Chiral HPLC and physical characterisation of orthoconic antiferroelectric liquid crystals |
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Authors: | Terézia Vojtylová Magdalena ?urowska Katarzyna Milewska Věra Hamplová David Sýkora |
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Institution: | 1. Department of Chemistry, Institute of Physics of the Czech Academy of Sciences, Prague 8, Czech Republic;2. Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Prague 6–Dejvice, Czech Republicvojtyl@fzu.cz;4. Faculty of Advanced Technologies and Chemistry, Military University of Technology, Warsaw, Poland;5. Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Prague 6–Dejvice, Czech Republic |
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Abstract: | New orthoconic antiferroelectric liquid crystalline materials were synthesised and characterised in their racemic forms and as (S) enantiomers. The materials possess oligo-methylene spacers of different lengths in semi-fluorinated achiral chains and lateral substitution by fluorine at two different positions of the molecular core. For comparison purposes, analogical materials without fluorine lateral substitutions were also prepared. Polysaccharide chiral stationary phases based on two different chiral selectors were used for the separation of the enantiomers of the individual racemic mixtures by high-performance liquid chromatography. A baseline separation of (S) and (R) enantiomers was obtained for four of the six studied liquid crystalline materials. Two of the materials were partially separated under the optimised separation conditions. The elution order of the individual enantiomers in the racemic mixtures was successfully assigned, as pure (S) enantiomers of all the studied materials were available. Both the position of the fluorine atom within the molecular core and the size of the achiral moiety had significant effects on the separation of the individual enantiomers of the studied compounds. Moreover, it was also found that the structure of the chiral stationary phase selector significantly influenced the enantiomeric resolution. |
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Keywords: | Liquid-crystalline materials antiferroelectric compounds liquid chromatography chiral HPLC semi-fluorinated non-chiral chain |
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