Bipyridines form a family of chemical compounds with the formula (C5H4N)2. They are derived by the coupling of two pyridine rings. Six isomers of bipyridine exist. Two isomers are prominent: 2,2'-bipyridine is a popular ligand in coordination chemistry and 4,4'-bipyridine is a precursor to the herbicide paraquat. The bipyridines are colourless solids, which are soluble in organic solvents and slightly soluble in water.
Inamrinone and Milrinone are used occasionally for short term. They inhibit phosphodiesterase by increasing cAMP, exerting positive inotropy and causing vasodilation. Amrinone causes thrombocytopenia; Milrinone decreases survival in heart failure.
2,2'-Bipyridine is a chelating ligand that forms complexes with most transition metal ions. Many of these complexes have distinctive optical properties and some are of interest for analysis. Also see bipyridyl.
2,2'-Bipyridine is used in the manufacture of Diquat. Diquat's toxicity is due to a similar mechanism to paraquat.
4,4'-Bipyridine (4,4'-bipy) 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.