Spectral, biological screening, and DNA studies of metal chelates of 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine

Article abstract of DOI:10.1080/00958972.2011.572965

Tridentate chelate complexes of Co(II), Ni(II), and Cu(II) have been synthesized from 4-[N,Nbis-( 3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine. Microanalytical data, UV-Vis, magnetic susceptibility, Infrared, ¹H- ¹³C-NMR, mass, thermal gravimetric analysis and electron paramagnetic resonance (EPR) techniques were used to confirm the structures. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted octahedral geometry for the metal. EPR spectra of the copper(II) complex at 77K confirm the distorted octahedral geometry of the copper(II) complex. The antimicrobial activities of the ligand and metal complexes against the bacteria such as Xanthomonas maltophilia, Chromobacterium violaceum, Acinetobacter, Staphylococci, Streptococci, and the fungus Candida albicans have been carried out. A comparative study of minimum inhibitory concentration values of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial and antifungal activity than the free ligand. The electrochemical behavior of copper(II) complex was studied by cyclic voltammetry. The complexes show nuclease activity in the presence of oxidant.

Full text of DOI:10.1080/00958972.2011.572965

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Spectral, biological screening, and
DNA studies of metal chelates of 4-
[N,N-bis-(3,5-dimethyl-pyrazolyl-1-
methyl)]aminoantipyrine
M. Kalanithi a , M. Rajarajan b & P. Tharmaraj c
a Department of Chemistry, Jayaraj Annapackiam College for
Women, Periyakulam – 625601, India
b Department of Chemistry, Cardamom Planters’ Association
College, Bodinayakkanur – 625 513, India
c Department of Chemistry, Thiagarajar College, Madurai –
625009, India
Published online: 14 Apr 2011.
To cite this article: M. Kalanithi , M. Rajarajan & P. Tharmaraj (2011): Spectral, biological
screening, and DNA studies of metal chelates of 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-
methyl)]aminoantipyrine, Journal of Coordination Chemistry, 64:8, 1436-1445
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Journal of Coordination Chemistry
Vol. 64, No. 8, 20 April 2011, 1436–1445
Spectral, biological screening, and DNA studies of metal
chelates of 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-
methyl)]aminoantipyrine
M. KALANITHIy, M. RAJARAJAN*z and P. THARMARAJ*x
yDepartment of Chemistry, Jayaraj Annapackiam College for Women,
Periyakulam – 625601, India
zDepartment of Chemistry, Cardamom Planters’ Association College,
Bodinayakkanur – 625 513, India
xDepartment of Chemistry, Thiagarajar College, Madurai – 625009, India
(Received 19 October 2010; in final form 4 March 2011)
Tridentate chelate complexes of Co(II), Ni(II), and Cu(II) have been synthesized from 4-[N,N-
bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine. Microanalytical data, UV-Vis, mag-
netic susceptibility, Infrared, 1H- 13C-NMR, mass, thermal gravimetric analysis and electron
paramagnetic resonance (EPR) techniques were used to confirm the structures. The electronic
absorption spectra and magnetic susceptibility measurements suggest a distorted octahedral
geometry for the metal. EPR spectra of the copper(II) complex at 77 K confirm the distorted
octahedral geometry of the copper(II) complex. The antimicrobial activities of the ligand and
metal complexes against the bacteria such as Xanthomonas maltophilia, Chromobacterium
violaceum, Acinetobacter, Staphylococci, Streptococci, and the fungus Candida albicans have
been carried out. A comparative study of minimum inhibitory concentration values of the
ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial and
antifungal activity than the free ligand. The electrochemical behavior of copper(II) complex was
studied by cyclic voltammetry. The complexes show nuclease activity in the presence of oxidant.
Keywords: Pyrazolyl aminoantipyrine; Metal complexes; Biological screening; DNA cleavage
studies
1. Introduction
Transition metal complexes of pyrazolone derivatives are of interest due to their
appreciable biological activities, especially antipyrine derivatives. Among the pyrazo-
lone derivatives, 4-aminoantipyrine forms a variety of Schiff bases with aldehydes/
ketones, and they are reported to be superior reagents in biological, pharmacological,
clinical and, analytical applications [1–15].
The carbonyl group in 4-aminoantipyrine is a potential donor due to the large dipole
moment (5.48 D) and strong basic character. Pyrazole derivatives have a unique
position in drug discovery due to their broad range of biological activities, including
*Corresponding authors. Email: rajarajan_1962@yahoo.com; ptharma@rediffmail.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2011 Taylor & Francis
DOI: 10.1080/00958972.2011.572965

