Porphyrins as nanoreactors in the carbon dioxide capture and conversion: a review

Abstract

On account of their unique properties and robust structures, porphyrins are nature's favorite catalysts. Porphyrins have attracted the attention of researchers for many decades as a result of their intense colors; but in recent years, interest in these molecules has sharply increased, due to their potential use in solving difficult problems in the fields of medicine and environmental protection. Much attention is currently focused on the development of materials for the capture and conversion of CO₂ into value-added products, and porphyrins are proving to be of interest in this area of research. Porphyrins were previously thought to be poorly-absorbant materials, as they are generally planar compounds. However, the development of new, efficient porphyrin-based materials and reliable synthetic routes for porphyrin-based nanoreactors, such as covalent–organic frameworks and metal–organic frameworks, for use as porous materials has helped to overcome the underlying challenges in CO₂ reactivity. Porphyrin-based materials that behave as nanoreactors are promising candidates in the capture and conversion of CO₂ as a result of the presence of the basic pyrrole structure that contains a macrocyclic cavity and large aromatic rings, which facilitate strong interactions with CO₂. This review provides an overview of progress in the area of CO₂ capture and conversion using porphyrin-based molecular materials and nanoreactors. These materials have important structural features in terms of surface area, porosity, CO₂ uptake and the possibility of the catalytic conversion of CO₂ to chemically valuable products.