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Studies on the Control of Photoinduced Electron Transfer Reaction of Porphyrins by Amphiphilic Polyelectrolytes

两亲性聚电解质控制卟啉光致电子转移反应的研究

基本信息

批准号：
04453116
负责人：
KAMACHI Mikiharu
金额：
$ 4.61万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Cyclododecyl (Cd) groups, bulky and rigid hydrophobic goups with a ring structure, covalently attached to a polysulfonic acid were found to form hydrophobic clusters in aqueous solution due to self-organization. Thus, the polymer, as a whole, forms unimolecular micelle. Zinc(II) tetraphenylporphyrin (ZnTPP) moieties covalently linked to such an amphiphilic polysulfonic acid were found to be tightly compartmentalized in the Cd clusters, leading to very unusual photophysical and photochemical properties. Particularly anomalous behavior was that phosphorescence and E-type delayd fluorescence due to thermal repopulation from the triplet-excited state were emitted by the compartmentalized ZnTPP moieties in aqueous solution at room temperature. These unusual observations are primarily due to the fact that triplet-triplet annihilation is rigorously prevented because the chromophores are statically isolated in the Cd cluster from each other and also protected from the bulk aqueous phase such that the ZnTPP triplets have virtually no chance to encounter each other and also protected from impurities in the bulk phase during their lifetimes. This leads to enormously long triplet lifetime even in fluid aqueous solution at room temperature. In the photoinduced electron transfer from the ZnTPP long-lived triplets to sulfonium salts, self-destructive electron acceptors, as studied by laser photolysis, efficient electron transfer was found to occur and generate radicals coming from the ZnTPP and the acceptors. A characteristic feature of this compartmentalized ZnTPP system was that the ZnTPP cation radical persisted for extremely long time (the radical was recognized for several hours by ESR).

环十二烷基（Cd）基团是具有环状结构的大而刚性的疏水基团，共价连接到聚磺酸上，由于自组织而在水溶液中形成疏水簇。因此，聚合物作为一个整体形成单分子胶束。研究发现，与这种两亲性多磺酸共价连接的四苯基卟啉锌 (II) 部分在 Cd 簇中紧密分隔，从而产生非常不寻常的光物理和光化学性质。特别异常的行为是，室温下水溶液中的区室化 ZnTPP 部分会发射磷光和 E 型延迟荧光，这是由于三重激发态的热再生所致。这些不寻常的观察结果主要是由于三重态-三重态湮灭被严格防止，因为发色团在Cd簇中彼此静态隔离，并且还受到本体水相的保护，使得ZnTPP三重态几乎没有机会彼此相遇，并且在其寿命期间也免受本体相中的杂质的影响。即使在室温下的流体水溶液中，这也会导致非常长的三线态寿命。通过激光光解研究，在从 ZnTPP 长寿命三重态到锍盐（自毁性电子受体）的光诱导电子转移中，发现发生了有效的电子转移并产生来自 ZnTPP 和受体的自由基。这种分隔的 ZnTPP 系统的一个特征是 ZnTPP 阳离子自由基持续极长的时间（ESR 可以识别自由基几个小时）。