Zinc(II)porphyrin-Based Porous Ionic Polymers (PIPs) as Multifunctional Heterogeneous Catalysts for the Conversion of CO<sub>2</sub> to Cyclic Carbonates
Xiaolong Bai, Zhenping Su, Jiaojiao Wei, Linjing Ma, Sujiao Duan, Ning Wang, Xiongfu Zhang, Jun Li
Abstract
The heterogeneous and multifunctional charged polymers have broad application prospects in modern catalysis. One of the valid methods of synthesizing multifunctional charged polymers is incorporating metalloporphyrins with halide anions. Herein, a series of zinc(II)porphyrin-based porous ionic polymers [PIP-ZnTIPP/DVB (1:m) (m = 20, 40, 60, 80)] were synthesized by combining imidazolium-functionalized Zn-porphyrin (ZnTIPP) and divinylbenzene (DVB) through the free-radical copolymerization by a solvothermal method. The rigid PIPs have many physical advantages such as spatial separation of Zn-porphyrin sites, high thermal stability, hierarchical pore structures, high specific surface area, and abundant imidazolium (Br–) group in the polymeric skeletons, which exhibit fantastic catalytic activity for the coupling reaction of epoxides and CO2 without any solvent or cocatalyst. In particular, the catalyst PIP-ZnTIPP/DVB (1:20) displayed the highest catalytic activity with a yield of 99% and a turnover frequency (TOF) of 759 h–1 and could be recycled six times without the loss of activity. The excellent catalytic activity results from a synergistic effect between zinc sites and nucleophilic bromide anions.