Pyrazolyl aminoantipyrine
1437
anti-inflammatory, antiangiogenic, antibacterial, antimicrobial, anticancer, and anti-
depressant activities [16–21]. Based on the number and the position of the pyrazole ring,
the number of coordination sites may be increased. Reactions of 3,5-dimethy-1-
(hydroxymethyl)-pyrazole and its derivatives with transition metals have been studied
[22–27]. Condensation product derived from 4-aminoantipyrine and 3,5-dimethy-1-
(hydroxymethyl)-pyrazole has not been studied. We present studies on metal complexes
of Cu(II), Ni(II), and Co(II) with 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]
aminoantipyrine(L) with their biological activities and DNA cleavage studies.
2. Experimental
All chemicals were obtained from Aldrich Chemical & Co. and used without
purification. The UV-Vis spectra of the ligand and metal complexes were recorded
using a JASCO V-530 spectrophotometer. Infrared (IR) spectra in KBr discs were
recorded on a SHIMADZU FT-IR 460plus spectrophotometer at USIC, Madurai
Kamaraj University, Madurai. Cyclic voltammetry measurements were carried out at
room temperature in DMSO (CH Instruments, USA, voltammograph) using a three
electrode cell containing a reference Ag/AgCl electrode, Pt wire auxiliary electrode and
glassy carbon working electrode with tetrabutylammonium perchlorate as supporting
electrolyte. Elemental analyses were performed at SAIF, CDRI, Lucknow. 1H- and 13C-
NMR spectra were recorded in CDCl3 using a Bruker DRX-300, 300 MHz NMR
spectrometer. Electron-ionization (EI) mass spectra were recorded by JEOL-GC
MATE-2 at IIT, Madras-Chennai. Thermal gravimetric analysis (TGA) studies were
done on a TGA 50 SHIMADZU MAKE- SOFTWARE TA-60WS at Thiagarajar
Engineering College, Madurai. Electron paramagnetic resonance (EPR) spectrum was
recorded at SAIF, IIT, Mumbai. Magnetic Susceptibility of the complexes was
measured on a MSB mark 1 Sherwood, UK at Thiagarajar College, Madurai. Effective
magnetic moments were calculated using the formula (ꢀeff ¼ 2.828ꢁM T)1/2, where ꢁM is
the corrected molar susceptibility. Molar conductances of the complexes (10ꢀ3 mol Lꢀ1
)
were measured in DMSO at room temperature using a Systronic conductivity bridge.
2.1. Synthesis of 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine(L)
To 4.06 g (20 mmol) of 4-aminoantipyrine dissolved in 20 mL of dichloroethane was
added 5.04 g (40 mmol) of 3,5-dimethyl-1-(hydroxymethyl)-pyrazole(hmdmp) [28] in
15 mL of dichloroethane and the mixture was stirred at room temperature for 24 h.
After the reaction was over, the reaction mixture was concentrated under reduced
pressure and oily liquid was washed with water and then extracted with diethylether.
A cream colored solid obtained after refrigeration was recrystallized from dichlor-
omethane. Elemental analysis (Found: C, 64.12; H, 6.55; N, 22.84; C23H30N7O. Calcd:
C, 65.71; H, 7.14; N, 23.33.) ꢂmax (KBr) cmꢀ1 1662 (C¼O), 1589 (C¼N), 1286 (N–N);
1H-NMR (300 MHz; CDCl3), 2.80 (12H, s, CH3), 5.763 (2H, s, Py–H), 7.253–7.471 (5H,
m, C6H5), 4.873 (4H, S, N–(CH2)2). 13C-NMR (CDCl3, ꢃ, ppm) ꢃ ¼ 8.5–13.241 (CH3);
36.5 (N–CH3); 59.9 (N–CH2–N); 66.1 (C¼O); 103–139 (aromatic and pyrazole
carbons); 146–164 (C¼N in pyrazole moiety). The EI mass spectrum of L gives a

