A spectroscopic study on Calf thymus DNA binding properties of nickel (II) complex with imidazole derivatives of 1,10-phenanthroline ligand

In this study, a nickel (II) complex with 1,10-phenanthroline based ligand, [Ni(FIP)2](OAC)2 (1) with FIP = 2-(Furan-2-yl)-1H-Imidazole[4,5-f][1,10] phenanthroline as ligand was synthesized and characterized by spectroscopic methods and elemental analysis. The interaction of [Ni(FIP)2](OAC)2 (1) with calf-thymus DNA (ct-DNA) was studied by UV-vis absorption, fluorescence spectroscopies and viscosity measurements in 20 mM Tris/HCl buffer solution, pH 7.0 at 25 °C. The complex (1) interacts with ct-DNA with an intrinsic binding constant of 1.11 ×105 M-1. Furthermore, the thermodynamic studies suggested that the interaction processes were endothermic disfavored (ΔH 0) and entropy favored (ΔS 0). The viscosity studies showed no considerable increasing changes in the viscosity of ct-DNA with increasing of the complex (1) concentration. Therefore, the [Ni(FIP)2](OAC)2 complex bind to ct-DNA via hydrophobic interaction as the main forces acting during the binding processes and the mode of binding is groove binding which was illustrated by hyperchromism in the UV-Vis absorption band of [Ni(FIP)2](OAC)2 (1) with addition of ct-DNA and the decreasing of ethidium bromide (EB)-ct-DNA complex fluorescence in the presence of different concentrations of [Ni(FIP)2](OAC)2 complex and the unchanged viscosity of ct-DNA.