ligand


ligand
/luy"geuhnd, lig"euhnd/, n.
1. Biochem. a molecule, as an antibody, hormone, or drug, that binds to a receptor.
2. Chem. a molecule, ion, or atom that is bonded to the central metal atom of a coordination compound. Cf. complexing agent.
[1945-50; < L ligandus, ger. of ligare to bind, tie]

* * *

Atom, group (see functional group), or molecule attached to a central atom, usually of a transition element, in a coordination or complex compound (see bonding).

It is almost always the electron-pair donor (nucleophile) in a covalent bond. Common ligands include the neutral molecules water (H2O), ammonia (NH3), and carbon monoxide (CO) and the anions cyanide (CN-), chloride (Cl-), and hydroxide (OH-). Rarely, ligands are cations and electron-pair acceptors (electrophiles). Organic ligands include EDTA (see chelate) and nitrilotriacetic acid. Biological systems rely on ligands such as the porphyrin in hemoglobin and chlorophyll, and numerous cofactors are ligands. In chelates, the ligand attaches at more than one point, sharing more than one electron pair, and is called bidentate or polydentate
having two or many "teeth." The ligands in a complex may be the same or different.

* * *

      in chemistry, any atom or molecule attached to a central atom, usually a metallic element, in a coordination or complex compound. The atoms and molecules used as ligands are almost always those that are capable of functioning as the electron-pair donor in the electron-pair bond (a coordinate covalent bond) formed with the metal atom. Examples of common ligands are the neutral molecules water (H2O), ammonia (NH3), and carbon monoxide (CO) and the anions cyanide (CN-), chloride (Cl-), and hydroxide (OH-). Occasionally, ligands can be cations (e.g., NO+, N2H5+) and electron-pair acceptors. The ligands in a given complex may be identical, as the CO ligands in Fe(CO)5 and the H2O ligands in [Ni(H2O)6]2+, or different, as the CO and NO ligands in Co(CO)3(NO). Attachment of the ligand to the metal may be through a single atom, in which case it is called a monodentate ligand, or through two or more atoms, in which case it is called a didentate or polydentate ligand.

* * *


Universalium. 2010.

Look at other dictionaries:

  • ligand — [ ligɑ̃ ] n. m. • 1959; mot angl., du lat. ligandum, gérond. de ligare « lier » ♦ Chim. Molécule, ion uni à l atome central d un complexe par une liaison de coordinence. ♢ Biochim. Petite molécule se fixant à une protéine par des liaisons… …   Encyclopédie Universelle

  • ligand — ligand. См. лиганд. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • ligand — (n.) 1952, from L. ligandus, gerundive of ligare to bind (see LIGAMENT (Cf. ligament)) …   Etymology dictionary

  • ligand —  Ligand  Лиганд   Атом, ион или молекула, непосредственно связанный(ая) с одним или несколькими центральными (комплексообразующими) атомами металла в комплексном соединении. Чаще всего такое связывание происходит с образованием так называемой… …   Толковый англо-русский словарь по нанотехнологии. - М.

  • ligand — [lig′ənd, lī′gənd] n. [< L ligandum, ger. of ligare, to bind: see LIGATURE] an atom, group, ion, radical, or molecule which forms a coordination complex with a central atom or ion …   English World dictionary

  • Ligand — This article is about ligands in inorganic chemistry. For ligands in biochemistry, see Ligand (biochemistry). For other uses, see Ligand (disambiguation). Cobalt complex [HCo(CO)4] with five ligands In coordination chemistry, a ligand is an ion… …   Wikipedia

  • Ligand — Die Bezeichnung Ligand (lat. ligare = binden) stammt aus der Komplexchemie (Organometallchemie, Metallorganik und Bioanorganik) und bezeichnet ein Atom oder Molekül, welches über eine dative Bindung (koordinative Bindung) an ein zentrales Metall… …   Deutsch Wikipedia

  • Ligand — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Ligand est un terme scientifique utilisé pour caractériser certains types d interactions. En chimie : Ligand (chimie) En biologie : Ligand… …   Wikipédia en Français

  • ligand — Any molecule that binds to another; in normal usage a soluble molecule such as a hormone or neurotransmitter, that binds to a receptor. The decision as to which is the ligand and which the receptor is often a little arbitrary when the broader… …   Dictionary of molecular biology

  • ligand — ligandas statusas Aprobuotas sritis augalininkystė apibrėžtis Molekulė ar jonas, kompleksiniame junginyje susijungęs koordinaciniu ryšiu su centriniu atomu (kompleksodariu). atitikmenys: angl. ligand vok. Ligande, f rus. лиганд pranc. ligand, m… …   Lithuanian dictionary (lietuvių žodynas)


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.