Modelling neurotransmitter functions: a laser spectroscopic study of (1S,2S)-N-methyl pseudoephedrine and its complexes with achiral and chiral molecules

Wavelength and mass resolved resonance-enhanced two photon ionization ( R2PI) excitation spectra of (1S, 2S)-N-methyl pseudoephedrine (MPE) and its complexes with several achiral and chiral solvent molecules, including water (W), methyl (R)- lactate (L-R), methyl (S)-lactate (L-S), (R)-2-butanol (B-R), and (S)-2-butanol (B-S), have been recorded after a supersonic molecular beam expansion and examined in the light of ab initio calculations. The spectral patterns of the selected complexes have been interpreted in terms of the specific hydrogen-bond interactions operating in the diastereomeric complexes, whose nature in turn depends on the structure and the configuration of the solvent molecule. The obtained results confirm the view that a representative neurotransmitter molecule, like MPE, "communicates" with the enantiomers of a chiral substrate through different, specific interactions. These findings can be regarded as a further contribution to modelling neurotransmitter functions in biological systems.