Photoelectron spectroscopic study of the negative ions of 4-thiouracil and 2,4-dithiouracil

Li, Xiang; Chen, Jing; Bowen, Kit H.

doi:10.1063/1.3555177

Cited by 8 publications

(7 citation statements)

References 62 publications

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“…Indeed, previous studies have found both sulfur and halogen modifications of uracil to give rise to significant changes in its electronic structure. 36,37 The objective of the present study is to investigate the influence of N-substitution at the C6 position of uracil on its resulting electrophilic properties. This was revealed through the differing characteristics of the uracil versus the 6azauracil negative ions.…”

Section: ■ Introductionmentioning

confidence: 99%

Photoelectron Spectroscopy of the 6-Azauracil Anion

et al. 2012

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We report the photoelectron spectrum of the 6-azauracil anion. The spectrum is dominated by a broad band exhibiting a maximum at an electron binding energy (EBE) of 1.2 eV. This spectral pattern is indicative of a valence anion. Our calculations were carried out using ab initio electron propagator and other many-body methods. Comparison of the anion and corresponding neutral of 6-azauracil with those of uracil shows that substituting a nitrogen atom for C−H at the C6 position of uracil gives rise to significant changes in the electronic structure of 6-azauracil versus that of uracil. The adiabatic electron affinity (AEA) of the canonical 6-azauracil tautomer is substantially larger than that of canonical uracil. Among the five tautomeric, 6-azauracil anions studied computationally, the canonical structure was found to be the most stable. The vertical detachment energies (VDE) of the canonical, valence-bound anion of 6-azauracil and its closest "very-rare" tautomer have been calculated. Electron propagator calculations on the canonical anion yield a VDE value that is in close agreement with the experimentally determined VDE value of 1.2 eV. The AEA value of 6-azauracil, assessed at the CCSD(T) level of theory to be 0.5 eV, corresponds with the EBE value of the onset of the experimental spectrum.

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Section: ■ Introductionmentioning

confidence: 99%

Photoelectron Spectroscopy of the 6-Azauracil Anion

et al. 2012

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“…19 In contrast to the UV absorption spectra, not much has been reported on the photoelectron spectra of thiouracils. The main interest in this respect has been laid on the anions of these compounds, 24,25 because ionizing radiation creates anions on the way to single and double strand breaks in DNA. A single study on the tautomerism of 2TU and its methyl derivates 26 contains a static He(I) photoelectron spectrum of neutral 2TU.…”

Section: Introductionmentioning

confidence: 99%

Photoelectron spectra of 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil

Ruckenbauer

Mai

Marquetand

et al. 2016

The Journal of Chemical Physics

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Ground-and excited-state UV photoelectron spectra of thiouracils (2-thiouracil, 4-thiouracil and 2,4-dithiouracil) have been simulated using multireference configuration interaction calculations and Dyson norms as measure for the photoionization intensity. Except for a constant shift, the calculated spectrum of 2-thiouracil agrees very well with experiment, while no experimental spectra are available for the two other compounds. For all three molecules, the photoelectron spectra show distinct bands due to ionization of the sulphur and oxygen lone pairs and the pyrimidine π system. The excited-state photoelectron spectra of 2-thiouracil show bands at much lower energies than in the ground state spectrum, allowing to monitor the excited-state population in time-resolved UV photoelectron spectroscopy (TRPES) experiments. However, the results also reveal that single-photon ionization probe schemes alone will not allow monitoring all photodynamic processes existing in 2-thiouracil. Especially, due to overlapping bands of singlet and triplet states the clear observation of intersystem crossing will be hampered.

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“…25 Other relevant experiments include measurements of dissociative electron attachment to 2TU 26,27 and anion photoelectron spectroscopy of the related species 4TU − and 2,4TU − . 28 Ortiz and co-workers 29 carried out electronic structure calculations on 2TU − , obtaining results for the adiabatic electron affinity (AEA) and vertical electron affinity (VEA) for 2TU and the vertical detachment energy (VDE) of the anion; these values are 0.26, −0.17, and 0.71 eV, respectively. These numbers apply to the VB state of 2TU − in which the lowest π * orbital [Fig.…”

Section: Introductionmentioning

confidence: 99%

Electron attachment dynamics following UV excitation of iodide-2-thiouracil complexes

Koga

Asplund

Neumark

2022

The Journal of Chemical Physics

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The dynamics of low energy electron attachment to the thio-substituted uracil analog 2-thiouracil are investigated using time-resolved photoelectron spectroscopy (TRPES) of iodide·2-thiouracil (I -·2TU) binary clusters. In these experiments, the anions are excited at pump energies of 4.16 and 4.73 eV, and the ensuing dynamics are probed by photodetachment at 1.59 and 3.18 eV. Upon excitation near the vertical detachment energy (4.16 eV), dipole bound (DB) and valence bound (VB) anion signals appear almost instantaneously, and the DB state of the 2TU anion undergoes ultrafast decay (~50 fs). At 4.73 eV, there is no evidence for a DB state, but features attributed to two VB states are seen. The transient negative ions formed by photoexcitation decay by autodetachment and I- fragmentation. The I- dissociation rates and their dependence on excitation energy agree reasonably well with the Rice-Ramsperger-Kassel-Marcus calculations. Notable differences with respect to TRPES of the related iodide-uracil anion are observed and discussed.

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Photoelectron spectroscopic study of the negative ions of 4-thiouracil and 2,4-dithiouracil

Cited by 8 publications

References 62 publications

Photoelectron Spectroscopy of the 6-Azauracil Anion

Photoelectron Spectroscopy of the 6-Azauracil Anion

Photoelectron spectra of 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil

Electron attachment dynamics following UV excitation of iodide-2-thiouracil complexes

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