Discrimination and analysis of the NMR spectra of enantiomers dissolved in chiral liquid crystal solvents through 2D correlation experiments
Résumé
The discrimination and analysis of the NMR spectra of optically active molecules dissolved
in chiral liquid crystal solvents through 2D correlation experiments is studied. The technique
allows the identification of the line positions of each enantiomer, thus providing a notable
simpliûcation of the spectral analysis. The 2D HOHAHA and multiple-quantum experiments
are investigated and discussed. The potential of the method is illustrated using a sample of
( + ) 3,3,3-trichloroepoxypropane dissolved in a thermotropic cholesteric solvent. The case of
chiral molecules bearing a fluorine or deuterium nucleus has also been studied. In addition,
it is shown that 2D heteronuclear correlation experiments are powerful methods for correlating
carbon and proton spectral data of two enantiomers. A specific example is given through
( * ) 2-bromopropanoic acid dissolved in a lyotropic polypeptide liquid crystal. Spectral
parameters of each enantiomer are calculated for the different examples