Photochemical Processes in Molecular Assemblies

接受光的生物具有高效、超快的光化学反应，这种光化学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地制备成Langmuir-Blodgett(LB)多层膜。本研究的目的是：(1)分析蓝鳍金龟光感受器和日本血吸虫光感受器中表现出趋光/趋光运动的初级光反应机理；(2)比较生物系统和人工分子系统的光化学反应行为；(3)构建人工功能分子体系和分子器件。主要研究结果如下：1.生物光感受器天线…的初级光化学过程分离到两种蛋白质：一种是光活性的从金丝桃素向环境蛋白质传递质子的蛋白质，另一种是捕光触角的蛋白质。利用皮秒时间分辨荧光光谱研究了微粒、分离的色素蛋白和金丝桃素的光化学反应速率。从蛋白质中分离出的金丝桃素的质子释放活性较弱，但光活性蛋白质的质子释放能力增强，这表明包括质子供体和受体在内的分子体系在限制分子几何构型方面具有显著的作用。质子释放的反应速率为6ps。利用不同染料分子依次堆积的LB多层膜，制备了基于Langmuir-Blodgett多层膜的人工聚光天线。与生物天线中的光子能量一样，光子能量通过多层膜以特定的方向传递。制备了含有金丝桃素的LB单分子膜，并考察了单层膜的光反应性。较少

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