Synthesis, characterization, DNA binding and cleavage of new symmetrical acyclic copper (II) complexes

New symmetrical acyclic binuclear copper (II) complexes [CuL](ClO4)2 1 and 2 were synthesized by template method, from bicompartmental ligand 2,6-bis((E)-(2-(2aminoethylamino)ethylimino)methyl)-4-methylphenol (L) and 2-((7E)-(2-((Z)-2-((naphthalen-1-yl) methyleneamino)ethylamino)ethylimino)methyl)-6-((9E)-(2-((Z)-2-((naphthalen-1-yl)methyleneamino) ethylamino)ethylimino) methyl)-4-methylphenol (L). These complexes were characterized by elemental analysis and spectroscopic techniques. The cyclic voltammogram of binuclear Cu(II) complexes exhibit two quasi-reversible reduction waves. The first reduction potential ranges from -0.6 V to -0.80 V and the second reduction potential lies in the range from -1.0 V to -1.25 V versus Ag/AgCl in Acetonitrile, 0.1 M TBAP. The DNA binding properties have been studied with the complexes 1 and 2 with calf thymus DNA. The complexes show good binding propensity to calf thymus DNA giving binding constant values in the range from 1.4 × 10 and 3.67 × 10M. The absorption, fluorescence and viscosity measurements spectral data suggests that the complexes are interacting strongly with DNA. These complexes display oxidative cleavage of supercoiled pBR322DNA in the presence of H2O2 at pH 7.2 and 37 ◦C using singlet oxygen as a reactive species. The binding affinities are in the following order: 2 > 1. KeywordsDNA binding and cleavage studies, copper (II) complexes DNA binding studies, intercalative binding mode and oxidative cleavage studies