Protonation-Induced Hyperporphyrin Spectra of meso-Aminophenylcorroles

[Image: see text] UV–vis spectrophotometric titrations have been carried out on meso-tris(o/m/p-aminophenyl)corrole (H(3)[o/m/p-TAPC]) and meso-triphenylcorrole (H(3)[TPC]) in dimethyl sulfoxide with methanesulfonic acid (MSA). Monoprotonation was found to result in hyperporphyrin spectra characterized by new, red-shifted, and intense Q bands. The effect was particularly dramatic for H(3)[p-TAPC] for which the Q band red-shifted from ∼637 nm for the neutral species to 764 nm in the near-IR for H(4)[p-TAPC](+). Upon further protonation, the Q band was found to blue-shift back to 687 nm. A simple explanation of the phenomena has been offered in terms of quinonoid resonance forms.