Radiationless deactivation process of 1-dimethylamino-9-fluorenone induced by conformational relaxation in the excited state: A new model molecule for the TICT process

Akimitsu Morimoto, L. Biczók, Tomoyuki Yatsuhashi, Tetsuya Shimada, Shingo Baba, Hiroshi Tachibana, Donald A. Tryk, Haruo Inoue

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The deactivation process of excited 1-(dimethylamino)-9-fluorenone (1-DMAF) was investigated by means of steady-state and time-resolved fluorescence spectroscopy. Fluorescence decay profiles for 1-DMAF, which has a relatively short lifetime (several tens of picoseconds in low viscosity solvents at ambient temperature) are much affected by the fluidity of the surrounding solvent. The lifetimes increase in glassy solvents at 77 K as well as with increasing viscosity. These results indicate that conformational relaxation by the dimethylamino group plays an important role in the deactivation process of 1-DMAF. Detailed analysis of the temperature dependence of the fluorescence lifetime revealed that the conformational relaxation process has a very small intramolecular activation barrier (5.4 kJ/mol). Results of MO calculations suggest that the dimethylamino moiety of 1-DMAF is pretwisted in the ground state and that the most stable structure in the excited state is a twisted intramolecular charge transfer (TICT) state. 1-DMAF could be a new model molecule that exhibits the TICT phenomena.

Original languageEnglish
Pages (from-to)10089-10095
Number of pages7
JournalJournal of Physical Chemistry A
Volume106
Issue number43
DOIs
Publication statusPublished - Oct 31 2002

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Excited states
deactivation
Charge transfer
charge transfer
life (durability)
fluorescence
Molecules
viscosity
excitation
molecules
ambient temperature
Fluorescence
Viscosity
activation
Fluidity
Fluorescence spectroscopy
Relaxation processes
temperature dependence
ground state
Ground state

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Radiationless deactivation process of 1-dimethylamino-9-fluorenone induced by conformational relaxation in the excited state : A new model molecule for the TICT process. / Morimoto, Akimitsu; Biczók, L.; Yatsuhashi, Tomoyuki; Shimada, Tetsuya; Baba, Shingo; Tachibana, Hiroshi; Tryk, Donald A.; Inoue, Haruo.

In: Journal of Physical Chemistry A, Vol. 106, No. 43, 31.10.2002, p. 10089-10095.

Research output: Contribution to journalArticle

Morimoto, Akimitsu ; Biczók, L. ; Yatsuhashi, Tomoyuki ; Shimada, Tetsuya ; Baba, Shingo ; Tachibana, Hiroshi ; Tryk, Donald A. ; Inoue, Haruo. / Radiationless deactivation process of 1-dimethylamino-9-fluorenone induced by conformational relaxation in the excited state : A new model molecule for the TICT process. In: Journal of Physical Chemistry A. 2002 ; Vol. 106, No. 43. pp. 10089-10095.
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abstract = "The deactivation process of excited 1-(dimethylamino)-9-fluorenone (1-DMAF) was investigated by means of steady-state and time-resolved fluorescence spectroscopy. Fluorescence decay profiles for 1-DMAF, which has a relatively short lifetime (several tens of picoseconds in low viscosity solvents at ambient temperature) are much affected by the fluidity of the surrounding solvent. The lifetimes increase in glassy solvents at 77 K as well as with increasing viscosity. These results indicate that conformational relaxation by the dimethylamino group plays an important role in the deactivation process of 1-DMAF. Detailed analysis of the temperature dependence of the fluorescence lifetime revealed that the conformational relaxation process has a very small intramolecular activation barrier (5.4 kJ/mol). Results of MO calculations suggest that the dimethylamino moiety of 1-DMAF is pretwisted in the ground state and that the most stable structure in the excited state is a twisted intramolecular charge transfer (TICT) state. 1-DMAF could be a new model molecule that exhibits the TICT phenomena.",
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AU - Shimada, Tetsuya

AU - Baba, Shingo

AU - Tachibana, Hiroshi

AU - Tryk, Donald A.

AU - Inoue, Haruo

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