Electrochemical synthesis of novel π-extended phenoxazine derivatives of porphyrincatecholes

Three new functionalized phenoxazine-catechol porphyrins 7a–c have been synthesized by a green one-pot method and structurally characterized by spectroscopic analysis. The electro-oxidation of 5,10,15,20-tetrakis(2,3-dihydroxyphenyl) porphyrins(1a–c) with four catechol units in the presence of 2-aminophenol 8 as bidentate nucleophile has been done and phenoxazine rings have been formed by intermolecular and intramolecular Michael addition reactions. Spectroscopic characterization and voltammetry results have allowed us to propose four independent ECEC mechanisms for the electrochemical oxidation pathway. The functionalization of the porphyrins affected their photophysical properties. Expansion of the UV–vis spectrum range and the decrease of the fluorescence intensity of the products would support the energy transfer between the porphyrin core excited states to the four substitutions as the electron acceptor subunits. SEM images indicate that this method produces regularly shaped manganese porphyrin nano-particles 7c that possess a cubic nano structure.