title: Mesomorphic properties of the neat enantiomers of a chiral pyramidic liquid crystal.
abstract: The crown form of nona-octanoyloxy tribenzocyclononatriene (C8) with C(3) symmetry was prepared and separated into its enantiomers (C8A and C8B) by HPLC. Like the racemate, the neat enantiomers are also mesogenic, exhibiting two mesophases, M and Col(h). Differential scanning calorimetry, X-ray diffraction, carbon-13 NMR and UV circular dichroism are used to study the structural and dynamic properties of these chiral mesophases. The high-temperature mesophase (Col(h)) was identified by X-ray diffraction as columnar hexagonal; this phase is thermally unstable, undergoing racemization on heating before its clearing point is reached. The low-temperature mesophase (M) is most likely also columnar, but its symmetry could not be determined. In comparison with the racemate, the chiral mesophases are less well ordered, more tightly packed and they have a lower tendency to crystallize. On the other hand they are considerably more mobile, as reflected in their NMR spectra. No helical structure has been identified in the X-ray diffraction of the mesophases.
authors.affiliation: The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Zeev
authors.initials: Z
authors.lastname: Luz
authors.forename: Raphy
authors.initials: R
authors.lastname: Poupko
authors.forename: Ellen J
authors.initials: EJ
authors.lastname: Wachtel
authors.forename: Herbert
authors.initials: H
authors.lastname: Zimmermann
mesh_terms: D002851:Chromatography, High Pressure Liquid; D050866:Liquid Crystals / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008853:Microscopy; D011083:Polycyclic Compounds / Q000737:chemistry* / Q000302:isolation & purification; D013237:Stereoisomerism; D013729:Terpenes / Q000737:chemistry* / Q000302:isolation & purification; D014961:X-Ray Diffraction
chemical_list: D011083:Polycyclic Compounds; D013729:Terpenes; C547434:nona-octanoyloxy tribenzocyclononatriene