Synthesis, electrochemical, structural, spectroscopic and biological activities of mixed ligand copper (II) complexes with 2-{[(Z)-(5-bromo-2-hydroxyphenyl)methylidene]amino} benzoic acid and nitrogenous bases

Three new copper (II) complexes viz. [Cu(L-1)(bipy)]center dot 2H(2)O 1, [Cu(L-1)(dmp)]center dot CH3CN 2, [Cu(L1)(phen)] 3 where (LH2)-H-1 = 2([(Z)-(5-bromo-2-hydroxyphenyl)methylidene]amino)benzoic acid, bipy = 2,2'-bipyridine; dmp = 2,9-dimethyl 1,10-phenanthroline, phen = 1,10-phenanthroline have been synthesized and characterized by physic-chemical and spectroscopic methods. The solid-state structures of 1 and 2 were determined by single crystal X-ray crystallography, which revealed distorted square pyramidal geometry. In solid-state structure, 1 is self-assembled via intermolecular pi...pi stacking and the distances between centroids of aromatic ring is 3.525 angstrom. (LH2)-H-1 is a diprotic tridentate Schiff base ligand having ONO donor site. Infrared spectra, ligand field spectra and magnetic susceptibility measurements agree with the observed crystal structures. The EPR spectra of these complexes in frozen DMSO solutions showed a single at g ca. 2. The trend in g-value (g(parallel to) > g(perpendicular to) > 2.0023) suggests that the unpaired electron on copper (II) has d(x2-y2) character. Copper (II) complexes 1-3 yielded an irreversible couple corresponding to the Cu (II)/Cu (I) redox process. Superoxide dismutase activity of all these complexes has been revealed to catalyze the dismutation of superoxide (O-2(-)) and IC50 values were evaluated and discussed. Antimicrobial and antifungal activities of these complexes were also investigated. (C) 2013 Elsevier B.V. All rights reserved.