title: Novel carbamoyl type quinine and quinidine based chiral anion exchangers implementing alkyne-azide cycloaddition immobilization chemistry.
abstract: The synthesis and chromatographic evaluation of a series of new Cinchona derived chiral weak anion exchangers is presented. Huisgen Cu(I) mediated alkyne-azide cycloaddition, so-called click chemistry, was used as an immobilization strategy. In this way it was possible to immobilize about 90% of offered selector via 1,2,3-triazole linker, which displays a more efficient way of binding the selector to modified silica compared to common radical mediated thiol-ene addition. Problems associated with potential radical scavenging properties of chiral selectors thereby could be circumvented. The evaluation of the synthesized chiral stationary phases regarding chromatographic behavior was carried out using polar organic mode mobile phase composition and a set of representative chiral organic acids. Different loading densities revealed an optimum selector density of about 310μmol/g chiral stationary phase with respect to resolution and selectivity. A decrease of performance was observed for higher loading, indicating mutual spatial influence of selector units leading to sterical hindrance. In addition, we observed that the effect of free azide groups on retention is negligible and the overall chromatographic behavior is comparable to other Cinchona derived chiral stationary phases.
authors.affiliation: Institute of Analytical Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna, Austria.
authors.forename: Hubert
authors.initials: H
authors.lastname: Hettegger
authors.affiliation: Department of Organic Chemistry, Institute of Chemical Technology Prague, Technická 5, 16628 Prague, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Kohout
authors.affiliation: Institute of Analytical Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna, Austria.
authors.forename: Vebi
authors.initials: V
authors.lastname: Mimini
authors.affiliation: Institute of Analytical Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna, Austria. Electronic address: wolfgang.lindner@univie.ac.at.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lindner
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry; D001386:Azides / Q000737:chemistry*; D002219:Carbamates / Q000138:chemical synthesis / Q000737:chemistry*; D002845:Chromatography; D057930:Click Chemistry; D061565:Cycloaddition Reaction; D007474:Ion Exchange; D011802:Quinidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D011803:Quinine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D012822:Silicon Dioxide; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D000596:Amino Acids; D001386:Azides; D002219:Carbamates; D012822:Silicon Dioxide; D011803:Quinine; D011802:Quinidine
keywords: Chiral anion exchange chromatography; Cinchona alkaloids; Click chemistry; Copper-catalysis; Enantiomer separation; Liquid chromatography