DFT analysis and DNA binding, cleavage of copper(II) complexes

Abstract

Ternary copper(II) complexes, [Cu(phen)(L-Ser)H2O](NO3) (1) and [Cu(bpy)2NO3](NO3) (2) (phen=1,10-phenanthroline, L-Ser=L-Serine, bpy=2,2′-bipyridine), has been synthesized and structurally characterized by elemental analyses, IR, UV‐visible and single-crystal X-ray crystallography and DFT studies. The complexes shows a distorted square-pyramidal (4+1) CuN3O2, CuN4O coordination sphere. The optimized structure of the present complexes has been studied using the DFT/B3LYP/6-31G⁎(d,p)/LANL2DZ level of theory. The vibrational assignments and HOMO–LUMO were theoretically examined by means of the hybrid DFT method. The interactions of the complexes with calf thymus DNA (CT-DNA) have been investigated by UV–Vis absorption titration, ethidium bromide displacement assay, viscometric titration experiment and cyclic voltammetric studies. Especially the complex 1, strongly bind to calf-thymus DNA. The intrinsic binding constants of the copper(II) complexes with CT-DNA are 1.42×105M−1 and 1.18×104M−1 for 1 and 2, respectively. Also, the cleavage of pBR322 DNA with copper(II) complexes was studied using gel electrophoresis method. The complexes were shown to be a partial intercalation mode of binding into DNA.