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

环十二基（Cd）是一种体积大、刚性的具有环状结构的疏水基团，与聚磺酸共价连接，在水溶液中由于自组织而形成疏水团簇。因此，聚合物作为一个整体，形成单分子胶束。锌（II）四苯基卟啉（ZnTPP）与这种两亲性多磺酸共价连接，在Cd簇中被紧密区隔，导致非常不寻常的光物理和光化学性质。特别异常的行为是，在室温下，区隔化的ZnTPP部分在水溶液中发出磷光和由三激发态热重新填充引起的e型延迟荧光。这些不寻常的观察结果主要是由于三重态-三重态湮灭被严格地阻止了，因为在Cd团簇中，发色团是静态地相互隔离的，并且也保护了它们不受体水相的影响，这样ZnTPP三重态几乎没有机会相遇，并且在它们的生命周期内也保护了它们不受体相杂质的影响。这导致即使在室温下的流体水溶液中也有极长的三重态寿命。激光光解研究了ZnTPP长寿命三重态电子向自毁电子受体磺酸盐的光致电子转移过程，发现在ZnTPP和自毁电子受体之间发生了有效的电子转移并产生自由基。这种分区化ZnTPP体系的一个特征是，ZnTPP阳离子自由基持续时间极长（ESR能识别几个小时）。

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).