Spectroscopic and biological studies on newly synthesized nickel(II) complexes of semicarbazones and thiosemicarbazones

Article abstract of DOI:10.1016/j.saa.2005.04.005

Nickel(II) complexes, having the general composition Ni(L) ₂X₂, have been synthesized [where L: isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and

Full text of DOI:10.1016/j.saa.2005.04.005

Spectrochimica Acta Part A 62 (2005) 1089–1094
Spectroscopic and biological studies on newly synthesized nickel(II)
complexes of semicarbazones and thiosemicarbazones
Sulekh Chandra∗, Lokesh Kumar Gupta
Department of Chemistry, Zakir Husain College, University of Delhi, J.L. Nehru Marg, New Delhi 110002, India
Received 10 February 2005; accepted 6 April 2005
Abstract
Nickel(II) complexes, having the general composition Ni(L)2X2, have been synthesized [where L: isopropyl methyl ketone semicarbazone
(LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemi-
carbazone (LLD) and X = Cl−, 1/2SO42−]. All the Ni(II) complexes reported here have been characterized by elemental analyses, magnetic
moments, IR, electronic and mass spectral studies. All the complexes were found to have magnetic moments corresponding to two unpaired
electrons. The possible geometries of the complexes were assigned on the basis of electronic and infrared spectral studies. Newly synthesized
ligand and its nickel(II) complexes have been screened against different bacterial and fungal growth.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Semicarbazones; Thiosemicarbazones; Nickel(II); Spectroscopic and biological screening
1. Introduction
found that nickel transport involves ATP-dependant Mg(II)
transport system and nickel toxicity can be prevented by
increasing the concentration of Mg(II) relative to Ni(II).
In this paper, we report the synthesis and spectro-
scopic characterization of nickel(II) complexes with ligands
isopropyl methyl ketone semicarbazone (LLA), isopropyl
methyl ketone thiosemicarbazone (LLB), 4-aminoaceto-
phenone semicarbazone (LLC) and 4-aminoacetophenone
thiosemicarbazone (LLD) (Fig. 1).
Metal complexes of semicarbazones and thiosemicar-
bazones were found to have pronounced carcinostatic prop-
erties against a wide range of transplanted neoplasia [1–4],
while the oxygen derivatives (semicarbazones) were found
to be inactive carcinostatic agents. Such differences in anti-
tumour activity can be co-related to the different chelating
properties of the semicarbazones. In a series of recent papers
[5–9], the synthetic and structural aspects of a number of tran-
sition metal complexes of NS and NO donor systems have
been described. Nickel is one of the most toxic metal among
transition metals. It shows the toxicity even in low doses to
both plants and animals [10,11]. Excess nasal and lung can-
cers are known to be associated with the refining of nickel.
Epimediological data and animal study confirm that crys-
talline nickel compounds are carcinogenic, while amorphous
nickel compounds are weak or non-carcinogenic. Nickel is
also involved in transport of metal in eukaryotic algae. It is
2. Experimental
All the chemicals used were of AnalaR grade, and pro-
cured from Sigma–Aldrich and Fluka. Metal salts were pur-
chased from E. Merck and were used as received.
2.1. Preparation of ligands
All the ligands were prepared by the methods reported
earlier [12] by coupling of semicarbazide hydrochloride
and thiosemicarbazide, respectively, with isopropyl methyl
ketone and 4-aminoacetophenone.
∗
Corresponding author. Tel.: +91 11 229 112 67; fax: +91 11 232 159 06.
E-mail addresses: schandra 00@yahoo.com (S. Chandra),
lokesh kg@rediffmail.com (L.K. Gupta).
1386-1425/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2005.04.005

