Enantiodifferentiation in jet-cooled van der Waals complexes of chiral molecules

Laser-induced fluorescence excitation spectroscopy in a supersonic expansion is used to evidence intermolecular chiral discrimination at the microscopic level. Measurements have been performed in (R)-(+)- and (S)-(−)-α-methyl-2-naphthalenemethanol (a naphthalene compound made chiral by the asymmetric carbon in the 2 position) in the presence of alcoholic solvents (methanol, 1-propanol, and (S)-(+)-chloro-1-propanol). While identical spectral shifts are observed for 1:1 complexes of (R)-(+)- and (S)-(−)-α-methyl-2-naphthalenemethanol with non-chiral solvents, complexation of each enantiomer with the chiral (S)-(+)-2-chloro-1-propanol molecule gives rise to different solvent shifts and allows differentiation between the two forms in the racemic mixture.