Cryptand ligands for selective lithium coordination

The binding properties, in aqueous solution, toward lithium ion of aza- and azaoxo-macrocycles with cage and cylindrical molecular topology are review ed. The synthetic procedures and the acid-basic behavior are reported. Most of these compounds are able to selectively encapsulate the small lithium i on in aqueous solution. NMR spectroscopy, mainly C-13 and Li-7, has been us ed to study the encapsulation equilibria. Few crystal structures of lithium complexes, indicating the lithium ion encapsulation have been reported, (C ) 1999 Elsevier Science S.A. All rights reserved.