The aqueous coumarin system as a low range chemical dosimeter

The reaction of coumarin with the OH radical revisited: hydroxylation product analysis determined by fluorescence and chromatography

“…1, the irradiation of aerated coumarin solutions (10 À4 mol dm À3 ) leads to the appearance of a fluorescence signal whose characteristics appear identical to that of the fluorescence emission spectrum of 7OHC (Petrola, 1986). In previous studies it has thus been assumed that the only fluorescence species produced is that of 7OHC (Gopakumar et al, 1977;Ashawa et al, 1979). Our first goal in this work was thus to verify this hypothesis.…”

“…For this study, we have chosen the latter. In recent decades a number of fluorescent probes have been used to study HOd scavenging, including terephthallic acid (Armstrong et al, 1963;Matthews, 1980;Fang et al, 1996), benzoic acid (Armstrong and Grant, 1960), and coumarin (Gopakumar et al, 1977;Ashawa et al, 1979;Makrigiorgos et al, 1993;Manevich et al, 1997).…”

Preparation and application of nanoglued binary titania–silica aerogel

“…In this experiment, low concentrations of coumarin (1 × 10 −3 M) and terephthalic acid (4 × 10 −4 M) were used, indicating the production of 7-hydroxycoumarin and 2-hydroxyterephthalic acid. Based on previous reports in the literature [32][33][34][35][36][37][38][39][40], it is reasonable to assume that these fluorescent compounds result from the reaction between the probe molecules and • OH. The fluorescence analysis results further indicate that the photocatalytic destruction of contaminants by the nanoglued binary TiO 2 -SiO 2 aerogel follows the assumed mechanism: generation of • OH during the photocatalytic reaction, and hydroxyl radical oxidation of contaminants.…”

“…radical in the photocatalytic degradation of methylene blue with our binary TiO 2 -SiO 2 aerogel[32]. Coumarin and terephthalic acid react with • OH to form the highly fluorescent intermediates, 7-hydroxycoumarin[32][33][34][35] and 2-hydroxyterephthalic acid[32,[36][37][38][39][40] as shown in Figs. 2 and 3.…”

Preparation, characterization and activity evaluation of heterostructure In2O3/In(OH)3 photocatalyst

“…More free • OH radicals imply stronger photocatalytic oxidation. Using terephthalic acid as a probe molecule by a photoluminescence (PL) technique to detect the formation of free • OH radicals has been a frequently used method in sonochemistry, biochemistry, and radiation chemistry [31,32]. Terephthalic acid readily reacts with • OH radicals to produce highly fluorescent product, 2-hydroxyterephthalic acid [19].…”