Formation and trapping of the thermodynamically unfavoured inverted-hemicucurbit[6]uril.

Formation of inverted-cis-cyclohexanohemicucurbit[6]uril (i-cis-cycHC[6]), with up to 33% isolated yield, can be induced at the expense of thermodynamically favoured cis-cycHC[6]. Reaction selectivity is governed by the solution-based template-aided dynamic combinatorial chemistry and continuous precipitation of the formed macrocycles. Different binding affinities of three diastereomeric cycHC[6]s with trifluoroacetic acid is demonstrated.

Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution.

A novel eight-membered macrocycle of the hemicucurbit[]uril family, chiral ()-cyclohexanohemicucurbit[8]uril () ‡The name cyclohexylhemicucurbituril, previously used for these macrocycles, is changed in accordance with the IUPAC nomenclature for fused cycles, as the cyclohexane substituents are fused with the parent hemicucurbituril. binds anions in a purely protic solvent with remarkable selectivity. The portals open and close to fully encapsulate anions in a 1 : 1 ratio, resembling a molecular Pac-Man™.

Template-controlled synthesis of chiral cyclohexylhemicucurbit[8]uril.

Enantiomerically pure cyclohexylhemicucurbit[8]uril (cycHC[8]), possessing a barrel-shaped cavity, has been prepared in high yield on a gram scale from either (R,R,N,N')-cyclohex-1,2-diylurea and formaldehyde or cycHC[6]. In either case, a dynamic covalent library is first generated from which the desired cycHC can be amplified using a suitable anion template.