SPIN CHEMISTRY OF MEMBRANE INTERFACE

本课题主要用于膜界面自旋化学现象的科学家交流和科学信息的讨论。我们这个项目的最终目的是研究生物活性膜，但对界面的基本物理理解对于开始研究更为重要。在项目期间，我们邀请了几位科学家，他们是自旋效应和膜现象的专家。Murai访问了北卡罗来纳大学和牛津大学，讨论并获得了有关膜的信息。前田还访问了牛津大学，讨论了磁共振在生物系统研究中的应用。在这个项目中，我们采用了几种不同的胶束和双层体系。观察膜界面自旋效应的方法是时间分辨ESR和反应产率检测磁共振。特别是方法2)是一种新发展的技术，主要采用瞬态光吸收检测来监测电子自旋共振条件下微波辐照下的反应变化。采用方法2)，我们用四苯基肼研究了SDS胶束中的单线态自由基对体系。在本研究中，我们成功地进行了有效的自旋翻转操作和胶束溶液中的化学反应控制。方法2)也适用于在SDS胶束中光还原山酮和t-丁基酚衍生物的体系。我们发现了微波双自旋同时激发的量子热现象。我们从量子拍态的数据中得出结论，拍态的衰减主要是由三重-三重脱相引起的，这是自由基对系统中自旋相弛豫的新概念。我们最近的项目目标是双层体系的光化学电子标记，使用方法1)的研究正在进行中。

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.