Development of supramolecular structure through alkylation of pendant pyridyl functionality

The complex 1(2+) which has two pendant 4-pyridyl substituents may be viewe d as a metal-containing analogue of 4,4'-bipyridine. The complex undergoes N-alkylation reactions with a variety of alkylating agents to give more hig hly functionalised tetracationic complexes which may be termed metalloviolo gens by analogy with viologens. These complexes may also be prepared by alk ylation of the free ligands and subsequent coordination of the pendant quat ernised ligand. Structural studies have established that the N-alkylated co mplexes possess the correct spatial characteristics for the preparation of metallocycles analogous to known cyclic bis(4,4'-bipyridinium) species whic h possess useful molecular recognition properties.