Wilhelmsson L Marcus, Westerlund Fredrik, Lincoln Per, Nordén Bengt
Department of Physical Chemistry, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
J Am Chem Soc. 2002 Oct 16;124(41):12092-3. doi: 10.1021/ja027252f.
We here report a remarkably slow rearrangement of binding modes for a binuclear ruthenium(II) complex upon interaction with DNA. It has been previously shown that Delta,Delta-[mu-(11,11'-bidppz)(phen)4Ru2]4+ binds to DNA in one of the grooves. However, we find that this is only an initial, metastable, binding mode, which is extremely slowly reorganized into an intercalative binding geometry. The slow rearrangement and dissociation, revealed by flow linear dichroism and fluorescence spectroscopy, are concluded to be a result from the complex being threaded through the DNA, with one of the bridging aromatic dppz ligands intercalated between the base pairs of the DNA, placing one metal center in the minor groove and one in the major groove. A negative LD, a high luminescence quantum yield, and long luminescence lifetimes, similar to the intercalating complex Delta-[Ru(phen)2dppz]2+, indicate intercalation of the bidppz moiety. The unique slow dissociation of the complex in its final DNA-binding mode suggests that this class of threading, partially intercalated binuclear complexes may be interesting in the context of cancer therapy. Also, their unique optical and photophysical properties could make such complexes, either alone or scaffolded by DNA structures, of interest for the development of nanometer-sized molecular optoelectronic devices.
我们在此报道了一种双核钌（II）配合物与DNA相互作用时结合模式的显著缓慢重排。先前已表明，Δ,Δ-[μ-(11,11'-联二吡啶并菲)(邻菲罗啉)4Ru2]4+在其中一条沟槽中与DNA结合。然而，我们发现这只是一种初始的、亚稳态的结合模式，它会极其缓慢地重新组织成一种插入式结合几何结构。流动线性二色性和荧光光谱揭示的缓慢重排和解离被认为是由于配合物穿过DNA，其中一个桥连芳族二吡啶并菲配体插入到DNA的碱基对之间，使一个金属中心位于小沟中，另一个位于大沟中。与插入式配合物Δ-[Ru(邻菲罗啉)2二吡啶并菲]2+相似的负线性二色性、高发光量子产率和长发光寿命表明二吡啶并菲部分发生了插入。该配合物在其最终DNA结合模式下独特的缓慢解离表明，这类穿线式、部分插入的双核配合物在癌症治疗方面可能具有吸引力。此外，它们独特的光学和光物理性质可能使这类配合物，无论是单独存在还是由DNA结构支撑，在纳米级分子光电器件的开发中具有吸引力。
