Investigation of the enantioselectivity of three polypeptide liquid-crystalline solvents using NMR spectroscopy

The enantioselective potentialities of three polypeptide liquid-crystalline solutions made of poly-gamma -benzyl-L-glutamate (PBLG), poly-gamma -ethyl -L-glutamate (PELG) or poly-epsilon -carbobenzyloxy-L-lysine (PCBLL) are in vestigated and compared using proton, carbon-13 and deuterium NMR spectrosc opy. From a practical point of view, we propose an efficient alternative to the PBLG system, which is essential when this chiral homopolymer fails in distinguishing between enantiomers or enantiotopic elements. From a theoret ical point of view, this study provides new information on the role of the lateral side chain of the polypeptide in the mechanisms of enantiodiscrimin ation. The various experimental results reported show the extraordinary ada ptability of this methodology, and so enlighten the very large potential of NMR in chiral liquid crystals in the field of enantiomeric and enantiotopi c analysis.