Budding Researchers Support Proposal Report

Purpose of the experiment: The materials with light-triggered and/or -driven function have been attractive in creating a novel conceptual function. To investigate those structures not only understand the mechanism of photo-induced phenomena but also lead new design of optical functional materials. For reasons detailed below, we focus on one of spin crossover complexes t-[Fe(abpt)2(NCS)2] polymorph C as a proto type of a photo-active molecular material. Recently we successfully synthesized the title complex. In a preliminary study it exhibits thermal spin transition at Tc = 86 K. The most interesting point in preliminary work is: By monitoring cell parameter in the range of 25-300 K, we found out that title complex exhibits not only spin transition at 86 K, but also intriguing commensurate modulated structure with cell parameter c tripled between the spin transition temperature 86 K and 170 K (Figure. 4). It remained a question whether after photo irradiation, the photo-induced structure of title complex also occurs commensurate modulated structure or not. Undoubtedly, X-ray diffraction provides an ultimate method to determine the photo-induced structure. However, suffering from conventional laboratory setup, we had several limitations, such as: (1) longer data collection time is difficult to completely keep in metastable state during data collection, and (2) the less laser penetration depth because of using relatively larger single crystal. Thus, to explore the origin of the photoreaction process, we carried out the single crystal structure analysis using high-brilliance and high-resolution synchrotron X-ray at BL02B1/SPring-8 (Figure. 1).