4,4' Bipyridine

4,4'-Bipyridine (4,4'-bipy) is a bipyridine which is mainly used as a precursor to N,N'-dimethyl-4,4'-bipyridinium [(C₅H₄NCH₃)₂]²⁺, known as paraquat. This species is electroactive, and its toxicity arises from the ability of this dication to interrupt biological electron transfer. Because of its structure, 4,4'-bipyridine can bridge between metal centres to give coordination polymers. 4,4'-bpy can also mediate electronic effects between two paramagnetic metal centers.