The Structure-Reactivity Relationship of Ion Pairs In Photoinduced Electron-Transfer

光致电子转移中离子对的结构-反应性关系

• 批准号: 06453032
• 负责人: MIYASHI Tsutomu
• 金额: $ 4.22万
• 依托单位: TOHOKU 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: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06453032/
• 关键词: Electron-transfer; Photochemistry; Solvent effects; Sensitizer effects; Ion radical pairs; 有機光反応; 電子移動; イオン対; カチオンラジカル; アニオンラジカル; 光増感反応; 競争反応; ビシクロヘキサン

We previously found that the photoinduced electron-transfer (PET) reaction of exo, cis-1,4-diary1-2,3-dimethylbicyclo[2.2.0]hexane was strongly sensitive to solvent polarity and the nature of cyanoaromatic sensitizers. "Lose" ion-radical pairs such as SSIP and FI favored a concerted cycloreversion to give E,E-1,8-dimethy1-3,6-diary-2,6-octadiene while E,Z-1,8-dimethy1-3,6-diary1-2,6-octadiene was formed predominantly from a "tight" ion-radical pair such CIP in a stepwise manner. For the generalization of the relationship between a structure of an ion-radical pair and products/mechanisms, we investigated the PET reactions of 2,2-diarylspiropentanes, which competitively afforded 1-(diarylmethylene) cyclobutane(I) and 2,2-diary1-1methylene-cyclobutane (II) in a concerted and stepwise mechanism, respectively. The ratio of [I : II] increased with an increse in solvent polarity and a decrease in negative charge density of anion radicals of cyanoaromatic sensitizers. Those facts are compatible with the facts observed in the PET reactions of exo, cis-1,4-diaryl1-2,3-dimethylbicyclo[2.2.0]hexane, showing that a structure of an ion-radical pairs significantly changes a reaction mechanism and then products.

我们以前发现，外，顺-1，4-二芳基-2，3-二甲基双环[2.2.0]己烷的光诱导电子转移（PET）反应对溶剂极性和氰基芳族敏化剂的性质非常敏感。“失去”的离子-自由基对如SSIP和FI有利于协同的环化逆转，得到E，E-1，8-二甲基-3，6-二芳基-2，6-辛二醇，而E，Z-1，8-二甲基-3，6-二芳基-2，6-辛二醇主要由“紧密”的离子-自由基对如CIP以逐步的方式形成。为了推广离子-自由基对结构与产物/机理之间的关系，我们研究了2，2-二芳基螺戊烷的PET反应，它们分别以协同和逐步机理竞争生成1-（二芳基亚甲基）环丁烷（I）和2，2-二芳基1 - 1亚甲基环丁烷（II）. [I：随着溶剂极性的增加和氰基芳族增感剂阴离子自由基负电荷密度的降低，[II]增加。这些事实与在外，顺-1，4-二芳基-2，3-二甲基双环[2.2.0]己烷的PET反应中观察到的事实一致，表明离子-自由基对的结构显著改变反应机理，然后改变产物。

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