Synthesis and reactivity studies on new copper(II) complexes: DNA binding, generation of phenoxyl radical, SOD and nuclease activities

Tridentate ligand PhimpH binds to Cu(II) centre after deprotonation affording a new family of complexes [Cu(Phimp)(H2O)](2)(ClO4)(2) (1). [Cu(Phimp)(2)] (2) and Ku(phimp)(L)] (3-5) where L are CH3COO-, SCN- and NO respectively. The molecular structures of complexes 1.CH3CN and 3 were determined by X-ray crystallography. Electrochemical studies depicted Cu(II)/Cu(I) couple in the range of -0.50 to -0.65 V vs. Ag/AgCl. EPR spectral studies for complexes 4 and 5 indicated the order of covalent character in 4 > 5 with dx(2)-y(2) ground state. The phenoxyl radical complexes have been generated in situ by the oxidation of these complexes. Superoxide dismutase activity and DNA binding studies were examined. These complexes exhibited nuclease activity and the mechanism of DNA cleavage was investigated. (C) 2010 Elsevier Masson SAS. All rights reserved.