Enhancement of chiral recognition by formation of a sandwiched complex in capillary electrophoresis

For chiral primary amino compounds not separable by cyclodextrins alone, ch iral recognition was successfully achieved by the formation of a sandwiched complex of the non-chiral 18-crown-6, the chiral amine and cyclodextrin (C D) [18-crown-6 + amino compound + CD]. The separation of 1-methyl-3-phenylp ropylamine and 1,2,3,4-tetrahydro-1-naphthylamine racemates showed the spec ial function of the non-chiral 18-crown-6 on chiral recognition. By formati on of the sandwiched complex, the chiral center of 1-methyl-3-phenylpropyla mine was successfully recognized, and resolution of 1,2,3,4-tetrahydro-1-na phthylamine dramatically increased. In these studies, the mobility differen ces of the enantiomers were evaluated as a function of the concentration of cyclodextrins with and without the 18-crown-6, and as a function of the co ncentration of the 18-crown-6. In addition, the separations by this method were compared to those by the chiral 18-crown-6 reagent. (C) 2000 Elsevier Science BN. All rights reserved.