Synthesis, structure, DNA-binding properties and antioxidant activity of a nickel(II) complex with bis(N-allylbenzimidazol-2-ylmethyl)benzylamine

A V-shape ligand bis(N-allylbenzimidazol-2-ylmethyl)benzylamine (babb) and its nickel complex, [Ni(babb)(2)](pic)(2) (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray revealed that the coordination sphere around Ni(II) is distorted octahedral with a N-6 ligand set, in which six nitrogen atoms were afforded by two tridentate ligand babb. The DNA-binding properties of the free ligand babb and Ni(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that babb and Ni(II) complex both bind to DNA via an intercalative binding mode, and the affinity for DNA is more strong in case of Ni(II) complex when compared with babb. The intrinsic binding constants (K-b) of the Ni(II) complex and ligand with DNA were 3.65 x 10(4) M-1 and 2.26 x 10(3) M-1, respectively. Additionally, Ni(II) complex also exhibited potential antioxidant properties in vitro studies. (C) 2011 Elsevier B.V. All rights reserved.