The UV photolysis of bimolecular charge transfer complexes is employed to yield reactive radical ions in their solvent-equilibrated electronic ground state. In polar protic media, noncovalent complexes of 1,2,4,5-tetracyanobenzene and toluene undergo efficient, ultrafast dissociation to ion pairs and equilibrate with their solvent environment before the resulting radical ions engage in electron transfer and proton abstraction on subnanosecond time scales. Solvent molecules play a critical role in these reactive pathways and in the dissociation and relaxation processes that precede them. We report a clear separation of time scales for these relaxation and reactive processes, which implies that solvent–solute interactions can be used as a tool for tuning the reaction pathways of equilibrated radical ions in solution.

中文翻译：

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极性质子溶剂在光生自由基离子对的解离和反应中的作用

双分子电荷转移络合物的紫外光解作用可在其溶剂平衡的电子基态下产生反应性自由基离子。在极性质子介质中，1,2,4,5-四氰基苯和甲苯的非共价络合物会高效，超快地离解成离子对，并在其溶剂环境达到平衡之前，所产生的自由基离子会在亚纳秒级上参与电子转移和质子提取。溶剂分子在这些反应性途径以及它们之前的离解和弛豫过程中起着至关重要的作用。我们报告了这些弛豫和反应过程的时间尺度明确分离，这意味着溶剂-溶质相互作用可用作调整溶液中平衡自由基离子反应路径的工具。