Copper(II) diclofenac complexes: Synthesis, structural studies and interaction with albumins and calf-thymus DNA

Abstract

The reaction of the copper(II) diclofenac complex [Cu(dicl)2(H2O)2] (1) (dicl = deprotonated diclofenac (Hdicl)) with the chelating N-donor ligands ethylenediamine (en), propan-1,3-diamine (pn), unsymmetrical dimethylethylene-diamine (unsym-dmen) and N,N,N′,N′-tetramethylethylene-diamine (temed) in methanol-water (4:1 v/v) yielded the novel copper(II) complexes [Cu(en)2(H2O)2](dicl)2·2H2O (2), [Cu(pn)2(H2O)2](dicl)2·2H2O (3), [Cu(unsym-dmen)2(H2O)](dicl)2·H2O (4) and [Cu(temed)(dicl)2] (5), respectively. All the synthesized complexes were characterized by spectroscopic (UV–vis, FT-IR) methods. The structures of complexes 2, 3 and 5 were unambiguously determined by single-crystal X-ray crystallography. X-ray structures of complexes clearly revealed the ionic structure of complexes 2, 3 and the covalent structure of complex 5. The geometry of complex 4 was optimized by Density Functional Theory (DFT) calculations. The ability of the complexes 1–5 to bind to calf-thymus DNA was monitored in vitro by diverse techniques (UV–vis spectroscopy, cyclic voltammetry, viscosity measurements) and via competitive studies with ethidium bromide. The interaction of complexes 1–5 with bovine serum albumin was studied in vitro by fluorescence emission spectroscopy and the corresponding binding constants were calculated. The biological behavior of complexes 1–5 was compared with previously reported Cu(II), Mn(II) and Ni(II) complexes of diclofenac.