ENANTIOMERIC RESOLUTION OF ANIONIC R/S-1,1'-BINAPHTHYL-2,2'-DIYL HYDROGEN PHOSPHATE BY CAPILLARY ELECTROPHORESIS USING ANIONIC CYCLODEXTRIN DERIVATIVES AS CHIRAL SELECTORS

The enantioseparation of racemic 1,1'-bi-2-naphthol (1), 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (2) and 1,1'-binaphthyl-2,2'-diamine (3) using native beta-cyclodextrin (beta-CD) and its anionic derivatives such as carboxymethyl-beta-CD (CM-beta-CD), sulfoethyl ether of beta-cyclodextrin (SEE-beta-CD) and sulfobutyl ether of beta-cyclodextrin (SBE-beta-CD) has been studied. The successful resolution of 2 in the anionic form using negatively charged cyclodextrin derivatives shows that the role of the Coulombic interactions is not critical for the chiral guest-host recognition in capillary electrophoresis (CE). The application of SEE-beta-CD as a chiral selector in CE has been demonstrated for the first time. Comparison of the enantioseparation efficiencies of SEE-beta-CD and SBE-beta-CD shows that the spacer length and the substitution pattern are factors with rather low importance and that the resolution efficiency is mainly determined by the counter-current mobility of the chiral selector.