Synthesis and Recognition Properties of Enantiomerically Pure Acyclic Cucurbit[n]uril-Type Molecular Containers

Enantiomerically pure acyclic cucurbit[n]uril containers 1 and 2 were synthesized by the condensation of enantiomerically pure aromatic sidewalls 3b and 4b with glycoluril tetramer 5. Containers 1 and 2 are C2-symmetric, feature four arms of the same handedness, and bind to a variety of guests (6-15) in aqueous solution including aliphatic and aromatic ammonium ions, amino acids, dyes, and viologens. The binding constants of hosts 1Ac and 1OH toward selected chiral ammonium ions were measured by (1)H NMR and UV/vis spectroscopy.