Influence of hydrophobic residues on the binding of CB[7] toward diammonium ions of common ammonium···ammonium distance.

We report the binding constants of CB[7] toward a series of naphthalene diammonium and 4,4'-dipiperidinium derivatives and compare the results with those obtained previously for CB[7]·3b by (1)H NMR and X-ray crystallography. The nature of binding in the host·guest complexes was investigated using quantum mechanical tools.