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Updated: Feb 27, 2026

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Published on: July 19, 2019
Theoretical study of excited-state proton transfer of 2,7-diazaindole·(H2O)2 cluster via hydrogen bonding dynamics
Abstract:
A new chromophore, 2,7-diazaindole (2,7-DAI), has been designed to surpass the limitation of 7-azaindole (7AI). It exhibits remarkable water catalyzed proton-transfer properties. Excited-state proton transfer (ESPT) has been investigated based on the time-dependent density functional theory method. The calculated vertical excitation energies in the S0 and S1 states agree well with the experimental values. Proton transfer couples with hydrogen-bonding dynamics between the 2,7-diazaindole and the surrounding water molecules. Hydrogen bond strengthening has been testified in the S1 state based on a comparison of primary bond lengths and hydrogen bond energy that is involved in the intermolecular hydrogen bond between the S0 and S1 states. Frontier molecular further suggest that the electron density changes between the ground and excited states serve as basic driving forces for proton transfer. We determined the potential-energy curves of the S0 and S1 states to characterize the ESPT process. This work explains that the ESPT process for 2,7-DAI·(H2O)2 clusters at the molecular level, and highlights the importance of hydrogen bonding in ESPT.
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