Synthesis, spectroscopic characterization, and biological activity of N-isonicotinoyl-N′-thiobenzoylhydrazine complexes of Co(II), Ni(II), Cu(II), and Zn(II)

Article abstract of DOI:10.1081/SIM-120003203

A new ligand, N-isonicotinoyl-N′-thiobenzoylhydrazine (HINTB), has been prepared by the reaction of isonicotinic acid hydrazide and carboxymethyl dithiobenzoate. The addition complexes [M(HINTB)₂Cl₂] [M = Co(II), Ni(II), Zn(II)], [Cu(HINTB)Cl₂], M(HINTB)2(CH₃COO)₂ [M = Co(II), Ni(II)] and deprotonated complexes [Cu(INTB)(CH₃COO)] and [Zn(INTB)₂] have been prepared and characterized by elemental analyses, magnetic susceptibility, electronic, NMR and IR spectral data. The room temperature ESR spectra of [Cu(HINTB)Cl₂] and [Cu(INTB)(CH₃COO)] are characteristic of monomeric and dimeric species, respectively. The ligand and the complexes have been screened for activity against a number of fungi and bacteria.

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SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION,
AND BIOLOGICAL ACTIVITY OF N-ISONICOTINOYL- N′-
THIOBENZOYLHYDRAZINE COMPLEXES OF Co(II), Ni(II),
Cu(II), AND Zn(II)
Nand K. Singh a & Dileep K. Singh a
a Department of Chemistry, Banaras Hindu University, 221 005, India
Published online: 15 Feb 2007.
To cite this article: Nand K. Singh & Dileep K. Singh (2002) SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION, AND BIOLOGICAL
ACTIVITY OF N-ISONICOTINOYL- N′-THIOBENZOYLHYDRAZINE COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II), Synthesis and
Reactivity in Inorganic and Metal-Organic Chemistry, 32:2, 203-218, DOI: 10.1081/SIM-120003203
To link to this article: http://dx.doi.org/10.1081/SIM-120003203
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SYNTH. REACT. INORG. MET.-ORG. CHEM., 32(2), 203–218 (2002)
SYNTHESIS, SPECTROSCOPIC
CHARACTERIZATION, AND BIOLOGICAL
ACTIVITY OF N-ISONICOTINOYL-
N0-THIOBENZOYLHYDRAZINE
COMPLEXES OF Co(II), Ni(II),
Cu(II), AND Zn(II)
Nand K. Singh* and Dileep K. Singh
Department of Chemistry, Banaras Hindu University,
221 005 India
ABSTRACT
A
new ligand, N-isonicotinoyl-N0-thiobenzoylhydrazine
(HINTB), has been prepared by the reaction of isonicotinic
acid hydrazide and carboxymethyl dithiobenzoate. The ad-
dition complexes [M(HINTB)2Cl2] [M ¼ Co(II), Ni(II),
Zn(II)],
[M ¼ Co(II),
[Cu(HINTB)Cl2],
Ni(II)] and
M(HINTB)2(CH3COO)2
deprotonated
complexes
[Cu(INTB)(CH3COO)] and [Zn(INTB)2] have been prepared
and characterized by elemental analyses, magnetic suscept-
ibility, electronic, NMR and IR spectral data. The room
temperature ESR spectra of [Cu(HINTB)Cl2] and
*Correspondingauthor. E-mail: nksingh@banaras.ernet.in
203
Copyright # 2002 by Marcel Dekker, Inc.
www.dekker.com

204
SINGH AND SINGH
[Cu(INTB)(CH3COO)] are characteristic of monomeric and
dimeric species, respectively. The ligand and the complexes
have been screened for activity against a number of fungi and
bacteria.
INTRODUCTION
The literature shows that some work has been done on the tran-
sition metal complexes of pyridine carboxylic acid hydrazides and their
hydrazones1711. The transition metal complexes of a few thiohydrazides
and their N-substituted derivatives have also been reported12717. Pyr-
idine carboxylic acid hydrazides, particularly isonicotinic acid hydra-
zide, show biological activity. Similarly, thiohydrazides which are
structurally similar to thiosemicarbazides also exhibit a wide variety
of biological activities viz., antifungal, antibacterial and antitumor.
In view of this, a new ligand, N-isonicotinoyl-N0-thiobenzoylhydrazine
(HINTB), containingthe pyridine carboxylic acid and thiohydrazide
moities has been synthesized (Fig. 1) and representative 3D metal
complexes have been prepared, characterized by various physico-
chemical techniques and their biological activity against several fungi
and bacteria tested.
EXPERIMENTAL
Starting Materials
All chemicals used were of analytical reagent or equivalent grade.
Isonicotinic acid hydrazide (INH) was purchased from Sigma Chemical Co.,
Figure 1. Structure of the ligand (HINTB).

