Journal article
Photophysical properties of the asymmetrically substituted spirobifluorenes spiro-DPO and spiro-MeO-DPO



Publication Details
Authors:
Brendel, C.; Saragi, T.; Salbeck, J.
Publication year:
2009
Journal:
Physica Status Solidi (A)
Pages range:
2715-2722
Volume number:
206
Start page:
2715
End page:
2722
ISSN:
1862-6300

Abstract
The photophysical behaviour of the oxadiazolyl (PBD) and diphenylamino (TAD) substituted spirobifluorenes 2',7'-bis-(N,N-diphenylamino)-2-(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)-9,9'-spirobifluoren (spiro-DPO) and 2',7'-bis-(N,N-diphenylamino)-2-(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)-9,9'-spirobifluoren (spiro-MeO-DPO) has been investigated by temperature-dependent steady-state absorption and luminescence spectroscopy and gated measurements. Fluorescence and phosphorescence lifetime measurements, relative quantum yields and dipole moments of the excited states have been determined. Asymmetrically substituted spirobifluorenes exhibit charge-transfer (CT) emission due to coupling (spiroconjugation) between the fluorene fragments of spirobifluorene. They show a considerable ground-state dipole moment and exist as equilibrating conformeres. Population of the CT state only occurs after absorption to the locally excited singlet state. The CT fluorescence is dominated by the emission of two equilibrating conformeres with similar dipole moments. At low temperature they planarize in both molecular halves and show strong phosphorescence that is still detectable at room temperature. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Last updated on 2019-01-11 at 16:05