Ternary paddlewheel copper(II) complexes: synthesis, structural elucidation, DNA-binding, anti-oxidant and conductance studies

Abstract

ABSTRACTTwo new binuclear Cu(II) complexes Cu2L4(DMS)2 (1) and Cu2L4(3BrPy)2 (2) where L = para-chlorophenyl acetate, DMS = dimethylsulfoxide and 3BrPy = 3-bromopyridine have been synthesised and characterised using FT-IR, single crystal XRD analysis, absorption and conductance studies. In both the complexes copper(II) ion lies in distorted square pyramidal geometry where the apical position is occupied by pyridine in monodentate fashion while the equatorial positions are occupied by four carboxylate ligands in bidentate coordination mode. The supramolecular structures of the complexes arise primarily as a result of C–H…O and H–C…H types of interactions and are different owing to the different apical ligands. The DNA-binding activity of the complexes has been studied through absorption spectroscopy, viscometry and competitive ethidium bromide displacement techniques. These techniques indicated a mixed electrostatic and intercalative mode of interaction with DNA-binding constant values Kb of 1.98 × 104 M−1 and 2.86 × 104 M−1 for complexes 1 and 2, respectively. These activities represent the preliminary biological relevance of the synthesised complexes.