Water-soluble aryl-extended calix[4]pyrroles with unperturbed aromatic cavities: synthesis and binding studies

We report the synthesis of a novel, water-soluble aryl-extended calix[4]pyrrole receptor. The water-solubilising groups are placed at the lower rim of the receptor, leaving the binding pocket unperturbed and open for modification. Binding studies were performed with a series of pyridineN-oxides. These studies revealed the ability of the receptor to bind neutral and charged N-oxides in basified water with stability constants higher than 10⁴ M⁻¹.