Photochemical Processes in Molecular Assemblies

光感受器生物具有高效、超快的光化学反应，这种反应发生在多肽网络的分子排列中，另一方面，这种分子排列可以人工制备Langmuir-Blodgett （LB）多层膜。在这样的人工分子系统中，人们可以期待一种与生物系统相似的高效、快速的光化学反应。本研究的目的是：(1)分析蓝索和日本布利法利马光感受器中表现出疏光/趋光运动的主要光反应机制；(2)比较LB多层膜生物体系和人工分子体系的光化学反应行为；(3)制备人工功能分子体系和分子器件。本文的研究结果总结如下：1。生物光感受器的主要光化学过程天线蛋白和光子/电子信号转导蛋白分离出两种蛋白：一种在金丝桃素向环境蛋白的质子转移中起光活性，另一种起光收集天线的作用。光化学反应速率采用皮秒时间分辨荧光光谱法研究了微颗粒、分离的色素蛋白和金丝桃素的光化学反应活性。从蛋白质中分离得到的金丝桃素的质子释放活性较弱，而光活性蛋白的质子释放能力增强，说明在受限制的分子几何结构中，包括质子供体和受体在内的分子体系对金丝桃素的质子释放能力有显著影响。测定质子释放的反应速率为6ps。采用不同染料分子顺序堆叠的LB多层膜制备了人工捕光天线。光子能量以特定的方向在多层膜中传递，类似于生物天线中的多层膜。制备了含有金丝桃素的LB单层膜，并对其光反应性进行了研究。少

Photorecepting bioorganisms are characterized by highly efficient and ultrafast photochemical reaction which occur in molecular arrangement of polypeptide networks, On the other hand, such molecular arrangements can be fabricated artificially a Langmuir-Blodgett (LB) multilayer film. One can expect in such artificial molecular systems a highly efficient and fast photochemical reaction likely to those of biological systems.The aim of the present research project is to : (1) analyze the primary photoreaction mechanism in photoreceptors of Stentor coeruleus and Blepharisma japonicum, which show photophobic/phototactic movements, (2) compare the photochemical reaction behaviors between the biological system and the artificial molecular system of LB multilayer films, and finally (3) fabricate artificially functional molecular systems and molecular devices. Results of the present research are summarized as follows :1. Primary photochemical processes in biological photoreceptors Antenna chrom … More oprotein and photonic/electronic signal transducing protein Two kinds of proteins were isolated : The one is photoactive in proton transfer from hypericin to environmental protein, and the other plays a role of light-harvesting antenna.Photochemical reaction rates The photochemical reactivities were investigated for microparticles, isolated chromoproteins and hypericin, by means of a picosecond time-resolved fluorescence spectroscopy. Hypericin isolated from protein is found to be weak in proton release activity, but the phtoactive protein is enhanced in ability of proton release, indicating a significant effect of molecular system including proton donor and acceptor in restricted molecular geometries. The reaction rate of proton release was determined to be 6 ps.2. Artificial molecular fabrication by means of Langmuir-Blodgett multilayers Artificial light-harvesting antenna was prepared by using LB multilayers in which different dye molecules are stacking sequentially. The photonic energy transfers in a specific direction through the multilayers likely to those in biological antenna. A LB monolayer film containing hypericin was prepared and examined the photoreactivities in the monolayer films. Less