Frustrated Lewis pairs (FLPs) can achieve efficient activation of inert small molecules (H2, CO2, NO, SO2) under mild conditions. However, the difficulty in customizing the catalytic ability of FLPs significantly limits their application. In this work, covalent organic framework (COF) with abundant Lewis alkaline sites was constructed from propeller structure triphenylamine. Accordingly, three TPA-COF-scales@X were in-situ assembled from three Lewis acids of different acid strength and molecular size on the above alkaline COF. Further experiments indicated that the strength of Lewis acid and base and the distance between them were positively and negatively correlated with the internal electric field intensity, which was also weakened by polar solvents. Encouragingly, TPA-COF-scales@X exhibited remarkable catalytic performance and recyclability for selective hydrogenation of alkynes to Z-olefins, achieving > 99 % conversion of 4-octyne and 96 % yield of Z-4-octene. To elucidate the catalytic mechanism, an internal electric field model for FLPs was proposed. Accordingly, the internal electric field intensity can be easily regulated by employing the appropriate Lewis acids, thus achieving customization of catalytic capacity. This work provides some guidance for the tailoring of FLP catalysts and a new idea for metal-free catalytic hydrogenation.

中文翻译：

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由原位组装的受挫路易斯对与共价有机框架定制的内部电场


沮丧路易斯对 （FLP） 可以在温和条件下实现惰性小分子（H2、CO2、NO、SO2）的有效活化。然而，定制 FLP 催化能力的难度极大地限制了它们的应用。在这项工作中，以螺旋桨结构三苯胺构建了具有丰富路易斯碱性位点的共价有机框架 （COF）。因此，三种 TPA-COF-scales@X 由三种不同酸强度和分子大小的路易斯酸在上述碱性 COF 上原位组装。进一步的实验表明，路易斯酸和碱的强度以及它们之间的距离与内部电场强度呈正负相关，而极性溶剂也削弱了内部电场强度。令人鼓舞的是，TPA-COF-scales@X 在炔烃选择性加氢制 Z-烯烃方面表现出卓越的催化性能和可回收性，实现了 > 4-辛炔 99% 的转化率和 Z-4-辛烯的 96% 产率。为了阐明催化机制，提出了一种 FLPs 的内部电场模型。因此，通过使用适当的路易斯酸，可以很容易地调节内部电场强度，从而实现催化容量的定制。这项工作为 FLP 催化剂的定制提供了一定的指导，并为无金属催化加氢提供了新思路。