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The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same metal. The thermodynamic principles underpinning the chelate effect are illustrated by the contrasting affinities of copper(II) for ethylenediamine (en) vs. methylamine.
Proteins can coordinate metal ions on their surface and it is possible to separate proteins using chromatography by making use of the difference in their affinity to metal ions. This is termed as immobilized metal ion affinity chromatography (IMAC), as originally introduced in 1975 under the name metal chelate affinity chromatography. [3]
Poly metal chelating resin has almost negligible affinity to both alkali and alkaline earth metals; small quantities of resin can be utilized to concentrate trace metals in natural water systems or biological fluids, in which there are three or four orders of magnitude greater alkali and alkaline earth metal concentration than the trace metal ...
Microbes usually release the iron from the siderophore by reduction to Fe 2+ which has little affinity to these ligands. [8] [2] Siderophores are usually classified by the ligands used to chelate the ferric iron. The major groups of siderophores include the catecholates (phenolates), hydroxamates and carboxylates (e.g. derivatives of citric ...
This enhanced stability, called the chelate effect, is usually attributed to effects of entropy, which favors the displacement of many ligands by one polydentate ligand. Related to the chelate effect is the macrocyclic effect. A macrocyclic ligand is any large ligand that at least partially surrounds the central atom and bonds to it, leaving ...
Due to the chelate effect and macrocyclic effect, crown ethers exhibit stronger affinities for diverse cations than their divided or acyclic analogs. Hereby, the cation selectivity for alkali metal ions is mainly dependent on the size and charge density of the ion and the cavity size of the crown ether.
DOTA is derived from the macrocycle known as cyclen.The four secondary amine groups are modified by replacement of the N-H centers with N-CH 2 CO 2 H groups. The resulting aminopolycarboxylic acid, upon ionization of the carboxylic acid groups, is a high affinity chelating agent for di- and trivalent cations.
Weak affinity chromatography [29] (WAC) is an affinity chromatography technique for affinity screening in drug development. [ 30 ] [ 31 ] WAC is an affinity-based liquid chromatographic technique that separates chemical compounds based on their different weak affinities to an immobilized target.