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

Salicylaldehyde 2-phenylquinoline-4-carboylhydrazone (H2L), and its novel cobalt(II), nickel(II) complexes (M·HL·3H2O)·NO3 (MCo (1), MNi (2)), have been synthesized and characterized by elemental analysis, molar conductivity, mass spectra and IR spectra. The interaction of these complexes with calf-thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. The two complexes showed absorption hyperchromism in the range of 190–280 nm. The binding constant have been determined using absorption measurement and found to be 0.89 × 105 M−1 and 2.2 × 105 M−1, respectively. Results suggest that the two complexes bind to DNA via a groove binding mode.