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Analysis of Fluorescence Quenching of Coumarin Derivatives by 4-hydroxy-TEMPO in Aqueous Solution

Analysis of Fluorescence Quenching of Coumarin Derivatives by 4-hydroxy-TEMPO in Aqueous Solution

Krzysztof Żamojć, Wiesław Wiczk, Bartłomiej Zaborowski, Dagmara Jacewicz, Lech Chmurzyński

J Fluoresc. 2014 May;24(3):713-8.

PMID: 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.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP5852108	7-Hydroxy-4-methyl-3-coumarinylacetic acid		5852-10-8	Price

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