中国科学院上海有机化学研究所赵新团队取得一项新突破。他们提出了具有fmj拓扑的斜方晶系共价有机框架（COFs），作为析氢光催化剂。相关论文发表在2025年1月6日出版的《德国应用化学》杂志上。

据悉，三维共价有机框架（3D COFs）是一类具有高孔隙度的结晶性聚合物，具有广阔的应用前景。然而，3D COFs的拓扑结构仅限于高度对称晶体系统，这极大地阻碍了此类功能材料发展。

在该研究中，研究团队首次展示了具有前所未有的fmj拓扑结构的高结晶正交3D COFs，基于可旋转单体。值得注意的是，fmj拓扑网络的单元胞中的方形单体采用了三种不同的构象，形成了高度复杂的三维网络。

此外，仅-C=N-键取向不同的同分异构体对（3DCOF-CN和3DCOF-NC）表现出不同的光电性质、质子化能力和光催化活性，这是首次在3D COF中发现这种同分异构体效应。两种异构体的光催化析氢速率相差32倍，其中一种达到了~31.1 mmol h^-1 g^-1。

本工作首次实现了复杂正交三维COFs的构建，为基于三维COFs的高性能光催化剂的开发提供了新见解。

附：英文原文

Title: Orthorhombic Covalent Organic Frameworks with fmj Topology as Photocatalyst for Hydrogen Evolution

Author: Wen-Zhuang Wang, Peng-Ju Tian, Yubin Fu, Xiaolong Wan, Xiaoling Lei, Chao Jia, Chao Liu, Qiao-Yan Qi, Shun-Qi Xu, Xin Zhao

Issue&Volume: 2025-01-06

Abstract: Three-dimensional covalent organic frameworks (3D COFs), a class of highly porous crystalline polymers, have exhibited great potentials in many applications. However, the reported topologies of 3D COFs have been limited to high-symmetry crystal systems, which significantly hindered the development of such functional materials. Herein, we demonstrate the first construction of four highly crystalline orthorhombic 3D COFs with an unprecedented fmj topology, based on judiciously choosing rotatable monomers. Notably, the square monomers in the unit cell of the fmj topological network adopt three different conformations, resulting in a highly complicated 3D network. Moreover, an isomeric pair (3DCOF-CN and 3DCOF-NC), differing only in the orientations of -C=N- bonds, exhibit distinct optoelectronic properties, protonation abilities, and photocatalytic activities, which is the first time to reveal such isomeric effects in 3D COFs. Particularly, a difference of 32-fold in photocatalytic hydrogen evolution rate was observed for the two isomers, with one achieving a superb rate up to ~31.1 mmol h-1 g-1. This work achieves the first construction of complex orthorhombic 3D COFs, and offers new insights for the development of 3D COF-based high-performance photocatalysts.

DOI: 10.1002/anie.202418086

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202418086