Some aspects of macrocycle-metal ion interactions in mixed solvents

Investigations on the structure of electrolyte solutions in aqueous and non-aqueous solutions have diverse practical applications in many fields ranging from biology to electrochemical power sources. The nature of ion-solvent and ion-ion interactions are strongly influenced by the nature of solvent as well the presence of ligands which often selectively co-ordinate metal ions. Macrocyclic poly ethers such as crown ethers and macrocyclic ligand such as cryptand 222 are particularly important in this context. They are known to interact selectively with alkali and alkaline earth metal cations depending on their size to form inclusion complexes of high stability in which the substrate is contained inside their molecular cavity. Several aspects of the inclusion complexes such as their ion solvation characteristics, voltammetric behaviour and their application to the development of ion sensors will be discussed.