A unified experimental/theoretical description of the ultrafast photophysics of single and double thionated uracils

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Artigo de periódico

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Resumo

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.

Abstract

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Análise espectral

Palavras-chave

Ultrafast spectroscopy, Thiobases

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Endereço externo

https://chemistry-europe.onlinelibrary.wiley.com/doi/epdf/10.1002/chem.201904541

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