title: Hydroxyethylammonium monosubstituted cyclodextrin as chiral selector for capillary electrophoresis.
abstract: A novel cationic cyclodextrin, mono-6(A)-(2-hydroxyethyl-1-ammonium)-6(A)-β-cyclodextrin chloride (HEtAMCD) has been successfully synthesized and applied as chiral selector in capillary electrophoresis. The NMR study revealed this chiral selector has three recognition sites: β-CD, ammonium cation and hydroxy group in the sidearm to contribute three corresponding driving forces including inclusion complexation, electrostatic interaction and hydrogen bonding. The effect of buffer pH and HEtAMCD concentration (2.5-10 mM) on enantioselectivity, chiral resolution as well as effective mobility of analytes was investigated. This elegantly designed CD exhibits outstanding enantioselectivities toward the studied hydroxyl acids and ampholytic racemates in CE with the aid of extra hydrogen bonding. Under optimum pH 6.0, chiral resolutions over 5 can be readily obtained for hydroxy acids with CD concentration below 5mM. The comparison study between HEtAMCD and our earlier reported ammonium CDs indicates the hydroxyethylammonium group of HEtAMCD significantly increased the enantioselective capability.
authors.affiliation: College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China; Division of Chemical and Biomedical Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
authors.forename: Feng
authors.initials: F
authors.lastname: Ai
authors.forename: Baojing
authors.initials: B
authors.lastname: Zhou
authors.forename: Jian
authors.initials: J
authors.lastname: Tang
authors.forename: Siu-Choon
authors.initials: SC
authors.lastname: Ng
authors.forename: Weihua
authors.initials: W
authors.lastname: Tang
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003505:Cyclodextrins / Q000138:chemical synthesis / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D019075:Electrophoresis, Capillary; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism; D047392:beta-Cyclodextrins / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D064751:Ammonium Compounds; D002412:Cations; D003505:Cyclodextrins; D004573:Electrolytes; D047392:beta-Cyclodextrins; C000588482:mono-6(A)-(2-hydroxyethyl-1-ammonium)-6(A)-beta-cyclodextrin chloride
keywords: Capillary electrophoresis; Cationic cyclodextrin; Chiral separation; Enantioselectivity; Hydrogen bonding