Synthesis, characterization, and DNA-binding properties of copper(II), cobalt(II), and nickel(II) complexes with salicylaldehyde 2-phenylquinoline-4-carboylhydrazone

Salicylaldehyde 2-phenylquinoline-4-carboylhydrazone (H2L), and its novel copper(II), cobalt(II), and nickel(II) complexes MHL · Cl · nH2O [M=Cu n = 3 (1), M=Co n = 2 (2), M=Ni n = 3.5 (3)] have been synthesized and characterized by elemental analysis, molar conductivity, spectroscopic, and thermal analysis. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements. The results suggest that these complexes bind to DNA via an intercalation binding mode and their affinity to DNA follows the order of 3 > 1> 2.