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metadata.dc.type: | Artigo de Periódico |
Title: | Photochemistry of thioxanthen-9-one-10,10-dioxide: A remarkably reactive triplet excited state |
Other Titles: | Journal of Photochemistry and Photobiology A: Chemistry |
Authors: | Netto Ferreira, José Carlos Silva, Eliete S. Lopes da Lucas, Nanci Camara de |
metadata.dc.creator: | Netto Ferreira, José Carlos Silva, Eliete S. Lopes da Lucas, Nanci Camara de |
Abstract: | The steady state photolysis of thioxanthen-9-one-10,10-dioxide (1) in dichloromethane does not result in any product formation. In hydrogen donor solvents, such as 2-propanol, toluene or cyclohexane, the formation of the corresponding pinacol was readily observed. The phosphorescence spectrum of 1 in EPA, at 77 K, reveals a triplet energy of 66.3 kcal mol−1. Laser flash photolysis irradiation of a degassed acetonitrile solution of 1 led to the formation of its triplet excited state (λmax = 375 and 520 nm, τ = 11 μs) that was quenched by oxygen, β-carotene and 1,3-cycloexadiene at a diffusion controlled rate constant. The quenching rate constants for the triplet of 1 with 1,4-cyclohexadiene, methanol, ethanol, 2-propanol, cyclohexane, substituted phenols and amines were determined, ranging from 7.1 × 106 (for methanol) to 3.1 × 1010 L mol−1 s−1 (for triethylamine). From the quenching rate constants observed for the triplet excited state and from the steady state photolysis, it was concluded that the remarkable reactivity of 1 is due to the n,π* character of the carbonyl chromophore. |
Keywords: | Laser flash photolysis Thioxanthen-9-one-10,10-dioxide Triplet excited state |
metadata.dc.rights: | Acesso Aberto |
URI: | http://repositorio.ufba.br/ri/handle/ri/14625 |
Issue Date: | 2011 |
Appears in Collections: | Artigo Publicado em Periódico (Química) |
Files in This Item:
File | Description | Size | Format | |
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José Carlos Netto-Ferreira.pdf | 626,93 kB | Adobe PDF | View/Open |
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