Empty-Level Structure and Reactive Species Produced by Dissociative Electron Attachment to tert-Butyl Peroxybenzoate

Temporary anion states of fluorine substituted benzenes probed by charge transfer in O2 -·C6H6-xFx (x = 0-5) ion-molecule complexes

The broadband photoelectron source realized by detaching O₂ ^-·X (X = neutral unsaturated molecule) complexes offers a unique opportunity to probe temporary anion states of the unsaturated species. Detachment of the ion molecule complex typically accesses a dissociative portion of the neutral potential, creating a continuum electron source that can undergo scattering with X. We present the application of this new approach to electron-neutral scattering toward a study of the series of fluorinated benzenes via photoelectron spectroscopy of O₂ ^-·C₆H_6-xF_x (x = 0-6) measured with several photon energies. We compare these spectra to the reference O₂ ^-·hexane spectrum and observe evidence of temporary anion states of C₆H_6-xF_x for species with x = 0-5 in the form of enhanced signal intensity at electron kinetic energies coinciding with the energies of the temporary anions. Furthermore, we observe autodetachment features in the x = 3, 5 spectra. Results of calculations on the isolated symmetric isomer of C₆H₃F₃ suggest that the molecule cannot support a weakly-bound non-valence state that could be associated with the observed autodetachment. However, C₆HF₅ ^- is predicted to support a valence bound state, which, if produced by charge transfer from O₂ ^- with sufficient vibrational energy, may undergo autodetachment. Finally, the [O₂·C₆F₆]^- spectrum is unique insofar as the spectrum is substantially higher in binding energy and qualitatively different from the x = 0-5 spectra. This result suggests much stronger interactions and charge delocalization between O₂ ^- and C₆F₆.

Can mitochondrial dysfunction be initiated by dissociative electron attachment to xenobiotics?

Resonance attachment of low-energy electrons to xenobiotic molecules, 2,4-dichlorophenoxyacetic acid (2,4-D), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE), was investigated under gas-phase conditions by means of complementary experimental techniques. Electron transmission spectroscopy (ETS) and dissociative electron attachment spectroscopy (DEAS), in the 0-6 eV and 0-15 eV energy range, respectively, were applied with the aim of modeling the behavior of these pesticide molecules under reductive conditions in vivo. Formation of long-lived parent molecular anions and fragment negative ions was observed at incident electron energies very close to zero, in agreement with the results of density functional theory calculations. The gas-phase DEA process, analogous to dissociative electron transfer in solution, was considered as a model for the initial step which occurs in the intermembrane space of mitochondria when a xenobiotic molecule captures an electron "leaked" from the respiratory chain. A possible involvement of the fragments produced by DEA to the pesticides under investigation into cellular processes is discussed. It is concluded that the free radicals and potential DNA adducts formed by DEA are expected to be dangerous for mitochondrial functionalities, while several of the products observed could act as messenger molecules, thus interfering with the normal cellular signaling pathways.