Functional Studies Of Ruthenium(Ⅱ) Polypyridine Complexes Binding With DNA

DNA is the most important substance in the inherited password's translation, convey, reproduction for the life. Studying the interactions and mechanism of metal complexes binding with DNA may be a more complete understanding of the origin of life on a molecular level, which have great theoretical significance and potential applied values in biological science. Ruthenium(II) polypyridyl complexes have aroused intense interest because of their extensive applications in the fields of photochemistry, photophysics and biochemistry. In particular, their important application for probes of DNA structure, DNA mediated electron transfer, DNA footprinting and sequence-specific cleaving agents are well known.The aim of this paper is the design complexes with high affinity and specific recognition to DNA, as well as the understanding of factors, which might influence the DNA-binding affinity of the complexes. In order to investigate and explore the DNA-binding mechanism, a series of novel polypyridyl ligands and their ruthenium(II) complexes have been synthesized. The major contents as follows:First, a new flexible ligand BPIP and its Ru(II) complexes [Ru(bpy)2(BPIP)](ClO4)2·H2O and [Ru(phen)2(BPIP)](ClO4)2·H2O (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized and characterized by UV-vis, 1H NMR, and mass spectra. The binding of the two complexes with calf thymus DNA has been investigated by absorption, steady-state luminescence, CD spectra and viscosity measurements. The experimental results indicate that methene group existence or not have a significant effect on the DNA-binding and cleavage mechanism of these complexes.Secondly, a new polypyridyl ligand btip (btip = 2-benzo[b]thiophenimidazo [4,5-f]1,10-phenan-throline) which contain S atom and its ruthenium(II) complexes, [Ru(bpy)2(btip)]2+ and [Ru(dmb)2(btip)]2+ (dmb = 4,4'-dimethyl-2,2'-bipyridine) have been synthesized and characterized. The interactions of these complexes with DNA have been investigated. The effect of Cu2+ on the DNA interaction of the two complexes was studied by electronic absorption and emission methods.Otherwise, a new polypyridyl ligand tbtc and its ruthenium(II) complexes have been synthesized and characterized. The binding of the two complexes with calf thymus DNA has been investigated by absorption, steady-state luminescence, CD spectra and viscosity measurements. The results suggest that the complex [Ru(bpy)2(tbtc)](ClO4)2·2H2O was a good molecular"light switch".