Metalloporphyrin-\nand Phosphonium-Bifunctionalized\nPorous Organic Polymers for Efficient Synergistic Catalysis of CO<sub>2</sub> Conversion under Mild Conditions

Functional porous organic polymers (POPs) have been widely\ndeveloped\nas heterogeneous catalysts for carbon dioxide (CO<sub>2</sub>) conversion.\nHowever, the integration of multifunctional active sites into POPs\nremains a major challenge. Herein, a facile postsynthesis modification\nstrategy was explored to fabricate metalloporphyrin- and phosphonium-bifunctionalized\nPOPs (TAPPM-PTBAR) as the heterogeneous catalysts for CO<sub>2</sub> conversion. The as-developed catalysts were characterized in detail\nusing various techniques. The results illustrated that the novel POP\ncatalysts featured abundant Lewis acid metal centers, nucleophilic\nactive sites, and phosphonium cation. These features enabled the catalyst\nto immobilize CO<sub>2</sub> under mild and solvent-free conditions.\nThe synergistic effect of cobalt as a Lewis acid site and halide anion\nas a bifunctional nucleophile site enhances the catalysis performance\nof TAPPM-PTBAR. Combining the experimental results and density functional\ntheory calculation, a plausible reaction mechanism involving hydrogen\nbonding and Co<sup>3+</sup> center for epoxides was proposed. Considering\nits good reusability and substrate expansibility, the developed TAPPCo<sup>3+</sup>-PTBANH<sub>2</sub> demonstrated great potential as a robust\nheterogeneous catalyst for the efficient utilization of C1 resources.