Aerial oxidation of a redox-active porphyrin in the presence of a spin trap

SUMMARY

Aerial oxidation of meso-tetrakis(3,5-dimethoxy-4-hydroxyphenyl)- porphyrin 3, in the presence of the water-soluble spin trap (4-pyridyl-1-oxide)-N-t-butylnitrone (POBN), gives the porphyrin radical 4, in which spin density is localized on a phenoxyl meso-substituent. Evidence is presented to show that the spin trap inhibits solution aggregation and spin exchange of 4, but does not, as originally expected, form spin adducts with reduced-oxygen species.