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S. Chandra, L.K. Gupta / Spectrochimica Acta Part A 62 (2005) 1089–1094
given in ppm relative to tetramethylsilane. IR spectra (KBr)
were recorded on a FTIR Spectrum BX-II spectrophotometer.
The electronic spectra were recorded in DMSO on Shimadzu
UV mini-1240 spectrophotometer.
3. Results and discussion
Molar conductance measurement for these complexes was
determined in nitrobenzene. All the complexes were found to
be non-electrolytes [14] (Table 1). Thus, on the basis of the
above data [Ni(L)2X2] [where L: LLA, LLB, LLC and LLD,
X = Cl− and 1/2SO42−] formula, reported in Table 2, may be
suggested for the nickel complexes.
3.1. Infrared spectra of the ligands
Infrared spectra of the ligands show bands in the
region ∼1636 and 1588 cm−1, which may be assigned to
the symmetric or asymmetric [ν(C N)] vibrations. Strong
bands in the region ∼791–813 cm−1 in thiosemicarbazones
and ∼1688–1712 cm−1 in semicarbazones are due to the
[ν(C S)] and [ν(C O)] groups, respectively. On complex
formation, these bands shifted toward lower frequency as
compared to metal free ligand, which indicates that the coor-
dination takes place through the nitrogen, oxygen and sulphur
atoms of (C N), (C O) and (C S) groups, respectively.
Thus, it has been concluded that the semicarbazones and
thiosemicarbazones act as bidentate chelating agent.
Fig. 1. Structure of the ligands.
2.2. Preparation of complexes
A general method has been adopted for the synthesis of
the complexes. A hot (∼75 ◦C) aqueous ethanolic solution
(20 mL, 1:1, v/v) of the hydrated metal salts (0.05 mol) and
a hot ethanolic solution (20 mL) of the respective ligand
(0.1 mol) were mixed with constant stirring. The mixture was
refluxed for about 5 h at a temperature of ∼80 ◦C. On cooling
the contents to a temperature of ∼5 ◦C, the complexes were
separated out. They were filtered, washed with 50% ethanol
and dried over P4O10 under vacuum.
3.2. 1H NMR spectra of the ligands
2.3. Physical measurements
1H NMR spectra of the ligands in DMSO show the signals
[15] as follows (chemical shift in ppm):
C, H and N were analyzed on a Carlo-Erba 1106 ele-
mental analyzer. The nitrogen content of the complexes was
determined using Kjeldahl’s method. The nickel content in
the complexes was determined gravimetrically as nickel-
dmg [13]. Molar conductances were measured on an Elico
(CM82T) conductivity bridge. Magnetic susceptibility was
measured at room temperature on a Gouy balance using
CuSO4·5H2O as a callibrant. Electron impact mass spectra
were recorded on a Jeol, JMS, DX-303 mass spectrometer. 1H
NMR spectra were recorded on Hitachi FT-NMR model R-
600 spectrometer using CDCl3 as solvent. Chemical shifts are
Ligand (LLA): δ1.82 ppm (t) (3H, H3C–C–), δ8.58 ppm (s)
(1H, HN–CO), δ3.45 ppm (d) (2H, H2N–CO), δ1.18 (t),
δ2.48 (sextet), δ4.41 ppm (d) (C3H7–C).
Ligand (LLB): δ1.84 ppm (t) (3H, H3C–C–), δ8.65 ppm (s)
(1H, HN–CS), δ3.59 ppm (d) (2H, H2N–CS), δ1.15 (t),
δ2.50 (sextet), δ4.44 ppm (d) (C3H7–C).
Ligand (LLC): δ1.80 ppm (t) (3H, H3C–C–), δ8.57 ppm (s)
(1H, HN–CO), δ3.45 ppm (d) (2H, H2N–CO), δ7.11 ppm
(m) (4H, –Ph–), δ3.80 ppm (d) (2H, –Ph–NH2).
Table 1
Molecular conductance, magnetic moment and electronic spectral data of the complexes
Complexes
Molar conductancea (ꢀ−1 cm2 mol−1
)
µeff (B.M.)
λmax (cm−1), ε (L mol−1 cm−1
)
[Ni(LLA)2Cl2]
[Ni(LLA)2SO4]
[Ni(LLB)2Cl2]
[Ni(LLB)2SO4]
[Ni(LLC)2Cl2]
[Ni(LLC)2SO4]
[Ni(LLD)2Cl2]
[Ni(LLD)2SO4]
4
6
5
3
4
2
5
1
2.93
3.07
2.95
3.05
2.98
3.14
2.97
3.12
10270 (32), 15610 (59), 24864 (122)
7072 (28), 10408 (45), 17018 (99)
10538 (34), 15872 (62), 24958 (122)
7195 (29), 10256 (44), 18662 (100)
10456 (37), 15578 (65), 25109 (125)
7246 (28), 10474 (47), 17846 (100)
10754 (35), 16966 (63), 25006 (124)
7184 (30), 10337 (46), 18324 (101)
a
Error limit, 3%.

