Bipyridine

Bipyridines are a family of chemical compounds with the formula (C₅H₄N)₂, which are formed by the coupling of two pyridine rings. Six isomers of bipyridine exist, but 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.

The 3,4'-Bipyridine derivatives inamrinone and milrinone are used occasionally for short term treatment of congestive heart failure. They inhibit phosphodiesterase by increasing cAMP, exerting positive inotropy and causing vasodilation. Inamrinone causes thrombocytopenia. Milrinone decreases survival in heart failure.

2,2'-bipyridine

Structure of 2,2'-bipyridine

Main article: 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. 2,2'-Bipyridine is used in the manufacture of Diquat.

4,4'-bipyridine

Main article: 4,4'-bipyridine

Structure of 4,4'-bipyridine

4,4'-Bipyridine (4,4'-bipy) is mainly used as a precursor to the N,N'-dimethyl-4,4'-bipyridinium dication commonly known as paraquat. This species is redox active, and its toxicity arises from its ability to interrupt biological electron transfer processes. Because of its structure, 4,4'-bipyridine can bridge between metal centres to give coordination polymers.