Iminas

Transition Metal Chemistry 29: 129–135, 2004.
Ó 2004 Kluwer Academic Publishers. Printed in the Netherlands.

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Synthesis, structural characterisation and electrochemical and antibacterial studies of
Schiff base copper complexes
Natarajan Raman*, Antonysamy Kulandaisamy and Chinnathangavel Thangaraja
Department of Chemistry, VHNSN College, Virudhunagar 626 001, India
ParamasivanManisankar, Subramanian Viswanathan and Chinnapayan Vedhi
Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003, India
Received 23 May 2003; accepted 21 July 2003

Abstract
Neutral complexes of CuII have been synthesised from the Schiff bases derived from salicylidene-4-aminoantipyrine
and PhNH2/substituted anilines. The structural features have been determined from theirmicroanalytical, i.r., u.v.–
vis., 1H-, 13C-n.m.r., mass and e.s.r. spectral data. All the complexes exhibit square-planar geometry. Their magnetic
susceptibility measurements and low conductance data provide evidence for the monomeric and non-electrolytic
natures of the complexes respectively. The electrochemical behaviour of the complexes in MeCN at 298 K was
studied. The kinetic parameters weredetermined and are discussed. The X-band e.s.r. spectra of the complexes in
DMSO at 300 and 77 K were recorded and their salient features are reported. The powder XRD diffraction patterns
for all the complexes are found to be similar. The antimicrobial activity of the ligands and their copper complexes
against the bacteria Staphylococcus aureus, Klebsiella pneumoniae, Salmonella typhi,Pseudomonas aerugenosa and
Bacillus subtilis are also reported. The complexes have higher activities than those of the free Schiff bases. Moreover,
they have higher activity than the control (ampicillin) except for Klebsiella pneumoniae and Pseudomonas
aerugenosa.

Introduction
Schiff bases of 4-aminoantipyrine and its complexes
have a variety of applications in biological, clinical,
analytical andpharmacological areas [1, 2]. Studies of a
new kind of chemotherapeutic Schiff bases are now
attracting the attention of biochemists [3, 4]. Earlier
work reported that some drugs showed increased
activity, when administered as metal complexes rather
than as organic compounds. Perusal of the literature
revealed that a further systematic study is required on
this subject. The coordinatingproperties of 4-aminoantipyrine have been modified to give a flexible ligand
system, formed by condensation with a variety of
reagents like aldehydes, ketones, thiosemicarbazides
and carbazides etc. [5–16]. A literature search reveals
that no work has been done on the condensation of
salicylidene-4-aminoantipyrine and aniline/substituted
anilines. As part of our continuing efforts to synthesise
andcharacterise simple Schiff base transition metal
complexes [16], in this paper we describe the synthesis,
structural characterisation, electrochemical and antimicrobial studies of Schiff base copper complexes
derived from salicylidene-4-aminoantipyrine and ani-

* Author for correspondence

line/p-substituted anilines. The proposed structures of
the ligands are

Experimental
All reagentsused for the preparation of ligands and
complexes were Merck products. Spectroscopic grade
solvents were used for spectral and cyclic voltammetric

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measurements. The carbon, hydrogen and nitrogen
microanalysis content of each sample was determined
at the RSIC, CDRI, Lucknow. FAB mass spectra were
recorded on a JEOL SX 102/DA-6000 mass spectrometer, using m-nitrobenzyl alcohol as amatrix, at the
Indian Institute of Technology, Hyderabad. 1H- and
13
C-n.m.r. spectra of the samples were recorded in
CDCl3 solution on a Brucker 300 MHz FT-n.m.r.
spectrophotometer. I.r. spectra using KBr pellets were
recorded on a Perkin-Elmer 783 spectrophotometer.
Electronic absorption spectra of the complexes in
DMSO were recorded on a Shimadzu u.v. 1601 spectrophotometer. The X-band...