Triphenylboroxine stability under low-energy-electron interactions

Abstract

Triphenylboroxine (TPB) has chemical properties of great interest in organic synthesis, enabling the development of promising molecular architectures. Based on the possibility of the geometric arrangement of N-coordinated boron atoms, the dynamic interconversion ability of boroxine cages enables the optimization of relevant pharmacological properties in drug delivery, such as guest recognition and porosity. In addition, the synthesis of a novel 2D boroxine framework showed distinctive electronic and morphological properties that can be used in the design of new electronic devices. In the present study, the electron-driven fragmentation pathways from electron interactions with TPB using a gas-phase crossed-beam experiment have been investigated. The abundance of the molecular parent cation in the mass spectrum at 70 eV reflects the stability of TPB. The appearance energies of three fragment cations were reported, and the experimental first ionization potential was found at 9.12 ± 0.10 eV. Only the parent cation is formed in the energy range (∼9–16 eV) between the first ionization potential and the remaining thresholds. Regarding negative ion formation, four low-abundant anions in the electron energy range of 0–15 eV are discussed. These results indicate an interesting energy selectivity and stability of TPB upon electron interaction, which may justify the development of recent molecular architectures containing TPB used in a wide range of applications. These results are supported by quantum chemical calculations based on bound state techniques, electron ionization models and thermodynamic thresholds.