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Photochemistry and Photophysics of Thienocarbazoles ¶
Author(s) -
Seixas de Melo J.,
Rodrigues L. M.,
Serpa C.,
Arnaut L. G.,
Ferreira I. C. F. R.,
Queiroz M.J. R. P.
Publication year - 2003
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2003)0770121papot2.0.co2
Subject(s) - intersystem crossing , phosphorescence , photochemistry , chemistry , triplet state , quantum yield , flash photolysis , singlet state , excited state , fluorescence , singlet fission , absorption (acoustics) , absorption spectroscopy , singlet oxygen , oxygen , molecule , materials science , atomic physics , reaction rate constant , physics , organic chemistry , quantum mechanics , kinetics , composite material
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 S 1 ∼∼→ T 1 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, S 1 and T 1 , are of π,π* origin, whereas for their precursors S 1 is n,π*, and T 1 is π,π*. In both thienocarbazoles it appears that the thianaphthene ring dictates the S 1 ∼∼→ T 1 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 φ T value.