Gadolinium(III) and dysprosium(III) complexes with a Schiff base bis(<i>N</i>-salicylidene)-3-oxapentane-1,5-diamine: synthesis, characterization, antioxidation, and DNA-binding studies

Abstract

A pentadentate Schiff base bis(N-salicylidene)-3-oxapentane-1,5-diamine (H2L) and its lanthanide(III) complexes, [GdL(NO3)(DMF)(H2O)] (1) and [Dy2L2(NO3)2]·2H2O (2), have been synthesized and characterized by physical, chemical, and spectroscopic methods. Single crystal X-ray structure reveals that 1 is a discrete mononuclear species with nine-coordinate Gd(III) in a distorted mono-capped square antiprism geometry. Complex 2 is a centrosymmetric binuclear neutral entity, in which Dy(III) is eight-coordinate in a distorted square antiprism. Electronic absorption titration spectra, ethidium bromide competitive experiments, and viscosity measurements indicate that both the ligand and complexes bind calf thymus DNA, presumably via groove binding. Investigations of antioxidant activities show that both complexes have some scavenging effects for hydroxyl and superoxide radicals.