Synthetic, structural, electrochemical and DNA-binding aspects of a novel oximato bridged copper(II) dimer

Abstract

A dimeric double oximato-bridged (μ1,2-N-O) Cu(II) complex, [Cu2L2(ClO4)2]·2H2O (1), was synthesized from the reaction of equimolar proportion of a novel Schiff base ligand, 1-phenyl-1-(pyridin-2-yl-hydrazono)-propan-2-one oxime (LH), and copper(II)perchlorate hexahydrate in methanol. C, H and N microanalyses, gravimetric copper estimation, FT-IR, UV–Vis (solid state as well as in solution), ESI-MS spectra, molar electric conductivity, EPR and room temperature magnetic susceptibility measurements were performed to characterize 1. The X-ray crystal structure of 1 shows that each copper center in 1 is in ‘N3O2’ coordination environment with a Cu⋯Cu separation of 3.595Å. 1 follows unique two-step mono-electronic oxidative steps in its CV in methanol. ESI-MS spectrum of 1 indicates that the dimeric core unit retains its identity in solution as well. Interaction of 1 with Calf thymus (CT) DNA was studied by spectroscopic and calorimetric techniques. The mode of binding was investigated by ethidium bromide displacement assay. This binding enhanced the stabilization of the DNA structure against thermal strand separation. The magnitudes of the association constant as derived from spectroscopic and calorimetric studies are in good harmony.