Bipyridines also known as bipyridyls, dipyridyls, and dipyridines, are a family of

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...

s with the formula (C₅H₄N)₂, consisting of two pyridyl (C₅H₄N) rings. Pyridine is an aromatic nitrogen-containing heterocycle. Bipyridines are of significance in pesticides. Bipyridine Isomers

Six

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. ...

s of bipyridine exist, but two are prominent: 2,2′-bipyridine is a popular ligand. 4,4'-Bipyridine is a precursor to the commercial herbicide paraquat. The bipyridines are all colourless solids, which are

soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

in organic solvents and slightly soluble in water.

2,2′-Bipyridine

2,2′-Bipyridine (2,2′-bipy) is a chelating

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...

that forms complexes with most

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that c ...

ions that are of broad academic interest. Many of these complexes have distinctive optical properties, and some are of interest for analysis. Its complexes are used in studies of electron and energy transfer,

supramolecular Supramolecular chemistry refers to the branch of chemistry concerning chemical systems composed of a discrete number of molecules. The strength of the forces responsible for spatial organization of the system range from weak intermolecular force ...

and materials chemistry, and

catalysis Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycl ...

. 2,2′-Bipyridine is used in the manufacture of

diquat Diquat is the ISO common name for an organic dication that, as a salt with counterions such as bromide or chloride is used as a contact herbicide that produces desiccation and defoliation. Diquat is no longer approved for use in the European Union ...

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 Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...

active, and its toxicity arises from its ability to interrupt biological

electron transfer Electron transfer (ET) occurs when an electron relocates from an atom or molecule to another such chemical entity. ET is a mechanistic description of certain kinds of redox reactions involving transfer of electrons. Electrochemical processes ar ...

processes. Because of its structure, 4,4′-bipyridine can bridge between metal centres to give coordination polymers.

3,4′-Bipyridine

The 3,4′-bipyridine derivatives inamrinone and milrinone are used occasionally for short term treatment of congestive heart failure. They inhibit

phosphodiesterase A phosphodiesterase (PDE) is an enzyme that breaks a phosphodiester bond. Usually, ''phosphodiesterase'' refers to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below. However, there are many o ...

and thus increasing cAMP, exerting positive inotropy and causing vasodilation. Inamrinone causes

thrombocytopenia Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients a ...

. Milrinone decreases survival in heart failure.

References

{{Reflist Chelating agents Ligands