Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||Hokkaido University |
YAMAZAKI Iwao Faculty of Engineering, Hokkaido University, Professor, 工学部, 教授 (80002111)
OHTA Nobuhiro Faculty of Engineering, Hokkaido University, Professor, 工学部, 助教授 (70113529)
PILLーSOON SO ネブラスカ州立大学, 化学科, 教授
SONG Pill-Soon Department of Chemistry, University of Nebraska, Professor
RENKE Dai ネブラスカ州立大学, 化学科, 博士後研究員
PILLーSOON So ネブラスカ州立大学, 化学科, 教授
西村 賢宣 北海道大学, 工学部, 助手 (60218211)
|Project Period (FY)
1991 – 1992
Completed (Fiscal Year 1992)
|Budget Amount *help
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1991: ¥3,000,000 (Direct Cost: ¥3,000,000)
|Keywords||Photomovement / Photoreceptors / Photochemical reaction / Picosecond laser / Time-resolved fluorescence / Langmuir-Blodgett films / Energy transfer / Proton release / ピコ秒レ-ザ- / 光分子デバイス / 分子組織体|
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
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