Gas Chromatographic Separation of Structural Isomers on Cholesteric Liquid Crystal Stationary Phase Materials

Lee, Yi-Wen; Lin, Cheng-Kuo

doi:10.14233/ajchem.2013.13927

Asian J. Chem.

2013

DOI: 10.14233/ajchem.2013.13927

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Gas Chromatographic Separation of Structural Isomers on Cholesteric Liquid Crystal Stationary Phase Materials

Yi-Wen Lee¹,

Cheng-Kuo Lin²

Abstract: A new series of liquid crystalline polysiloxanes with a very wide range of mesomorphic temperatures had been prepared. They contained 4-cholesteryl-(10-undecen-1-yloxy)biphenyl-4′-carboxylate mesogenic and 4-biphenyl-4′-allyloxybenzoate mesogenic side groups displaying an enantiotropic cholesteric phases. The mesomorphic polysiloxane specimen with the widest temperature range was used as the stationary phase in a gas chromatography capillary column and it showed high column efficiency and made great promise fo… Show more

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Cited by 2 publications

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SAMPL4, a blind challenge for computational solvation free energies: the compounds considered

Guthrie

2014

J Comput Aided Mol Des

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For the fifth time I have provided a set of solvation energies (1 M gas to 1 M aqueous) for a SAMPL challenge. In this set there are 23 blind compounds and 30 supplementary compounds of related structure to one of the blind sets, but for which the solvation energy is readily available. The best current values of each compound are presented along with complete documentation of the experimental origins of the solvation energies. The calculations needed to go from reported data to solvation energies are presented, with particular attention to aspects which are new to this set. For some compounds the vapor pressures (VP) were reported for the liquid compound, which is solid at room temperature. To correct from VPsubcooled liquid to VPsublimation requires ΔSfusion, which is only known for mannitol. Estimated values were used for the others, all but one of which were benzene derivatives and expected to have very similar values. The final compound for which ΔSfusion was estimated was menthol, which melts at 42 °C so that modest errors in ΔSfusion will have little effect. It was also necessary to look into the effects of including estimated values of ΔCp on this correction. The approximate sizes of the effects of inclusion of ΔCp in the correction from VPsubcooled liquid to VPsublimation were estimated and it was noted that inclusion of ΔCp invariably makes ΔGS more positive. To extend the set of compounds for which the solvation energy could be calculated we explored the use of boiling point (b.p.) data from Reaxys/Beilstein as a substitute for studies of the VP as a function of temperature. B.p. data are not always reliable so it was necessary to develop a criterion for rejecting outliers. For two compounds (chlorinated guaiacols) it became clear that inclusion represented overreach; for each there were only two independent pressure, temperature points, which is too little for a trustworthy extrapolation. For a number of compounds the extrapolation from lowest temperature at which the VP was reported to 25 °C was long (sometimes over 100°) so that it was necessary to consider whether ΔCp might have significant effects. The problem is that there are no experimental values and possible intramolecular hydrogen bonds make estimation uncertain in some cases. The approximate sizes of the effects of ΔCp were estimated, and it was noted that inclusion of ΔCp in the extrapolation of VP down to room temperature invariably makes ΔGs more negative.

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SAMPL4, a blind challenge for computational solvation free energies: the compounds considered

Guthrie

2014

J Comput Aided Mol Des

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Enantioseparation of liquid crystals and their utilization as enantiodiscrimination materials

Vaňkátová

Kubíčková

Kalíková

2022

Journal of Chromatography A

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Gas Chromatographic Separation of Structural Isomers on Cholesteric Liquid Crystal Stationary Phase Materials

Cited by 2 publications

References 12 publications

SAMPL4, a blind challenge for computational solvation free energies: the compounds considered

SAMPL4, a blind challenge for computational solvation free energies: the compounds considered

Enantioseparation of liquid crystals and their utilization as enantiodiscrimination materials

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