Remarkable salt effect on stability of supramolecular complex between modified cucurbit[6]uril and methylviologen in aqueous media.

The supramolecular complex formed by partial inclusion of methylviologen in MeCB6 was described both in solution and in the solid state. The association constant of the complex was determined using (1)H NMR and UV-vis spectrophotometric titration. An extraordinary 2000-fold drop in the association constant of the complex was observed when pure water was replaced by 50 mM NaCl solution.