No abstract

No abstract

When modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-2′-deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry was used to detect the anionic products of dissociative electron attachment (DEA), and the experimental results were supported by quantum chemical calculations performed at the M062X/aug-cc-pVTZ level of theory. Experimentally, we found that BrSU predominantly captures low-energy electrons with kinetic energies near 0 eV, though the abundance of bromine anions was rather low compared to a similar experiment with bromouracil. We suggest that, for this reaction channel, proton-transfer reactions in the transient negative ions limit the release of bromine anions.

Density functional theory (DFT) method used to investigate the interaction of thioguanine isomers with B12N12 nanocage in several media to earn electronics properties. To achieve this purpose, adsorption of thioguanine isomers on the exterior surface of B12N12 investigated in the gas phase and water media. Optical structures, electronic properties, and natural bond orbitals (NBO) analysis display that the adsorption of thioguanine on B12N12 nanocage is a strong chemisorption in the gas phase as well as water media. Besides, the electronic conductance of nanocage is significantly altered once the thioguanine isomers molecules are adsorbed. Thus, the energy gap between HOMO and LUMO orbitals is reduced which could be applied as a chemical signal to confirm chemical adsorption. Moreover, the relative dipole moments calculated for obtained configurations suggest that these structures could be solubilized or dispersed in polar mediums like water. Based on results, B12N12 nanocage could be a potential carrier for delivering thioguanine isomers in nanomedicine applications.

No abstract