Chiral discrimination of monofunctional alcohols and amines in the gas phase

Abstract

A methodology has been developed for enantiodiscriminating chiral monoalcohols and monoamines by mass spectrometry. The approach is based on the generation of supersonically expanded complexes of these molecules with suitable chromophores, i.e. R-(+)-1-phenyl-ethanol (ER) or R-(+)-1-phenyl-1-propanol (PR). The jet-cooled diastereomeric complexes, otherwise elusive at room temperature, have been ionized by one-color resonant two-photon absorption (R2PI) and their fragmentation pattern analyzed by time-of-flight (TOF) spectrometry. Enantiodifferentiation of the chiral monoalcohols and monoamines is based on: (1) the different spectral shifts of the band origin of their molecular complexes relative to that of the bare chromophore (Δ) and (2) the different mass spectral fragmentation patterns of the jet-cooled diastereomeric adducts. Detection of stable aggregates of methane, n-butane, and other simple molecules with the selected chromophores suggests that the R2PI/TOF method can be a potential tool for enantiodifferentiating chiral hydrocarbons in the gas phase.