S. Chandra, L.K. Gupta / Spectrochimica Acta Part A 62 (2005) 1089–1094
1091
Ligand (LLD): δ1.78 ppm (t) (3H, H3C–C–), δ8.63 ppm (s)
(1H, HN–CS), δ3.55 ppm (d) (2H, H2N–CS), δ7.10 ppm (m)
(4H, –Ph–), δ3.86 ppm (d) (2H, –Ph–NH2).
3.3. Electron impact mass spectra of the ligands
EI mass spectra of the ligands (Fig. 2) confirm the pro-
posed formula by showing the following peaks:
Ligand (LLA): Appearance of final peak at 144 amu
(C6H13N3O, calculated atomic mass 143 amu) and other
peaks at 15, 43, 78, 99 and 127 amu may be due to different
fragments. The intensity of these peaks gives an idea of the
stability of these fragments.
Ligand (LLB): Under the EI mass spectral study, it gives
a final peak at 158 amu which confirms the proposed for-
mula (C6H13N3S, calculated atomic mass 159 amu) and
other peaks at 15, 44, 60, 77, 89, 127 and 143 amu may
be attributed to different fragments.
Ligand (LLC): The presence of EI mass spectral peak at
193 amu confirms the proposed formula (C9H12N4O calcu-
lated atomic mass 192 amu). A set of peaks observed in the
range 16, 44, 59, 77, 92, 104, 119 and 134 amu is assigned
to various fragments.
Ligand (LLD): Presence of a peak at 208 amu supports
the proposed formula (C9H12N4S, calculated atomic mass
208 amu). The peaks due to the various fragments appear at
15, 60, 78, 92, 105, 134, 192 and 208 amu.
3.4. Chloro complexes [Ni(L)2Cl2]
Room temperature magnetic moments of the nickel(II)
chloride complexes lie in the range 2.93–2.98 B.M. These
values are in tune with a high spin configuration.
The electronic spectra of the complexes display three
absorption bands in the range 10,270–10,754 cm−1 (ε =
32–37 L mol−1 cm−1), 15,578–16,966 cm−1 (ε = 59–65 L
mol−1 cm−1
)
and 24,869–25,109 cm−1 (ε = 122–125 L
mol−1 cm−1). The ground state of Ni(II) in an octahedral
coordination is 3A2g. Thus, these bands may be assigned to
3
3
the three spin allowed transitions [16–18]: A2g(F) → T2g
3
3
3
3
(F) (ν1), A2g(F) → T1g (F) (ν2) and A2g(F) → T1g (P)
(ν3), respectively. The positions of bands indicate that the
complexes have six-coordinated octahedral geometry.
3.5. Sulphato complexes [Ni(L)2]SO4
Room temperature magnetic moments of the nickel(II)
sulphate complexes lie in the range 3.05–3.14 B.M. These
values are in tune with a high spin configuration.
The infrared spectra of the sulphate complexes (Fig. 3)
show two bands ν3 and ν1 in the range 1137–1106
and 984 cm−1, respectively [19]. This suggests that the
sulphate group coordinates to the metal as unidentate.
Thus, a five-coordinate geometry may be assigned to
these complexes. The electronic spectra of the complexes

