Li Han, Wenger Oliver S
Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
Angew Chem Int Ed Engl. 2022 Jan 26;61(5):e202110491. doi: 10.1002/anie.202110491. Epub 2021 Dec 20.
The two-electron reduced forms of perylene diimides (PDIs) are luminescent closed-shell species whose photochemical properties seem underexplored. Our proof-of-concept study demonstrates that straightforward (single) excitation of PDI dianions with green photons provides an excited state that is similarly or more reducing than the much shorter-lived excited states of PDI radical monoanions, which are typically accessible after biphotonic excitation with blue photons. Thermodynamically demanding photocatalytic reductive dehalogenations and reductive C-O bond cleavage reactions of lignin model compounds have been performed using sodium dithionite acts as a reductant, either in aqueous solution or in biphasic water-acetonitrile mixtures in the presence of a phase transfer reagent. Our work illustrates the concept of multi-electron reduction of a photocatalyst by a sacrificial reagent prior to irradiation with low-energy photons as a means of generating very reactive excited states.
苝二亚胺（PDIs）的双电子还原形式是发光的闭壳物种，其光化学性质似乎尚未得到充分探索。我们的概念验证研究表明，用绿色光子直接（单次）激发PDI二价阴离子会产生一种激发态，该激发态的还原性与PDI自由基单阴离子的激发态相似或更强，而后者通常在双光子蓝光激发后才能获得，且寿命更短。使用连二亚硫酸钠作为还原剂，在水相溶液中或在相转移试剂存在下的水 - 乙腈双相混合物中，已经进行了木质素模型化合物的热力学要求较高的光催化还原脱卤和还原C - O键断裂反应。我们的工作阐述了在低能光子照射之前，通过牺牲试剂对光催化剂进行多电子还原的概念，以此作为产生高活性激发态的一种手段。
