Effect of diffusion on the photoinduced reaction between a tetra-anionic porphyrin and methylviologen cation in methanol.
J Phys Chem A
; 112(24): 5378-84, 2008 Jun 19.
Article
em En
| MEDLINE
| ID: mdl-18507362
ABSTRACT
The quenching of the fluorescence decay of electronically excited 5,10,15,20-tetraphenyl- 21H, 23H-porphinetetrasulfonate (TPPS (4-)*) in the presence of methylviologen cations (MV (2+)) was measured at various ionic strengths in methanol. Analysis of the fluorescence decay curves revealed strong evidence for the presence of a second fluorescent species over the entire range of ionic strength used in this work, which is attributed to solvent-separated ion pairs (TPPS (4-)-S-MV (2+)). Transient effects of the fluorescence decays were analyzed, and values for the effective reaction distance, R NH, and the diffusion coefficients, D, were obtained. Diffusion coefficients were independently measured for TPPS (4-) and MV (2+) using the Taylor dispersion method. The values for D obtained by the analysis of the transient effect were found to be smaller than those for the sum of the diffusion coefficients of TPPS (4-) and MV (2+) obtained by the Taylor dispersion method and a possible explanation for this result is given.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Paraquat
/
Porfirinas
/
Metanol
Idioma:
En
Revista:
J Phys Chem A
Assunto da revista:
QUIMICA
Ano de publicação:
2008
Tipo de documento:
Article