title: Cucurbit[7]uril host-guest and pseudorotaxane complexes with alpha,omega-bis(pyridinium)alkane dications.
abstract: The host molecule cucurbit[7]uril forms very stable host-guest complexes (1:1 and 2:1) and [2]pseudorotaxanes with alpha,omega-bis(pyridinium)alkane dications in aqueous solution. With the dications containing pyridinium, 2- and 3-picolinium, and 4-dimethylaminopyridinium end groups and a hexyl chain, [2]pseudorotaxanes are formed with one equivalent of CB[7] positioned over the central chain. A second equivalent of CB[7] encapsulating one of the end groups results in the translocation of the first CB[7] to the other end group. For the dications with these end groups, the 2:1 host-guest complexes exhibit stability constants which are considerably smaller than the 1:1 values as the result of steric and electronic repulsions between the two CB[7] hosts.
authors.affiliation: Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, ON K7L 3N6, Canada.
authors.forename: Ian W
authors.initials: IW
authors.lastname: Wyman
authors.forename: Donal H
authors.initials: DH
authors.lastname: Macartney