Proton-transfer mediated quenching of pyrene/indole charge-transfer states in isooctane solutions.
J Phys Chem A
; 112(4): 589-93, 2008 Jan 31.
Article
em En
| MEDLINE
| ID: mdl-18177025
ABSTRACT
The fluorescence quenching of pyrene (Py) by a series of N-methyl and N-H substituted indoles was studied in isooctane at 298 K. The fluorescence quenching rate constants were evaluated by mean of steady-state and time-resolved measurements. In all cases, the quenching process involves a charge-transfer (CT) mechanism. The I(o)/I and tau(o)/tau Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviation with increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CT intermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-H indoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysis of the experimental data obtained in the presence of pyridine provides unambiguous evidence that the self-quenching process involves proton transfer from the CT states to indoles.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pirenos
/
Indóis
/
Octanos
Idioma:
En
Revista:
J Phys Chem A
Ano de publicação:
2008
Tipo de documento:
Article