30)
9.7
(9.76)
1.86
230.70 Dark black
564.4 Black
67.2
(67.32)
4.2
(4.31)
7.6
(6.04)
–
–
⋅
2H2O (
5
)
55.2
(55.27)
3.2
(3.38)
5.6
11.6
1.70
5.12
3.10
1.86
13.6
17.9
8.5
(4.96) (11.87)
6.7 10.4
(5.03) (10.58)
6.7 10.4
(5.03) (10.55)
5.5 11.2
(4.99) (11.31)
[Co(C13H9NOCl)2(H2O)2] (
6
)
556.3 Dark brown 76.1
556.1 Dark brown 74.5
56.0
(56.08)
3.8
(3.95)
[Ni(C13H9NOCl)2(H2O)2] (
7
)
56.0
(56.10)
3.8
(3.95)
[Cu(C13H9NOCl)2(H2O)2] (
8
)
561
Black
73.2
55.5
(55.61)
3.8
(3.92)
16.8
Synthesis of Schiff Bases (Ligand)
Br
Cl
H
H
Two Schiff bases (BAP, CAP) have been syntheꢀ
sized by condensing the 3ꢀbromobenzaldehyde
(L1)/3ꢀchlorobenzaldehyde (L2) (0.07/0.06 mol) with
2ꢀamino phenol (0.07/0.06 mol) in equimolar ratio
(99.9%). The reaction mixture was then refluxed on a
water bath for about 5–7 h. The condensation product
was filtered, thoroughly washed with ethanol and
petroleum ether, reꢀcrystallized and dried in vacuo.
The purity of the synthesized compounds was moniꢀ
tored by TLC using silica gel (yield, (L1) = 75% and
C N
C N
OH
OH
(BAP)
(CAP)
EXPERIMENTAL
Apparatus and Reagents
(
L2) = 78.96%).
All the used chemicals and solvents were of AnalaR
grade. Oxovanadium(IV), cobalt(II), nickel(II) and
copper(II), chloride/sulphate were obtained from
Loba Chemie. Elemental analysis and FAB mass specꢀ
tra were recorded at SAIFCDRI, Lucknow. Magnetic
measurements have been done by Gouy’s method.
Electronic spectra (in MeOH), were recorded on Perꢀ
kinꢀElmer Lambaꢀ2BꢀSpectrophotometer. Molar
conductance (10–3 M) was measured by Elicoꢀconꢀ
ductivity bridge at room temperature. FTꢀIR (in
KBr), was recorded at SAIF, IIT, Dehli. Xꢀray powder
Preparation of Metal Complexes
All the complexes have been prepared by mixing
the methanolic solution of MCl2/SO4 H2O
⋅ x
(0.003/0.004 mol) with the methanolic solution of
Schiff bases (BAPꢀ(L1)/CAPꢀ(L2)) (0.007/0.008 mol)
in 1 : 2 molar ratio. The resulting mixture was refluxed
on water bath for 7–8 h. A coloured product appeared
on standing and cooling the above solution. The comꢀ
plexes were filtered, washed with ether and dried
under reduced pressure over anhydrous CaCl2 in a desꢀ
iccator. It was further dried in an electric own at 60–
diffraction (CuKα, 1.54060 Å) was recorded at SAIF
Punjab University, Chandigarh. The ESR spectra were
recorded at SAIF, IIT, Mumbai.
70°C.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 11 2011

SYNTHETIC, SPECTRAL, STRUCTURAL AND ANTIMICROBIAL STUDIES
1759
Table 2. IR spectral data (cm–1) of the BAPꢀ(L1) Schiff base and their metal complexes
OH, Phenolic
(Deformation)
νO–H water
(Rocking)
Comp./Complexes
(C13H10NOBr) (L1)
νC=N νC–O
νC=C
νM–O
νM–N
νV=O
3341(1363)
1581
1576
1572
1575
1577
1240
1266
1252
1270
1260
1479
1475
1474
1471
1473
–
–
–
–
970
–
[VO(L1)2]
[Co(L1)2]
[Ni(L1)2]
[Cu(L1)2]
⋅
2H2O (
2H2O (
1
)
–
–
–
–
3355
3360
3334
3348
525
535
533
530
475
480
482
478
⋅
2)
⋅
2H2O (
3
)
–
⋅
2H2O (
4
)
Antimicrobial Activity
measured. The MIC of the complexes was determined
by the use of serial dilution technique.
