Bipyridine
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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.
[edit] 2,2'-Bipyridine
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.
[edit] 4,4'-Bipyridine
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.
