Facile aerial oxidation of porphyrins. Part 16. Phenolic porphyrins without tert-butyl substituents
Abstract
Non-tert-butyl-substituted phenolic porphyrins 5, 7 and 9 undergo aerial oxidation in acidic and basic solutions. Radicals are produced whose singlet EPR spectra differ significantly from those observed for the tert-butyl-substituted phenolic porphyrin 1. In the radical derived from 5a, for example, the unpaired electron is not (as in 1) localised on the macrocycle or the meso-substituent. Simulation of the EPR spectrum obtained for the zinc complex 7b in basic solution, suggests two species coexisting on the EPR time-scale.