Reconstructed covalent organic frameworks

Zhang, Weiwei and Chen, Linjiang and Dai, Sheng and Zhao, Chengxi and Ma, Cheng and Wei, Lei and Zhu, Minghui and Chong, Samantha Y. and Yang, Haofan and Liu, Lunjie and Bai, Yang and Yu, Miaojie and Xu, Yongjie and Zhu, Xiao Wei and Zhu, Qiang and An, Shuhao and Sprick, Reiner Sebastian and Little, Marc A. and Wu, Xiaofeng and Jiang, Shan and Wu, Yongzhen and Zhang, Yue Biao and Tian, He and Zhu, Wei Hong and Cooper, Andrew I. (2022) Reconstructed covalent organic frameworks. Nature, 604 (7904). pp. 72-79. ISSN 0028-0836 (https://doi.org/10.1038/s41586-022-04443-4)

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Abstract

Covalent organic frameworks (COFs) are distinguished from other organic polymers by their crystallinity1–3, but it remains challenging to obtain robust, highly crystalline COFs because the framework-forming reactions are poorly reversible4,5. More reversible chemistry can improve crystallinity6–9, but this typically yields COFs with poor physicochemical stability and limited application scope5. Here we report a general and scalable protocol to prepare robust, highly crystalline imine COFs, based on an unexpected framework reconstruction. In contrast to standard approaches in which monomers are initially randomly aligned, our method involves the pre-organization of monomers using a reversible and removable covalent tether, followed by confined polymerization. This reconstruction route produces reconstructed COFs with greatly enhanced crystallinity and much higher porosity by means of a simple vacuum-free synthetic procedure. The increased crystallinity in the reconstructed COFs improves charge carrier transport, leading to sacrificial photocatalytic hydrogen evolution rates of up to 27.98 mmol h−1 g−1. This nanoconfinement-assisted reconstruction strategy is a step towards programming function in organic materials through atomistic structural control.

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