5-Nitro-2,4-Dichloropyrimidine as an Universal Model for Low-Energy Electron Processes Relevant for Radiosensitization

We report experimental results of low-energy electron interactions with 5-nitro-2,4-dichloropyrimidine isolated in the gas phase and hydrated in a cluster environment. The molecule exhibits a very rare combination of many so far hypothesized low-energy electron induced mechanisms, which may be responsible for synergism in concurrent chemo-radiation therapy of cancer. In contrast to many previous efforts to design an ideal radiosensitizer based on one mode of action, the present model molecule presents an alternative approach, where several modes of action are combined. With respect to the processes induced by the low-energy electrons, this is not a trivial task because of strong bond specificity of the dissociative electron attachment reaction, as it is discussed in the present paper. Unfortunately, low solubility and high toxicity of the molecule, as obtained from preliminary MTT assay tests, do not enable further studies of its activity in real biological systems but it can advantageously serve as a model or a base for rational design of radiosensitizers.