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Updated: Dec 20, 2025

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Published on: April 22, 2022
Excited State Deactivation Mechanism in Protonated Uracil: New Insights from Theoretical Studies
Reza Omidyan1, Fatemeh Abedini1, Leila Shahrokh1
1Department of Chemistry, University of Isfahan, 81746-73441 Isfahan, Iran.
Abstract:
We have conducted here a theoretical exploration, discussing the distinct excited state lifetimes reported experimentally for the two lowest lying protonated isomers of uracil. In this regard, the first-principal computational levels as well as the nonadiabatic surface hopping dynamics have been employed. It has been revealed that relaxation of the 1ππ* state of enol-enol form (EE+) to the ground is barrier-free via out-of-plane coordinates, resulting in an ultrashort S1 lifetime of this species. For the second most stable isomer (EK+), however, a significant barrier predicted in the CASPT2 S1 potential energy profile along the twisting coordinate has been proposed to explain the relevant long lifetime reported experimentally.
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