Light-induced excited state X-ray crystallography of multinuclear copper complexes

多核Cu(I)配合物如[Cul(py)]4在紫外光照射下显示出发光。在光激发态下，金属团簇核的畸变是可以预料到的。为了通过单晶x射线衍射分析直接观察这种光激发态的分子畸变，我们进行了衍射仪的研制，建立了激发态结构精细计算，并对目标化合物进行了调查。在“低温真空x射线相机”中安装了照明装置，用于在低温下获得低噪声衍射图像。多重曝光成像板（IP）方法是本项目开发的一种新的检测技术，安装在该相机中，通过该方法可以在同一IP上记录光照和非照射条件下测量的衍射图样。x射线照相机已在利用高亮度x射线辐射源的Spring-8光束线上固定下来。光照射晶体中的分子畸变可以通过利用x射线衍射强度在光照和关闭条件下的变化进行微分傅立叶合成来检测，然后使用最小二乘改进对晶体中的激发态人口和几何变化进行定性计算。成功地对蓝激光照射下发光的二铂（II）配合物（Bu_4N）_2H_2[Pt_2(pop)_4]单晶进行了结构分析。1.4%居群的光激发分子在蓝光照射下显示出0.23 A的Pt-Pt键收缩，这与光谱研究结果一致。

Multinuclear Cu(I) complexes such as [Cul(py)]4 have shown luminescent by UV light irradiation. In the photoexcited states, distortion of metal cluster core has been expected. To observe this molecular distortion in the photoexcited states directly by single crystal X-ray diffraction analyses, we have performed development of a diffractometer, establishment of excited states structure refinement calculations, and survey of target compounds. Light illuminating devices has been installed in the "low-temperature vacuum X-ray camera" which are designed for obtaining low noise diffraction images at low temperature. The multiple-exposure image plate (IP) method is a new detection technique developed in this project and installed in this camera, by which both diffraction patterns measured for light irradiated and non-irradiated conditions are recorded on the same IP. The X-ray camera has settled in a Spring-8 beamline utilizing highbrilliant X-ray radiation sources. Molecular distortion in the light irradiated crystal can be detected by a differential Fourier syntheses using X-ray diffraction intensity changes between light-on and off conditions, followed by qualitative calculation of excited state population and geometrical changes in a crystal, using least square refinements. Structure analysis of a luminescent a diplatinum(II) complex (Bu_4N)_2H_2[Pt_2(pop)_4] single crystal under blue laser irradiation has been successfully performed. Photoexcited molecule of 1.4% population shows Pt-Pt bond shrinkage of 0.23 A under blue laser irradiation which is consistent with spectroscopic investigations.