Skip to Main content Skip to Navigation
Journal articles

Why Replacing Different Oxygens of Thymine with Sulfur Causes Distinct Absorption and Intersystem Crossing

Abstract : Recent experiments replacing oxygen atoms by sulfur in thymine have revealed that absorption and intersystem crossing properties of these derivatives are strongly dependent on the position and number of the substitutions, affecting their potential performance for photodynamical therapy. Using multireference quantum chemical methods (CASPT2 and DFT/MRCI), we calculated absorption spectra and spin orbit coupling matrix elements for thymine (Thy), 2-thiothymine (2tThy), 4-thiothymine (4tThy), and 2,4-dithiothymine (2,4dtThy), to investigate this relation between structure and photophysics. The simulations showed that a simple 4-electrons/4-orbital minimum model can explain the main experimentally observed spectral features. Moreover, the computational estimate of intersystem crossing lifetimes in this sequence of molecules revealed that the experimental value attributed to thymine in water might be underestimated by a factor 20, most probably due to an overlap of singlet/triplet absorption signals in the transient absorption spectrum. The difference between the absorptivity of 2tThy and 2tThd was also investigated, but no conclusive explanation could be found.
Document type :
Journal articles
Complete list of metadatas

https://hal-amu.archives-ouvertes.fr/hal-01415147
Contributor : Didier Siri <>
Submitted on : Monday, December 12, 2016 - 6:48:57 PM
Last modification on : Wednesday, November 6, 2019 - 9:16:02 AM

Links full text

Identifiers

Collections

Citation

Shuming Bai, Mario Barbatti. Why Replacing Different Oxygens of Thymine with Sulfur Causes Distinct Absorption and Intersystem Crossing. Journal of Physical Chemistry A, American Chemical Society, 2016, 120 (32), pp.6342--6350. ⟨10.1021/acs.jpca.6b05110⟩. ⟨hal-01415147⟩

Share

Metrics

Record views

129