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S. Chandra, L.K. Gupta / Spectrochimica Acta Part A 62 (2005) 1089–1094
Fig. 3. IR spectral peaks of the coordinated sulphate group.
Fig. 4. Suggested structures of the complexes: (a) chloro complexes of semi-
carbazone; (b) chloro complexes of thiosemicarbazone; (c) sulphato com-
plexes of semicarbazones; (d) sulphato complexes of thiosemicarbazone.
R = C3H7 and H2N–Ph.
3B1(F) → E(F) and 3B1(F) → A2(P), characteristic to five-
3
3
coordinate square pyramidal geometry [22] (Fig. 4).
4. Ligand field parameters
Various ligand field parameters were calculated and listed
in Table 3. The values of Dq have been calculated from
transition energy ratio diagram [18]. Our results are in agree-
ment with those reported earlier [23]. The Nephelauxetic
parameter β was readily obtained by using the relation
β = B(complex)/B(free ion), where B(free ion) for Ni(II) is
1041 cm−1 [21]. The values of β lie in the range 0.62–0.64.
These values indicate the covalent character in metal ligand
‘␴’ bond.
Fig. 2. Electron impact mass spectra of the ligands.
show bands at 7072–7246 cm−1 (ε = 28–30 L mol−1 cm−1
)
(ν1), 10,256–10,474 cm−1 (ε = 44–47 L mol−1 cm−1) (ν2)
and 17,018–18,662 cm−1 (ε = 99–101 L mol−1 cm−1) (ν3)
[20,21], which may be assigned to the transitions

S. Chandra, L.K. Gupta / Spectrochimica Acta Part A 62 (2005) 1089–1094
1093
Table 3
Ligand field parameters of the complexes
Complexes
Dq (cm−) B (cm−1
)
β
LFSE
(kJ mol−1
ν2/ν1
)
[Ni(LLA)2Cl2]
[Ni(LLA)2SO4]
[Ni(LLB)2Cl2]
[Ni(LLB)2SO4]
[Ni(LLC)2Cl2]
[Ni(LLC)2SO4]
[Ni(LLD)2Cl2]
[Ni(LLD)2SO4]
1027
707
1054
719
1046
725
1075
718
642
–
659
–
654
–
672
–
0.62 147.24
101.36
0.63 151.11
103.08
0.63 149.96
103.94
0.64 154.12
102.94
1.52
1.47
1.51
1.42
1.49
1.44
1.58
1.44
–
–
–
–
5. Biological activities
The newly synthesized Ni(II) complexes have been
screened against a number of bacteria and plant pathogenic
fungi [24,25].
5.1. Antibacterial screening
The antibacterial activities of the purified metal com-
plexes were determined at different concentrations (100 and
30 ␮g/disc) against a series of Gram-positive and Gram-
negative pathogenic bacteria by using disc diffusion tech-
nique and were compared with the results obtained with
the results obtained with standard antibiotic, Kanamycin (K:
30 ␮g/disc). The results are shown in the Table 4. It was
found that the metal complexes were active against all of
the test bacteria but the metal complexes (C4 and C8) exhib-
ited moderate to strong activity against the test pathogenic
bacteria. The antibacterial activities of the eight metal com-
plexes (C1–C8) against 14 pathogenic bacteria are presented
in Table 4. It was found that the metal complexes C4 and
C8 were most effective against all pathogenic bacteria. The
zones of inhibition of the complexes were approximately
same as standard Kanamycin. But the individual activity of
the complexes C1 and C2 was moderate against all pathogenic
bacteria and on comparison with the results of zones of
inhibition with standard Kanamycin, these activities were
much lower than those of standard Kanamycin. On the other
hand, the remaining complexes such as C3 and C5 were less
active against all pathogenic bacteria. On comparison with
the results of zones of inhibition with standard Kanamycin,
these activities were approximately zero.
5.2. Antifungal screening
The antifungal activity of the complexes was checked, by
the disc diffusion technique for the 11 pathogenic fungi as
test organisms in vitro. The antifungal activities of the com-
plexes against 10 pathogenic fungi are presented in Table 5.
The complexes C4, C6 and C8 were moderate active against
all pathogenic fungi and much lower than those of standard
fungicide, Nistatin. Remaining all the complexes were found