The in vitro biological screening effects of the
investigated compounds were tested against Streptoꢀ
coccus fecalis, Staphylococcus aureus and Escherichia
coli by the Well diffusion technique using agar nutrient
as the medium and Getamycin as the control.
The disc diffusion technique has been used in vitro
antifungal assay. The synthesized metal complexes and
their precursor ligand were tested on the fungi Trichoꢀ
derma polysporum, Aspergillus niger and Candida albiꢀ
cans. The potato dextrose agar was used as a cultured
medium. In a general procedure, a well was prepared
on the agar medium and Nystatin as the control inocꢀ
ulated with the fungi. The well was filled with the
required test solution. After diffuses the growth of the
inoculated fungi was affected by test solution. The
inhibition zone developed on the plate was carefully
RESULTS AND DISCUSSION
All the metal chelates are coloured, solid, stable
towards air and moisture. They decompose at high
temperature and more or less soluble in common
organic solvents. The analytical data of the complexes
are consistent with the given molecular formulae. All
the metal chelates have 1 : 2 (metal : ligand) stoichimꢀ
etry. The molar conductance values of the complexes
in methanol (10–3 M) suggest the non electrolytic
nature [19]. The analytical results of complexes are
presented in (Table 1).
FAB Mass Fragmentation
–2H O
2
–Part ligand
[Cu(BAP)2]
⋅
2H2O
[Cu(BAP)2]
623 (614)
[Cu1/n(BAP)2]
348
659 (650)
Ni(II), with some
O and N ligand moiety
95 (93)
The FAB mass spectra of [Cu(BAP)2]
⋅
2H2O (4)
ing and deformation of phenolic –OH. These do not
complex has been studied as one of the representative appear in spectra of complexes. An intense ligand
case. The peaks of appreciable intensity have been band at about 1240 cm–1 (phenolic C–O) shift to
observed at
gesting the fragmentation pattern. The
m/z
values 659, 623, 348, 281 and 95 sugꢀ higher frequency (1260 10 cm–1) in the complexes.
m/z value 659 This suggest deprotonation of the phenolic –OH
corresponds to nearest composition [Cu(BAP)2]
⋅
group after its chelation with metal ion. The appearꢀ
n
2H2O, 623 to [Cu(BAP)2], 348 to [Cu1/ (BAP)2], 281 to ance of broad band around 3348 15 cm–1 in comꢀ
ligand alone and 95 to Cu(II) with chelated O and N plexes may be due to νOH water molecules. The new
ligand moiety.
bands at 530
5
and 478 5 cm–1 in the complexes
have tentatively been assigned to νM–O and νM–N
mode respectively [20]. The characteristic band at
970 cm–1 in VO(II) complex has been assigned to
ν(V=O) vibration (Table 2).
Infrared Spectra
The IR spectrum of the BAP (L1) ligand shows a
strong band at 1581 cm–1 due to (C=N) azomethine
group. This on chelation with metal ions shifts down
The IR spectrum of ligand CAP (L2) show a band
(
1618 cm–1) due to C=N (azomethine) group [20].
by about 10 cm–1, suggesting participation of azomeꢀ This shifts down by about 10 cm–1 in the complexes
thine group in complexation. The ligand spectrum [21]. The negative shift indicates the participation of
shows bands at 3341 and 1363 cm–1 due to the stretchꢀ azomethine group in complexation. The ligand specꢀ
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 11 2011

1760
MISHRA et al.
Table 3. IR spectral data (cm–1) of the CAPꢀ(L2) Schiff base and their metal complexes
OH,
Phenolic
(Deformation)
O–H, water
(Rocking)
Comp./Complexes
(C13H10NOCl) (L2)
C=N
C–O
C=C
M–O
M–N
V=O
3345(1362)
1618
1610
1608
1612
1610
1240
1255
1262
1248
1253
1470
1473
1470
1475
1472
–
–
–
–
978
–
[VO(L2)2]
⋅
2H2O (5)
–
–
–
–
3352
520
469
473
480
475
[Co(L2)2(H2O)2] (
6)
3355 (838) 508
3350 (847) 525
3357 (842) 530
[Ni(L2)2(H2O)2] (
7)
–
[Cu(L2)2(H2O)2] (
8)
–
trum shows band at 3345 and 1362 cm–1 due to the Therefore a squareꢀplanar stereochemistry has been
stretching and deformation of phenolic –OH; which
are absent in spectra of complexes. An intense ligand
band at about 1240 cm–1 (phenolic C–O) shift to
higher frequency (1255 10 cm–1) in the complexes.
