Self-Assembly of Imidazolium-Functionalized Zr-Based Metal–Organic Polyhedra for Catalytic Conversion of CO₂ into Cyclic Carbonates

Three cationic capsule-shaped Zr-based metal-organic polyhedra (MOPs) with different cavity sizes were successfully constructed through the self-assembly of trinuclear zirconocene clusters and imidazolium-functionalized dicarboxylic ligands. Owing to the imidazolium groups in the MOPs, they show good CO₂ adsorption uptake. Moreover, the halogen anions of the imidazolium groups and Brønsted acid sites (-OH) in the Zr-based knots are in close proximity, making these MOPs able to catalyze synergistically the cycloaddition reaction of CO₂ with epoxides into cyclic carbonates. This is the first report of using MOPs as catalysts for this reaction without the addition of a cocatalyst.