title: External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4'-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films.
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.
authors: Department of Chemistry, Faculty of Sciences, Kyushu University , 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors: Kazuki
authors: K
authors: Furukawa
authors: Department of Chemistry, Faculty of Education, Aichi University of Education , 1 Hirosawa, Igaya, Kariya, Aichi 448-8542, Japan.
authors: Kazuyuki
authors: K
authors: Hino
authors: Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology , Tsudanuma 2-17-1, Narashino, Chiba 275-0016, Japan.
authors: Norifumi
authors: N
authors: Yamamoto
authors: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University 1001 , Ta-Hsueh Road, Hsinchu 30010, Taiwan.
authors: Kamlesh
authors: K
authors: Awasthi
authors: Graduate School of Pharmaceutical Sciences, Tohoku University , Aoba-Ku, Sendai 980-8578, Japan.
authors: Takakazu
authors: T
authors: Nakabayashi
authors: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University 1001 , Ta-Hsueh Road, Hsinchu 30010, Taiwan.
authors: Nobuhiro
authors: N
authors: Ohta
authors: Department of Chemistry, Faculty of Sciences, Kyushu University , 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors: Hiroshi
authors: H
authors: Sekiya
mesh_terms: D004560:Electricity; D005419:Flavonoids / Q000737:chemistry*; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: C090856:4'-diethylamino-3-hydroxyflavone; D005419:Flavonoids; D011522:Protons; D019904:Polymethyl Methacrylate