Department of Chemistry, NIS Centre of Excellence, and INSTM Reference Centre, University of Turin, Turin, Italy.
Dalton Trans. 2013 May 14;42(18):6564-71. doi: 10.1039/c3dt32865a.
The excited state dynamics and structure of the photochemically active complex cis-Ru(bpy)2(py)2 have been investigated using optical transient absorption (OTA) and X-ray transient absorption (XTA) spectroscopy, and density functional theory (DFT). Upon light-excitation in aqueous solution cis-Ru(bpy)2(py)2 undergoes ultrafast dissociation of one pyridine ligand to form cis-Ru(bpy)2(py)(H2O). OTA measurements highlighted the presence of two major time components of 1700 ps and 130 ps through which the system decays to the ground-state and evolves towards the photoproduct. XTA data were acquired after 150 ps, 500 ps, and 3000 ps from laser excitation (λexc = 351 nm) and provided the transient structure of the (3)MLCT state corresponding to the longer time component in the OTA experiment. In excellent agreement with DFT, XTA shows that the (3)MLCT geometry is characterized by an elongation of the dissociating Ru-N(py) bond and a shortening of the trans Ru-N(bpy) bond with respect to the ground state. Conversely, calculations show that the (3)MC state has a highly distorted structure with Ru-N(py) bonds between 2.77-3.05 Å.
采用光瞬态吸收（OTA）和 X 射线瞬态吸收（XTA）光谱法以及密度泛函理论（DFT）研究了光化学活性配合物顺式-[Ru（bpy）2（py）2]（2+）的激发态动力学和结构。在水溶液中用光激发后，顺式-[Ru（bpy）2（py）2]（2+）超快离解一个吡啶配体，形成顺式-[Ru（bpy）2（py）（H2O）]（2+）。OTA 测量突出显示系统通过 1700 ps 和 130 ps 的两个主要时间分量衰减到基态，并向光产物演化。XTA 数据是在激光激发后 150 ps、500 ps 和 3000 ps 时采集的（λexc = 351 nm），提供了与 OTA 实验中较长时间分量相对应的（3）MLCT 状态的瞬态结构。与 DFT 非常吻合，XTA 表明（3）MLCT 几何形状的特征是离解的 Ru-N（py）键伸长，与基态相比，反式 Ru-N（bpy）键缩短。相反，计算表明（3）MC 状态具有高度扭曲的结构，Ru-N（py）键在 2.77-3.05 Å 之间。
