Bifunctional Zr-MOF grafted by dicationic ionic liquid and porphyrin for enhanced Lewis acid–base catalysis of cocatalyst-free CO2 cycloaddition

The catalytic transformation of epoxides into cyclic carbonates offers a promising strategy to mitigate excessive CO 2 emissions while producing valuable chemicals. However, attaining high catalytic efficiency and selectivity with MOF-based catalysts under mild conditions continues to be a significant challenge. Additionally, many existing catalytic systems rely on cocatalysts or solvents, compromising sustainability and practicality. In this study, a series of alkyl chain-tunable Zr-MOF catalysts, denoted as TCPP-UiO-66-PDC-DIL(R) (R = Et, Pr, Bu, Pe), were synthesized via a two-step approach. Initially, Zr 4 + ions were coordinated with meso-tetra(4-carboxyphenyl) porphine (TCPP) and 2,5-pyridine dicarboxylic acid (PDC) to create TCPP-UiO-66-PDC. Subsequently, dicationic ionic liquids (DIL) with varying alkyl chains lengths were decorated through post-synthetic modification. Their catalytic performance was assessed for CO 2 -epoxide cycloaddition without the use of cocatalysts or solvents. Among them, TCPP-UiO-66-PDC-DIL(Bu) exhibited the best catalytic performance, achieving a 98 % yield for producing chloropropene carbonate at a low CO 2 pressure (1.0 bar) within 12 h. This exceptional activity was attributed to the synergistic interplay of Lewis-acidic Zr 4+ nodes for epoxide activation, the porphyrin moiety of the TCPP ligand enhancing CO 2 adsorption, and the strong nucleophilicity of bromide anions in DIL to facilitate the halide ion-mediated nucleophilic attack on the epoxide-CO 2 adduct. Additionally, the catalyst demonstrated superior universalities toward other substrates and recyclability. These findings expand the potential of the multifunctional MOF-based heterogeneous catalysts, enhancing their efficiency and sustainability for use in CO 2 conversion.