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
205
U.S.A. Ammonium polysulfide18 and carboxymethyl dithiobenzoate19 were
prepared by literature methods.
N-Isonicotinoyl-N0-thiobenzoylhydrazine (HINTB)
N-Isonicotinoyl-N0-thiobenzoylhydrazine (HINTB) was prepared by
reactingsolutions of isonicotinic acid hydrazide (3.5 g, 25 mmol) and car-
boxymethyl dithiobenzoate (5.3 g, 25 mmol) each dissolved separately in
50 mL of 0.5 N NaOH, and allowingthe mixture to stand at room tem-
perature for 2 h. The product precipitated by addingdropwise dilute acetic
acid to this reaction mixture. It was filtered, washed with water, dried and
recrystallized from hot ethanol, m.p. 186 ꢀC. Yield, 4.5 g(70%).
Preparation of the Complexes
[M(HINTB)2Cl2] and [Cu(HINTB)Cl2]
[M(HINTB)2Cl2] (M ¼ Co(II), Ni(II) and Zn(II)) and [Cu(HINTB)Cl2]
were prepared by refluxing20 mL of methanolic solutions each of the
respective metal(II) chlorides (1 mmol) and HINTB (0.514 g, 2 mmol) in the
presence of HCl (576 drops) for 15 minutes on a water bath. The precipitated
complexes were filtered, washed with methanol and dried in vacuo.
M(HINTB)2(CH3COO)2, [Cu(INTB)(CH3COO)], and [Zn(INTB)2]
M(HINTB)2(CH3COO)2 (M ¼ Co(II) and Ni(II)), [Cu(INTB)
(CH3COO)] and [Zn(INTB)2] were prepared by adding20 mL of a metha-
nolic solution of HINTB (0.257 g, 1 mmol) to an aqueous-methanolic (50%
v/v) solution of the respective metal(II) acetate (0.5 mmol) in the presence of
sodium acetate (0.5 g) and digesting the reaction mixture for about 30
minutes in a boilingwater bath. The precipitated complexes were filtered,
washed with methanol-water mixture (50 v=v), water and finally with
ethanol and dried in vacuo.
Analyses and Physical Measurements
The complexes were analysed for their metal content followingstan-
dard procedures20 after decomposition with aqua regia followed by H2SO4.
Chloride and sulfur were determined as silver chloride and barium sulphate,
respectively. Carbon, hydrogen and nitrogen were determined on a Carlo
Erba microanalyzer. Magnetic susceptibility measurements were made at

206
SINGH AND SINGH
room temperature on a Cahn-Faraday balance using[Co(NCS) 4Hg] as
calibrant. Electronic spectra were recorded on a Cary 2390 UV-Vis spec-
trophotometer as Nujol mulls21. IR spectra were recorded in the region
40007400 cmÀ1 as a KBr discs on a Jasco FT-IR spectrophotometer. 1H and
13C NMR spectra were obtained in DMSO-d6 on a Jeol FX-90Q spectro-
meter usingTMS as internal reference. ESR spectra of the complexes were
recorded on an X-band model EPR-112 spectrometer usingDPPH
(g ¼ 2.0036) as a hgi marker.
Fungicidal Screening
The antifungal activity was evaluated by the spore germination tech-
nique22. A stock solution prepared by dissolving2 mg/mL of each com-
pound in DMSO was serially diluted with sterilized distilled water up to four
dilutions, giving concentrations of 1000, 750, 500 and 250 mg=mL. Spores of
the test fungi Stemphylium sp., Fusarium udum, Alternaria tennuissima and
Helminthosporium rostratum grown on potato dextrose agar medium were
incorporated into culture tubes containingthe various concentrations of the
compounds separately and thoroughly agitated in order to break up the
spore clumps. A drop of the suspensions was transferred on clear slides
which were then kept in Petri dishes containingmoist cotton. A parallel set
of control samples was also maintained without the compound usingwater
and a solvent-water (50% v=v) mixture. The Petri dishes were incubated at
25 Æ 1 ꢀC for 24 h. The counts of germinated spores were made from three
random microscopic fields of each slide in order to calculate the inhibition
percentage using the following formula:
Germination in treatment
Inhibition percentage ¼ 1 À
 100:
Germination in control
Bactericidal Screening
The antibacterial activity of the ligand and its complexes was eval-
uated by the Agar plate diffusion technique23. A stock solution of
1000 mg=mL was made by dissolving1 mgof each compound in 1 mL
DMSO. Filter paper (Whatmann no. 4) discs (6 mm diameter) were soaked
in solutions of the test compounds and placed, after dryingoff the solvent,
on Muller Hinton agar plates containing lawn cultures of different bacteria.

