Pyridine and pyridinium-based anion receptors

Pyridine and pyridinium heterocycles play an important role in anion receptor chemistry. Hydrogen bond arrays are frequently preorganized by the presence of the pyridine nitrogen lone pair of electrons, whilst the positively charged pyridinium group is capable of interacting with anions via a number of polarized noncovalent interactions. This review describes the development of pyridine and pyridinium-based anion receptors, separated into topologically distinct acyclic, macrocyclic, macrobicyclic and interlocked host systems.