1438
M. Kalanithi et al.
N
N
N
N
N
MCl2 xH2O
Ethanol
N
N
N
N
Y
N
Y
O
N
N
M
Cl
C H
6
5
N
N
C H
6
5
O
M= Cu(II),Co(II) and Ni(II)
Y = H2O
Scheme 1. Synthesis of metal(II) complexes.
molecular ion peak m/z at 418. The mass fragmentation of the ligand is given in on-line
‘‘Supplementary material’’.
2.2. Preparation of complexes
All the complexes were prepared from hydrated metal salts. To a solution of 4.20 g
(10 mmol) 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine in 20 mL
ethanol was added 10 mmol of MCl2 ꢁ xH2O (M¼Cu(II), Co(II), and Ni(II)). The
solution was refluxed at 70–80ꢂC with constant stirring for 3 h and the resulting
solution was refrigerated for 1 day. The complexes were precipitated by adding
petroleum ether (60–80ꢂC). The colored complexes were filtered and washed with hot
water and dried under vacuum (scheme 1).
3. Results and discussion
The ligand was obtained as a low melting solid and stored in vacuum desiccators. The
ligand forms stable complexes in ethanol. The analytical data of the ligand and the
complexes with their physical properties are given in table 1. The ligand is a tridentate
chelating ligand. The elemental analyses of the complexes were in good agreement with
calculated data for 1 : 1 (M : L) ratio. Based on elemental analysis, spectra, TGA and
conductance data the formula [ML(H2O)2Cl]Cl was suggested. Lee et al. [27]
characterized the cobalt complex of [N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]N,N-
dimethylethylenediamine in which the ligand acts as (NNNN) donor and the geometry
reported was square pyramidal. The present NNO donor ligand derived from
condensation between 4-aminoantipyrine and 3,5-dimethy-1-(hydroxymethyl)-pyrazole
leads to octahedral geometry on complexation with metal(II) ions.

Pyrazolyl aminoantipyrine
1439
Table 1. Physical characterization, analytical, molar conductance data ÃM of the ligand, and its metal
complexes.
Experimental (Calcd) %
No.
Compound
Color
m.p. (ꢂC) FW(g molꢀ1
)
C
H
N
ÃM (ꢀꢀ1 cm2 molꢀ1
)
1
2
3
4
C
23H30N7O(L)
Yellow
60
110
130
122
420
64.12 6.55 22.84
(65.71) (7.14) (23.33)
49.25 4.98 16.23
(46.74) (5.08) (16.59)
47.00 4.88 16.00
(47.11) (5.12) (16.73)
47.03 4.89 16.31
(47.13) (5.12) (16.73)
–
[CuL(H2O)2Cl]Cl Pale green
[CoL(H2O)2Cl]Cl Blue
590.46
585.85
585.61
60
62
59
[NiL(H2O)2Cl]Cl Green
3.1. Electronic spectra and magnetic moment
Electronic spectra recorded in ethanol are presented in table 2. The ligand shows strong
peaks at 34,965 and 41,152 cmꢀ1 which are attributed to ꢄ–ꢄ* and n–ꢄ* transitions,
respectively. The copper(II) chelate shows a broad band at 11,248 cmꢀ1 assignable to
2
2B1g ! A1g characteristic of octahedral Cu(II) split under the influence of the
2
2
2
2
tetragonal distortion; the others, B1g ! B2g and B1g ! Eg, remain unresolved, in
agreement with the general observation of Cu(II) d–d transitions [8]. The electronic
spectrum of cobalt(II) shows three peaks at 15,037, 15,625, and 16,778ꢂcmꢀ1 assigned
4
4
4
4
4
4
to A2g ! T2g, A2g ! T1g(F) and A2g ! T1g(P), suggesting the octahedral environ-
ment around Co(II) [29]. Nickel complex exhibits absorptions at 9514 and 15,220 cmꢀ1
3
3
3
3
assignable to A2g ! T2g and A2g ! T1g(F), indicating octahedral geometry of the
complex [30].
The magnetic moment data (table 2) indicate paramagnetic Cu(II), Co(II), and
Ni(II). The magnetic moment value of 1.98 B.M. for copper complex falls within the
range normally observed for octahedral Cu(II) complexes [31]. For cobalt(II) complex,
the magnetic moment is 4.88 B.M. (normal range for octahedral Co(II) complex is
4.7–5.2 B.M.), which is an indicative of distorted octahedral geometry [32]. The Ni(II)
complex reported has a room temperature magnetic moment of 3.57 B.M., which
indicates that the complex of Ni(II) is six-coordinate and probably octahedral [33, 34].
The slight deviation from the normal range may be due to distortion from perfect
octahedral geometry.
3.2. IR spectra
The IR spectral data of the ligands and their metal complexes are presented in table 3.
The strong band at 1662ꢂcmꢀ1 in spectra of the ligand is assigned to ꢂ(C¼O) of the
antipyrine [35]. A considerable shift (ꢃ56 cmꢀ1) of the carbonyl frequency in complexes
indicates coordination through carbonyl oxygen. The band at 1589 cmꢀ1 assigned to
pyrazole ring nitrogen ꢂ(C¼N) of the ligand shifted to lower frequency (ꢃ14–27 cmꢀ1
)
in the complexes, indicating coordination of ring nitrogen to metal [36, 37]. The broad
band at 3416 cmꢀ1 indicates coordination of water ꢂ(O–H) to the metal.