Deprotonation of the phenolic OH group on chelation
with metal ions, has been inferred on this basis. The
appearance of broad band around 3352 5 cm–1 in the
spectra of complexes suggest the presence of water molꢀ
ecules. A band of medium intensity at 842 5 cm–1
(OHꢀrocking) suggests, the presence of coordinated
water in Co(II), Ni(II) and Cu(II) complexes. The
new bands at 520 10 and 475 5 cm–1 have been
assigned to νM–O and νM–N modes respectively. The
characteristic band at 978 cm–1 in VO(II) complex has
been assigned to ν(V=O) vibration (Table 3).
suggested [24–28].
The electronic spectra of the [VO(L2)2] ⋅ 2H2O (5)
complex exhibit one band at 16393 cm–1 which is
assignable to 2B2ꢀ2B1 (ν2
) transition. The geometry of is
five coordinated monomolecular complex can be
described in terms of a trigonal bipyramid or tetragoꢀ
nal pyramid. The value of the magnetic moment is
1.70 B.M. This indicates the presence of one unpaired
electron [22, 23].
The electronic spectra of the [Co(L2)2(H2O)2]
(
6
)
complex shows two distinct bands at 15527 and
20618 cm–1. These bands are assigned to 4T1g(F)ꢀ
4A2g(F) (ν2 and 4T1g(F)ꢀ4T1g(P) (ν3
transitions,
respectively. The various ligand field parameters
)
)
10Dq, B, β, β%, ν2/ν1, λ and LFSE have been calcuꢀ
lated and values are as: 8626, 1029 cm–1, 0.91, 8.12,
Electronic Spectra
2.2, (–) 545 cm–1, 82.44 kJ mol–1 respectively. The ν1
The electronic spectrum of the [VO(L1)2] ⋅ 2H2O (1)
transition is expected to appear at larger
λ (beyond
complex in methanol exhibit bands at 15873, 19607
10000 cm–1) hence it could not be observed. The magꢀ
netic moment value of the complex is 5.12 B.M. The
observed transitions are consistent with an octahedral
geometry [7, 28].
and 21739 cm–1 which are assignable to transitions
2B2ꢀ2E (ν1), B2ꢀ2B1 (ν2
)
and 2B2ꢀ2A1 (ν3
)
respectively.
2
The geometry of this complex has been proposed to be
five coordinated monomolecular distorted towards a
tetragonal pyramid. The value of the magnetic
moment is 1.73 B.M; which indicates presence of one
unpaired electron [22, 23].
The electronic spectrum of the [Ni(L2)2(H2O)2] (
complex show only two bands at 19607 and 23255 cm–1
These transitions have tentatively been assigned to
3A2gꢀ3T1g(F) (ν2 and 3A2gꢀ3T1g(P) (ν3
which are charꢀ
7)
.
The electronic absorption spectra of the [Co(L1)2]
2H2O ( complex show the bands at 14705 and
20408 cm–1. These transition have tentatively been
assigned to 4A2ꢀ4T1(F) (ν1 and 4A2ꢀ4T1(P) (ν3
transiꢀ
⋅
)
)
2
)
acteristic for hexa coordinated geometry for Ni(II)
complex. The values of various ligand field parameters
)
)
10Dq, B, β, ν2/ν1, λ
and LFSE are as 10892, 679 cm–1,
tions, respectively. The magnetic moment value of this
complex is 4.39 B.M. Thus the tetrahedral geometry
has been suggested for this Co(II) complex.
0.62, 1.8, (–) 259 cm–1, 156 kJ mol–1 respectively. Since
the value of the magnetic moment is 3.10 B.M; hence
highꢀspin octahedral geometry for this complex has
been proposed [24, 29–31].
The electronic spectrum of [Ni(L1)2]
complex shows two bands at 12608 and 21749 cm–1
These are assignable to 1A1gꢀ1Eg (ν1 and 1A1gꢀ1B2g
ν2 , transitions, respectively. This complex is diamagꢀ
netic in nature. Therefore a squareꢀplanar geometry
has been suggested [24–28].
