SELECTIVE COMPLEXATION OF BIOGENIC-AMINES BY MACROCYCLIC POLYETHERS AT A LIQUID LIQUID INTERFACE

Electrochemical results show that selective complexation of beta-phenylethylammonium ions by dibenzo-18-crown-6 at the water/nitrobenzene interface arises both from discrimination in binding these ions to the crown-ether macrocycles and from resolvation effects, which modify the energetics of the ion transfer. Since these effects are closely related to the structure of the transferred ion, chemical substitution (e.g. the introduction of OH or CH3 groups into the substrate ion molecule) can eventually reverse the ion exchange equilibrium at the interface. The results throw some light on the regulation of the passage of polar molecules through the lipidic barriers of biological systems.