| Texto completo | |
| Autor(es): |
Augusto, Felipe A.
[1]
;
Bartoloni, Fernando H.
[2, 1]
;
Pagano, Ana Paula E.
[1]
;
Baader, Wilhelm J.
[1]
Número total de Autores: 4
|
| Afiliação do(s) autor(es): | [1] Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, Sao Paulo - Brazil
[2] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Santo Andre, SP - Brazil
Número total de Afiliações: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Photochemistry and Photobiology; v. 97, n. 2 NOV 2020. |
| Citações Web of Science: | 0 |
| Resumo | |
The peroxyoxalate reaction is one of the most efficient chemiluminescence transformations, with emission quantum yields of up to 50%; additionally, it is widely utilized in analytical and bioanalytical assays. Although the real reason for its extremely high efficiency is still not yet understood, the mechanism of this transformation has been well elucidated in anhydrous medium. Contrarily, only few mechanistic studies have been performed in aqueous media, which would be of great importance for its application in biological systems. We report here our experimental results of the peroxyoxalate reaction in completely aqueous carbonate buffer, using fluorescein as chemiluminescence activator. The kinetics are very fast in the used basic conditions (pH > 9); despite this, reproducible kinetic results were obtained. The reaction proceeds by specific base catalysis, with rate-limiting attack of hydrogen peroxide anion to the oxalic ester, in competition with ester hydrolysis by hydroxide ion. Emission quantum yields increase with the hydrogen peroxide concentration up to an optimal concentration of 10 mmol L-1. The infinite singlet quantum yield of (5.8 +/- 0.2) x 10(-7) is much lower than in anhydrous medium; however, it is similar to quantum yields measured before in partially aqueous media. (AU) | |
| Processo FAPESP: | 14/22136-4 - Uso de solventes verdes e suas misturas na otimização de processos químicos |
| Beneficiário: | Omar Abou El Seoud |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 12/13807-7 - Novas ferramentas para o estudo de reações de transferência de elétron em sistemas modelo do PS II |
| Beneficiário: | Fernando Heering Bartoloni |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |