Abstract
Aminophenyl-substituted adamantane-dipyrromethane receptors 1 and 2 and aminophenylpyrrole 3 showed a very pronounced and unique UV spectral response with in aprotic as well as in aqueous media. The fitting of the binding isotherms with indicated formation of the complexes with the 1:2 (host–anion) stoichiometry. ESI-MS study with mixtures of receptor 3 and tetrabutylammonium hydrogensulfate of different ratios indicated an association of the and receptor 3, as well as association of the species into dimers. The unique UV spectral response with is proposed to be due to proton transfer from to the amino group of the receptor, which in an aprotic solvent probably takes place in the corresponding H-bonded complexes. The assignations of the spectral changes were corroborated by computation. Moreover, theoretical study indicated that ‘intra-supramolecular’ proton transfer took place, whereas the presence of the second was required to enhance the acidity of the first H-bonded anion.