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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Oligo(Cyclohexylidene)s and Oligo(Cyclohexyl)s as Bridges for Photoinduced Intramolecular Charge Separation and Recombination
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Oligo(Cyclohexylidene)s and Oligo(Cyclohexyl)s as Bridges for Photoinduced Intramolecular Charge Separation and Recombination

机译：寡（环己基）和寡（环己基）作为光诱导分子内电荷分离和重组的桥梁。

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摘要

A series of semirigid donor-bridge-acceptor (D-B-A) molecules was synthesized to study the effect of the position and number of nonconjugated olefinic bonds in the bridge on the photoinduced charge-separation and charge-recombination kinetics. The molecules consist of a phenylpiperidine electron donor, an oligo(cyclohexylidene) or oligo(cyclohexyl) bridge, and a dicyanovinyl acceptor. Partly saturated ter(cyclohexylidene) bridges were used as well. The edge-to-edge donor-acceptor separation of the compounds under study varies between 2.89 and 15.4 A. The replacement of a C-C single bond by an olefinic bond increases the rate of charge separation with a factor of 3.0 ± 0.8 per replaced bond. For all D-B-A compounds the extended fully charge-separated state folds to a compact charge-transfer (CCT) conformer. The rate of charge recombination (CR) of the CCT state increases with solvent polarity for those compounds having an olefinic bond located three σ bonds from the acceptor. Thus, while in cyclohexane the CR rate is equal for all compounds, in benzene the CR rate in compounds with an olefinic bond near the acceptor is 10 times larger than in compounds with a single bond instead. It is believed that a (virtual) charge-transfer state involving the radical cation of the olefinic bond and the radical anion of the acceptor (D-B~(·+)-A~(·-)) is responsible for the enhanced CR process.
机译：合成了一系列的半刚性供体桥受体（D-B-A）分子，以研究桥中非共轭烯烃键的位置和数量对光诱导电荷分离和电荷重组动力学的影响。该分子由苯基哌啶电子给体，低聚（环己叉基）或低聚（环己基）桥以及双氰基乙烯基受体组成。也使用了部分饱和的叔（亚环己基）桥。所研究化合物的边缘对边缘供体-受体分离在2.89至15.4 A之间变化。用烯烃键取代C-C单键可提高电荷分离速率，每个取代键的电荷分离率为3.0±0.8。对于所有D-B-A化合物，扩展的完全电荷分离状态折叠成紧凑的电荷转移（CCT）构象异构体。对于那些具有位于受体的三个σ键上的烯键的化合物，CCT状态的电荷复合率（CR）随着溶剂极性的增加而增加。因此，尽管在环己烷中，所有化合物的CR率均相等，但在苯中，具有靠近受体的烯烃键的化合物的CR率比具有单键的化合物大10倍。据认为，涉及烯烃键的自由基阳离子和受体（D-B〜（+）-A〜（-））的自由基阴离子的（虚拟）电荷转移状态是导致CR过程增强的原因。

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