Effect of the local environment on the structure and reactivity of metalloporphyrins

Phosphonium ionic liquids were utilized as novel reaction media in order to detect new chemistry for catalytic metalloporphyrins. This research involves two general areas: (1) EPR and ENDOR spectroscopic studies of metalloporphyrins in different hosts: ionic liquids, porous materials, and conventional molecular solvents; (2) catalytic reactivity and mechanism studies of metalloporphyrins in different hosts. Spectroscopic results indicate a distortion in geometry of copper porphyrins in ionic liquids, which shifts the spin density distribution within the molecule. Similar studies of iron porphyrins indicate that component ions from ionic liquids can bind to the metal centres of these catalytic molecules. Some ionic liquids were found to improve the reactivity of porphyrin catalysts in oxidation reactions due to their ability to solubilize all reaction components and to prevent aggregation of porphyrins. A porphyrin radical cation intermediate was detected in the oxidation reaction of 4-methoxythioanisole by iron meso-tetra(4-sulfonatophenyl)porphyrin.