Highly Efficient CO₂ Fixation Into Cyclic Carbonates Catalyzed by Imidazolium‐Functionalized Zn‐Based MOFs

ABSTRACT The coupling between epoxide and carbon dioxide into cyclic carbonates in the absence of co‐catalyst and solvents is a feasible strategy for removing CO 2 from the atmosphere and achieving a carbon‐neutral cycle. In this context, two new bifunctional catalytic systems prepared by modification metal–organic frameworks (MOFs) with ionic liquids (ILs) and catalytic activities have been compared in converting CO 2 into cyclic carbonates. IL methylimidazolium bromide (MI‐Br) is grafted into both Zn‐MOF‐NH 2 and Zn 3 (L) 3 (H 2 L) MOF to produce the dual‐functional one‐component systems with a high density of Lewis acidic Zn(II) metal sites and IL functional sites to carry out co‐catalyst/solvent‐free cycloaddition of CO 2 to epoxides. The characteristics of the MI‐Br IL@MOFs were revealed via different techniques, including FE‐SEM, EDX, FT‐IR, XRD, N 2 adsorption, NH 3 ‐TPD, and ICP‐OES. Further, two efficient catalysts act as excellent recyclable catalysts for 4 successive cycles without substantial loss in catalytic activity cycloaddition of CO 2 to epoxides to cyclic carbonates. Herein, a synergistic catalytic mechanism between Lewis acidic sites and Br − ions is proposed to carry out the cycloaddition of CO 2 to epoxides under co‐catalyst/solvent‐free conditions.