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-trihydroxybenzaldehyde with anthranilic acid (L1–L3) 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 P21 with cell constants a = 9.6820(13), b = 7.1446(11), c = 9.9315(13) Å, β = 98.385(8)°, 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.