Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA.
Inorg Chem. 2010 May 3;49(9):4257-62. doi: 10.1021/ic9025365.
A new ruthenium polypyridyl complex, Ru(bpy)(2)(dpqp) (bpy = 2,2'-bipyridne; dpqp = pyrazino[2',3':5,6]pyrazino[2,3-f][1,10]phenanthroline), shows strong luminescence in water at room temperature, a behavior that is strikingly different from that of the nonemissive "DNA light-switch" prototype Ru(bpy)(2)(dppz) (dppz = dipyrido[3,2-a:2'-3'-c]phenazine) under similar conditions. Variation of the absorption and emission spectra of Ru(bpy)(2)(dpqp) as a function of the pH is consistent with the occurrence of two ground-state protonation steps associated with the dpqp ligand and an apparent pK(a)* of 2.1. Electrochemistry and theoretical calculations indicate that the lowest unoccupied molecular orbital (LUMO) of Ru(bpy)(2)(dpqp) is localized on the distal portion of the dpqp ligand and lies at a lower energy than the dppz-based LUMO of Ru(bpy)(2)(dppz). The combination of its strong DNA binding affinity and relatively long-lived triplet metal-to-ligand charge-transfer excited state in an aqueous solution results in more efficient DNA photocleavage by Ru(bpy)(2)(dpqp) than Ru(bpy)(2)(dppz).
一种新型钌多吡啶配合物Ru(bpy)(2)(dpqp)（bpy=2,2'-联吡啶；dpqp=吡嗪并[2',3':5,6]吡嗪并[2,3-f][1,10]菲咯啉），在室温下的水中具有强烈的发光性，这种行为与非发光的“DNA 光开关”原型Ru(bpy)(2)(dppz)（dppz=二吡啶并[3,2-a:2',3'-c]吩嗪）在类似条件下的行为明显不同。Ru(bpy)(2)(dpqp)吸收和发射光谱随 pH 值的变化与 dpqp 配体的两个基态质子化步骤的发生以及表观 pK(a)*为 2.1 相一致。电化学和理论计算表明，Ru(bpy)(2)(dpqp)的最低未占据分子轨道（LUMO）定域在 dpqp 配体的远端部分，其能量低于Ru(bpy)(2)(dppz)的基于 dppz 的 LUMO。Ru(bpy)(2)(dpqp)在水溶液中具有较强的 DNA 结合亲和力和相对长寿命的三重态金属-配体电荷转移激发态，这导致其比Ru(bpy)(2)(dppz)更有效地进行 DNA 光切割。
