The influence of photoinduced isomerization on the enantiomeric separation of two newly synthesized liquid crystalline materials, liquid crystals 1 and 2, was studied by high-performance liquid chromatography on a chiral stationary phase Chiralpack AD-3. Both materials have one chiral center and one diazene moiety. The compounds were separated into their E and Z isomeric forms. The conditions and time scale of the ultraviolet-induced E to Z transition were briefly evaluated. Under the optimized conditions, we were able to baseline separate the S and R enantiomers of both the studied materials in their E isomeric form. The chiral separation of liquid crystal 2 after ultraviolet irradiation was unsuccessful. In contrast, the chiral separation of liquid crystal 1 possessing a similar structure to liquid crystal 2 provided baseline separation in its Z isomeric form as well. Previously, we have shown the influence of photoinduced isomerization and its utilization in the enantioseparation on relatively simple molecules. Here, we demonstrate that (1) much more complex compounds can also be successfully separated despite the bulkiness of the achiral part of the structure and (2) photoinduced isomerization even for such complex molecules still strongly influences their chromatographic properties.

Department of Chemistry Czech Academy of Sciences Institute of Physics Prague Czech Republic

Faculty of Chemical Engineering Department of Analytical Chemistry University of Chemistry and Technology Prague Prague Czech Republic

References provided by Crossref.org

Determination of Optical Purity of Lactic Acid-Based Chiral Liquid Crystals and Corresponding Building Blocks by Chiral High-Performance Liquid Chromatography and Supercritical Fluid Chromatography