Five new cobalt(II) complexes based on indazole derivatives: synthesis, DNA binding and molecular docking study

Abstract

Five cobalt(II) complexes based on 1H-indazole-3-carboxylic acid (H2L), [Co(phen)(HL)2]·2H2O (1), [Co(5,5′-dimethyl-2,2′-bipy)(HL)2] (2), [Co(2,2′-bipy)2(HL)2]·5H2O (3), [Co2(2,9-dimethyl-1,10-phen)2(L)2] (4) and [Co2(6,6′-dimethyl-2,2′-bipy)2(L)2]·H2O (5) (2,2'-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and structurally characterized by elemental analyses, IR and UV-vis spectroscopies and single-crystal X-ray crystallography. The results indicate that 1–3 possess mononuclear Co(II) structures, while 4 and 5 exhibit binuclear structure. 1D water tape which is linked by the multiple hydrogen bonds was embedded in the 3D motif of complex 3. Complexes 4 and 5 show two orthogonal planes of motif that was constituted by phen/2,2′-bipy and indazole acid, respectively. The intermolecular interactions including hydrogen bonding and π-π stacking interactions are stabilizing these complexes. The interactions of the synthesized complexes with calf-thymus DNA (CT-DNA) have been investigated by UV-vis absorption titration, ethidium bromide displacement assay and viscosity measurements. The results reveal that the complexes could interact with CT-DNA via a groove binding mode. Their behavior rationalization was further theoretically studied by molecular docking.