Supramolecular binding of amines with functional magnesium tetraphenylporphyrin for CO2 capture

In this work,magnesium tetraphenylporphyrin (MgTPP) was used as a new supramolecular amine-fixing agent. Once introduced, CO2 easily competes with MgTPP for amines, leading to the release of MgTPP. The processes can be explained by the fact that the association constant (Kassoc) values of MgTPP with amines were in the range of 0.6 (ethanolamine) to 3.9 (ethylenediamine), which are lower than the Kassoc values of CO2 with these amines. MgTPP interacted with aniline, ethanolamine, pyrrolidine, or ethylenediamine to form 1:1 adducts. Ethylenediamine presents a stronger Kassoc value for MgTPP, so it was considered an optimal agent for CO2 capture.