- Synthesis and photophysical studies of donor-acceptor substituted tetrahydropyrenes
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The tetrahydropyrene derivatives 2-N,N-dimethylamino-7-nitro-4,5,9,10- tetrahydropyrene (1) and 2-N,N-dimethylamino-7-acetyl-4,5,9,10-tetrahydropyrene (2) were synthesized and characterized. Photophysical properties of these molecules were investigated in several solvents. The absorption spectrum of 1 shows a slight red shift with solvent polarity, whereas that of 2 remains more or less unchanged. Fluorescence spectra of these compounds exhibit large, solvent-polarity-dependent Stokes shifts. The Stokes shifts are correlated to ET(30) and ETN parameters and were quantitatively analyzed by the Mataga-Liptay equation. Both compounds show low fluorescence quantum yields in cyclohexane. Nanosecond flash photolysis studies suggested that the low quantum yield in cyclohexane is due to intersystem crossing to a triplet state. In the case of 2, the fluorescence quantum yields are high in all other solvents. In the case of 1 fluorescence quantum yields are very low in polar solvents and this is explained by invoking a twisted intramolecular charge transfer state. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Sumalekshmy,Gopidas
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- Metacyclophanes and Related Compounds. 21. Nitration of Metacyclophanes
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Various metacyclophanes were prepared from the corresponding benzene derivatives by using the tert-butyl group as a positional protective function and their nitrations were carried out under various conditions.It was found that nitration of 8,16-dime
- Tashiro, Masashi,Mataka, Shuntaro,Takezaki, Yoshinori,Takeshita, Michinori,Arimura, Takashi,et al.
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p. 451 - 458
(2007/10/02)
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