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Author: search.filters.author.Inporn, WutthanaSubject: search.filters.subject.Excited state proton transfer

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    A proton transfer competition of 1,8-di(pyridin-2-yl)-9H-carbazole in excited-state intramolecular proton transfer through on-the-fly dynamic simulation
    (2025-10-01)
    Inporn, Wutthana
    ;
    Kungwan, Nawee
    ;
    Daengngern, Rathawat
    Excited-state intramolecular proton transfer (ESIPT) of 1,8-di(pyridin-2-yl)-9H-carbazole (DPyCz) was investigated using static and excited-state dynamic simulations. Three-distinct configurations, each involving a different pyridyl moiety forming an intramolecular hydrogen bond, were identified to explore the competition in ESIPT. Additionally, slower PT, occurring at ∼200 fs, was found to depend on the competition between the pyridyl nitrogen atoms as acceptors. In contrast, DPyCz-B, which features only a single acceptor site, facilitated twice faster PT than that of DPyCz-A. Thus, our findings suggested that the ESIPT process of DPyCz is possibly governed by the interplay of intramolecular hydrogen bonding and excited-state charge redistribution.
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    Tautomeric enhancement of 2-(1H-pyrazol-5-yl)pyridine in photoinduced proton transfer by water-assisted molecules
    (2024-09-20)
    Salaeh, Rusrina
    ;
    Inporn, Wutthana
    ;
    Chansen, Warinthon
    ;
    Kungwan, Nawee
    ;
    Daengngern, Rathawat
    Theoretical insight of excited state proton transfer (ESPT) in 2-(1H-pyrazol-5-yl)pyridine abbreviated as PPP interacting with water wires: PPP(H<inf>2</inf>O)<inf>n</inf> where n = 1–3 has been presented in both static and dynamics studies. Explicit water molecules placed around PPP have been simulated to elucidate the intermolecular hydrogen bonding interactions between them. Hydrogen bond strengthening in the excited state (S<inf>1</inf>) has been verified by shorter bond distances and redshift of IR vibrational spectra involving the proton transfer (PT) process. Furthermore, on-the-fly excited state dynamics simulations of all complexes have been performed to provide detailed information on the PT mechanism. The dynamic results show that one water molecule added to the neighboring PPP as an intermolecular hydrogen bonding bridge can promote double excited state intermolecular proton transfer up to 36% compared with its intrinsic intramolecular hydrogen bond of the PPP system. Meanwhile adding a second or third water molecule could decrease the probabilities of PT. Especially in PPP(H<inf>2</inf>O)<inf>3</inf>, a rearrangement of water molecules is observed that PT occurs via one water molecule. Hence, the models with explicit water molecules interacting with PPP as intermolecular hydrogen bonding bridge are a great representative role played by water molecules of the PT process at the molecular level.