Ionothermal Synthesis of Imide‐Linked Covalent Organic Frameworks. (7th August 2020)

• Record Type: Journal Article
• Authors: Maschita, Johannes; Banerjee, Tanmay; Savasci, Gökcen; Haase, Frederik; Ochsenfeld, Christian; Lotsch, Bettina V.
• Is Part Of: Angewandte Chemie. Volume 132:Number 36(2020)
• Page Start: 15880
• Page End: 15888
• Publication Date: 2020-08-07
• Subjects: covalent organic frameworks -- eutectic salt mixtures -- ionothermal synthesis -- polyimides; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202007372
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF. Abstract : Aiming for synthetic diversity and simplification of the synthesis, a generic ionothermal approach for imide‐linked covalent organic frameworks has been developed. By using ZnCl2 and eutectic salt mixtures, highly crystalline COFs were synthesized with a significantly reduced reaction time of 10 hours. Unlike common solvothermal methods this approach does not require soluble precursor molecules.