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
207
The plates were incubated at an optimum growth temperature of 37 ꢀC. The
zones of inhibition around the discs were measured after 24 h. The test
bacteria included (a) Staphylococcus aureus, (b) Staphylococcus epidermidis,
(c) Enterococcus faecalis, (d) Escherichia coli, (e) Pseudomonas aeruginosa,
(f) Proteus vulgaris, (g )Shigella flexneri, (h) Vibrio cholerae and (i) Sta-
phylococcus aureus (ATCC 25923). All experiments were performed in
duplicate and gentamicin was used as a standard drug.
RESULTS AND DISCUSSION
All of the complexes are insoluble in water, ethanol and methanol but
are soluble in polar organic solvents such as DMF and DMSO. Zn(II) and
Cu(II) give deprotonated ligand complexes, [Zn(INTB)2] and Cu(INTB)
(CH3COO)], respectively, formed by loss of one proton from each ligand,
other metal salts yield non-deprotonated complexes (Table I). The com-
plexes formed by Co(II), Ni(II) and Cu(II) acetates melt in the temperature
range 1907260 ꢀC but [Zn(INTB)2] and the metal(II) chloride complexes do
not melt up to 300 ꢀC. The formation of the ligand and the complexes may
be represented by the followingequations:
NaOH
C6H5CSSCH2COOH þ ðC5H4NÞCONHNH2 À!
AcOH
C6H5CSNHNHCOðC5H4NÞðHINTBÞ þ HSCH2COOH
ð1Þ
ð2Þ
½MðH2OÞ ꢁCl2 þ 2HINTB MÀe!OH ½MðHINTBÞ Cl2ꢁ þ 6H2O
6
2
M ¼ CoðIIÞ; NiðIIÞ
MeOH
CuCl2 ꢂ2H2O þ HINTB À! ½CuðHINTBÞCl2ꢁ þ 2H2O
ð3Þ
ð4Þ
MeOH
ZnCl2 þ 2HINTB À! ½ZnðHINTBÞ2Cl2ꢁ
MðCH3COOÞ ꢂ4H2O þ 2HINTB MÀe!OH
2
AcONa
MðHINTBÞ2ðCH3COOÞ2 þ 4H2O
ð5Þ

208
SINGH AND SINGH

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
209
M ¼ CoðIIÞ; NiðIIÞ
CuðCH3COOÞ ꢂH2O þ HINTB MÀe!OH
2
AcONa
½CuðINTBÞðCH3COOHÞꢁ þ CH3COOH þ H2O
ð6Þ
ð7Þ
ZnðCH3COOÞ ꢂ4H2O þ 2HINTB MÀe!OH
2
AcONa
½ZnðINTBÞ2ꢁ þ 2CH3COOH þ 4H2O
Magnetic Moments and Electronic Spectra
The magnetic moment and electronic spectral data of the complexes
are given in Tables I and II, respectively. The magnetic moment of 4.75 B.M.
for [Co(HINTB)2](CH3COO)2 lies in the range reported for tetrahedral
cobalt(II) complexes. It shows two bands at 15,820 and 16,780 cmÀ1 which
4
4
may be assigned to the split components of the A2 ? T1(P) transition,
usually observed for tetrahedral cobalt(II) complexes. [Co(HINTB)2Cl2]
shows a magnetic moment of 5.2 B.M. and exhibits two bands at 16,890
4
4
4
and 19,085 cmÀ1 which may be assigned to the T1g ? A2g and T1g(P)
transitions, respectively, in an octahedral geometry of cobalt(II). The
magnetic moments of [Ni(HINTB)2X2] suggest their octahedral structure
Table II. Electronic Spectral Data for the Complexes and Their Assignments
Compound
Band Maxima (cmÀ1
)
Assignments
HINTB 26455
[Co(HINTB)2](CH3COO)2 15820, 16780, 25775, 33115
L
4A2?4T1(P), C.T., L
4T1g?4A2g,4T1g(P), L
3A2g?3T1g(F),3T1g(P), L
3A2g?3T1g(F),3T1g(P), L
Envelope of
[Co(HINTB)2Cl2]
16890, 19085, 33555
14285, 24040, 33335
14045, 23925, 33110
15770, 20575, 35210
[Ni(HINTB)2(CH3COO)2]
[Ni(HINTB)2Cl2]
[Cu(INTB)(CH3COO)]
2B1g?2A1g,2B2g,2EgC.T., L
Envelope of
2B1g?2A1g,2B2g,2EgC.T., L
C.T.
C.T.
[Cu(HINTB)Cl2]
16890, 28410, 34245
[Zn(INTB)2]
[Zn(HINTB)2Cl2]
32680
28410
C.T. ¼ Charge transfer; L ¼ Intraligand.

