Readily tuneable porosity and redox properties of covalent organic frameworks (COFs) result in highly customizable photocatalysts featuring extended electronic delocalization. However, fast charge recombination in COFs severely limits their photocatalytic activities. Herein a new mode of COF photocatalyst design strategy to introduce systematic trap states is programmed, which aids the formation and stabilization of long-lived charge-separated excitons. Installing cationic acridinium functionality in a pristine electron-rich triphenylamine COF via postsynthetic modification resulted in a semiconducting photocatalytic donor–acceptor dyad network that performed rapid and efficient oxidative Diels-Alder type [4+2] annulation of styrenes and alkynes to fused aromatic compounds under the atmospheric condition in good to excellent yields. Large mesopores of ≈4 nm diameter ensured efficient mass flow within the COF channel. It is confirmed that the catalytic performance of COF originates from the ultra-stable charge-separated excitons of 1.9 nm diameter with no apparent radiative charge-recombination pathway, endorsing almost a million times better photo-response and catalysis than the state-of-the-art.

中文翻译：

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介孔吖啶基共价有机框架，用于长寿命电荷分离激子介导的光催化 [4+2] 环化


共价有机框架 （COF） 易于调节的孔隙率和氧化还原特性导致高度可定制的光催化剂具有扩展的电子离域功能。然而，COF 中的快速电荷复合严重限制了它们的光催化活性。在此，编程了一种新的 COF 光催化剂设计策略模式，以引入系统陷阱态，这有助于长寿命电荷分离激子的形成和稳定。通过合成后修饰在原始的富电子三苯胺 COF 中安装阳离子吖啶官能团，产生了半导体光催化供体-受体二元网络，该网络在大气条件下将苯乙烯和炔烃快速有效地氧化 Diels-Alder 型 [4+2] 环化为熔融芳香族化合物，产率从好到极好。直径为 ≈4 nm 的大介孔确保了 COF 通道内的高效质量流。经证实，COF 的催化性能源于直径为 1.9 nm 的超稳定电荷分离激子，没有明显的辐射电荷复合途径，其光响应和催化性能比最先进的高出近一百万倍。