Synthesis, characterization and DNA binding investigations on 1D polymeric copper(II) complexes of 1-amidino-O-alkylurea (alkyl = methyl, ethyl or propyl) having both dicyanamido and chloro bridges

Abstract

Three new copper(II) complexes, [(CuL)2Cl{N(CN)2}3]n, where L = 1-amidino-O-methylurea (1), 1-amidino-O-ethylurea (2), or 1-amidino-O-propylurea (3), have been synthesized and characterized. The single crystal X-ray structure of 2 and X-ray powder diffraction analysis on 1 and 3 show that they crystallize in the monoclinic system. The neutral dinuclear entity of 2 contains a crystallographic 2-fold axis passing through the amido nitrogen of a bridging dicyanamido ligand. The dinuclear units are bridged by weak Cu … Cl interactions through the axial position of both copper ions to form a 1D polymer. The interaction of 1–3 with calf-thymus DNA (CT-DNA) has been explored by using absorption, emission, thermal denaturation, cyclic voltammetric studies, and viscosity experiments. The complexes bind to CT-DNA by non-intercalative mode and the order of binding ability is 1 > 2 > 3.