Cheng Yuanpeng, Xin Junjie, Xiao Libang, Wang Xuejiao, Zhou Xu, Li Danyang, Gui Bo, Sun Junliang, Wang Cheng
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
College of Chemistry and Molecular Engineering Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
J Am Chem Soc. 2023 Aug 30;145(34):18737-18741. doi: 10.1021/jacs.3c06159. Epub 2023 Aug 16.
Herein, we report the introduction of steric hindrance in molecular building blocks to prevent π···π stacking, thus allowing two-dimensional (2D) covalent organic sheets to form three-dimensional (3D) covalent organic frameworks (COFs) through entanglement. Starting from the rationally designed precursors containing a bulky anthracene unit in the vertical direction, a highly crystalline COF (3D-An-COF) was successfully synthesized. Very interestingly, 3D-An-COF was determined as an entangled 2D square net () structure, and the high-resolution data (1.1 Å) obtained by the continuous rotation electron diffraction technique allowed us to directly locate all non-hydrogen atoms. Structurally, the presence of an anthracene group outside the symmetry plane strongly reduces the π···π interactions and promotes the formation of square entanglements. In addition, 3D-An-COF is fluorescent and can be used as a sensor to detect the trace amount of antibiotics in water. This study provides a new strategy for the structural diversification of 3D COFs and will certainly motivate us to construct more entangled COFs for interesting applications in the future.
在此，我们报道了在分子构建单元中引入空间位阻以防止π···π堆积，从而使二维（2D）共价有机片通过缠结形成三维（3D）共价有机框架（COF）。从在垂直方向上含有庞大蒽单元的合理设计的前体出发，成功合成了一种高度结晶的COF（3D-An-COF）。非常有趣的是，3D-An-COF被确定为一种缠结的2D方形网（）结构，并且通过连续旋转电子衍射技术获得的高分辨率数据（1.1 Å）使我们能够直接定位所有非氢原子。在结构上，对称平面外蒽基团的存在极大地降低了π···π相互作用并促进了方形缠结的形成。此外，3D-An-COF具有荧光性，可作为传感器用于检测水中痕量抗生素。本研究为3D COF的结构多样化提供了一种新策略，必将激励我们在未来构建更多缠结的COF以用于有趣的应用。