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S. Chandra, L.K. Gupta / Spectrochimica Acta Part A 62 (2005) 1089–1094
Table 5
Antifungal activities of the complexes and standard Nystatin
a
a
a
a
a
a
a
a
Test organisms
C1
C2
C3
C4
C5
C6
C7
C8
Nystatinb
Achlya bisexualis
Saprolegnia monoeca
Albugo bliti
8
8
9
8
7
6
0
11
9
8
15
7
20
25
10
15
12
18
25
35
9
10
15
10
8
10
7
7
10
8
10
11
9
12
10
11
9
12
10
11
7
25
9
20
8
13
15
14
20
15
10
9
8
11
10
8
12
9
10
12
11
9
10
11
12
10
9
18
15
8
20
12
30
20
16
22
30
20
20
16
21
20
20
10
14
Ustilago avenae
Morchella conica
Peziza vesiculosa
Peziza pustulata
Aspergilus niger
Aspergilus flavus
Candida albicans
a
10
8
18
11
10
C1: [Ni(LLA)2Cl2]; C2: [Ni(LLA)2SO4]; C3: [Ni(LLB)2Cl2]; C4: [Ni(LLB)2SO4]; C5: [Ni(LLC)2Cl2]; C6: [Ni(LLC)2SO4]; C7: [Ni(LLD)2Cl2]; C8:
[Ni(LLD)2SO4].
b
200 ␮g/disc.
to possess less activity against pathogenic fungi under study,
as compared with standard drug Nistatin.
[9] S. Chandra, L.K. Gupta, Spectrochim. Acta-A 60 (2004) 2767;
D.X. West, A.A. Nassar, M.I. Ayad, F.A. El-Saied, Trans. Met.
Chem. 24 (1999) 617.
[10] J.K. Swearingen, D.X. West, Trans. Met. Chem. 26 (2001) 252.
[11] J.M. Wood, in: H. Sigel (Ed.), Microbial Strategies in Resistance
to Metal Ion Toxicity Metal Ions in Biology, Marcel Dekker, New
York, 1984.
Acknowledgements
[12] S. Talwar, U. Bansal, S. Chandra, R. Singh, P. Veeraswamy, Synth.
React. Inorg. Met.-Org. Chem. 21 (1991) 131.
[13] A.I. Vogel, Textbook of Quantitative Inorganic Analysis, fourth ed.,
ELBS and Longman, 1978.
[14] W.G. Geary, Coord. Chem. Rev. 7 (1971) 81.
[15] P.S. Kalsi, Spectroscopy of Organic Compounds, fourth ed., New
Age International (P) Ltd., New Delhi, 1999.
The authors are thankful to the University Grant Commis-
sion, New Delhi, for financial assistance and the Principal,
Zakir Husain College, for providing research facilities. We
also express our sincere thanks to Dr. Mordhwaj ACBR, Uni-
versity of Delhi, for recording IR spectra.
[16] S. Chandra, L.K. Gupta, Spectrochim. Acta-A 60 (2004) 1563;
N.K. Singh, S.B. Singh, Trans. Met. Chem. 26 (2001) 487.
[17] F. Athar, F. Arjmand, S. Tabassum, Trans. Met. Chem. 26 (2001)
426.
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