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.

Keywords:

• Dicyanamide
• 1-Amidino-O-alkylurea
• DNA
• EPR
• Chloro bridge
• Polymer

Acknowledgements

We thank Prof Ashutosh Ghosh, Department of Chemistry, Calcutta University for his valuable crystallographic discussions. One of the authors (S. Pramodini Devi) is grateful to DST, Government of India for financial support under the DST-Women Scientist Scheme-A.