Electron-Induced Decomposition of Uracil-5-yl <i>O-</i>(<i>N,N</i>-dimethylsulfamate): Role of Methylation in Molecular Stability

• Main Authors: Eugene Arthur-Baidoo, Karina Falkiewicz, Lidia Chomicz-Mańka, Anna Czaja, Sebastian Demkowicz, Karol Biernacki, Witold Kozak, Janusz Rak, Stephan Denifl
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: International Journal of Molecular Sciences
• Subjects: uracil derivatives; gas phase; radiosensitizers; low-energy electrons; electron attachment; resonance energy
• Online Access: https://www.mdpi.com/1422-0067/22/5/2344
• ISSN: 1661-6596; 1422-0067

The incorporation of modified uracil derivatives into DNA leads to the formation of radical species that induce DNA damage. Molecules of this class have been suggested as radiosensitizers and are still under investigation. In this study, we present the results of dissociative electron attachment to uracil-5-yl <i>O</i>-(<i>N</i>,<i>N</i>-dimethylsulfamate) in the gas phase. We observed the formation of 10 fragment anions in the studied range of electron energies from 0–12 eV. Most of the anions were predominantly formed at the electron energy of about 0 eV. The fragmentation paths were analogous to those observed in uracil-5-yl <i>O</i>-sulfamate, i.e., the methylation did not affect certain bond cleavages (O-C, S-O and S-N), although relative intensities differed. The experimental results are supported by quantum chemical calculations performed at the M06-2X/aug-cc-pVTZ level of theory. Furthermore, a resonance stabilization method was used to theoretically predict the resonance positions of the fragment anions O⁻and CH₃⁻.