Synthesis and Application of Macrocyclic and Macroacyclic Schiff Bases.

The challenge presented by the design and synthesis of ligands capable of organising more than two metal centres into a predetermined arrangement in order to develop new materials is discussed. The design and synthesis of macropolycyclic and/or macropolyacyclic Schiff bases, which have the potential to act as metal-specific ligands, or can allow the simultaneous incorporation of two or more metals in well defined homo- or heterodinuclear arrays, is presented together with the role of metal ions as templating devices and the opportunities to utilise transmetallation reactions. Formation of Schiff bases followed by reductive demetallation leads to a variety of more stable, and flexible, ligands useful in metal transfer studies. C- and N-functionalisation of macrocyclic Schiff bases produces pendant-armed ligands which permit a more dynamic complexation of the metal ion than is found in bicyclic ligands.