Thermodynamic and kinetic analysis of metal ion complexation by photochromic spiropyrans

This review focuses on the results of the studies of metal ion complexation by spiropyrans published mostly in recent years. Introduction of ionophore substituents in the molecules of photochromic spiropyrans induces a reasonably strong bonding in the complexes of these compounds with metal ions. The degree of complexation depends on the state (open or closed) of the photochromic spiropyran fragment. Directed synthesis of structures able to form complexes with metal ion requires knowledge of structure-property relationships based, among other, on the studies of the compounds synthesized earlier. This requires accurate determination of thermodynamic and kinetic parameters of complex formation. Difficulties of such quantitative analysis due to the presence of several interrelated equilibria in the system are discussed.