Nguyen Phuong Ngoc, Watanabe Hiroshi, Tamaki Yusuke, Ishitani Osamu, Kimura Shin-Ichi
Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
Sci Rep. 2019 Aug 13;9(1):11772. doi: 10.1038/s41598-019-48191-4.
To reveal highly efficient photocatalytic properties of an artificial photosynthesis material Re(CO)(bpy){P(OEt)}, we have directly observed the photo-induced relaxation dynamics and reductive quenching process of the photo-excited state on a photosynthesis material in Triethanolamine (TEOA) solvent as an electron donor by time-resolved attenuated total reflection spectroscopy in the terahertz (THz) region. The spectrum of the complex in TEOA has an intermolecular vibrational mode between the complex and TEOA molecules, which reflects the precursor of the reductive quenching process. The intermolecular vibrational mode has three-step relaxation process in a picosecond timescale after photo-excitation, where firstly the triplet metal-to-ligand charge transfer excited state is vibrationally cooled down, secondly the distance between Re and TEOA is reduced by the rotation of TEOA molecules due to dipole-dipole interaction accelerated by heat transfer, and finally electrons transfer from TEOA to Re. These observations provide us the detailed information of the electron transfer process of photocatalytic properties of Re(CO)(bpy){P(OEt)} in TEOA solvent.
为了揭示人工光合作用材料Re(CO)(bpy){P(OEt)}的高效光催化性能，我们通过太赫兹（THz）区域的时间分辨衰减全反射光谱，直接观察了作为电子供体的三乙醇胺（TEOA）溶剂中光合作用材料上光激发态的光致弛豫动力学和还原猝灭过程。TEOA中该配合物的光谱在配合物与TEOA分子之间存在分子间振动模式，这反映了还原猝灭过程的前体。光激发后，分子间振动模式在皮秒时间尺度上有一个三步弛豫过程，首先是三重态金属到配体电荷转移激发态被振动冷却，其次是由于热传递加速的偶极 - 偶极相互作用，TEOA分子的旋转使Re与TEOA之间的距离减小，最后电子从TEOA转移到Re。这些观察结果为我们提供了Re(CO)(bpy){P(OEt)}在TEOA溶剂中光催化性能的电子转移过程的详细信息。
