Photochemistry and photophysics of thienocarbazoles

• Autor(a) principal: Melo, J. Seixas de
• Data de Publicação: 2003
• Outros Autores: Rodrigues, L.M., Serpa, C., Arnaut, L.G., Ferreira, Isabel C.F.R., Queiroz, Maria João R.P.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/816

Two methylated thienocarbazoles and two of their synthetic nitro-precursors have been examined by absorption, luminescence, laser flash photolysis and photoacoustic techniques. Their spectroscopic and photophysical characterization involves fluorescence spectra, fluorescence quantum yields and lifetimes, and phosphorescence spectra and phosphorescence lifetimes for all the compounds. Triplet–singlet difference absorption spectra, triplet molar absorption coefficients, triplet lifetimes, intersystem crossing S1 ~~→T1 and singlet molecular oxygen yields were obtained for the thienocarbazoles. In the case of the thienocarbazoles it was found that the lowest-lying singlet and triplet excited states, S1 and T1, are of ╥, ╥* origin, whereas for their precursors S1 is n,╥*, and T1 is ╥, ╥*. In both thienocarbazoles it appears that the thianaphthene ring dictates the S1 ~~→T1 yield, albeit there is less predominance of that ring in the triplet state of the linear thienocarbazole, which leads to a decrease in the observed /T value