以三种新合成的钌配合物[Ru(bpy)2(7-CH3-dppz)]^2+、[Ru(bpy)2(7-F-dppz)]^2+、[Ru(phen)2(7- F-dppz)]^2+为研究对象,采用时间分辨的荧光光谱技术分别测量了这三种钌配合物与小牛胸腺DNA相互作用时的瞬态荧光动力学过程.结果表明:[Ru(bpy)2(7-CH3-dppz)]^2+的发光寿命最长(约382 ns),而[Ru(bpy)2(7-F-dppz)]^2+的发光寿命最短(约65 ns).分析表明:钌配合物的发光来源于配合物分子中的电荷转移态到基态的辐射跃迁.通过钌配合物与DNA的相互作用,使得配合物激发态分子的无辐射弛豫几率减小,从而导致发光寿命的增加.配合物的分子与DNA相互作用越强,激发态分子的无辐射弛豫几率越小,发光寿命也越长,最终导致高的发光效率. 配合物的分子结构对配合物的分子与DNA的相互作用具有重要的影响.
To study the emission dynamics for the Ru( Ⅱ ) complexes bond to DNA , and show the effects of the molecular structure of complexes on bonding to DNA, three kinds of Ru ( Ⅱ ) complexes [ Ru (bpy) 2 (7- CH3-dppz) ]^2+, [Ru(bpy)2 (7-F-dppz) ]^2+ and [ Ru(phen)2 (7- F-dppz) ]^2+, [ bpy = 2,2'-bipyridine, dppz = dipyrido [ 3,2-a :2', 3 '-c ] phenazine , phen = 1,10-phenanthroline ] , have been synthesized. Their electronic absorption spectras and steady-state fluorescence spectra have been investigated . The electronic absorption spectra show that the wavelength of metal-to-ligand charge transfer (MLCT) peaks of the three kinds of Ru complexes are all at about 400 nm. Under the same power of photoexcitation at the wavelength of the MLCT peaks , the binding of [ Ru (bpy) 2 (7-CH3-dppz) ] ^2+ to calf thymus DNA has the strongest fluorescence, and [ Ru(bpy)2(7-F-dppz) ]^2+ to calf thymus DNA has the feeblest one. On the base of the study for the absorption spectra and steady-state fluorescence spectra, the transient luminescence in three kinds of Ru ( Ⅱ ) complexes bond to DNA have been studied by using picosecond time resolved spectroscopy. The results show that the fluorescence decay for the Ru ( Ⅱ) complexes bond to DNA exhibits as a biexponential form. Among the three kinds of Ru (Ⅱ ) complexes, [ Ru (bpy) 2 (7-CH3-dppz) ] ^2 + bonds to DNA has the longest luminescence lifetime(about 382 ns and 108 ns), [ Ru(bpy)2 (7-F-dppz)]^2 + bonds to DNA has the shortest lifetime( about 65 ns and 16 ns ), and [ Ru (phen)2 (7- F-dppz)] ^2 + bonds to DNA has the lifetime (about 326 ns and 37 ns) shorter then [ Ru(bpy)2 (7-CU3-dppz) ]^2 + and longer then [ nu(bpy)2 (7-F-dppz) ]^2 + The possible origin of the luminescence dynamics has been discussed. The luminescence is attribute to radiative decay from the MLCT excited state to the ground state. Through the interaction with th