| Full text | |
| Author(s): |
Khalid, Muhammad
;
Souza Jr, Sergio P.
;
Cabello, Maidileyvis C.
;
Bartoloni, Fernando H.
;
Ciscato, Luiz Francisco M. L.
;
Bastos, Erick L.
;
El Seoud, Omar A. A.
;
Baader, Wilhelm J.
Total Authors: 8
|
| Document type: | Journal article |
| Source: | JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY; v. 433, p. 11-pg., 2022-12-01. |
| Abstract | |
The parameters which determine the efficiency of chemiluminescence, and bioluminescence transformations are a continuous matter of experimental and theoretical studies. In this sense, we report here a study of the solvent polarity influence on four Chemically Initiated Electron Exchange Luminescence (CIEEL) systems. Two of them comprise intermolecular CIEEL systems with low efficiency - catalyzed decomposition of diphenoyl peroxide and spiroadamantyl-1,2-dioxetanone; the other two are highly efficient in producing excited states - the peroxyox-alate reaction through an intermolecular CIEEL, and the induced decomposition of a phenoxy-substituted 1,2-dioxetane derivative via intramolecular CIEEL. These four CIEEL systems are studied in binary solvent mix-tures with similar viscosity but different polarity, as measured by the empirical solvent polarity parameter ET(30). Reaction rate constants for all the systems increase with increasing polarity, indicating the occurrence of electron or charge transfer in the rate-limiting step of these transformations. For the intermolecular systems, singlet quantum yields generally rise with medium polarity to a maximum value and decrease for higher po-larities. This agrees with stabilization of the radical ion pair intermediate by solvation at an optimal medium polarity. In contrast, higher polarity promotes the separation of these charged species, thereby avoiding electron back-transfer between radical ion pairs, essential for chemiexcitation. The singlet quantum yields in the intra-molecular CIEEL system show a steady increase with the medium polarity, reaching values close to the maximum possible quantum yield of 1.0 E mol(-1), indicating the importance of biradical ion stabilization and the occur-rence of the whole reaction sequence in an intramolecular manner. (AU) | |
| FAPESP's process: | 14/22136-4 - Use of green solvents and their mixtures for optimizing chemical processes |
| Grantee: | Omar Abou El Seoud |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 22/02183-4 - 21st International Symposium on Bioluminescence and Chemiluminescence & XIX International Symposium on Luminescence Spectrometry |
| Grantee: | Fernando Heering Bartoloni |
| Support Opportunities: | Research Grants - Meeting - Abroad |
| FAPESP's process: | 12/13807-7 - New tools for the study of electron transfer reactions in PS II model systems |
| Grantee: | Fernando Heering Bartoloni |
| Support Opportunities: | Regular Research Grants |