Effect of ligand substitution on DNA binding ability of two new square planar copper(II)–Schiff base complexes

Two terdentate NNO donor Schiff base ligands CH3C(OH)CHC(CH3)NCH2C5H4N [HL1] and C6H5C(OH)CHC(CH3)NCH2C5H4N [HL2] were used to synthesize two mononuclear square planar copper(II) complexes, [CuL1(CF3COO)] (1) and [CuL2(CF3COO)] (2). The complexes were characterized by elemental analyses, FT-IR, UV–vis spectral methods and their structures were established by single crystal X-ray diffraction study. The biochemical activity of the complexes towards DNA binding were performed using absorbance and fluorescence titration methods and their mode of binding with calf thymus DNA has been established by viscosity measurement technique.