Macrocyclic anion receptors based on directed hydrogen bonding interactions

Natural anion receptors use charge-neutral dipoles to bind small anions with high affinities and selectivities. A convergent and rigid display of hydrogen bond donors such as amide, thiourea and urea functional groups in macrocyclic scaffolds would be one of the most efficient ways to create synthetic anion receptors that mimic natural ones. In this article, we present examples of natural anion receptors and discuss the synthesis of neutral macrocyclic receptors and their anion binding properties.