Analysis of fluorescence quenching of coumarin derivatives by 4-hydroxy-TEMPO in aqueous solution.
J Fluoresc
; 24(3): 713-8, 2014 May.
Article
em En
| MEDLINE
| ID: mdl-24337873
ABSTRACT
The fluorescence quenching of different coumarin derivatives (7-hydroxy-4-methylcoumarin, 5,7-dimethoxycoumarin, 7-amino-4-methyl-3-coumarinylacetic acid, 7-ethoxy-4-methylcoumarin, 7-methoxycoumarin, 7-hydroxycoumarin, 7-hydroxy-4-methyl-3-coumarinylacetic acid and 7-amino-4-methylcoumarin) by 4-hydroxy-TEMPO in aqueous solutions at the room temperature was studied with the use of UV-Vis absorption spectroscopy as well as a steady-state and time-resolved fluorescence spectroscopy. In order to understand the mechanism of quenching the absorption and fluorescence emission spectra of all coumarins along with fluorescence decays were recorded under the action of 4-hydroxy-TEMPO. The Stern-Volmer plots (both from time-averaged and time-resolved measurements) displayed no positive (upward) deviation from a linearity. The fluorescence quenching mechanism was found to be entirely dynamic, what was additionally confirmed by the registration of Stern-Volmer plots at different temperatures. The Stern-Volmer quenching constants and bimolecular quenching rate constants were obtained for all coumarins studied at the room temperature. The findings demonstrate the possibility of developing an analytical method for the quantitative determination of the free radicals' scavenger, 4-hydroxy-TEMPO.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Água
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Sequestradores de Radicais Livres
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Hidroxilamina
/
Cumarínicos
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Óxidos N-Cíclicos
/
Fluorescência
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article