TY - JOUR
T1 - External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4′-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films
AU - Furukawa, Kazuki
AU - Hino, Kazuyuki
AU - Yamamoto, Norifumi
AU - Awasthi, Kamlesh
AU - Nakabayashi, Takakazu
AU - Ohta, Nobuhiro
AU - Sekiya, Hiroshi
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/8/24
Y1 - 2015/8/24
N2 - 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.
AB - 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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U2 - 10.1021/acs.jpca.5b03672
DO - 10.1021/acs.jpca.5b03672
M3 - Article
C2 - 26301571
AN - SCOPUS:84941788970
VL - 119
SP - 9599
EP - 9608
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 37
ER -