Crystal structures of three partially cyclopentano-substituted cucurbit[6]urils

Three new alkyl-substituted cucurbit[6]urils, symmetrical tetracyclopentano cucurbit[6]uril {TCyPQ[6]}, meta-tricyclopentano cucurbit[6]uril {m-TriCyPQ[6]} and meta-dicyclopentano cucurbit[6]uril {m-(CyP)2Q[6]}, were synthesized by using the controlled synthesis utilizing the readily available dimer of the unsubstituted glycouril, diether of cyclopentano glycoluril and the unsubstituted glycouril. These partial cyclopentano-substituted cucurbit[6]urils were characterized by single-crystal X-ray diffractions. In the crystal structure of compounds 2{TCyPQ[6]}·57H2O (1) and {m-TriCyPQ[6]}·23H2O (2), both of Q[6]s formed a molecular capsule included water molecules, and the capsules assembled one-dimensional supramolecular chains through the hydrogen bonding. In the crystal structure of compound 2{m-(CyP)2Q[6]}·(HV)2+·4Cl−·2(H3O)+·44H2O (3), a dumbbell shape host–guest inclusion complex N,N-dihexyl-4,4′-bipyridinium(HV2+) with m-(CyP)2Q[6] was formed, the m-(CyP)2Q[6] host selectively included the alkyl moiety of the guest through the hydrophobic cavity interaction and the ion-dipole interaction.