Three interconverting excited species: experimental study and solution of the general photokinetic triangle by time-resolved fluorescence
✍ Scribed by J. Seixas de Melo; A.L. Maçanita
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 511 KB
- Volume
- 204
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
✦ Synopsis
Intermolecular photokinetics with the neutral, the anionic and the tautomeric forms of 7-hydroxy4methylcoumarin (7H4MC) is fully resolved using time-resolved fluorescence techniques. From the triple exponential fluorescence. decays of these species, and from the separately determined fluorescence lifetimes of the neutral and anionic forms, the six rate constants and the fluorescence lifetime of the tautomeric form are determined. With these rate constants the steady state fluorescence data (fluorescence quantum yields as a function of [H+ ] ) are accurately reproduced.
' To whom correspondence should be addressed. Scheme 1.
anion and tautomer (scheme 1). The fluorescence decays of this compound in several solvent mixtures and water were previously measured [lo-121 but the authors did not report a clear separation of the three decay times.
2. Model
In scheme 1 there are nine unknowns (six rate constants and three reciprocal lifetimes), so that nine