A novel 1,2,4-triazole-based copper(II) complex: Synthesis, characterization, magnetic property and nuclease activity

A novel binuclear copper(II) complex [Cu2L(mu-SO4)](PF6)(2) (1) (L = 3,5-bis (bis(pyridine-2-ylmethyl)amino)methyl)-4H-1,2,4-triazol-4-amine) has been synthesized and structurally characterized. X-ray structure shows that the two copper(II) atoms are bridged by one bidentate sulfate ion and the 1,2,4-triazole ring of L with Cu1 center dot center dot center dot Cu2 distance of 4.404 angstrom. Each copper(II) center has a distorted trigonal-bipyramidal configuration. Variable-temperature magnetic susceptibility studies (2-300 K) indicate the existence of weak antiferromagnetic coupling between the copper(II) ions in complex 1. The interaction of complex I with calf thymus DNA (CT-DNA) has been studied by UV absorption, fluorescence spectroscopy, circular dichroism spectroscopy, viscosity and cyclic voltammetry. Furthermore, complex 1 was able to promote single and double strand DNA cleavage in both aerobic and anaerobic conditions, the pseudo-Michaelis-Menten kinetic parameters k(cat) = 2.58 h(-1) and K-m = 1.2 x 10(-4) M were obtained for 1. The hydrolytic cleavage of DNA by the complex was supported by the evidence from free radical quenching, anaerobic experiment, thiobarbituric acid-reactive substances (TBARS) assay. (C) 2009 Elsevier Inc. All rights reserved.