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.