Reactivity toward low-energy electrons (LEE) has been hypothesized as a cause of radio-modifying properties for various molecules. LEE's transient nature, however, prevents the establishment of clear links between initial processes at the sub-ps time scale and the final products of radiolysis. Here, such links are explored for the radio-modifying compound RRx-001 (1-bromoacetyl-3,3-dinitroazetidine). Picosecond pulse radiolysis demonstrates the high scavenging capacity of the molecule for secondary quasi-free and solvated electrons forming stable parent anions confirmed by studies of microsolvated RRx-001 in clusters. The anions decay either via auto-detachment of an electron or dissociate involving hydrogen transfer from solvent, resulting in NO2 and 1-(bromoacetyl)-3-nitroazetidine. Surprisingly, no Br dissociation is observed despite its high electron affinity. We assign this behavior to the "inaccessibility" of sigma virtual states for electrons in the solvent, which can be of a general nature.

• Klíčová slova
• catalytic electron, electron attachment, low‐energy electrons, radiosensitizer, state selective,
• Publikační typ
• časopisecké články MeSH

Bromine and hydrogen play unusual roles as mobile atom and dissociation dynamics moderator, respectively, during roaming in the 3-bromo-4H-1,2,4-triazole anion. The present study of the reactivity of 3-bromo-1H-1,2,4-triazole and 3-bromo-4H-1,2,4-triazole with low-energy electrons reveals the effect of the hydrogen position on the reaction dynamics. We report energy-dependent ion yields for both molecules showing significant differences. Quantum chemical calculations reveal that heavy Br atom migration is energetically more favored than H atom migration in the case of the H atom adjacent to Br. This is enabled by the energetically favorable formation of a noncovalent complex of Br- around the triazole ring. Recently, such complexes have been reported for several other biologically relevant molecules. In the present work, we demonstrate that the position of hydrogen on the ring influences the character of the lowest resonant state and, consequently, the Br- roaming and dissociation dynamics, particularly the neutral release of hydrogen bromide.

• Publikační typ
• časopisecké články MeSH