title: A Family of Single-Isomer Chiral Resolving Agents for Capillary Electrophoresis. 3. Heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin.
abstract: The third member of a new family of single-isomer charged cyclodextrins, the sodium salt of heptakis(2,3-dimethyl-6-sulfato)-β-cycldextrin, has been synthesized, characterized, and used for the capillary electrophoretic separation of the enantiomers of neutral, acidic, basic, and zwitterionic analytes. Though heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin complexes much less strongly with any of the analytes tested here than the previously synthesized heptakis(2,3-diacetyl-6-sulfato)-β-cyclodextrin and heptakis-6-sulfato-β-cyclodextrin, it offers excellent enantioselectivities, complementary to those of the other two single-isomer, differently functionalized charged cyclodextrins. Confirming the predictions of the charged resolving agent migration model, heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin allowed for the reversal of the migration order of the enantiomers of neutral analytes as the cyclodextrin concentration was increased. Just as with the previous two single-isomer charged resolving agents, separation selectivity for the acidic, basic, and zwitterionic analytes could increase, decrease, or pass a maximum as the cyclodextrin concentration was increased, depending on the respective binding strength of the enantiomers and the ionic mobilities of both the complexed and noncomplexed forms of the enantiomers.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, Texas 77845-3255.
authors.forename: H
authors.initials: H
authors.lastname: Cai
authors.forename: T V
authors.initials: TV
authors.lastname: Nguyen
authors.forename: G
authors.initials: G
authors.lastname: Vigh