화학공학소재연구정보센터
Electrophoresis, Vol.25, No.4-5, 743-752, 2004
Combination of cyclodextrins and polymeric surfactants for chiral separations
A cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) method was applied to the enantioseparation of three binaphthyl derivatives using neutral CDs (i.e., beta- and gamma-CD) in combination with various chiral amino acid-based polymeric surfactants (PSs). Both the D- and L-configurations of poly(sodium N-undecanoyl alaninate), poly(sodium N-undecanoyl leucinate), and poly(sodium N-undecanoyl valinate) (poly(L-SUV)) were synthesized. The retention behavior of the three binaphthyl derivatives under optimum electrophoretic conditions using a single chiral additive (PS or CID) is discussed. In addition, the effect of CID cavity size and stereochemical configuration of polymeric surfactants on selectivity (alpha) and resolution (R-s) was investigated. The enantioseparation of (+/-)1,1'-binaphthyl-2,2'-diamine gave a reversal of enantiomeric order when using P-CD in combination with any of the three D-configuration PS. However, better enantioseparation is obtained when using the corresponding L-configuration PS with P-CD. A reversal of migration order (RMO) for the enantiomers of (+/-)1,1'-bi-2-naphthol was observed upon the addition of 10 mm gamma-CD to poly(L-SUV). However, no RMO of (+/-)1,1'-bi-2-naphthol was seen when either beta-CD or gamma-CD was combined with D-PS. The enantiomers of (+/-)1,1'-binaphthyl-2,2'-diyl hydrogen phosphate showed little enantioselective behavior toward the PS alone. However, combined D- or L-PS and beta-CD or gamma-CD systems gave increased R-s and alpha values. The chiral recognition of binaphthyl derivatives observed resulting from the various combinations of two chiral selectors is discussed.