Topochemical conversion of an imine- into a thiazole-linked covalent organic framework enabling real structure analysis

• Published in: Nature communications Vol. 9; no. 1; pp. 2600 - 10
• Main Authors: Haase, Frederik, Troschke, Erik, Savasci, Gökcen, Banerjee, Tanmay, Duppel, Viola, Dörfler, Susanne, Grundei, Martin M. J., Burow, Asbjörn M., Ochsenfeld, Christian, Kaskel, Stefan, Lotsch, Bettina V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03-07-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 147/143; 639/301/357/537; 639/301/923/3931; 639/638/298/923/3931; Catalysis; Conversion; Crystal structure; Crystallinity; Edge dislocations; Electron beams; Electron diffraction; Electrons; Grain boundaries; Humanities and Social Sciences; multidisciplinary; Organic chemistry; Polymers; Porosity; Science; Science (multidisciplinary); Structural analysis; Sulfur; Transmission electron microscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-04979-y

Stabilization of covalent organic frameworks (COFs) by post-synthetic locking strategies is a powerful tool to push the limits of COF utilization, which are imposed by the reversible COF linkage. Here we introduce a sulfur-assisted chemical conversion of a two-dimensional imine-linked COF into a thiazole-linked COF, with full retention of crystallinity and porosity. This post-synthetic modification entails significantly enhanced chemical and electron beam stability, enabling investigation of the real framework structure at a high level of detail. An in-depth study by electron diffraction and transmission electron microscopy reveals a myriad of previously unknown or unverified structural features such as grain boundaries and edge dislocations, which are likely generic to the in-plane structure of 2D COFs. The visualization of such real structural features is key to understand, design and control structure–property relationships in COFs, which can have major implications for adsorption, catalytic, and transport properties of such crystalline porous polymers.
Stabilization of covalent organic frameworks (COFs) by post-synthetic locking is a powerful tool to push the limits of COF utilization. Here the authors demonstrate a sulfur-assisted conversion of an imine-linked COF into a thiazole-linked COF, with retention of crystallinity and porosity, allowing for direct imaging of defects in COFs.