Pair of Diastereomeric Uranyl Salen Cavitands Displaying Opposite Enantiodiscrimination of α-Amino Acid Ammonium Salts

A pair of diastereomeric salen cavitands and their uranyl complexes combine a chiral (R,R) salen bridge and an inherent chiral tris-bridged quinoxaline cup within the same molecule. Whereas the free ligands show a preference for the same enantiomer of an a-amino acid pair, the corresponding UO2 complexes display opposite enantiodiscrimination and exceptionally high enantioselectivities (K-D/K-L = 26.4)