SPIN CHEMISTRY OF MEMBRANE INTERFACE

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We used this grant project mainly for the purpose of exchange of scientists and discussion of scientific information about the spin chemical phenomena of membrane interface. Our final aim of this project is the investigation of biological active membrane, but the basic physical understanding of the interface is much more important to start the studies. During the project period, we invited several scientists who were experts of spin effect and membrane phenomenon. Murai visited University of North Carolina and Oxford University to discuss and obtain information concerning membranes. Maeda also visited Oxford University to discuss the application of magnetic resonance to the investigation of biological systems. In this project we employed several different micellar and bilayer systems. The methods of the observation of the spin effects in the membrane interface were 1) time-resolved ESR and 2) reaction yield detected magnetic resonance. Especially, method 2) was newly developed technique and a transient optical absorption detection was mainly used to monitor the reaction change by the irradiation of microwave under the conditions of electron spin resonance. Using method 2), we studied a singlet born radical pair system in an SDS micelle employing tetraphenylhydrazine. In this study we succeeded in effective spin flip operation and chemical reaction control in the micellar solution. Method 2) was also applied to the photoreduction system of xanthone and t-butylphenol derivatives in an SDS micelle. We discovered a quantum beat phenomenon of two-spin simultaneous excitation by microwave. From the data of the quantum beat we concluded that the decay of the beat is mainly due to the triplet-triplet dephasing that is a new concept of spin-phase relaxation in radical pair systems. Our recent aim of the project is photochemical electron labeling of a bilayer system and the investigation using method 1) is underway.