Synthesis, characterization and DNA-binding studies of mono and heterobimetallic complexes Cu-Sn2/Zn-Sn2 and their DNA cleavage activity

Heterobimetallic complexes C6H24N4O6CuSn2Cl6 3, C6H24N4O6ZnSn2Cl6 4 have been synthesized from their monometallic analogs C6H16N4O2CuCl2 1, C6H16N4O2ZnCl2 2, and were characterized by various spectroscopic and analytical methods. The complexes 1-4 reveal an octahedral geometry for both central metal ions Cu/Zn as well as for Sn metal ion. The interaction of complexes 1-4 with CT-DNA, were investigated by using absorption, emission, cyclic voltammetry, viscometry and DNA cleavage studies. The emission quenching of 3 and 4 by [Fe(CN)(6)](4-) depressed greatly when bound to CT-DNA. The results of spectroscopic. viscometric and cyclic voltammetry of complexes 3 and 4 revealed electrostatic mode of binding of the complexes with CT-DNA. These results revealed that 4 bind more avidly in comparison to 3 with CT-DNA. Gel electrophoresis of DNA with complexes 3 and 4 demonstrated that the complexes exhibit excellent cleavage activity under physiological conditions. (C) 2009 Elsevier B.V. All rights reserved.