Anion encapsulation and dynamics in self-assembled coordination cages.

The ability of cationic coordination cages to act as anion receptors is reviewed, with an emphasis on the anion encapsulation chemistry and the dynamics of cage assembly, anion exchange, and other anion-induced structural transformations. The first part of the review describes various examples of anion-encapsulating coordination cages, categorized on the basis of their M(x)L(y) stoichiometry (M = metal cation; L = organic ligand). The second part deals with the dynamic aspects of anion encapsulation, including the kinetics and mechanism of anion binding, release, and exchange, as well as the structural evolution of the coordination complexes involved.