Optical absorption and magnetic circular dichroism spectra of thiouracils: a quantum mechanical study in solution. Issue 9 (26th July 2017)

• Record Type: Journal Article
• Authors: Martinez-Fernandez, L.; Fahleson, T.; Norman, P.; Santoro, F.; Coriani, S.; Improta, R.
• Is Part Of: Photochemical & photobiological sciences. Volume 16:Issue 9(2017)
• Page Start: 1415
• Page End: 1423
• Publication Date: 2017-07-26
• Subjects: Photochemistry -- Periodicals; Photobiology -- Periodicals; 541.35
• DOI: 10.1039/c7pp00105c
• Languages: English
• ISSNs: 1474-905X

Abstract

Abstract : The excited electronic states of thiouracils, the analogues of uracil where the carbonyl oxygens are substituted by sulphur atoms, have been investigated by computing the magnetic circular dichroism (MCD) and one-photon absorption (OPA) spectra at the TD-DFT level of theory. Abstract : The excited electronic states of 2-thiouracil, 4-thiouracil and 2, 4-dithiouracil, the analogues of uracil where the carbonyl oxygens are substituted by sulphur atoms, have been investigated by computing the magnetic circular dichroism (MCD) and one-photon absorption (OPA) spectra at the time-dependent density functional theory level. Special attention has been paid to solvent effects, included by a mixed discrete/continuum model, and to determining how our results depend on the adopted DFT functional (CAM-B3LYP and B3LYP). Whereas including solvent effects does not dramatically impact the MCD and OPA spectra, though improving the agreement with the experimental spectra, the performances of CAM-B3LYP and B3LYP are remarkably different. CAM-B3LYP captures well the effect of thionation on the uracil excited states and provides spectra in good agreement with the experiments, whereas B3LYP shows some deficiency in describing 2-TU and 2, 4-DTU spectra, despite being more accurate than CAM-B3LYP for 4-TU.