| Autor: | Andrey O. Doroshenko, E. A. Posokhov, K. M. Sytnik, S. N. Kovalenko |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Chemistry of Heterocyclic Compounds. 37:633-644 |
| ISSN: | 0009-3122 |
| DOI: | 10.1023/a:1011621025169 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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