Imidazolium-Salt-Functionalized Covalent Organic Frameworks for Highly Efficient Catalysis of CO2 Conversion

Abstract

The conversion of CO₂ into valuable chemicals is an ideal pathway for CO₂ utilization in industry, although the development of highly efficient catalysts remains a challenge. Herein, the design and synthesis of two covalent organic frameworks (COFs) functionalized with imidazolium salts were reported as catalysts for CO₂ conversion. The resultant COFs possessed highly crystalline structures, showed high stability and surface area, and contained dense catalytic active sites on the pore walls. They exhibited outstanding catalytic performances for the reaction of CO₂ with epoxides without any solvent or cocatalyst under mild conditions and afforded a record turnover number of 495 000. In addition, the COFs could serve as effective catalysts in the reductive reaction of CO₂ with amines. The results presented here thus demonstrate the exceptional potential of the functionalized COFs for various challenging CO₂ transformations.

Keywords: carbon dioxide; carbonates; covalent organic frameworks; heterogeneous catalysis; imidazolium salts.