Imidazolium-functionalized metalloporphyrin porous organic polymers for catalytic CO₂ conversion into cyclic...

Porous organic polymers (POPs) have emerged as a versatile platform for constructing advanced functional materials, particularly in the field of heterogeneous catalysis. By covalently incorporating metalloporphyrin units into POP frameworks, a new class of biomimetic catalysts, i.e. metalloporphyrin-based POPs (MPOPs), has been developed, combining structural robustness with tailored active sites. Significant progress has been achieved through further integration of ionic liquid (IL) functionalities, yielding IL-MPOPs capable of synergistic activation of CO₂ and epoxides without the need for external co-catalysts. This review offers a systematic overview of recent advances in the rational design, synthesis, and catalytic application of imidazolium-based IL-MPOPs for efficient CO₂ conversion into cyclic carbonates. Particular emphasis is placed on the unique role of imidazolium cations as hydrogen-bond donors and nucleophilic promoters, which contribute to reduced energy barriers and suppressed metal leaching. Through a comparative analysis of different metal centers (Al, Mg, Zn, and Co), metal-specific design principles are established: Al-porphyrins enhance substrate activation via strong Lewis acidity; Mg-porphyrins achieve record-high turnover frequencies; Zn-porphyrins provide an optimal trade-off between activity and stability; and Co-porphyrins enable photocatalytic cycloaddition via redox-mediated pathways. These insights reveal fundamental structure-property-performance relationships and provide a strategic roadmap for developing multifunctional, recyclable catalytic systems that bridge biomimetic catalysis with industrial applicability in CO₂ conversion.