PHOTOSENSITIZATION OF STILBENE ISOMERIZATION BY PALLADIUM AND PLATINUM PORPHYRINS, AN INTER-MOLECULAR QUANTUM CHAIN PROCESS
PHOTOSENSITIZATION OF STILBENE ISOMERIZATION BY PALLADIUM AND PLATINUM PORPHYRINS, AN INTER-MOLECULAR QUANTUM CHAIN PROCESS
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DOI：
10.1021/ja00477a006
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发表时间：
1978-01-01
影响因子：
15
通讯作者：
WHITTEN, DG
中科院分区：
文献类型：
--
作者：
MERCERSMITH, JA;WHITTEN, DG
研究了强溶液磷光钯(II)和铂(II)卟啉对二苯乙烯异构化反应的增敏作用。这些化合物具有相对较长的三重态寿命和远低于二苯乙烯类化合物光谱三重态的能量，是有效的增敏剂。虽然1，2-二苯基丙烯的敏化看起来“正常”，但二苯乙烯的敏化导致顺式到反式过程的量子产率大于单位和富反式的光静止状态。这一结果可以用一个量子链过程来解释，在这个过程中，金属卟啉既是能量供体，又是受体。与以前用共轭双烯观察到的量子链过程不同，这些过程涉及受体三重态的交换，并在相对较高的浓度下发生，而这里观察到的现象发生在相对较低的给体和受体浓度。结果表明，敏化剂-受体笼-偶合络合物的中间体可能具有不同的择优构型，并改变了与自由二苯乙烯三联体相比的非辐射衰变性质。
The sensitization of stilbene isomerization by the strongly solution phosphorescent palladium (II) and platinum (II) porphyrins has been investigated. These complexes, which have relatively long triplet lifetime and triplet energies well below the spectroscopic triplets of the stilbenes, are efficient sensitizers. Although sensitization of the 1, 2-diphenylpropenes appears “normal”, sensitization of the stilbenes results in quantum yields for the cis to trans process greater than unity and trans-rich photostationary states. The results can be explained by a quantum chain process inwhich the metalloporphyrin serves both as an energy donor and an acceptor. In contrast to quantum chain processes previously observed with conjugated dienes which involve interchange of acceptor triplets and occur at relatively high concentrations, the phenomena observed here occur at rela-tively low donorand acceptor concentrations. The results suggest the intermediacyof a sensitizer-acceptor cage-encounter complex which may have different preferred geometryand altered nonradiative decay properties compared to the free stilbene triplet.