Δ-和Λ-[Ru(bpy)2(HPIP)2+两种异构体对小牛胸腺DNA不同键合速率的CD光谱证明

Wilson1]于1997年发表了关于DNA导电性的评论性文章, 介绍了各种学派的观点. 争论焦点在于DNA是否为导体. 将两种配合物键合于DNA作为接头, 通过研究电子转移可确定DNA是否为导线, 其中配合物和DNA键合模式是研究的关键. Barton2]和Norden3]均认为2+ 配合物能强烈插入DNA中. 我们4]曾从改变辅助配体角度出发, 研究2+和DNA的作用, 结果证明2+具有更强的插入能力, 并结合文献把键合模式归纳为3类, 即静电键合、沟面键合和插入键合5]. 最近, 我们报道了新体系2+/DNA/2+(bpy=2,2′-bipyridine), 其中2+和2+均可插入DNA中. 2+是光诱导电子给予体, 2+是电子接受体, 荧光光谱证明前者的电子通过DNA中的π电子转移给后者, 导致后者荧光猝灭, 结果支持DNA是导线的观点6]. 2+中的PIP芳香环和DNA碱基芳环组成π电子的堆积力7], 从而增强了对DNA的插入能力.

Observation of the Different Binding Rates of Δ- and Λ-2+ with Calf Thymus DNA via CD Spectra

The complexes of \| and \|\{\ \}\+\{2+\}(bpy=2,2\|bipyridine, HPIP=2\|(2\|hydroxyphenyl)imidazo\{\ \}\ phenanthroline) were prepared and their racemic complex were dialysed against calf thymus DNA(CT\|DNA). During the course of dialysis with the solution stirring for 48 h, the CD signals of the dialyzate experience disappearing\|appearing\|disappearing. However, in the similar conditions except for not stirring, strong CD signals appeared. From the results obtained, several novel opinions were suggested. Firstly, the evidence of different binding rates of \| and \|enantiomers of polypyridyl ruthenium() complexes with CT\|DNA, the first example, was demonstrated. As for the dialysis experiment, binding of \|enantiomer is dynamically preferred for CT\|DNA. Secondly, the different binding rates may be deduced from different binding modes of the enantiomers.