Bipyridine:: The most widely used ligand.: A review of molecules comprising at least two 2,2′-bipyridine units

The different varieties of molecules comprising at least two bipyridine units in the form of an exhaustive database is reviewed considering the structural and synthetic features. The bipyridine ligand has been widely used as metal chelating ligand due to its robust redox stability and ease of functionalization. Since bipyridine is a neutral ligand, it forms charged complexes with metal cations for which it is used in the design and synthesis of metal-bipyridine complexes.