Host-guest complexation of a pyrogallol[4]arene derivative at the air-water interface.

The host–guest properties of acetylated aryl pyrogallol[4]arene (AcPy) were studied as a Langmuir monolayer at the air–water interface. The self-assembled Langmuir monolayer properties and interactions with monovalent and divalent metal cations were investigated using surface pressure– and surface potential–area isotherms, compression–decompression cycles, stability, and infrared reflection–absorption spectroscopy (IRRAS). A favorable interaction is observed for complexation between acetylated aryl pyrogallol[4]arene with divalent calcium and cadmium cations, while no interaction is observed for monovalent sodium and potassium cations. Spectroscopic techniques allow for discrimination between cadmium and calcium complexation.