1440
M. Kalanithi et al.
Table 2. Electronic spectral data of ligand and their metal complexes.
Compound
23H30N7O (L)
ꢅmax (cmꢀ1
)
Transition
INCT
INCT
Geometry
–
ꢀeff (B.M.)
C
34,965
41,152
11,248
15,037
15,625
16,778
9514
–
2
[CuL(H2O)2Cl]Cl
[CoL(H2O)2Cl]Cl
2B1g ! A1g
Distorted octahedral
Distorted octahedral
1.98
4.88
4
4T1g(F) ! T2g(F)
4
4T1g(F) ! A2g(F)
4
4T1g(F) ! T2g(P)
3
[NiL(H2O)2Cl]Cl
3A2g ! T2g
Distorted octahedral
3.57
3
15,220
3A2g ! T1g(F)
Table 3. IR spectral data of the ligand and their metal complexes.
Compound
ꢂ(O–H)
ꢂ(C¼O)
ꢂ(C¼N) ring
ꢂ(N–N)
Ligand(L)
–
1662
1610
1606
1623
1589
1570
1575
1562
1286
1270
1245
1278
Cu complex
Co complex
Ni complex
3394
3423
3446
3.3. Mass spectra
The mass spectrum of ligand(L), Cu(II), Co(II), and Ni(II) complexes are recorded (on-
line Supplementary material). The molecular ion peak for L was observed at 418 m/z,
whereas molecular ion peaks of Cu(II), Co(II), and Ni(II) complexes were observed at
554, 548 and 547 m/z, respectively, which corresponds to [ML(H2O)2Cl]þ.
Fragmentation pattern of mass spectra is compared with TGA data and the percentage
loss of water and chlorine and organic moiety is found to be in good agreement.
3.4. Thermogravimetric studies
Thermogravimetric studies carried out from 29ꢂC to 800ꢂC (on-line Supplementary
material) are listed in table 4. In the first step all the complexes lose one molecule of
water, then the second step is removal of chlorine and water at 139ꢂC–321ꢂC. The third
step corresponds to removal of two pyrazoles from 321ꢂC to 506ꢂC and the fourth step
corresponds to loss of antipyrine group at 504ꢂC–691ꢂC leaving metal oxide as residue.
In the mass spectra of cobalt complex molecular ion peaks m/z at 530, 483, 208, and 173
are due to loss of water, chlorine and water, pyrazole, and antipyrine group,
respectively.
3.5. EPR spectra
The EPR spectra of the copper(II) complex were recorded at 300 and 77ꢂK. No splitting
was observed in room temperature spectra, however, in the LNT spectrum all three
components were resolved (figure 1). The g values g|| ¼ 2.47 and g ¼ 2.185 suggest a
?
tetragonal distortion around Cu(II) corresponding to elongation along the fourfold

