After the development of synthetic cation receptors in the late 1960s,
only in the past decade has work started on the development of synthe
tic neutral anion receptors. Combination and preorganization of differ
ent anion binding groups, like amides, urea moieties, or Lewis acidic
metal centers lead to receptor molecules that strongly bind inorganic
anions with high selectivity. Combined with neutral cation ligands, di
topic receptors were obtained for the complexation of inorganic salts.
The molecular complexation properties of anion receptors has been tra
nsduced into macroscopic properties in membrane separation processes a
nd in sensors for selective anion detection.