2000 Fiscal Year Final Research Report Summary
STUDIES ON SELF-REPAIRING PHOTOINDUCED ELECTRON TRANSFER PROCESS FROM THIOKETONES
| Project/Area Number |
11440211
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
物質変換
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
ITO Osamu INSTITUTE FOR CHEMICAL REACTION SCIENCE, TOHOKU UNIVERSITY, PROFESSOR, 反応化学研究所, 教授 (30006332)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
FUJITSUKA Mamoru INSTITUTE FOR CHEMICAL REACTION SCIENCE, TOHOKU UNIVERSITY, RESEARCH ASSOCIATE, 反応化学研究所, 助手 (40282040)
ONODERA Shinji INSTITUTE FOR CHEMICAL REACTION SCIENCE, TOHOKU UNIVERSITY, ASSOCIATE PROFESSOR, 反応化学研究所, 助教授 (30006316)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Keywords | self-repairing photoinduced electron transfer / thioketone / methylviologen / S-center radical / H-atom abstruction / laser photolysis |
|---|
| Research Abstract |
Steady-state light irradiation to thioketones (pyridinethiones etc.) in the presence of methylviologen dication generates radical cation persistently by self-repairing photoinduced electron transfer process. This novel photoinduced electron transfer process will be useful for light energy conversion systems, since the reaction system does not use sacrificial reagent. In the present project, we investigated the mechanism and optimization of the novel photoinduced electron transfer process by means of steady-state and laser-flash photolysis methods. The initial step of the present cycle is electron transfer from the triplet excited pyridinethiones to electron acceptors such as methylviologen. Deprotonation and dimerization of the radical cation of pyridinethiones generate disulfide which is less reactive to methylviologen radical cation due to the endothermic back electron transfer process. Thus, generated methylviologen radical cation decayed slowly over several hundred seconds. The proposed reaction mechanisms are supported by the products analysis and kinetic analysis of the reaction systems under the various pH conditions. The self-repairing photoinduced electron transfer process can be also applied to photocatalytic H-atom abstruction system. Steady-state photolysis of 4-pyridinethione and methylviologen in the presence of alcohol generated viologen radical cation. The radical cation of viologen did not decay completely even in the dark, indicating deprotonation of alcohol by the thio radical which was generated from initial pyridinethione. This finding indicates catalytic dehydrogenation of alcohol by the self-repairing photoinduced electron transfer process.
|
Research Products
(18 results)
