Studies on Crystal Structural Change of Molecule-based Materials under Pressure

In this work, structural studies of molecule-based materials under pressure are described. The author succeeded in developing the method of single crystal X-ray structural analysis under pressure using diamond anvil cell (DAC). The diffraction spots observed by overlapping with the diffraction from DAC, such as the halo pattern from Be backing-disks and gasket, and strong spots from diamond anvils, were deleted, and the program of the absorption correction for DAC was developed. The studies in the crystal and electronic structures of pressure-induced molecule-based superconductor β-(BDA-TTP)_2FeCl_4 induced by lowering temperature and by increasing pressure is described. The author succeeded in providing structural evidence for the 2-fold structure and charge separation causing the metal-insulator (MI) transition in β-(BDA-TTP)_2FeCl_4 by X-ray structure analysis below TMI = 113 K. The author also found that the application of pressures causes variations in the conformation of donor molecule and the donor arrangement, which are responsible for almost uniform interaction in the donor stacking and for an increase in bandwidth (W) an a result, the suppression of MI transition and subsequent occurrence of superconductivity would be observed in β-(BDA-TTP)_2FeCl4 increasing pressure. The structural change of the molecule-based chiral ferrimagnet (R)-GN under pressure is described. The novel structure that cannot be obtained under ambient pressure, High-Pressure Form, was found out by applying pressure. The preparation, crystal structure, and magnetic properties of new dithiolene ligand dttt? and its chromium tris(dithiolene) complex, Cr(dttt)_3・CS_2 are described. The crystal structure and magnetic properties of Cr(dttt)_3・CS_2 are expected to change under pressure. The method of the structure analysis under pressure, established in this work, is very useful to the structural analysis for other various molecule-based materials under pressure, and wide application for this method are expected.首都大学東京, 2013-03-25, 博士(理学