Photoinduced Intramolecular Charge Transfer in a Series of Differently Twisted Donor−Acceptor Biphenyls As Revealed by Fluorescence
| Autor: | Michael Maus, Wolfgang Rettig, René Lapouyade, Dominique Bonafoux |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 103:3388-3401 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp9905023 |
| Popis: | This photophysical study addresses the general question of how electron transfer in bichromophoric molecules influences the conformational relaxation, which can be toward either more or less π-conjugation. The effects of photoinduced intramolecular charge transfer on the electronic and molecular properties of a series of differently twisted 4-N,N-dimethylamino-4‘-cyanobiphenyls are investigated by steady-state and time-resolved fluorescence. The dipole moments, radiative rates, and torsional relaxations in the excited state are analyzed by comparison with the absorption spectra and interannular twist angle (φ)-dependent CNDO/S calculations. Independent of the twist angle φ and solvent polarity, the first excited singlet state of these donor−acceptor (D−A) biphenyls (I−III) is an emissive intramolecular 1CT state of the 1La-type transferring charge from the dimethylaminobenzene (D) to the cyanobenzene (A) subunit. Similar to the planar restricted D−A fluorene I, the flexible D−A biphenyl II shows only a we... |
| Databáze: | OpenAIRE |
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