Cucurbit[7]uril: a very effective host for viologens and their cation radicals.
[reaction: see text] The host cucurbit[7]uril (CB7) forms very stable inclusion complexes with simple 4,4'-bipyridinium (viologen) dication guests in aqueous solution. The binding constants were measured by electronic absorption spectroscopy and found to be as high as 1 x 10(5) L/mol. One-electron reduction of the viologen guest results in a modest 2-fold decrease of the binding constant. The rate of the heterogeneous electron-transfer reaction between the complexed viologen dication and cation radical remained fast in the voltammetric time scale.
Ong
Winston
W
Center for Supramolecular Science and Department of Chemistry, University of Miami, Coral Gables, Florida 33124-0431, USA.
Gómez-Kaifer
Marielle
M
Kaifer
Angel E
AE