Synthesis, crystal structure, antioxidation and DNA-binding properties of a dinuclear copper(II) complex with bis(N-salicylidene)-3-oxapentane-1,5-diamine

A Schiff base bis(N-salicylidene)-3-oxapentane-1,5-diamine (H2L) and its Cu(II) complex, [Cu-2(L)(2)]center dot CHCl3, have been synthesized and characterized by physicochemical and spectroscopic methods. Single-crystal X-ray analysis revealed that the complex is a centrosymmetric binuclear neutral entity, in which Cu(II) is a five-coordinate in a distorted trigonal bipyramidal geometry. The DNA-binding properties of the free ligand and the complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the H2L and the complex to DNA via the intercalation mode and the binding affinity of the complex were higher than that of the H2L. The intrinsic binding constants K-b of the ligand and the complex are 2.2x10(4) and 2.7x10(4)M(-1), respectively. Antioxidant assay in vitro shows the Cu(II) complex possesses significant antioxidant activities and better scavenging activity than the H2L and other antioxidants.