Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects

dc.creatorThomas, Andrés Héctor
dc.creatorLorente, Carolina
dc.creatorCapparelli, Alberto Luis
dc.creatorPokhrel, Megh Raj
dc.creatorBraun, André M.
dc.creatorOliveros, Esther
dc.date2002-06
dc.date2022-11-29T13:19:43Z
dc.date.accessioned2023-07-15T05:12:29Z
dc.date.available2023-07-15T05:12:29Z
dc.identifierhttp://sedici.unlp.edu.ar/handle/10915/146538
dc.identifierissn:1474-905X
dc.identifierissn:1474-9092
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/7472489
dc.descriptionSteady-state and time-resolved studies have been performed on four compounds of the pterin family (pterin, 6-carboxypterin, 6-formylpterin and folic acid) in aqueous solution, using the single photon counting technique. The fluorescence characteristics (spectra, quantum yields, lifetimes) of these compounds and their dependence on the pH have been investigated. Most pterins can exist in two acid–base forms over the pH range between 3 and 13. Emission spectra and excitation spectra were obtained for both forms of each compound studied. Fluorescence quantum yields (Φ<sub>F</sub>) in acidic and basic media were measured. The Φ<sub>F</sub> of folic acid (<0.005 in both media) is very low compared to those of pterin (0.27 in basic media and 0.33 in acidic media), 6-carboxypterin (0.18 in basic media and 0.28 in acidic media) and 6-formylpterin (0.07 in basic media and 0.12 in acidic; media). The variation in integrated fluorescence intensity and fluorescence lifetimes (τ<sub>F</sub>) was analysed as a function of pH. Dynamic quenching by OH⁻ was observed and the corresponding bimolecular rate constants for quenching of fluorescence (k<sub>q</sub>) were calculated. The reported values for k<sub>q</sub>; (M⁻¹ s⁻¹) are 3.6 × 10⁹, 1.9 × 10⁹ and 1.1 × 10¹⁰ M⁻¹ s⁻¹ for pterin, 6-carboxypterin and 6-formylpterin, respectively.
dc.descriptionInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas
dc.formatapplication/pdf
dc.format421-426
dc.languageen
dc.rightshttp://creativecommons.org/licenses/by/4.0/
dc.rightsCreative Commons Attribution 4.0 International (CC BY 4.0)
dc.subjectFísica
dc.subjectQuímica
dc.subjectsteady-state studies
dc.subjecttime-resolved studies
dc.subjectpterin family
dc.subjectphoton counting technique
dc.titleFluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects
dc.typeArticulo
dc.typeArticulo


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