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 element ...

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. Is ...

s of bipyridine exist, but two are prominent:

2,2′-bipyridine 2,2′-Bipyridine (bipy or bpy, pronounced ) is an organic compound with the formula C10H8N2. This colorless solid is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition meta ...

is a popular ligand.

4,4'-Bipyridine 4,4′-Bipyridine (abbreviated to 4,4′-bipy or 4,4′-bpy) is an organic compound with the formula . It is one of several isomers of bipyridine. It is a colorless solid that is soluble in organic solvents. is mainly used as a precursor to '' ...

is a precursor to the commercial herbicide

paraquat Paraquat ( trivial name; ), or ''N'',''N''′-dimethyl-4,4′-bipyridinium dichloride ( systematic name), also known as methyl viologen, is an organic compound with the chemical formula C6H7N)2l2. It is classified as a viologen, a family of re ...

. 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 solubi ...

in organic solvents and slightly soluble in water.

2,2′-Bipyridine

2,2′-Bipyridine (2,2′-bipy) is a

chelating Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

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 elect ...

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 can ...

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 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 recyc ...

. 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 Un ...

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

. This species is

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

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 Milrinone, sold under the brand name Primacor, is a pulmonary vasodilator used in patients who have heart failure. It is a phosphodiesterase 3 inhibitor that works to increase the heart's contractility and decrease pulmonary vascular resistan ...

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 ot ...

and thus increasing

cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...

, 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 Milrinone, sold under the brand name Primacor, is a pulmonary vasodilator used in patients who have heart failure. It is a phosphodiesterase 3 inhibitor that works to increase the heart's contractility and decrease pulmonary vascular resistan ...

decreases survival in heart failure.

References

{{Reflist Chelating agents Ligands