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
in 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pyrenes
/
Indoles
/
Octanes
Language:
En
Journal:
J Phys Chem A
Journal subject:
QUIMICA
Year:
2008
Document type:
Article
Affiliation country:
Argentina