Authors
Guillermo E Quintero, Kevin Droguett, Costantino Zazza, Margarita E Aliaga
Published in
ChemistryOpen. Volume 15. Issue 8. Pages e70275.
Abstract
Herein we report an experimental and theoretical study of the reactivity of the dye (E)-7-(diethylamino)-1-methyl-3-(2-(3-methyl-4-nitroisoxazol-5-yl)vinyl)quinolin-2-one (DQI) toward bisulfite (HSO3 -) in the presence of an aqueous micellar solution of the cationic surfactant cetyltrimethylammonium bromide (CTABr), which was used as the reaction medium. We observe that aqueous DQI exhibits very weak emission, accompanied by a low fluorescence quantum yield. Interestingly, upon addition of CTABr, a pronounced enhancement of the fluorescence intensity is observed, together with a hypsochromic shift in the emission. Additionally, the cationic surfactant acts as an efficient reaction promoter by enhancing the solubility of the proposed hydrophobic DQI dye and increasing its local concentration within the Stern layer, where bisulfite ions are also accumulated, thereby favoring a nucleophilic attack. The formation of thiol adducts is investigated via photophysical (absorption and fluorescence) and nuclear magnetic resonance measurements and the derived data are further supported by density functional theory-correlated wavefunctions to identify the most favorable sites for electrophilic and nucleophilic attack in the DQI probe. The overall evidence clearly indicates a distinctive reactivity, supporting the formation of a DQI•SO3H Michael adduct in the proposed CTABr micellar medium.
PMID:
42571963
Bibliographic data and abstract were imported from PubMed on 10 Aug 2026.
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