Observation of the different binding rates of Delta- and Lambda-[Ru(bpy)(2)(HPIP)](2+) with calf thymus DNA via CD spectra

The complexes of Delta- and Lambda-[Ru(bpy)(2)(HPIP)](2+) (bpy = 2,2'-bipyr idine, HPIP = 2(8-hydroxyphenyl) imidazo [4,5-f][1,10] phenanthroline) were prepared and their racemic complex were dialysed against calf thymus DNA(C T-DNA). During the course of dialysis with the solution stirring for 48 h, the CD signals of the dialyzate experience disappearing-appearing-disappear ing. However, in the similar conditions except for not stirring, strong CD signals appeared, From the results obtained, several novel opinions were su ggested, Firstly, the evidence of different binding rates of Delta- and Lam bda-enantiomers of polypyridyl ruthenium(II) complexes with CT-DNA, the fir st example, was demonstrated. As for the dialysis experiment, binding of La mbda-enantiomer is dynamically preferred for CT-DNA, Secondly, the differen t binding rates may be deduced from different binding modes of the enantiom ers.