A synthetic supramolecular complex has been adapted to quantify cation–π interactions in chloroform by using chemical double-mutant cycles. The interaction of a pyridinium cation with the π-face of an aromatic ring is found to be very sensitive to the π-electron density. Electron-donating substituents lead to a strong attractive interaction (−8 kJ/mol ⁻¹ ), but electron-withdrawing groups lead to a repulsive interaction (+2 kJ/mol ⁻¹ ).

An amide macrocycle with a highly preorganised cavity containing both polar and non-polar recognition sites forms stable complexes with cyclic dipeptides in water via amide–amide hydrogen-bonds, NH–π hydrogen-bonds and hydrophobic contacts.