Acridine‐Functionalized Covalent Organic Frameworks (COFs) as Photocatalysts for Metallaphotocatalytic C−N Cross‐Coupling

• Published in: Angewandte Chemie 2022-05, Vol.134 (21), p.n/a
• Main Authors: Traxler, Michael, Gisbertz, Sebastian, Pachfule, Pradip, Schmidt, Johannes, Roeser, Jérôme, Reischauer, Susanne, Rabeah, Jabor, Pieber, Bartholomäus, Thomas, Arne
• Format: Article
• Language: English
• Subjects: Acridine; Benzene; Bromides; Catalysis; Chemical synthesis; Chemistry; Clean energy; Covalence; Covalent Organic Frameworks; Cross coupling; Crystal structure; Crystallinity; C−N Cross-Coupling; Energy sources; Irradiation; Photocatalysis; Photocatalysts; Photoredox; Polymers; Radiation; Recyclability
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202117738

Covalent organic frameworks (COFs) are structurally tuneable, porous and crystalline polymers constructed through the covalent attachment of small organic building blocks as elementary units. Using the myriad of such building blocks, a broad spectrum of functionalities has been applied for COF syntheses for broad applications, including heterogeneous catalysis. Herein, we report the synthesis of a new family of porous and crystalline COFs using a novel acridine linker and benzene‐1,3,5‐tricarbaldehyde derivatives bearing a variable number of hydroxy groups. With the broad absorption in the visible light region, the COFs were applied as photocatalysts in metallaphotocatalytic C−N cross‐coupling. The fully β‐ketoenamine linked COF showed the highest activity, due to the increased charge separation upon irradiation. The COF showed good to excellent yields for several aryl bromides, good recyclability and even catalyzed the organic transformation in presence of green light as energy source. A new family of porous crystalline COFs bearing acridine moieties was synthesized and applied as photocatalysts in metallaphotocatalytic C−N cross‐coupling. Among these materials the fully β‐ketoenamine‐linked COF showed the highest catalytic activity and was shown to be recyclable and even catalyzed the cross‐coupling efficiently under green light irradiation.