⋅ 2H2O (3)
.
The electronic spectrum of the [Cu(L2)2(H2O)2] (8)
)
complex exhibit a broad band at around 14388 cm–1
(
)
which is assignable to 2Egꢀ2T2g transition. The various
ligand field parameters viz; 10Dq, λ, and LFSE have been
calculated; their values are as 14388 cm–1, (–) 540 cm–1,
103.13 kJ mol–1 respectively. The magnetic moment
value of the complex is 1.86 B.M. This suggests the
The electronic spectrum of the [Cu(L1)2] ⋅ 2H2O (4)
complex exhibit bands at 19607 and 22727 cm–1 which
have been assigned to 2B1gꢀ2B2g and 2B1gꢀ2Eg transitions.
The magnetic moment of the complex is 1.86 B.M. octahedral geometry [22–24, 29–31].
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 11 2011

SYNTHETIC, SPECTRAL, STRUCTURAL AND ANTIMICROBIAL STUDIES
1761
Table 4. ESR data of complexes
Complex
2H2O (
2H2O (
g||
g⊥
gav
Δ
g
G
[Cu (L1)2]
[VO (L2)2]
⋅
4
)
2.213946
1.960415
2.120196
1.984395
2.151446
1.976401
0.09375
0.02398
1.894133
–
⋅
5)
Table 5. XRD data of [Co(L1)2] ⋅ 2H2Oꢀ(2) complex
Sin2
θ
Peak
Relative intensity
I0 100
DꢀSpacing (Å)
No.
I
/ ×
Obs
Cal
hkl
1
2
3
4
5
6
7
8
9
12.940
5.965
3.961
3.663
3.435
3.055
3.112
2.980
2.897
19.07
70.45
26.40
0.0035
0.0166
0.0378
0.0442
0.0504
0.0560
0.0613
0.0668
0.0733
0.0035
0.0163
0.0378
0.0442
0.0507
0.0560
0.0613
0.0667
0.0729
200
331
610
650
730
800
743
752
900
100.00
51.61
93.38
38.45
38.81
18.56
Electron Spin Resonance Spectra
The ESR Spectra of Cu(II) ( ) and VO(II) (
complex were recorded at room temperature. The
spectrum of the [Cu(BAP)2] 2H2O ( complex show
two peaks, one of low intensity in low field region and
the other of high intensity in high field region from
which g|| and g⊥ have been calculated. The g|| value
(<2.3) indicates covalent character of the metal ligand
bond (Table 4). The G value less then 4.0 suggest covaꢀ
onal system. These have 9 to 10 reflections of
between 6.83 to 31.42 and 8.35 to 30.1 with maxima at
2θ
4
5)
2θ= 24.29 and 24.55, d = 3.66 and 3.62 Å are observed.
Sin2θ and hkl values for different lattice planes have
⋅
4)
been calculated. Crystal data for Co(II) complex a =
26.0406276 Å, c = 34.448512 Å,
D(obs) =1.100547 g cm–3,
D(cal) =1.129650 g cm–3. Observed and calculated valꢀ
ues of density and sin2θ show good agreement. The
other parameters such as cell volume and particle size
were calculated, the values are as 23360.01 Å3 and
lent nature. The value g|| > g⊥ is well consistent “With a
10.77 nm respectively. The number of molecules (
per unit cell are 10 molecules. Crystal data for Ni(II)
n)
primarily dx2ꢀy2 ground state having elongated tetragꢀ
onal or square planar structure [32].
complex;
a = 23.659335 Å, c = 34.448512 Å, D(obs) =
The
', 51V, I = 7/2) complex has been recorded. The calꢀ
culated values of g|| g⊥ gav and for VO(II) ( ) comꢀ
plex has been given in (Table 4). Here av = 1/3 [2g⊥
g|| . The values are typical of the spectra displayed by
xꢀband ESR spectrum of oxovanadium(IV)
1.388390 g cm–3, D(cal) = 1.422514 g cm–3. Observed and
calculated value of density and sin2θ show good agreeꢀ
ment. The other parameters such as cell volume and
particle size were calculated; which are as 19283.02 Å3
and 10.68 nm respectively. The number of molecules
(
d
,
,
Δg
5
g
+
]
square pyramidal VO(II) complex with one unpaired
electron in an orbital of mostly dxy character. The gav
values determined from the spectrum is nearer to spin
only value. A slight variation may be accounted to
spinꢀorbit coupling. In square pyramidal complex
(
n) per unit cell are 25 molecules.
