Zhang Xiaoyi, Pápai Mátyás, Møller Klaus B, Zhang Jianxin, Canton Sophie E
X-ray Sciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA.
Department of Chemistry, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark.
Molecules. 2016 Feb 19;21(2):235. doi: 10.3390/molecules21020235.
Characterizing the geometric and electronic structures of individual photoexcited dye molecules in solution is an important step towards understanding the interfacial properties of photo-active electrodes. The broad family of "red sensitizers" based on osmium(II) polypyridyl compounds often undergoes small photo-induced structural changes which are challenging to characterize. In this work, X-ray transient absorption spectroscopy with picosecond temporal resolution is employed to determine the geometric and electronic structures of the photoexcited triplet state of Os(terpy)₂ (terpy: 2,2':6',2″-terpyridine) solvated in methanol. From the EXAFS analysis, the structural changes can be characterized by a slight overall expansion of the first coordination shell [OsN₆]. DFT calculations supports the XTA results. They also provide additional information about the nature of the molecular orbitals that contribute to the optical spectrum (with TD-DFT) and the near-edge region of the X-ray spectra.
表征溶液中单个光激发染料分子的几何结构和电子结构是理解光活性电极界面性质的重要一步。基于钌（II）多吡啶化合物的“红色敏化剂”大家族通常会发生微小的光致结构变化，这些变化很难进行表征。在这项工作中，采用具有皮秒时间分辨率的X射线瞬态吸收光谱来确定在甲醇中溶剂化的Os(terpy)₂（terpy：2,2':6',2″-三联吡啶）光激发三重态的几何结构和电子结构。通过EXAFS分析，结构变化可以通过第一配位层[OsN₆]的轻微整体扩张来表征。DFT计算支持XTA结果。它们还提供了有关对光谱（使用TD-DFT）和X射线光谱近边缘区域有贡献的分子轨道性质的额外信息。
