Isostructural Three‐Dimensional Covalent Organic Frameworks

Abstract

Herein, we reported the designed synthesis of three isostructural three-dimensional covalent organic frameworks (3D COFs) with -H, -Me,or-Fsubstituents,which have similar crystallinity and topology.T heir crystal structures were determined by continuous rotation electron diffraction (cRED), and all three 3D COFs were found to adopt af ivefold interpenetrated pts topology.M ore importantly,t he resolution of these cRED datasets reached up to 0.9-1.0 ,e nabling the localization of all non-hydrogen atomic positions in aC OF framework directly by 3D ED techniques for the first time.In addition, the precise control of the pore environments through the use of different functional groups led to different selectivities for CO 2 over N 2 .W eh ave thus confirmed that polycrystalline COFs can be definitely studied to the atomic level as other materials,a nd this study should also inspire the design and synthesis of 3D COFs with tailored pore environments for interesting applications.

Single crystal of a one-dimensional metallo-covalent organic framework

“…2c, inset) confirm its single-crystal nature. The single-crystal structure of mCOF-Ag is determined directly from the SCED data 39,40 (Fig. 2a).…”

2D and 3D Porphyrinic Covalent Organic Frameworks: The Influence of Dimensionality on Functionality

“…Owing to their periodic architectures,l ow densities,h igh surface areas,a nd high stability,C OFs are considered as ah ighly designable and functionalized materials platform with various potential applications.S ince first discovered by Yaghi and co-workers in 2005, [2] intensive attentions have been devoted to constructing functional COFs with desired properties.T hanks to the efforts of many groups,al arge number of functional COFs have been reported over the past decade,w hich have found interesting applications in gas adsorption and separation, [3] heterogeneous catalysis, [4] molecular sensing, [5] energy storage, [6] proton conductivity, [7] and optoelectronics. [8] To construct COFs with desired functionalities,afacile way is incorporating specific functional moieties during their synthesis process.F rom as tructural viewpoint, these functional moieties can be integrated into either two-dimensional (2D) layered structures [9] or three-dimensional (3D) extended networks, [10] depending on the geometry and connectivity of the precursors.F or 2D COFs,the 2D flat sheets usually stack in af ace-to-face mode,a nd the functional moieties in the adjacent layers have strong p-p interactions that could be beneficial for the charge mobility.I nc ontrast, 3D COFs will allow the functional moieties to be three-dimensionally organized into the framework and thus feature open sites.…”

Fluorinated Organic Porous Materials

“…Sun and coworkers prepared three isostructural imine-based COFs from tetraphenylbenzene tetraaldehydes which were disubstituted with hydrogen, methoxy, or fluoro groups. 30 Their structures were solved using continuous rotation electron diffraction and were found to be five-fold interpenetrated and very similar to each other. The fluorinated material had a much higher affinity for CO 2 than the nonfluorinated framework, as well as a higher (50:1) IAST (ideal adsorbed solution theory) selectivity for CO 2 over N 2 .…”