210
SINGH AND SINGH
which is supported by the occurrence of two bands in the regions
3
3
14,045714,285 and 23,925724,040 cmÀ1 for the transitions A2g ? T1g(F)
and T1g(P), respectively. The magnetic moment of [Cu(HINTB)Cl2] is
3
normal and corresponds to the presence of one unpaired electron. A lower
value of the magnetic moment (1.43 B.M.) for [Cu(INTB)(CH3COO)] sug-
gests antiferromagnetic interaction between two Cu(II). The presence of a
broad band at 15,770716,890 cmÀ1 suggests a square-planar geometry for
the copper(II) complexes.
The high-energy band in the ligand at 26,455 cmÀ1 and in the com-
plexes at 28,000735,000 cmÀ1 may be assigned to intra-ligand or charge-
transfer transitions.
NMR Spectra
The 1H NMR spectrum of HINTB shows a signal at d 11.8 ppm due to
two NH protons which disappears on D2O exchange. A multiplet is
observed between d 7.8778.34 ppm due to the benzene ringprotons. In
addition, two doublets at d 7.76 and 9.10 ppm are observed for the pyridine
ringprotons. The assignments for the pyridine ringprotons have been made
by comparingthe 1H NMR spectrum of HINTB with that of isonicotinic
1
acid hydrazide, INH (Table III). The H NMR spectra of [Zn(INTB)2] and
[Zn(HINTB)2Cl2] show the pyridine ringprotons almost at the same posi-
tions as those of HINTB, indicatingnon-involvement of ringnitrogen in
bonding. The spectra of [Zn(INTB)2] and [Zn(HINTB)2Cl2] show a signal at
d 11.85 and 11.79 ppm, respectively, for the NH proton(s).
The 13C NMR spectrum of HINTB (Table IV) shows 11 signals, of
which two at d 197.69 and 160.50 ppm are due to the C¼S and C¼O car-
bons, respectively. By comparingthe spectra of INH and HINTB, the
chemical shifts for the pyridine and benzene ringcarbons are: ( d, ppm) C(4),
143.40; C(2), C(6), 150.50; C(3), C(5), 121.47; C0(1), C0(4), 131.87, 131.33;
C0(2), C0(6), 127.58, 127.91; C0(3), C0(5), 128.24, 129.65.
The low solubility of [Zn(INTB)2] and [Zn(HINTB)2Cl2] precluded the
recordingof their 13C NMR spectra.
ESR Spectra
The solid state ESR spectrum of [Cu(INTB)(CH3COO)] at room
temperature shows a strongabsorption at 3275 G ( DMs ¼ 1 transition) with
a gav value of 2.08 and a weak absorption at 1675 G (DMs ¼ 2 transitions)
with g ¼ 4.06, indicatingthe dimeric nature of the complex. The room