The Xꢀray powder diffractogram of (CAP) (L2)
cobalt(II) ( ) (Table 7) and nickel(II) ( ) (Table 8)
complexes were recorded using CuKα source in the
range –75 . The complexes crystallized in tetragꢀ
onal system. Both the complexes gives 12 reflections of
between 8.5 to 37.2 and 6.89 to 32.76 with maxima
6
7
with C4V symmetry, the V=O band is along
other four donor atoms (O2N2) are along the
z
and the
5°
° 2θ
x, y axes.
Here an anisotropic ESR spectrum is expected exhibꢀ
iting two g values (gz g|| g⊥ gx gy) [33–36, 38].
2
θ
=
<
=
=
2θ = 8.5° and 27.38°, d = 10.29 and 3.25 Å are
observed. Sin2θ and hkl values for different lattice
planes have been calculated. Crystal data for Co(II)
Xꢀray
The Xꢀray powder diffractogram of (BAP) (L1)
cobalt(II) ( ) (Table 5) and nickel(II) ( ) (Table 6)
complex
a = 23.439243 Å, c = 34.448512 Å, D(obs) =
1.07365 g cm–3, D(cal) = 1.09662 g cm–3. Observed and
calculated values of density and sin2θ show good
2
3
complexes were recorded using CuKα source in the agreement. The other parameters such as cell volume
range –75 . The complexes crystallized in tetragꢀ and particle size were also calculated these are as
5°
°2θ
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 11 2011

1762
MISHRA et al.
Table 6. XRD data of [Ni(L1)2]
⋅
2H2O (
3) complex
Sin2
θ
Peak
Relative intensity
DꢀSpacing (Å)
No.
I
/I0
×
100
Obs
Cal
hkl
1
2
10.581
7.558
5.882
5.196
4.938
4.064
3.767
3.623
3.082
2.967
96
80
86
80
89
90
98
0.0053
0.0105
0.0171
0.0219
0.0243
0.0359
0.0418
0.0452
0.0624
0.0675
0.0053
0.0105
0.0170
0.0217
0.0236
0.0359
0.0417
0.0454
0.0620
0.0678
210
222
400
421
333
442
444
542
731
800
3
4
5
6
7
8
100
82
9
10
88
Table 7. XRD data of [Co(L2)2(H2O)2] (
6) complex
Sin2
θ
Relative intensity
I0 100
Peak No.
DꢀSpacing (Å)
I
/ ×
Obs
Cal
hkl
1
2
10.394
8.262
5.882
5.622
3.645
3.504
3.405
3.235
2.967
2.82
100
88
94
81
97
81
82
83
81
78
64
59
0.0054
0.0086
0.0171
0.0187
0.0447
0.0484
0.0511
0.0566
0.0674
0.0746
0.0909
0.1017
0.0054
0.0086
0.0172
0.0186
0.0447
0.0486
0.0506
0.0566
0.0671
0.0747
0.0909
0.1017
210
220
400
411
541
630
641
733
743
843
933
3
4
5
6
7
8
9
10
11
12
2.555
2.415
18925.87 Å3 and 25.09 nm respectively. The number of 100
molecules (n) per unit cell are 22 molecules. Crystal
data for Ni(II) complex = 25.676643, = 34.448512
D(obs) = 1.035018 g cm–3, D(cal) = 1.023835 g cm–3
Observed and calculated, the values of density and
sin2θ show good agreement. The other parameters
such as cell volume and particle size were calculated
values are as 22711.58 Å3 and 10.78 nm respectively.
°
C
corresponds to the loss of lattice water moleꢀ
cules from complexes. The remaining weight meaꢀ
sured after heating at 500 , corresponded with the
loss of ligand moiety. The weight of pyrolysis product
after heating at 750 corresponds to metalꢀoxide to
be an ultimate product.
a
c
Å,
.
