ENANTIOMERIC ANALYSIS IN A POLYPEPTIDE LYOTROPIC LIQUID-CRYSTAL BY DEUTERIUM NMR

A new method for enantiomeric analysis through the measurements of nuclear magnetic resonance in a lyotropic chiral liquid crystal is presented. Under favourable circumstances proton NMR can be used; however, deuterium NMR is in general more convenient for this purpose. Partly deuterated chiral molecules dissolved in liquid-crystalline solutions of poly-gamma-benzyl-L-glutamate (PBLG) in methylene chloride, or other organic solvents, exhibit different deuterium NMR spectra for each enantiomer. This phenomenon is caused by the fact that the enantiomers interact with the chiral centers of the PBLG helix and consequently each of them orients differently in this medium (a differential ordering effect). We show that our technique is convenient in use and very general in application. A detailed analysis is given for one particular molecule, and other results are presented and discussed according to the functional groups present in the molecules.