A Pyridinium-Pyridinium Zinc(II) Porphyrin Ion Porous Organic Polymer as Efficient Heterogeneous Catalyst for Cycloaddition of Epoxides with CO2

A zinc(II)porphyrin-based ion porous organic polymer (ZnTPyPBr4-iPOP) is successfully synthesized from newly designed pyridinium-functionalized cationic Zn-porphyrin monomer (ZnTPyPBr4) by free radical self-polymerization, and is employed as an efficient bifunctional heterogeneous catalyst for CO2 cycloaddition reaction with epoxides. The ZnTPyPBr4-iPOP exhibits excellent catalytic performance and good substrate expansion in CO2 cycloaddition reaction under solvent-free and cocatalyst-free conditions with a TOF as high as 15,500 h(-1) for the cycloaddition of CO2 and epichlorohydrin. The synergistic effect of zinc(II)porphyrin as the Lewis acidic site and the Br- anion as the nucleophile in ZnTPyPBr4-iPOP responds to the high catalytic activity. Moreover, ZnTPyPBr4-iPOP can easily be recovered and reused at least seven times without the loss of activity. This work provides a valuable approach for the synthesis of novel and efficient heterogeneous catalyst for CO2 cycloaddition.