°C
°C
The CAP (L2), ( ), (
been studied at four temperature (100, 300, 500,
750 ). The resulting weights were measured. The
remaining weight at 100 corresponds to loss of latꢀ
tice water molecules from complexes [37–39]. The
weight measured after heating at 300 indicates loss
of coordinated water molecules from complexes. On
heating at 500 , the weight corresponds to loss of
parts of ligand moiety. The weight of pyrolysis product,
after heating at 750 corresponds to metal oxide, to
were measured [37–39]. The remaining weight at be an ultimate product.
5
6), (7) and (8) complexes have
The number of molecules (n) per unit cell are 23 molꢀ
ecules.
°
C
°C
Thermal Decomposition
°C
The thermal degradation behaviour of the BAP
°C
(
L1), (
(as heated in muffle furnace for 35–40 min) at three
temperatures (100, 500, 750 ), the resulting weights
1), (2), (3) and (4) complexes have been studied
°C
°C
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 11 2011

SYNTHETIC, SPECTRAL, STRUCTURAL AND ANTIMICROBIAL STUDIES
1763
Table 8. XRD data of [Ni(L2)2 (H2O)2] (7) complex
Sin2
θ
Peak
No.
Relative intensity
I0 100
DꢀSpacing (Å)
I/ ×
Obs
Cal
hkl
1
2
12.817
6.869
6.303
5.952
4.592
3.669
3.452
3.256
3.120
2.976
2.849
2.733
23.69
20.93
7.28
0.0036
0.0125
0.0149
0.0167
0.0281
0.0441
0.0498
0.0560
0.0610
0.0670
0.0731
0.0795
0.0036
0.0122
0.0144
0.0167
0.0281
0.0441
0.0497
0.0554
0.0612
0.0671
0.0729
0.0791
200
321
400
331
522
700
722
651
820
751
900
755
3
4
99.74
16.53
95.31
55.08
5
6
7
8
100.00
57.84
43.28
35.80
15.05
9
10
11
12
Table 9. Antimicrobial data (at MIC) of the investigated compounds
E. coli S. aureus S. fecalis
25* 50* 100* 25* 50* 100* 25* 50* 100* 25* 50* 100* 25* 50* 100* 25* 50* 100*
10 14 16 11 13 17 12 15 24 15 17 12 14 17
A. niger
T. polysporum C. albicans
Compounds
(CAP)ꢀ(L2)
–
–
–
–
[Co(CAP)2(H2O)2] (
[Co(CAP)2(H2O)2] (
Gentamycin
6
)
)
21 23 29 17 18 24 11 13 17 10 16 21 12 17 19 13 16 19
23 27 31 16 19 23 10 12 18 11 15 20 14 16 20 14 19 21
18 20 19 19 22 20 18 21 23
8
Nystatin
20 23 24 23 23 24 20 21 20
Standard DMSO
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Note: Diameter of inhibition zone (mm).
* Concentration in ppm. (–) Inactive/ Not measurable.
Antimicrobial activity. The in vitro antiꢀmicrobial
These observations show that the majority of the
activity of the investigated compounds was, tested complexes are more active than their respective Schiff
against the microorganisms E. coli, S. aureus, S. fecaꢀ base ligands. In some cases Schiff bases are more
lis, A. niger, T. polysporum, C. albicans by the serial active than their metal complexes against bacteria.
dilution method. The minimum inhibitory concentraꢀ The chelation either enhances or reduces the antimiꢀ
tion (MIC) values of the compounds against the crobial activity; sometimes it remains neutral. Thus,
growth of microꢀorganisms are summarized in Table 9. A metal chelation may increase or decrease/suppress the
comparative study of the ligand and its cobalt(II) and therapeutic value of organic compounds (drug). It may
copper(II) complexes (MIC values) indicates that keep the property intact by further stabilizing the drug
both the complexes (6) and (8) exhibit either higher or and/or reducing the biodegradability/metabolic decay
lower antimicrobial activity than the free ligand (A) [7, of the organic ligands through chelation.
40]. Thus showing the effect of chelation.
Antibacterial. The complexes (
better antibacterial activity than their SBꢀligand (L2
against all the three bacteria. Complex ( ) shows betꢀ
ter activity than complex ( ).
Antifungal. Complexes (
activity in comparison to SBꢀligand (L2), against
A. niger. But complexes ( ) and ( ) exhibit better
activity than SBꢀligand (L2), against T. polysporum and
C. albicans fungi.
6) and (8) exhibit
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