title: Chiral separation of novel diazenes on a polysaccharide-based stationary phase in the reversed-phase mode.
abstract: Chiral high-performance liquid chromatography separation of two recently synthesized liquid crystalline materials C1 and C2 was studied in the reversed-phase mode. Both materials have an azo-moiety and one chiral center in their molecular structures. They were available in racemic and pure S forms. For the enantiomeric separations, a Chiralpak AY-RH stationary phase based on amylose tris(5-chloro-2-methylphenylcarbamate) coated on 5 μm silica was used. The compounds were analyzed in both of their possible forms, the more thermodynamically stable E form and the labile Z form. The conditions and time scale of the UV-induced E to Z transition were briefly evaluated. Under the optimized conditions, we were able to baseline separate S and R enantiomers of both of the studied materials not only in their E forms, but also in their Z forms. In comparison to the separation in the normal-phase mode, which we have reported recently, the resolution in the reversed-phase mode is significantly better. Interestingly, peak reversal was noticed for the S and R enantiomers when the separation was carried out with E versus Z forms of both compounds.
authors.affiliation: Department of Chemistry, Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.|Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Prague, Czech Republic.
authors.forename: Terézia
authors.initials: T
authors.lastname: Vojtylová
authors.affiliation: Department of Chemistry, Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
authors.forename: Věra
authors.initials: V
authors.lastname: Hamplová
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Galewski
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland.
authors.forename: Izabela
authors.initials: I
authors.lastname: Korbecka
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Prague, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Sýkora
keywords: azobenzene; chiral separation; high-performance liquid chromatography; liquid-crystalline materials; photo-induced isomerization