Chiral HPLC for a study of the optical purity of new liquid crystalline materials derived from lactic acid

Abstract

New liquid crystalline (LC) materials were prepared by derivatization of lactic acid. First compound possesses the lactic acid unit as the only chiral center and the second group of LC materials contains two chiral centers. Mesomorphic properties of both the newly synthesized LC materials were studied and the presence of the SmA*–SmC* or exhibit the twist grain boundary (TGB) phases, namely TGBA and TGBC, in a wide range of temperatures down to the room temperature was established. The potential of high-performance liquid chromatography (HPLC) applying chiral stationary phases to separate enantiomers or diastereoisomers of the synthesized LC compounds was evaluated. Two different brands of commercial chiral sorbents, Lux Amylose-2 and Chiralpak AD-3, both based on modified silica with derivatized polysaccharide, were employed in the development of separation procedures. The optimized chiral HPLC method provided a baseline separation of the individual enantiomers for the LC material containing one chiral center. In the case of the more complex compound with two asymmetric carbon atoms, where four isomers exist, partial separation was reached only using the current chiral HPLC.

Keywords:

• lactic acid derivative
• smectic phase
• high performance liquid chromatography, chiral separation

Additional information

Funding

This work was supported by the Czech Science Foundation [grant number CSF 13-14133S]; the Ministry of Education of the Czech Republic [grant number MSM6046137307].