Structural analysis of C8H6˙+ fragment ion from quinoline using ion-mobility spectrometry/mass spectrometry

Abstract

This study investigated the structures of fragment ions derived from the quinoline (C₉H₇N) radical cation using ion-mobility spectrometry and mass spectrometry. Ion mobility and mass analysis revealed that C₈H₆˙⁺ is the primary dissociation product resulting from the loss of HCN during collision-induced dissociation of the quinoline radical cation. The reduced mobility (K₀) of the C₈H₆˙⁺ fragment product in helium gas was measured over a range of reduced electric fields (E/N = 20.8–27.4 Td) at room temperature. The experimental K₀ values indicated that C₈H₆˙⁺ is a mixture of phenylacetylene and pentalene radical cations. Furthermore, quantum chemical calculations revealed two potential energy surfaces delineating the loss of HCN from the quinoline radical cation to form phenylacetylene radical cations.