Studies on Photo-excited State Crystal Structure of Multinuclear Metal Complexes by X-ray Structure Analyses.

我们已经开发了仪器和方法，通过在同步辐射装置上使用单晶x射线结构分析来研究发光多核金属配合物在光激发态下分子结构的几何变化。特别地，引入了激发光和X射线同步间歇的装置，以抑制激光照射时晶体热负荷的影响。与未照射条件相比，在光照射下的热上升能够从25 K或更高降低至约5 K。结果，抑制了由晶体的热膨胀引起的晶体结构变化，并且可以更精确地检测由光激发引起的分子结构变化。1.在蓝光（442 nm）照射下，对铜（I）高分子配合物[Cu_2I_2（PPh_3）_2（4，4 '-bpy）]_∞进行了光激发结构分析。光差傅里叶合成 关于我们 Cu_2I_2单元中的两个I原子相互靠近，而两个Cu原子则相互远离，这表明铜的配位环境由一价转变为二价。这些几何变化是由于金属到配体的电荷转移（MLCT）。2.铑（III）配合物trans-[RhX_2（py）_4（BPh_4）]（X=Cl，Br，I ; py=C_5H_5N）的d-d跃迁发光。光激发结构分析表明，卤素原子的温度因子在光照射下比其他原子增加得多。这种热运动的幅度在垂直于Rh-X键的方向上增强。结果表明，Rh-X键的弯曲运动降低了分子结构的对称性，从而稳定了光激发态，3.研究了室温和低温下结晶态光异构化速率随时间的变化规律，[Rh（Cp'Rh）_2（CH_2）_2（O_2SSO_2）]（Cp'= Me_5C_5）的X-射线结构分析。在室温下，光产物的四种立体异构体中只有一种被发现，而在低温下观察到所有的立体异构体。这表明光产物的某些立体异构体可以通过热平衡转化为其他异构体。少

We have developed instrumentation and method for investigating geometrical change in molecular structure at photo-excited state of luminescent multi-nuclear metal complexes by using single crystal x-ray structure analyses at a synchrotron radiation facility. Especially, the device that synchronously intermitted the excitation light and X-rays was introduced to suppress the influence of the heat load of the crystal when the laser was irradiated. The rise in heat at the light irradiation comparing to non-irradiated condition was able to be decreased from 25K or more to around 5K. As a result, the crystal structure change by the thermal expansion of the crystal was suppressed, and the change in a molecular structure by photo-excitation can be detected more accurately. Summary of results is as follows :1.Photo-excited structure analyses of copper (I) polymer complex [Cu_2I_2(PPh_3)_2(4,4'-bpy)]_∞ have been performed under blue laser (442nm) illumination. Photo-difference Fourier syntheses … More revealed that two I atoms in a Cu_2I_2 unit approached close each other, while two Cu atoms moved slightly apart from each other, which suggest the coordination environment around copper is changed from monovalent to divalent. These geometrical changes due to metal-to-ligand charge transfer (MLCT). When green laser (532 nm), which is away from the MLCT band, was irradiated, this movement of the atoms is not observed.2.A rhodium (III) complex trans-[RhX_2(py)_4(BPh_4)] (X=Cl,Br,I ; py=C_5H_5N) shows a luminescence phenomenon assigned to the d-d transition. Photo-excited structure analyses showed that the temperature factor of the halogen atom increased more than other atoms in the light irradiations. The amplitude of this thermal motion is enhanced perpendicular to the Rh-X bond. The results suggested that bending motion of Rh-X bond decrease the symmetry of a molecular structure, which can stabilize the photo-excited state, derived from d-d prohibited electron migration.3.The time dependence of photo-isomerization rate in crystalline state at room temperature and low temperature of (Cp'=Me_5C_5) of [Rh(Cp'Rh)_2(CH_2)_2(O_2SSO_2) has been performed by X-ray structure analyses. Only one of four stereoisomers of the photoproducts is found at room temperature, while all stereo isomers are observed at the low temperature. This shows that the some stereo isomers of the photoproducts can be converted to other isomers via thermal equilibrium. Less