A Preparative and Solution Study of a Modified b-Cyclodextrin and its Europium(III) Complex, and their Interactions with Racemic Amino Acid Anions

Abstract

The synthesis and characterization of 6^A-deoxy-6^A-(1,4,7-tri(carboxylatomethyl)-1,4,7,10-tetraazacyclododecan-10-yl)-β-cyclodextrin (1b) are reported. A fluorescence lifetime study of its Eu³⁺ complex (1c) is consistent with one water coordinating Eu³⁺ in addition to hepta-coordination by (1b). ¹H NMR studies are consistent with (1b) forming host–guest complexes with (R/S)-histidinate (2a), (R/S)-tyrosinate (2b), (R/S)-phenylalaninate (2c), and (R/S)-tryptophanate (2d), with enantioselectivity shown for (2b). Similar studies are consistent with (1c) complexing (2a–d), with enantioselectivity shown for (2a).