External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4′-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films

Kazuki Furukawa, Kazuyuki Hino, Norifumi Yamamoto, Kamlesh Awasthi, Takakazu Nakabayashi, Nobuhiro Ohta, Hiroshi Sekiya

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16 Citations (Scopus)

Abstract

The external electric field effects on the steady-state electronic spectra and excited-state dynamics were investigated for 4′-N,N-(dimethylamino)-3-hydroxyflavone (DMHF) in a poly(methyl methacrylate) (PMMA) film. In the steady-state spectrum, dual emission was observed from the excited states of the normal (N∗) and tautomer (T∗) forms. Application of an external electric field of 1.0 MV·cm-1 enhanced the N∗ emission and reduced the T∗ emission, indicating that the external electric field suppressed the excited-state intramolecular proton transfer (ESIPT). The fluorescence decay profiles were measured for the N∗ and T∗ forms. The change in the emission intensity ratio N∗/T∗ induced by the external electric field is dominated by ESIPT from the Franck-Condon excited state of the N∗ form and vibrational cooling in potential wells of the N∗ and T∗ forms occurring within tens of picoseconds. Three manifolds of fluorescent states were identified for both the N∗ and T∗ forms. The excited-state dynamics of DMHF in PMMA films has been found to be very different from that in solution due to intermolecular interactions in a rigid environment.

Original languageEnglish
Pages (from-to)9599-9608
Number of pages10
JournalJournal of Physical Chemistry A
Volume119
Issue number37
DOIs
Publication statusPublished - 2015 Aug 24

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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