Effect of substitution pattern of ancillary ligands on the DNA-binding behavior of two new Ru(II)-polypyridyl complexes.
The new ligand 2-(4-phenoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (ppip) and its Ru(II) complexes [Ru(2,9-dmp)2(ppip)]2+ (1) and [Ru(4,7-dmp)2(ppip)]2+ (2; 2,9- and 4,7-dmp = 2,9- and 4,7-dimethyl-1,10-phenanthroline, resp.) were synthesized and characterized. The binding properties of the two complexes towards calf-thymus DNA (CT-DNA) in buffered H2O (pH 7.2) were investigated by different spectrophotometric methods and viscosity measurements. Both 1 and 2 strongly bind to CT-DNA by means of intercalation, but with different binding strengths. In contrast to the more tightly bound complex 2, the sterically more-demanding complex 1 showed no fluorescence emission, neither alone nor in the presence of CT-DNA. Our results demonstrate that the position of Me groups on phenanthroline (phen) ancillary ligands significantly affects the overall DNA-recognition propensities of Ru(II)-polypyridyl complexes. Further, the partly resolved complex 2 was shown by circular dichroism (CD) to stereoselectively recognize CT-DNA, in contrast to 1.
Tan
Li-Feng
LF
College of Chemistry, Xiangtan University, Xiangtan 411105, PR China. lfwyxh@ya hoo.com.cn
Liu
Jian-Hua
JH
Wang
Fang
F
Zhang
Sheng
S
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000737:chemistry*; D013053:Spectrophotometry; D013237:Stereoisomerism; D014783:Viscosity
D008024:Ligands; D010455:Peptides; D017975:Ruthenium Compounds; D004247:DNA; C427203:calf thymus DNA