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A Unified Experimental/Theoretical Description of the Ultrafast Photophysics of Single and Double Thionated Uracils
Author(s) -
TelesFerreira Danielle Cristina,
Conti Irene,
BorregoVarillas Rocío,
Nenov Artur,
Van Stokkum Ivo H. M.,
Ganzer Lucia,
Manzoni Cristian,
Paula Ana Maria,
Cerullo Giulio,
Garavelli Marco
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904541
Subject(s) - ultrashort pulse , chemical physics , chemistry , physics , quantum mechanics , laser
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.