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Updated: Apr 5, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
External Electric Field Effects on Excited-State Intramolecular Proton Transfer in
Kazuki Furukawa1, Kazuyuki Hino2, Norifumi Yamamoto3
1Department of Chemistry, Faculty of Sciences, Kyushu University , 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
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.
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