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

The reaction of the copper(II) diclofenac complex [Cu(dicl)(HO)] (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)(HO)](dicl)·2HO (2), [Cu(pn)(HO)](dicl)·2HO (3), [Cu(unsym-dmen)(HO)](dicl)·HO (4) and [Cu(temed)(dicl)] (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.