Synthesis of novel, boron-containing cavitands derived from calix[4]resorcinarenes and their molecular recognition of biologically important polyols in Langmuir films

An efficient synthetic route for the synthesis of cavitands derived from calix[4]resorcinarene and its tetrabromo derivative was elaborated. A large-scale preparation was achieved in excellent yield, by replacing the high-boiling solvents with acetone. The tetrabromocavitands were transformed into tetra-boronic acid cavitands via lithiation with butyllithium and reaction with triethylborate. Two lipophilic cavitands bearing four boronic acid residues were demonstrated to form stable Langmuir monolayers at the water–air interface. These cavitand receptors differ in bridging unit between oxygen atoms, i.e. one contains a one-carbon unit and the other a two-carbon unit. l-sorbose, d-galactose, d-glucose, and d-cellobiose were selected for molecular recognition studies using the Langmuir techniques. The unsubstituted tetra-n-undecyl calix[4]resorcinarene was used as a reference receptor compound. Differences in surface potential were diagnostic of the different types of binding forces, which can occur.