Wang Wen-Zhuang, Tian Peng-Ju, Fu Yubin, Wan Xiaolong, Lei Xiaoling, Jia Chao, Liu Chao, Qi Qiao-Yan, Xu Shun-Qi, Zhao Xin
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
School of Energy and Environment, Southeast University, Nanjing, 211189, Jiangsu, China.
Angew Chem Int Ed Engl. 2025 Feb 17;64(8):e202418086. doi: 10.1002/anie.202418086. Epub 2025 Jan 28.
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 g. 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.
三维共价有机框架（3D COF）是一类高度多孔的结晶聚合物，在许多应用中展现出了巨大潜力。然而，已报道的3D COF拓扑结构仅限于高对称晶体系统，这严重阻碍了此类功能材料的发展。在此，我们基于精心选择可旋转单体，首次构建了具有前所未有的fmj拓扑结构的四种高度结晶的正交晶系3D COF。值得注意的是，fmj拓扑网络晶胞中的方形单体采用三种不同构象，形成了高度复杂的三维网络。此外，仅在-C=N-键取向上不同的一对异构体（3DCOF-CN和3DCOF-NC）表现出截然不同的光电性质、质子化能力和光催化活性，这是首次在3D COF中揭示此类异构效应。特别地，观察到这两种异构体的光催化析氢速率相差32倍，其中一种达到了高达约31.1 mmol h g的优异速率。这项工作首次实现了复杂正交晶系3D COF的构建，并为基于3D COF的高性能光催化剂的开发提供了新见解。
