Synthesis, Characterization And Interaction With DNA Of Complexes Containing Copper And Cobalt

In recent years, much attention has been paid to the interactions between metal complexes and DNA, which not only provide an opportunity to understand the structure and function of DNA further,but also give important theoretical basis for the synthesis of artificial nucleases and anti-cancer drug. In this study, two cobalt(Ⅱ) complexes and two copper(Ⅱ) complexes were synthesized and structurally characterized. The DNA-binding and DNA cleavage activities of these metal complexes were also studied.The ligand9-anthraldehyde thiosemicarbazone (ATSC) derived from thiosemicarbazide and9-anthraldehyde was synthesized. The cobalt(Ⅱ)[Co(ATSC)3] was synthesized and characterized by infrared spectrum, elemental analysis, X-Ray crystal diffraction, thermogravimetric analysis and ESI-MS. The complex is distorted six-coordinate octahedral geometry, in a monoclinic system with space group P-1. The interactions of the complex with CT-DNA were investigated by UV-Vis absorption spectra, circular dichroism (CD) spectra and fluorescence spectra. The results suggested that it binds to DNA through a groove binding mode. The ligand9-anthraldehyde-N4-methyl thiosemicarbazone (MeATSC) derived from4-Methylthiosemicarbazide and9-anthraldehyde was synthesized. The cobalt(Ⅱ)[Co(MeATSC)3] was synthesized and characterized by infrared spectrum, elemental analysis, thermogravimetric analysis and ESI-MS. The interactions of the complex with CT-DNA were investigated by complex-DNA binding experiments. The results suggested that it binds to DNA through a groove binding mode.The Cu(Ⅱ) complex [Cu(PDPH)Cl] derived from bispyridylpyrrolide(PDPH) and CuCl was synthesized. The complex is four-coordinate square planar geometry, in a orthorhombic system with space group Pccn. The interaction of the copper(Ⅱ) complex with calf thymus DNA (CT-DNA) is investigated by UV-Vis absorption spectra, CD spectra and fluorescence spectra. It is proposed that the complex binds to CT-DNA through groove binding mode. Nuclease activity of the complex is also studied by gel electrophoresis method. The complex can efficiently cleave supercoiled pBR322DNA in the presence of ascorbate (H2A) via oxidative pathway. The preliminary mechanism of DNA cleavage by the complex with different inhibiting reagents indicates that the hydroxyl radicals was involved as the active species in the DNA cleavage process.The Cu(Ⅱ) complex [Cu2(PDPH)2(N3)2] derived from [Cu(PDPH)Cl] and NaN3was synthesized. The complex is four-coordinate geometry, in a orthorhombic system with space group Pbcn. The interaction of the copper(Ⅱ) complex with calf thymus DNA (CT-DNA) is investigated by UV-Vis absorption spectra, CD spectra and fluorescence spectra. It is proposed that the complex binds to CT-DNA through groove binding mode. Nuclease activity of the complex is also studied by gel electrophoresis method. The complex can efficiently cleave supercoiled pBR322DNA in the presence of H2A.