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
211
Table III. 1H NMR Spectral Data (d, ppm)
Compound
INH
NH
Phenyl RingPyridine Ring
10.40 (s, 1H)
7
9.00 (d, 2H, J ¼ 6 Hz);
7.90 (d, 2H, J ¼ 6 Hz)
9.10 (d, 2H, J ¼ 6 Hz);
7.76 (d, 2H, J ¼ 6 Hz)
9.00 (d, 2H, J ¼ 6 Hz);
7.76 (d, 2H, J ¼ 6 Hz)
9.03 (d, 2H, J ¼ 6 Hz);
7.79 (d, 2H, J ¼ 6 Hz)
HINTB
11.80 (s, 2H)
11.85 (s, 1H)
11.79 (s, 2H)
7.87À8.34 (m, 5H)
7.90À8.16 (m, 5H)
7.93À8.40 (m, 5H)
[Zn(INTB)2]
[Zn(HINTB)2Cl2]
Table IV. 13C NMR Spectral Data (d, ppm)
Compound >C¼O >C¼S C4 C3,5
C2,6 C01, C04 C02, C06 C03, C05
INH
HINTB
163.99
160.50 197.69 143.40 121.47 150.50 131.87 127.58 128.24
7
140.26 121.03 150.18
7
7
7
131.33 127.91 129.65
temperature spectrum of [Cu(HINTB)Cl2] shows only a strongabsorption
at 3225 G (gav ¼ 2.115).
IR Spectra
The IR spectrum of HINTB in KBr shows two bands at 3240 and
3135 cmÀ1 due to n(NH). The bands at 1700, 830 and 970 cmÀ1 are assigned
to n(C¼O), n(C¼S) and n(N-N), respectively. The spectra of M(HINTB)2X2
(X ¼ CH3COO and Cl) and [Cu(HINTB)Cl2] show a strongband in the
161071676 cmÀ1 region due to n(C¼O). A shift to lower frequency of
24790 cmÀ1 indicates the involvement of the carbonyl oxygen in bonding.
Bondingthrough the sulfur of C ¼S is not indicated because n(C¼S) remains
practically unchanged in the complexes (Table V). However, the n(N-N)
frequency shows a shift to higher frequency of 20750 cmÀ1 indicatingthat
one hydrazinic nitrogen is coordinated to the metal ion. The pyridine ring
vibrations in all the complexes remain unchanged as compared to the ligand
(1000, 635 cmÀ1) indicating that the ring nitrogen is not involved in bonding.
Thus, HINTB behaves as a neutral bidentate ligand in M(HINTB)2X2 and
[Cu(HINTB)Cl2], bonding through the carbonyl oxygen and one hydrazinic
nitrogen. The spectra of [Cu(INTB)(CH3COO)] and [Zn(INTB)2] show the

212
SINGH AND SINGH

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
213
Table VI. Inhibition of Spore Germination by HINTB and Its Complexes
Percentage inhibition of spore germination in
different fungi
Conc. Stermphylium Fusarium Alternaria
(ppm)
Compound
HINTB
sp.
udum tenuissima H. rostratum
250
500
750
1000
250
500
750
1000
250
500
750
1000
250
500
750
1000
250
500
750
1000
250
500
750
1000
250
500
750
1000
7
16.73
23.11
27.33
35.55
15.31
31.21
55.85
71.68
15.30
20.75
42.00
44.09
25.65
62.73
80.16
88.23
68.15
88.44
89.85
98.24
20.25
56.56
74.20
79.50
58.15
78.44
79.80
88.24
1.02
11.25
18.75
34.67
38.85
19.81
30.35
53.33
72.81
13.88
21.78
29.71
51.55
26.75
59.76
76.61
85.27
76.68
81.59
86.14
96.59
21.20
52.75
72.58
76.54
66.68
71.40
75.50
86.54
2.29
11.67
14.58
32.67
47.68
14.06
49.65
51.25
74.96
14.20
23.48
29.66
40.13
34.52
60.05
74.63
84.16
73.93
84.85
84.96
89.53
27.04
53.80
70.60
75.45
64.04
74.85
75.04
79.53
0.80
14.50
17.71
3.80
45.61
13.24
52.92
60.26
68.80
25.49
26.20
46.34
54.17
29.04
67.95
78.49
89.90
66.90
84.26
89.04
96.40
22.84
58.50
73.28
79.90
56.90
74.50
79.04
86.40
2.11
[Co(HINTB)2Cl2]
[Ni(HINTB)2Cl2]
[Cu(HINTB)Cl2]
[Zn(HINTB)2Cl2]
[Cu(INTB)(CH3COO)]
[Zn(INTB)2]
Control (water)
Control (solvent þ water)
7
2.59
3.66
3.50
4.83

