Few organic ligands have received more attention than 2, 2'-bipyridine (bpy) and its analogues (eg 1, lO-phenanthroline).'A large proportion of the recent interest in this ligand stems from the very interesting photophysical and photochemical properties exhibited by several of its transition metal complexes, in particular those of ruthenium, 2 smium,~ and rheni~ m.~ As more elaborate systems exploiting such properties have started to emerge, ...