INTRAMOLECULAR PHOTOTRANSFER OF PROTONS AND THE QUENCHING OF FLUORESCENCE OF DERIVATIVES OF 2-(COUMARINYL-3)-5-(<i>ortho</i>-HYDROXYPHENYL)-1,3,4-OXADIAZOLE

Abstract

The spectral-luminescence properties of ortho-hydroxy derivatives of 2-(coumarinyl-3)-5-phenyl-1,3,4-oxadiazole have been studied. It is shown that the basic reason for the decreased quantum yield of emission for the compounds studied is the high-speed phototransfer of a proton (estimated as ~10⁹ s^-1). Fluorescence of the products of this reaction (phototautomers) was not observed. It was confirmed by quantum-chemical calculations that the increase in efficiency of nonradiative dissipation of the electron excitation energy in phototautomeric forms of ortho-hydroxycoumarinyloxadiazoles is explained by an increase in intramolecular donor-acceptor interaction on introduction of the coumarin unit into the molecule. As a result of the high efficiency of nonradiative deactivation of the excited state, the ortho‑hydroxyderivatives studied have promise as UV photostabilizers in polymeric materials.

How to Cite
Doroshenko, A. O.; Posokhov, E. A.; Sytnik, K. M.; Kovalenko, S. N. Chem. Heterocycl. Compd. 2001, 37, 633. [Khim. Geterotsikl. Soedin. 2001, 686.]

For this article in the English edition, see DOI https://doi.org/10.1023/A:1011621025169