“Ship in a bottle” Porph@MOMs as highly efficient catalysts for selective controllable oxidation and insights into different mechanisms in heterogeneous and homogeneous environments

Abstract

In the present work, three “ship in a bottle” Porph@MOMs are reported as biomimetic oxidation catalysts for different reactions. These frameworks are constructed from trimesic acid and metal ions (M = Fe, Co and Mn) in which tetra(N-methyl-4-pyridyl)porphyrin (MTMPyP) is encapsulated within the cavities. Additionally, the catalytic activities of the corresponding homogeneous compounds, FeTMPyP, CoTMPyP and MnTMPyP, and the frameworks without porphyrins within the cavities were investigated in the foregoing oxidation reactions. The prepared 3D porous structures have the ability to control selectivity toward the desired product. Furthermore, they are capable of acting as effective peroxidase mimics, which successfully catalyze the oxidation of diverse olefins as well as hydrocarbons using TBHP as an oxidant. The heterogeneous catalysts significantly enhance conversion in contrast to their corresponding homogeneous systems. Remarkably, an insight into the catalyst behavior was gained from the proposed mechanism based on the reversal of selectivity. Investigation of the stability and reusability of the catalysts revealed the heterogeneity character of the catalyst with no desorption during the course of oxidation reactions. The high yields, clean reactions, high thermal stability and reusability of the catalysts make them good candidates for heterogeneous catalysts in various oxidation reactions.