Assessing the chirality-dependent conformational distribution of small flexible opposite enantiomers dissolved in weakly ordering enantiopure media by means of liquid crystal NMR techniques

Abstract

The unique power of Liquid Crystal NMR (LXNMR) in obtaining information about the conformational equilibrium of small solutes dissolved in orienting media can be effectively used to study chirality-related phenomena. In this work we have been able, for the first time in our knowledge, to fully resolve the two different conformational distributions for the R and S enantiomers of a case test molecule (the chiral flexible 4FMBOH: 4-F-α-methyl benzyl alcohol), dissolved in a typical chiral non-racemic aligning solvent, made of PBLG (poly- γ -benzyl-L-glutamate, a helical chiral polypeptide) co-dissolved in CDCl3. The two enantiomers show significant differences in their conformational behaviors, due to the different solute–solvent orientational molecular interactions experienced by the R and S species. In our opinion, fundamental studies of this kind could pave the way for a better understanding of chirality-dependent molecular interactions, often involved in a number of important chemical processes (concerning pharmaceuticals, biochemistry, advanced materials, etc.)