| Co-Investigator(Kenkyū-buntansha) |
NAGAMURA Toshihiko Unisoku Co. Ltd.,Institute for Scientific Instruments, Chief Researcher, 科学機器開発研究所, 主任研究員
INADA Yasuhiro Nagoya University, Research Center for Materials Science, Research Associate, 物質科学国際研究センター, 助手 (60242814)
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| Research Abstract |
The purpose of this study was to develop some instruments to characterize the metal complexes in supercritical carbon dioxide (scCO_2) and to clarify the microscopic interactions around the metal complexes in scCO_2.
We developed some spectroscopic cells to measure the UV-vis, IR, NMR, and high-frequency resonance spectra in scCO_2, and a circulation pump to connect the observation cells and to circulate the scCO_2 solution. We also developed the stopped-flow instrument to monitor the fast reactions, which are initiated by the rapid mixing of two scCO_2 solutions of reactants under a constant temperature and pressure. Furthermore, we developed the two-phase distribution cell for the UV-vis absorption measurements. Owing to the developments of these instruments, it becomes to be possible to measure the spectral change as a function of the concentration of species in addition to the temperature and pressure.
By using these instruments, (1) the solubility of porphyrins and metal complexes,
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(2) the metalation rate of porphyrin with bis(β-diketonato)metal(II) complexes (metal = Cu, Ni, and Co), and (3) the complexation and ligand substitution equilibria of the tris(β-diketonato)gadolinium(III) complex with the aromatic amine ligand were investigated in scCO_2 at a variety of temperatures and pressures. Furthermore, under the conditions containing the cosolvent, such as alcohols, water, acetonitrile, and tributyl phosphate (TBP), the reaction rates and the equilibrium constants were systematically determined in order to clarify microscopically the effect of cosolvent. For the metalation reactions of porphyrin, the existence of the cluster shell of cosolvents in the vicinity of solutes and the stabilization of the partial charges generated during the activation process due to the cluster shell are suggested. In the case of the system (3), the equilibrium constants of the ligand substitution reactions were decided in scCO_2, and the Gd(III) species concerning the supercritical extraction were characterized for the scCO_2/water and scCO_2/TBP extraction systems. Less
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