Photoinduced processes in thiouracil derivatives have lately attracted considerable attention due to their suitability for innovative biological and pharmacological applications. Here, sub-20 fs broadband transient absorption spectroscopy in the near-UV are combined with CASPT2/MM decay path calculations to unravel the excited-state decay channels of water solvated 2-thio and 2,4-dithiouracil. These molecules feature linear absorption spectra with overlapping ππ* bands, leading to parallel decay routes which we systematically track for the first time. The results reveal that different processes lead to the triplet states population, both directly from the ππ* absorbing state and via the intermediate nπ* dark state. Moreover, the 2,4-dithiouracil decay pathways is shown to be strongly correlated either to those of 2- or 4-thiouracil, depending on the sulfur atom on which the electronic transition localizes.
Teles-Ferreira D.C., Conti I., Borrego-Varillas R., Nenov A., Van Stokkum I.H.M., Ganzer L., et al. (2020). A Unified Experimental/Theoretical Description of the Ultrafast Photophysics of Single and Double Thionated Uracils. CHEMISTRY-A EUROPEAN JOURNAL, 26(1), 336-343 [10.1002/chem.201904541].
A Unified Experimental/Theoretical Description of the Ultrafast Photophysics of Single and Double Thionated Uracils
Conti I.;Nenov A.;de Paula A. M.;Garavelli M.
2020
Abstract
Photoinduced processes in thiouracil derivatives have lately attracted considerable attention due to their suitability for innovative biological and pharmacological applications. Here, sub-20 fs broadband transient absorption spectroscopy in the near-UV are combined with CASPT2/MM decay path calculations to unravel the excited-state decay channels of water solvated 2-thio and 2,4-dithiouracil. These molecules feature linear absorption spectra with overlapping ππ* bands, leading to parallel decay routes which we systematically track for the first time. The results reveal that different processes lead to the triplet states population, both directly from the ππ* absorbing state and via the intermediate nπ* dark state. Moreover, the 2,4-dithiouracil decay pathways is shown to be strongly correlated either to those of 2- or 4-thiouracil, depending on the sulfur atom on which the electronic transition localizes.File | Dimensione | Formato | |
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Conti_Garavelli_postprint_2020 (1).pdf
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Supplementare_Conti_chem201904541-sup-0001-misc_information.pdf
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