Polypyridyl Ni(II) complex, [Ni(tppz)2]2+: Structure, DNA- and BSA binding and molecular modeling

Abstract

The mononuclear Ni(II) complex, [Ni(tppz)2]2+, where tppz is 2,3,5,6-tetra(2-pyridyl)pyrazine, has been prepared and characterized by elemental analysis, spectroscopic methods and single crystal X-ray structure analysis. The interaction of the complex with calf-thymus DNA (CT-DNA) has been monitored by UV-Vis, competitive fluorescence titration, circular dichroism (CD), voltammetric techniques and gel electrophoresis. The results have indicated that the complex binds to CT-DNA by three biding modes, viz., electrostatic, groove and partial insertion of a pyridyl ring of the tppz ligand between the base stacks of double-stranded DNA. The molecular docking of the complex with DNA sequence d(ACCGACGTCGGT)2 suggests two binding modes, viz., groove and partial intercalative binding. The results have also shown good binding propensity of the complex to BSA. The molecular modeling has indicated that the binding mode of the complex to BSA is of hydrophobic forces and hydrogen bond interaction. © 2013 Elsevier Ltd. All rights reserved.