The synthesis and optical properties of meso-substituted porphyrins bearing quinoxaline derivatives

Porphyrins bearing quinoxaline derivatives were synthesized by the condensation reaction of 2,2′-(p-tolylmethylene)bis(1H-pyrrole) and a bisstyryl derivative containing 6,7-diisopentyloxyquinoxaline. The highly conjugated porphyrin macrocycle showed intense absorption at ∼425 nm (Soret band), followed by several weaker absorptions (Q band) at higher wavelengths (680 nm). The porphyrins showed strong fluorescence at ∼480 nm. The chromophoric system of the fluorescent and highly conjugated porphyrin macrocycles were studied from the viewpoint of protonation and deprotonation effects on their absorption and emission spectra in solution.