# Nitro‐Group π System Drives the Interaction of RRx‐001 with Electrons in Solution

## TL;DR

This study explores how the molecule RRx-001 interacts with low-energy electrons in solution, revealing how it scavenges electrons and forms stable anions, which could help understand radiation damage processes.

## Contribution

The study establishes a direct link between initial electron interactions and final radiolysis products for RRx-001, using a combination of experimental and theoretical methods.

## Key findings

- RRx-001 efficiently scavenges secondary and solvated electrons, forming stable anions.
- Anion decay involves hydrogen transfer from solvent, producing NO2 and a modified azetidine derivative.
- No bromide dissociation occurs due to the inaccessibility of sigma virtual states for solvent electrons.

## Abstract

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.

The combination of cluster experiments, transient absorption spectroscopy, and NMR spectroscopy with theory enables tracking of the chemistry induced by secondary low‐energy electrons to RRx‐001 in solution from the initial interaction to the final radiolysis products. The catalytic and state‐selective nature of the LEE interaction is identified, with consequences for the understanding of the LEE action in radiation damage in general.