A novel bifunctional metalloporphyrin-based hyper-crosslinked ionic polymer as heterogeneous catalyst for efficiently converting CO₂ into cyclic carbonates

The rapid development of industrialization generated an urgent requirement for the catalytic conversion of CO₂ into high-value-added chemical products. Herein, a class of novel bifunctional metalloporphyrin-based hyper-crosslinked ionic polymer (ImHCP-Co) was synthesized via one-pot Friedel–Crafts alkylation and quaternization reactions. The obtained bifunctional ImHCP-Co showed a high BET surface area and sufficient CO₂ adsorption capacity. Relying on the synergistic effect of the electrophilic and nucleophilic functionalities, the as-prepared ImHCP-Co showed an excellent performance in CO₂ cycloaddition using epichlorohydrin as the substrate (99% conversion and 99% selectivity) and can be carried out without any solvents or cocatalysts to afford a high turnover number. Importantly, it could also convert various epoxide substrates into the corresponding cyclic carbonates and can maintain 82.5% of its catalytic ability after 5 cycles. The catalytic mechanism was systematically explained by DFT calculation and proved the cooperative effect of Co²⁺ centers and nucleophilic Cl⁻ in the catalytic process. This study provides a new avenue for the design and preparation of HCP-based multifunctional catalysts used for the treatment of greenhouse gases.