Supramolecular complexes of α,α′,δ,δ′-tetramethyl-cucurbit[6]uril binding with enantiomeric amino acids

Abstract

The reaction of α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) with seven enantiopure amino acids (D,L-Gln; D,L-Met; D,L-Ser; D-Val) yields seven supramolecular assemblies under different conditions. Single-crystal X-ray diffraction analyses reveal that the seven supramolecular assemblies are classified into two structural types (inclusion and exclusion structures), which mainly depend on the length of the alkyl chain of the amino acids. In contrast, the reaction of TMeQ[6] with L-Val does not form any crystalline materials, suggesting that TMeQ[6] may be suitable for the separation of D-Val from its enantiomer.