Atmospheric Pressure Chemical Ionization Q-Orbitrap Mass Spectrometry Analysis of Gas-Phase High-Energy Dissociation Routes of Triarylamine Derivatives.

Triarylamine groups have been widely utilized in the development of high-performance charge-transporting or luminescent materials for fabricating organic light-emitting diodes (OLEDs). In this study, atmospheric pressure chemical ionization (APCI) Q-Orbitrap mass spectrometry was adopted to investigate the dissociation behaviors of these triarylamine derivatives. Specifically, taking [M+H] as the precursor ion, high-energy collision dissociation (HCD) experiments within the energy range from 0 to 80 eV were carried out. The results showed that triarylamine derivatives with specific structures exhibited distinct fragmentation patterns. For diarylamine, the formation of odd-electron ions was ascribed to the single-electron transfer (SET) reaction mediated by ion-neutral complexes (INCs). In the low-energy range (below 40 eV), proton transfer served as the predominant mechanism for generating even-electron ions. Conversely, in the high-energy range (60 eV and above), the INC-SET reaction dominated. The precursor ion's structure affects compliance with the "even-electron rule", which has exceptions. Here, even-electron ion fragmentation was energy-dependent and could deviate from the rule, yet did not conflict with its concept, reflecting dissociation complexity. This research provides insights for triarylamine-based OLED materials, facilitating analysis and identification, and is expected to aid OLED material development.