Asymmetric Photoreactions in Supramolecular Assemblies.
Asymmetric Photoreactions in Supramolecular Assemblies.
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DOI：
10.1021/acs.accounts.3c00234
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发表时间：
2023-06
影响因子：
18.3
通讯作者：
Jie Ji;Xueqin Wei;Wanhua Wu;Cheng Yang
中科院分区：
文献类型：
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作者：
Jie Ji;Xueqin Wei;Wanhua Wu;Cheng Yang
概述激发态不对称光反应的立体化学控制一直是现代光化学中最具挑战性的课题之一。电子激发光底物的短暂特性及其形成两种对映体的低活化能垒是在激发态不对称光化学中实现显着对映选择性的主要障碍。最近的研究表明，超分子策略有望通过基态和激发态下相对较强且持久的非共价相互作用来控制不对称光反应的立体化学结果。在该方法中，手性主体/组装体通过相对较强的超分子相互作用（例如氢键、范德华力、π-π、静电和疏水相互作用）提供手性环境，以光化学方式将手性转移到基态和激发态的络合光底物上。光底物的取向和构象可以通过超分子络合进行严格控制，以确保随后有效的立体选择性光化学转化。本报告描述了我们在超分子组装体中不对称光反应方面的最新进展。多种手性光反应，包括环烯烃的光异构化以及蒽和萘衍生物的光环二聚，已由各种超分子主体介导，例如环糊精（CD）、葫芦脲、柱芳烃和手性聚合物。超分子不对称光化学具有以下优点：（1）通过精心设计和制造手性主体分子可以提高立体选择性。 （2）超分子络合可以有效调节光底物的取向和构象，从而产生新的反应途径，产生传统反应条件无法实现的不寻常的光产物。 (3)超分子体系中的不对称光反应与温度、溶剂、辐照波长和压力等外部环境变量具有很强的相关性，因此为调控激发态光反应的立体选择性提供了有力的工具。 (4)利用超分子络合可以显着加速光反应，适当的光敏剂/光催化剂的组合能够有效驱动催化的手性光反应。 (5)手性超分子体系中的光异构化已应用于手性光学分子器件，表现出多种刺激响应功能和先进的开关性能。我们相信，由此衍生的这些概念、方法和原理对于设计手性超分子主体、阐明基态和激发态的立体分化机制以及分析和改进各种超分子手性光反应的立体化学结果具有指导意义。
ConspectusStereochemical control of excited-state asymmetric photoreactions has been one of the most challenging topics of modern photochemistry. The short-lived character of electronically excited photosubstrates and their low activation energy barriers to form both enantiomers are the major obstacles to achieving significant enantioselectivity in excited-state asymmetric photochemistry. Recent research demonstrated that the supramolecular strategy is promising to control the stereochemical outcome of asymmetric photoreaction through relatively strong and long-lasting noncovalent interaction at both ground and excited states. In this methodology, chiral hosts/assemblies provide the chiral environment for photochemically transferring chirality to the complexed photosubstrate in both the ground and the excited states by virtue of relatively strong supramolecular interactions, such as hydrogen bonding, van der Waals, π-π, electrostatic, and hydrophobic interactions. The orientation and conformation of the photosubstrate can be critically manipulated by the supramolecular complexation to ensure the subsequent effective stereoselective photochemical conversion.This Account describes our recent advance in asymmetric photoreactions in supramolecular assemblies. Several chiral photoreactions, including photoisomerization of cycloolefins and photocyclodimerization of anthracene and naphthalene derivatives, have been mediated by various supramolecular hosts, such as cyclodextrin (CD), cucurbituril, pillararene, and chiral polymer. The following advantages of supramolecular asymmetric photochemistry were evidenced: (1) The improvement of stereoselectivity can be enabled by the careful design and fabrication of chiral host molecules. (2) Supramolecular complexation could effectively regulate the orientation and conformation of photosubstrates, thus resulting in novel reaction pathways which create unusual photoproducts that are not achievable through traditional reaction conditions. (3) Asymmetric photoreactions in supramolecular systems showed strong correlations with the external environmental variants, such as temperature, solvent, irradiation wavelength, and pressure, which therefore provide a powerful tool for the regulation of stereoselectivities of excited-state photoreactions. (4) Utilizing supramolecular complexation can dramatically speed up photoreactions, a combination of appropriate photosensitizers/photocatalysts being able to drive catalyzed chiral photoreactions effectively. (5) Photoisomerization in chiral supramolecular systems has been applied to chiroptical molecular devices, which exhibited multiple stimulus-response functions and advanced switching performances. We believe that these concepts, methods, and principles derived therefrom are instructive in designing chiral supramolecular hosts, elucidating the stereodifferentiation mechanisms in the ground and excited states, and analyzing and improving the stereochemical outcomes of a diverse range of supramolecular chiral photoreactions.