Synthesis, crystal structure, and DNA cleavage activity of a dinuclear nickel(II) complex with a macrocyclic ligand

Abstract

A new Ni(II) complex, namely [Ni2(OAc)L]·ClO4·H2O, was synthesized by [2 + 2] cyclo-condensation between 2,6-diformyl-4-methylphenol and N,N-bis(3-aminopropyl)-4-methoxybenzylamine (amba) in the presence of nickel(II) and characterized by spectroscopy, elemental analysis, and X-ray single crystal diffraction. The interactions of the complex with DNA have been measured by spectroscopy and viscosity measurements. Absorption spectroscopic investigation reveals intercalative binding of the Ni(II) complex with DNA, with a binding constant of 2.6 × 104 M−1. Fluorescence spectroscopy shows that the Ni(II) complex can displace ethidium bromide and bind to DNA, with a quenching constant of 7.57 × 103 M−1. The appearance of increased CD bands near 245 and 275 nm gives evidence for effective complex DNA binding. The agarose gel electrophoresis studies show that the complex displays effective DNA cleavage activity in the absence of any external agents.