迅速X線構造解析の現状と展望

抄録

X-Ray crystal structure analysis has become very easy and an enormous number of crystal structures have been determined. Although such a development is partly brought about by the four-circle diffractometer, recent developments in technique of crystal structure analysis and computation require another diffractometer for quick data collection. Two methods are proposed; the synchrotron radiation to obtain more intense X-rays, and the Imaging-plate as a two-dimensional detector. Several types of diffractometer using the Imaging-plate have been made, for example, IPD-WAS, R-AXIS IIc, DIP-320 W and FIXD. The three-dimensional intensity data can be collected within 35 hours whereas about 23 days are necessary for the four-circle diffractometer. The data will be collected more quickly at photon Factory, using the synchrotron radiation.
Recently an unstable intermediate structure has been observed by the step-wise structure analysis for the crystalline-state racemization of the cobaloxime complex crystal using the above IPD-WAS. A desolvation process has been observed for another cobaloxime complex crystal. Such a dynamical process observed in crystals should make clear the reaction mechanism more precisely.
A new type of diffractometer is now designed to analyze the crystal structure within a submillisecond at SPring-8. Some structures at the excited states will be analyzed in near future.