Chiral discrimination of amino acids and their potassium or sodium salts by optically active crown ether derived from D-mannose

Chiral naphtho-18-crown-6 incorporating alpha-methyl D-mannopyranoside unit exhibits a pronounced chiral discrimination of amino acids in their zwitterionic form, or as potassium and sodium salts in transport across the bulk liquid membrane containing the carrier, as well as in the extraction experiments from the water phase to chloroform phase containing the receptor. The D/L selectivity strongly depends on the species used (neutral amino acids, or their salts), and in some cases the reversed selectivity within the same amino acid enantiomers has been observed, indicating the influence of the cation involved. (C) 1998 Elsevier Science B.V.