The dual fluorescence of cyano-5-phenyltetrazoles

Abstract

Absorption, excitation and luminescence spectra of ortho-, meta- and para-cyano-5-phenyltetrazole in solvents of different polarity and proton-accepting ability, werer examined. The dual fluorescence, which appears in some solvents at room temperature, can by explained by the formation of the hydrogen-bonded complexes between the solute and solvent molecules which can results in proton transfer in the excited state, and formation of anion. In the excited anion of cyano-5-phenyl tetrazole, a considerable charge transfer from tetrazole to phenyl ring take place, accompanied by mutual twisting of the rings. That twisted conformation of the anion is responsible longwave band of dual fluorescence.