Syntheses, crystal structures, and DNA-binding of some nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane and pseudohalides

Abstract

A series of neutral octahedral nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane (L) and pseudohalide (X), formulated as [Ni^II(L)X₂] (where X = azide (1), cyanate (2), and isothiocyanate (3)), was synthesized. The complexes were characterized by physico-chemical and spectroscopic methods, and 1 and 3 also by single-crystal X-ray diffraction analyses. The structural study shows nickel in a distorted octahedral geometry comprised of the tetradentate NSSN ligand with trans pyridines and monocoordinated pseudohalides in cis positions. In dimethylformamide solution, the complexes had quasi-reversible Ni^II/Ni^III redox couples in cyclic voltammograms with E _1/2 values of +0.732, +0.747, and +0.815 V for 1, 2, and 3, respectively. To examine the biological activities of these complexes, interaction of 3 with calf thymus DNA was studied spectroscopically, showing groove-binding interaction.

Keywords:

• Nickel(II) complex
• Crystal structure
• DNA-binding study

Acknowledgments

Financial support from the Department of Science and Technology, New Delhi, India is gratefully acknowledged.