Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects
Steady-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 c...
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| Autores principales: | , , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2002
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/146538 |
| Aporte de: |
| id |
I19-R120-10915-146538 |
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| record_format |
dspace |
| institution |
Universidad Nacional de La Plata |
| institution_str |
I-19 |
| repository_str |
R-120 |
| collection |
SEDICI (UNLP) |
| language |
Inglés |
| topic |
Física Química steady-state studies time-resolved studies pterin family photon counting technique |
| spellingShingle |
Física Química steady-state studies time-resolved studies pterin family photon counting technique Thomas, Andrés Héctor Lorente, Carolina Capparelli, Alberto Luis Pokhrel, Megh Raj Braun, André M. Oliveros, Esther Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| topic_facet |
Física Química steady-state studies time-resolved studies pterin family photon counting technique |
| description |
Steady-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. |
| format |
Articulo Articulo |
| author |
Thomas, Andrés Héctor Lorente, Carolina Capparelli, Alberto Luis Pokhrel, Megh Raj Braun, André M. Oliveros, Esther |
| author_facet |
Thomas, Andrés Héctor Lorente, Carolina Capparelli, Alberto Luis Pokhrel, Megh Raj Braun, André M. Oliveros, Esther |
| author_sort |
Thomas, Andrés Héctor |
| title |
Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| title_short |
Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| title_full |
Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| title_fullStr |
Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| title_full_unstemmed |
Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects |
| title_sort |
fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: ph effects |
| publishDate |
2002 |
| url |
http://sedici.unlp.edu.ar/handle/10915/146538 |
| work_keys_str_mv |
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Repositorios |
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1764820461391183873 |