Self-activating nuclease activity of copper(II) complexes of hydroxyl-rich ligands

Copper (II) complexes of Schiff bases derived from [1 + 1] condensation of salicylaldehyde, 2,3-dihydroxybenzaldehyde and 2,3,4-tri-hydroxybenzaldehyde with anthranilic acid (L-1-L-3) have been synthesized and characterized by elemental analyses, IR, UV-Vis spectra, room temperature magnetic susceptibility, electron paramagnetic resonance spectroscopy and cyclic voltammetry. The X-ray structure of [CuL1](n) has been solved and refined to R = 0.0314. The crystals are monoclinic with space group P2(1) with cell constants a = 9.6820(13), b = 7.1446(11), c = 9.9315(13) angstrom, beta = 98.385(8)degrees, Z = 2. The copper (II) ions are in a distorted tetrahedral environment sequentially bridged by carboxylate groups in the syn-anti conformation giving rise to a helix-like chain. The copper complexes with the inherent redox active hydroquinone functionality cleave plasmid pBR322 DNA without exogenous agents by a self-activating mechanism. (C) 2005 Elsevier Inc. All rights reserved.