Ionic Liquid Immobilized Fe-MIL-101-NH₂ Efficiently Catalyzes the Chemical Fixation of CO₂ with Epoxides to Form Cyclic Carbonates

In this work, two ionic liquids (ILs) immobilized metal-organic frameworks (MOFs), Fe-MIL-101-3N(BuBr) and Fe-MIL-101-N(Bnme(2))Br, were obtained by modifying amino groups in Fe-MIL-101-NH2 with bromobutane and quaternary ammonium salt. The ionic liquid immobilized MOFs have Lewis acid sites (Fe3+) and nucleophilic sites (Br-), which can synergistically catalyze the cycloaddition reaction of CO2 and epoxides. Various cyclic carbonate derivatives were obtained in excellent yields under the optimal conditions. Additionally, we found that Fe-MIL-101-N(Bnme(2))Br exhibited the highest catalytic activity and it can be easily recovered and reused for at least 5 times without loss of catalytic activity. Our method of preparing bifunctional catalysts provides a new approach to design catalysts for the chemical conversion of CO2.