Facile Grafting of Imidazolium Salt in Covalent Organic Frameworks with Enhanced Catalytic Activity for CO2 Fixation and the Knoevenagel Reaction

Ionic liquids (ILs) have gained significant attention in past decades due to their important characteristics and superior application potential. However, liquid nature is a big hindrance to the further development and applications of ILs. In this work, we report a simple acid–base neutralization strategy used to graft imidazolium salts into covalent organic frameworks (COFs) for the catalysis of CO2 chemical fixation and the Knoevenagel condensation reaction. It is found that in comparison with liquid IL, the as-synthesized material shows much better catalytic ability for the above reactions. In addition, both of the reactions proceed efficiently under solvent-free conditions, which provides a green and sustainable way in potential applications.