Photoinduced Charge Shifts and Electron Transfer in Viologen-Tetraphenylborate Complexes: Push-Pull Character of the Exciplex
| Autor: | Victor M. Deflon, Alexander N. Tarnovsky, Malcolm D. E. Forbes, Willy G. Santos, Daniel R. Cardoso, Darya S. Budkina |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Tetraphenylborate
010405 organic chemistry ESPECTROSCOPIA MOLECULAR Viologen Electron donor General Chemistry 010402 general chemistry Photochemistry 01 natural sciences Biochemistry Catalysis Photoinduced electron transfer 0104 chemical sciences Dication chemistry.chemical_compound Electron transfer Colloid and Surface Chemistry chemistry Ultrafast laser spectroscopy medicine Triplet state medicine.drug |
| Zdroj: | Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| ISSN: | 1520-5126 |
| Popis: | Viologen–tetraarylborate ion-pair complexes were prepared and investigated by steady-state and time-resolved spectroscopic techniques such as fluorescence and femtosecond transient absorption. The results highlight a charge transfer transition that leads to changes in the viologen structure in the excited singlet state. Femtosecond transient absorption reveals the formation of excited-state absorption and stimulated emission bands assigned to the planar (kobs < 1012 s–1) and twisted (kobs ∼ 1010 s–1) structures between two pyridinium groups in the viologen ion. An efficient photoinduced electron transfer from the tetraphenylborate anionic moiety to the viologen dication was observed less than 1 μs after excitation. This is a consequence of the push–pull character of the electron donor twisted viologen structure, which helps formation of the borate triplet state. The borate triplet state is deactivated further via a second electron transfer process, generating viologen cation radical (V•+). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|