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

Abstract

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.

Hematin supported on Colour Catcher®: a biodegradable heterogeneous catalyst for halogen-free CO2 cycloadditions

“…On the other hand, in a bifunctional porphyrin system, the tetrapyrrolic core serves as the electrophilic center responsible for interacting with the heteroatom of the three-membered cycle, while the porphyrin periphery carries the nucleophile responsible for the ring-opening reaction. [31][32][33][34][35][36][37] The use of bifunctional catalysts, rather than binary systems, improves the sustainability and cost-effectiveness of the process by reducing the number of species involved and minimizing the necessary purification steps. Environmental friendliness of the procedure can be further enhanced by employing biocompatible catalysts and/or by immobilizing the catalyst onto a solid support.…”

“…The environmental friendliness of the procedure can be further enhanced by employing biocompatible catalysts and/or by immobilizing the catalyst onto a solid support. 31,32,34 Porphyrin-like complexes inherently exhibit biocompatibility due to the tetrapyrrolic scaffold, which is present in essential biological molecules, including hemin and hematin. These latter molecules play pivotal roles in biological functions and present different pharmaceutical and catalytic activities.…”

“…The environmental friendliness of the procedure can be further enhanced by employing biocompatible catalysts and/or by immobilizing the catalyst onto a solid support. 31,32,34…”