N,N′-disubstituted methylenediimidazolium salts:: A versatile guest for various macrocycles

N,N'-Disubstituted methylenediimidazolium salts allow the formation of flexible inclusion complexes with P-cyclodextrin, cucurbit[7]uril, tetrapropoxycalix[4]arene, and dibenzo-24-crown-8 ether. Due to the salt nature of the imidazolium guest, the counterion largely determines its solubility in a given solvent. Moreover, by the judicious choice of the imidazolium substituents, inclusion complexes of guest salts were obtained with a variety of macrocyclic hosts, and the binding parameters of the inclusion were deter-mined for each complex.