C2-phenyl-substituted benzimidazolium-based covalent organic framework as efficient catalyst for CO₂ conversion without solvents, metals, and cocatalysts

Covalent organic frameworks (COFs) are a potential platform for carbon dioxide (CO2) conversion owing to their periodic permanent porosity, adjustable structure, and chemical stability. For good catalytic performance in CO2 conversion, collaborative multifunctions should be strategically integrated into the catalytic system design and construction. In this study, a four-in-one high-efficiency catalyst was synthesized and tested for CO2 cycloaddition to form cyclic carbonate. The obtained Tp-MPB-Br-COF had a high nitrogen content, which enhanced its CO2 affinity through substantial Lewis acid-base or dipole-quadrupole interactions; moreover, the acid (protons transferring from oxygen (-OH) to nitrogen (-NH)), hydrogen bond donor (hydroxyl group), and Br- (nucleophile group) served as three active sites, further improving the catalyst activity. These results provide a basis for designing efficient and stable CO2 -conversion catalysts.