214
SINGH AND SINGH
absence of one n(NH) and n(C¼O) and the presence of a new band due to
n(NCO), indicatingenolisation of the C ¼O group and its subsequent
deprotonation duringcomplex formation.
[Ni(HINTB)2(CH3COO)2] shows bands at 1570 and 1330 cmÀ1
(Dn ¼ 240 cmÀ1) due to nas(C-O) and ns(C-O), respectively, indicatingthe
presence of a monodentate acetato group. These bands are observed at 1508
and 1437 cmÀ1 (Dn ¼ 71 cmÀ1) in [Co(HINTB)2](CH3COO)2, suggesting the
ionic nature of the acetato group24. The correspondingbands in
[Cu(INTB)(CH3COO)] are observed at 1540 and 1420 cmÀ1 (Dn ¼
120 cmÀ1) and indicate the bridging bidentate behaviour of the acetato
group and thus explains the dimeric nature of the complex as indicated by
the ESR spectrum.
Fungicidal Screening
The results of antifungal activity given in Table VI show that the
complexes are fungitoxic against the fungi, Stemphylium sp., Fusarium
udum, Alternaria tenuissima and Helminthosporium rostratum. The anti-
fungal activity increases with increasing the concentration of the compound
and is believed to be due to the presence of the toxophoric groups thio-
carbonyl and hydrazine. The ligand HINTB shows fungitoxic activity of
27748%, whereas, its metal complexes show 30798% fungitoxicity at the
concentrations of 750 and 1000 ppm. [Zn(HINTB)2Cl2] and [Zn(INTB)2]
Table VII. Antibacterial Activity of HINTB and the Complexes
Microbial Species
Compound
a
b
c
d
e
f
gh
i
HINTB
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
þ
7
7
7
7
7
7
7
þ
7
7
7
7
7
7
7
7
7
7
þ
7
7
7
7
7
7
7
þ
7
7
7
7
7
7
7
7
þ
7
7
7
7
7
7
7
7
7
[Co(HINTB)2Cl2]
[Ni(HINTB)2Cl2]
[Cu(HINTB)Cl2]
[Zn(HINTB)2Cl2]
[Cu(INTB)(CH2COO)]
[Zn(INTB)2]
7
7
7
7
7
7
þ
þ
þ
7
7
7
7
7
Gentamicin
Solvent (DMSO)
7
7
7
7
7
Zone diameter of inhibition >8 mm is taken as sensitive and shown as ( þ ). a, b, c, d
etc., denote the bacterial species mentioned in the text.

COMPLEXES OF Co(II), Ni(II), Cu(II), AND Zn(II)
215
Figure 2. Proposed structure of the complexes.

216
SINGH AND SINGH
show greater fungitoxicity as compared to [Cu(HINTB)Cl2],
[Ni(HINTB)2Cl2], [Co(HINTB)2Cl2], [Cu(INTB)(CH3COO)] and the
ligand, as expected due to the greater basic nature of Zn(II) as compared to
other metal ions.
Antibacterial Screening
The results of antibacterial screeningof HINTB and its complexes
against Staphylococcus aureus (a), Staphylococcus epidermidis (b), Enter-
ococcus faecalis (c), Escherichia coli (d), Pseudomonas aeruginosa (e), Proteus
vulgaris (f ), Shigella flexneri (g), Vibrio cholerae (h) and Staphylococcus
aureus (ATCC 25923) (i) are shown in Table VII. It may be observed that
[Co(HINTB)2Cl2], [Ni(HINTB)2Cl2] and [Cu(HINTB)Cl2] inhibit the
growth of only Pseudomonas aeruginosa. [Zn(HINTB)2Cl2], [Cu(INTB)
(CH3COO)], [Zn(INTB)2] and the ligand are inactive against all of the nine
bacteria.
On the basis of the analytical data and physico-chemical studies
described above, the proposed structures of the complexes are shown in
Fig. 2.
ACKNOWLEGMENTS
The authors thank Dr. V. B. Chauhan, Plant Pathology Division,
Institute of Agricultural Sciences, B.H.U. and Dr. Gopal Nath, Micro-
biology Division, Institute of Medical Sciences, B.H.U. for antimicrobial
screening. Thanks are also due to the Head, Regional Sophisticated
Instrumentation Centre, Central DrugResearch Institute, Lucknow for
microanalyses.
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Received January 17, 2000
Accepted October 30, 2001
Referee I: D. X. West
Referee II: E. K. Haub