Selective binding of cucurbit[7]uril and beta-cyclodextrin with a redox-active molecular triad Ru(bpy)(3)-MV2+-naphthol

A 1:1:1 inclusion complex is formed by the binding interactions among beta-CD, CB[ 7] hosts, and Ru(bpy)(3)-terminated viologen naphthalene guest in aqueous solution, in which the positions of both CB[7] and beta-CD are closer to the Ru stopper than in the respective 1:1 inclusion complexes, forming a tightened nut on bolt'' structural mode.