Synthesis and fluorescence studies of porphyrin appended 1,3,4-oxadiazoles

Abstract

A modular synthetic approach for preparing a family of porphyrin appended 1,3,4-oxadiazoles 9 is described. The porphyrin hydrazides are reacted with aryl aldehydes in presence of Yb(OTf)3 as catalyst to give porphyrin hydrazones 8 which are then cyclized to porphyrin appended 1,3,4-oxadiazoles 9 using iodobenzene diacetate. Photophysical studies in CHCl3 solvent shows that the electronic structure of the porphyrin chromophore is not greatly perturbed by the incorporation of the oxadiazole group onto the meso-phenyl ring. Efficient quenching of porphyrin fluorescence was observed in 9g with a pyridinium moiety.