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

<p>Three new copper(II) complexes, [(CuL)₂Cl{N(CN)₂}₃]_n, where L = 1-amidino-O-methylurea (<b>1</b>), 1-amidino-O-ethylurea (<b>2</b>), or 1-amidino-O-propylurea (<b>3</b>), have been synthesized and characterized. The single crystal X-ray structure of <b>2</b> and X-ray powder diffraction analysis on <b>1</b> and <b>3</b> show that they crystallize in the monoclinic system. The neutral dinuclear entity of <b>2</b> 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 <b>1</b>–<b>3</b> 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 <b>1</b> > <b>2</b> > <b>3</b>.</p