In this study, we focused on the evaluation of optical purity of lactic acid-based building blocks used for the synthesis of a broad range of chiral liquid crystals (CLCs) (including the target LCs). We have shown that frequently utilised synthetic procedures do not afford enantiomerically pure building blocks. Partial racemisation occurring during the synthesis of CLCs could result in modification of mesomorphic properties of the target materials. Slight modification of enantiomeric composition of the chiral material could potentially lead to malfunctioning of a CLC-based device.
Using a chiral polysaccharide-based column operated in liquid chromatography mode, we show that not all published methods of LC synthesis are enantioselective, which could lead to significant differences in the properties of the resulting materials. We show that high-performance liquid chromatography with UV detection and supercritical fluid chromatography with UV (see figure) and mass spectrometry detection enable full control over the chemical and optical purity of the target LCs and the corresponding chiral building blocks.
For the first time, we utilise supercritical fluid chromatography with mass detection for the direct chiral analysis of liquid crystalline materials and impurities formed during the synthesis.
