TY - JOUR
T1 - Ultrafast Ground-State Intramolecular Proton Transfer in Diethylaminohydroxyflavone Resolved with Pump-Dump-Probe Spectroscopy
AU - Kuang, Zhuoran
AU - Guo, Qianjin
AU - Wang, Xian
AU - Song, Hongwei
AU - Maroncelli, Mark
AU - Xia, Andong
N1 - Publisher Copyright:
Copyright © 2018 American Chemical Society.
PY - 2018/8/2
Y1 - 2018/8/2
N2 - 4′-N,N-Diethylamino-3-hydroxyflavone (DEAHF), due to excited-state intramolecular proton transfer (ESIPT) reaction, exhibits two solvent-dependent emission bands. Because of the slow formation and fast decay of the ground-state tautomer, its population does not accumulate enough for its detection during the normal photocycle. As a result, the details of the ground-state intramolecular proton-transfer (GSIPT) reaction have remained unknown. The present work uses femtosecond pump-dump-probe spectroscopy to prepare the short-lived ground-state tautomer and track this GSIPT process in solution. By simultaneously measuring femtosecond pump-probe and pump-dump-probe spectra, ultrafast kinetics of the ESIPT and GSIPT reactions are obtained. The GSIPT reaction is shown to be a solvent-dependent irreversible two-state process in two solvents, with estimated time constants of 1.7 ps in toluene and 10 ps in the more polar tetrahydrofuran. These results are of great value in both fully describing the photocycle of this four-level proton transfer molecule and for providing a deeper understanding of dynamical solvent effects on tautomerization.
AB - 4′-N,N-Diethylamino-3-hydroxyflavone (DEAHF), due to excited-state intramolecular proton transfer (ESIPT) reaction, exhibits two solvent-dependent emission bands. Because of the slow formation and fast decay of the ground-state tautomer, its population does not accumulate enough for its detection during the normal photocycle. As a result, the details of the ground-state intramolecular proton-transfer (GSIPT) reaction have remained unknown. The present work uses femtosecond pump-dump-probe spectroscopy to prepare the short-lived ground-state tautomer and track this GSIPT process in solution. By simultaneously measuring femtosecond pump-probe and pump-dump-probe spectra, ultrafast kinetics of the ESIPT and GSIPT reactions are obtained. The GSIPT reaction is shown to be a solvent-dependent irreversible two-state process in two solvents, with estimated time constants of 1.7 ps in toluene and 10 ps in the more polar tetrahydrofuran. These results are of great value in both fully describing the photocycle of this four-level proton transfer molecule and for providing a deeper understanding of dynamical solvent effects on tautomerization.
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U2 - 10.1021/acs.jpclett.8b01826
DO - 10.1021/acs.jpclett.8b01826
M3 - Article
C2 - 29991264
AN - SCOPUS:85049897018
SN - 1948-7185
VL - 9
SP - 4174
EP - 4181
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 15
ER -