Structural Study of Photo-Induced Phenomena in Crystals by Synchrotron Radiation Crystallography

为了用单晶结构分析来揭示光诱导的微小结构变化，人们已经理解，晶体样品在光照射下的热上升应该是一个重要的问题。通过引入新的分时激电多次曝光方法，成功地抑制了晶体在0.1K以下的升温。在这种方法中，入射X射线和激发光通过两个旋转斩光器同步中断。将光激发结构分析应用于双铜(I)配合物[Cu2I2(PPh3)2(4，4‘-bpy)]_∞，它是由形成无限链结构的二亚胺配体桥联的{Cu2I2}平面单元组成的。利用SPRING-8BL02B1光束线低温真空X射线相机，在40K的条件下进行了单晶X射线光衍射实验。利用分时IP Mu…测量了两组光强变化的反射数据多次曝光法在吸收带(442 Nm)和尾部(532 Nm)两个波长的激光下进行。442 nm辐照数据的光差分傅里叶合成显示铜和碘原子周围有明显的正负峰，而532 nm数据的光差分傅立叶合成没有明显的峰。基于光致强度变化的最小二乘精修表明，约1.1%的铜原子和碘原子发生了移动，使铜-碘键缩短了0.2Å，I-I距离缩短了0.6Å。在高压汞灯下进行紫外光照射前后，用低温真空X射线相机采集了25K下的强度数据。结果表明，约7%的三线态氮和孤立的氮分子生成，三线态氮分子中的C-N键距离为1.34(4)Å。较少

In order to reveal the photo-induced small structural changes using the single crystal structure analyses, it has been understood that the rise in heat of the crystal specimen according to the light irradiation should be a significant problem. We succeeded in the suppression of the crystal heating less than 0.1K by introducing the new timesharing IP multiple exposure method, in which incident X-ray and excitation light was intermitted synchronously by using a couple of rotary choppers.Photo-excited structure analysis was applied to the luminescent dicopper(I) complexes [Cu_2I_2(PPh_3)_2(4,4'-bpy)]_∞, which consist of {Cu_2I_2 } planer units bridged by diimine ligands constructing infinite chain structures. Single crystal X-ray diffraction experiments under photo-illumination were performed at 40 K by using the low-temperature vacuum X-ray camera at SPring-8 BL02B1 beamline. Two set of reflection data of intensity changes owing to light irradiation were measured by the timesharing IP mu … More ltiple exposure method under two laser light of wavelengths on the absorption band (442 nm) and on its tail (532 nm). Photo-difference Fourier syntheses for the 442 nm irradiation data show significant positive and negative peaks around Cu and I atoms, though that for the 532 nm data show no significant peak. The least-squares refinement based on the photo-induced intensity changes revealed that ca. 1.1% of the Cu and I atoms moved and resulted in the shortening of the Cu-I bond and I...I distance of 0.2Å and 0.6Å, respectively.Crystal structure analysis of the photo-induced nitrene has been determined successfully by using the host-guest complex of [(PhCH_2)_2NH_2]^+[m-C_6H_4(N_3)(COO)]^-. The intensity data were collected at 25 K using the low-temperature vacuum X-ray camera at SPring-8 before and after UV-irradiation with a high-pressure mercury lamp. It has been revealed that ca. 7% of the triplet nitrene and the isolated nitrogen molecule were generated and the C-N bond distance in the triplet nitrene was 1.34(4)Å. Less