Amino Acid Anion Paired Mesoporous Poly(ionic liquids) as Metal-/Halogen-Free Heterogeneous Catalysts for Carbon Dioxide Fixation

Carbon dioxide (CO₂) fixation into high-value-added chemicals over eco-friendly heterogeneous catalysts has attracted a long-lasting concern but remains a huge challenge. Herein, we report the efficient metal-/halogen-/solvent-/additive-free heterogeneous CO₂ coupling with aziridines catalyzed by amino acid anion paired mesoporous poly(ionic liquids) (AA-MPILs). A combination of solvothermal synthesis and ion exchange facilely regulated the cations and anions of framework ionic moieties, enabling multifunctional active sites including an acidic carboxyl group, a basic amino group, and a carboxylate as a halogen-free nucleophile with superior leaving ability. The amino group tethered cation and carboxyl groups in the anions promoted the CO₂ adsorption capacity. High yield (>95%) and regioselectivity (>99% for 5-substituted oxazolidinone) and remarkable reusability were reached in the CO₂ cycloaddition with aziridines under mild conditions. The catalyst was also highly active in the coupling of CO₂ with epoxides for the synthesis of cyclic carbonates.