Pyrazolyl aminoantipyrine
1441
Table 4. Thermogravimetric data of Co(II), Ni(II), and Cu(II) complexes.
%Weight loss
Complex
Temperature (ꢂC)
observed (Calcd)
Process
[CoL(H2O)2Cl]Cl
29–140
139–321
321–506
504–691
4700
3.86(3.35)
10.289(9.62)
30.95(31.65)
34.28(34.55)
Residue
Loss of one molecule of water
Loss of Cl and water molecules
Loss of two pyrazole moiety
Loss of antipyrine group
CoO
[NiL(H2O)2Cl]Cl
[CuL(H2O)2Cl]Cl
29–140
139–321
321–506
504–691
4700
29–140
139–321
321–506
504–691
4700
3.16(3.37)
10.35(9.72)
31.25(31.75)
34.28(34.65)
Residue
3.86(3.35)
10.3(9.62)
29.95(30.65)
32.28(32.55)
Residue
Loss of one molecule of water
Loss of Cl and water molecules
Loss of two pyrazole moiety
Loss of antipyrine group
NiO
Loss of one molecule of water
Loss of Cl and water molecules
Loss of two pyrazole moiety
Loss of antipyrine group
CuO
Figure 1. EPR spectrum of [CuL(H2O)2Cl]Cl at 77 K.
symmetry Z-axis [38]. The g|| value (2.47) for the complex is greater than 2.3, suggesting
significant ionic character of the metal ligand bond. Calculated values of g|| and g
?
show the order g|| 4 g 4 ge (2.0023), which is consistent with the dx2ꢀy2 ground state
?
[39, 40]. The odd electron may be located in the B1g antibonding orbital.
The geometric parameter G (2.96) estimated from the expression G ¼ (g||ꢀ2.0023)/
(g ꢀ2.0023) G 5 4 suggests significant exchange coupling is present and the
?
misalignment is appreciable. The covalency parameter ꢆ2 is calculated using the
following equation.
ꢆ2Cu¼ A =pþð g ꢀ 2:0023Þ þ 3=7ðg ꢀ 2:0023Þ þ 0:04:
jj
?
jj

1442
M. Kalanithi et al.
Figure 2. Cyclic voltammogram of copper(II) complex in DMSO.
where ꢆ2 ¼ 0.5 indicates complete covalent bonding and ꢆ2 ¼ 1 suggests complete ionic
bonding. The observed value of ꢆ2 ¼ 1.4582 indicates that the complex has ionic
character. The orbital reduction factor K was calculated using the expression
K2 ¼ K2 þ 2K2 /3, where K|| and K are the parallel and perpendicular components of
?
jj
?
the orbital reduction factor. The high value of K (1.1927) also indicates the ionic nature
of the complex.
3.6. Electrochemical studies
Cyclic voltammetry of the copper complex with scan rate 0.1 V sꢀ1, figure 2, shows a
well-defined redox process corresponding to formation of Cu(II)/Cu(I) couple at
Epa ¼ 0.344 V and Epc ¼ 0.103 V. This couple is quasireversible with DEp ¼ 0.241 V and
the ratio of anodic to cathodic peak currents (Ipc/Ipa ꢄ 1) corresponding to a simple one
electron process. The DEp (EpaꢀEpc) values are greater than 200 mV, indicating
quasireversible reduction and a chemical change occurring with electron transfer [41].
3.7. Molar conductance
The molar conductances of the complexes of copper, cobalt, and nickel, given in table 1,
indicate that the complexes are 1 : 1 electrolytes. One chloride was also confirmed by
silver nitrate test [42].
3.8. Biological activities
Most Schiff bases of 4-aminoantipyrine show antibacterial, antimalarial, and antitumor
activities [1]. Similarly the 4-aminoantipyrine derivative obtained by condensing amino
group and hydroxyl group of pyrazole shows remarkable antimicrobial activities. The
well diffusion method was employed for screening the antibacterial and antifungal

