Copper(II), palladium(II) and platinum(II) complexes with 2,2-thiophen-yl-imidazole: Synthesis, spectroscopic characterization, X-ray crystallographic studies and interactions with calf-thymus DNA

New Cu(II), Pd(II) and Pt(II) complexes with 2,2-thiophen-yl-imidazole (Thim) were synthesized. Elemental and MS analyses indicate the [MCl2(Thim)(2)] composition. The Cu(II) and Pd(II) complexes had their structures solved by single crystal XRD, where each molecule of the ligand coordinates to the metal by the imine nitrogen of the imidazole group. The free ligand had its structure solved by powder XRD studies. Due to the absence of crystallographic data, the Pt(II) complex was analyzed by solid state NMR and IR spectroscopies. DFT studies were also performed and an analogous structure to the Pd(II) complex is proposed for Pt-Thim. Thim, Cu-Thim and Pd-Thim were evaluated about their DNA interactions by UV-Vis spectroscopy, fluorescence measurements with ethidium bromide, Circular Dichroism and determination of denaturation temperature. The results permitted proposing the interaction of Thim with DNA by hydrogen bonding, while for the complexes a covalent bonding is proposed. (C) 2016 Elsevier B.V. All rights reserved.