Oxidations of (2,2′-Diphenyl)ethylidene-Bridged Porphyrin Dimers

Abstract

Oxidation reactions of (2,2′-diphenyl)ethylidene-bridged porphyrin dimers were examined for the synthesis of (2,2′-diphenyl)ethylidene-inserted porphyrin arch tape dimers. These reactions provided, in addition to the target arch tape dimers, unexpected products such as a bicyclo[3.3.0]octane-fused porphyrin dimer, a (2,2′-fluorenyl)ethylidene-inserted porphyrin arch tape dimer, and a meso- and ortho-phenyl-linked free base dimer, depending upon the substrate and reaction conditions, demonstrating the high promise of these porphyrin substrates. The target arch tape dimers, which were synthesized by the oxidation with DDQ and CF₃SO₃H, exhibit red-shifted and enhanced Q-bands and small electrochemical HOMO–LUMO gaps, indicating effective conjugation.