Molecular recognition of pyridine N-oxides in water using calix[4]pyrrole receptors.

The incorporation of four carboxylic acids or four amino groups to the upper rim of an aryl extended calix[4]pyrrole produces water-soluble receptors which are able to effectively bind aromatic N-oxides in water by a combination of hydrogen bonding, pi-pi, CH-pi, and hydrophobic interactions.