Pyrazolyl aminoantipyrine
1443
Table 5. MIC of the synthesized compounds against growth of bacteria and fungi (mg mLꢀ1).
Compounds
X. maltophilia C. violaceum Acinetobacter Staphylococci, Streptococci C. albicans
C23H30N7O(L)
[CuL(H2O)2Cl]Cl
[NiL(H2O)2Cl]Cl
[CoL(H2O)2Cl]Cl
Amikacin
58
20
24
16
10
–
56
23
28
14
11
–
65
30
32
20
12
–
65
38
40
25
15
–
75
40
42
30
16
–
80
40
42
35
–
Ketokonazole
20
Each value observed is within the error limits of ꢅ2.
activities [43]. The bacteria used are Xanthomonas maltophilia, Chromobacterium
violaceum, Acientobacter (Gram-negative) and Staphylococci, Streptococci (Gram-
positive). The fungus used is Candida albicans. Stock solution (0.001 mol) was prepared
by dissolving the compounds in ethanol and the solutions were serially diluted to find
the minimum inhibitory concentrations (MICs) values (mg mLꢀ1). The diameters of the
inhibition zones were measured in millimeters. Antimicrobial activities were performed
in triplicate and the average was taken as the final reading. MICs of the compounds are
summarized in table 5. A comparative study of the MIC values for the ligands and their
complexes indicates that the complexes exhibit higher antimicrobial activity [44, 45].
The diameter of the inhibition zones was measured in millimeters. Cobalt complex was
more active than the other two complexes.
3.9. CT-DNA cleavage study
The cleavage of CT-DNA was determined by agarose gel electrophoresis. The gel
electrophoresis experiments were performed by incubation of the samples containing
30 mmol Lꢀ1 CT-DNA, 50 mmol Lꢀ1 copper complex and 50 mmol Lꢀ1 H2O2 in tris–
HCl/NaCl buffer (pH 7.2) at 37ꢂC for 2 h. After incubation, the samples were
electrophoresed for 2 h at 50 V on 1% agarose gel using tris–acetic acid–EDTA buffer
(pH 7.0). The gel was then stained using 1 mg cmꢀ3 ethidiumbromide and photographed
under ultraviolet light at 360 nm. All the experiments were performed at room
temperature. The cleavage efficiency of the complexes compared to that of the control is
due to their efficient DNA-binding ability. The metal complex is able to convert
supercoiled DNA into open circular DNA. General oxidative mechanisms account for
DNA cleavage by hydroxyl radicals via abstraction of a hydrogen from sugar units and
predict the release of specific residues arising from transformed sugars, depending on
the position from which the hydrogen is removed [46]. The cleavage is inhibited by free
radical scavengers, implying that hydroxyl radicals or peroxy derivatives mediate the
cleavage reaction. The reaction is modulated by a bound hydroxyl radical or a peroxo
species generated from H2O2. In this study, the CT-DNA gel electrophoresis experiment
was conducted at 35ꢂC using the synthesized complex in the presence of H2O2 as an
oxidant. As can be seen from figure 3, at very low concentration, copper and cobalt
complexes exhibit nuclease activity in the presence of H2O2. Control experiments using
DNA alone do not show significant cleavage of CT-DNA even on longer exposure time.

1444
M. Kalanithi et al.
Lane
4
3
2
1
Lane 1 : DNA + H2O2
2 : DNA + H2O2 + Cu complex
3 : DNA + H2O2 + Ni complex
4 : DNA + H2O2 + Co Complex
Figure 3. DNA cleavage studies.
From the observed results, the complexes cleave DNA as compared to control DNA.
Further, the presence of a smear in the gel diagram indicates radical cleavage [47].
4. Conclusion
Complexes of 4-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminoantipyrine with
Cu(II), Co(II), and Ni(II) were synthesized and characterized by various analytical
techniques. The ligand is a tridentate (NNO) chelate and yields complexes with
distorted octahedral geometry. EPR studies of copper complex confirm the ionic
character of the metal ligand linkage. The ligand and all metal complexes possess
appreciable antibacterial and antifungal activities and the cobalt(II) complex was found
to be more potent than the other two complexes. Gel electrophoresis experiment
indicates that the complexes cleave DNA in the presence of hydrogen peroxide.
Acknowledgments
The authors thank the Management of Thiagarajar College, Madurai, and one of the
authors (MK) thanks the UGC, SERO, Hyderabad for awarding Teacher Fellowship
and SAIF-IIT-Bombay, USIC-MKU-Madurai, SAIF-IIT-Madras-Chennai and CDRI
(SAIF), Lucknow for providing analytical facilities.
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