Chelation

In a nutshell, Chelation is a reaction of multiple ligands or, say, chelating agents. Chelation reactions commonly create the chelate effect, which is the attraction of chelating agents towards metal ions. The chelate effect is caused by the chelating agents, often known as ligands. Moreover, Chelation is used in the chemical industry and medicine and biological field. For detailed information, here’s a Chelation study material curated by the field experts comprising chelate effect, agents, characteristics and uses of Chelation along with all general and essential concepts of the topic.

About Chelation

Chelation can be defined as the reaction of two or more coordinate bonds between organic complexing agents. It is also known as ligands which are polydentate or have multiple bonds and a central metal ion. The ligands in these reactions are chelants or chelating agents, and the complex thus formed is known as the coordination complex. These complexes can be ionic or non-ionic depending upon the nature of the central metallic ion and the ligands. The complexes that are non-reactive can be isolated as stable compounds- solid or liquid. A metal ion kept in solution usually forms this type of complex by combination with the ligands.

History

The term chelate in chemistry was first used by Sir Gilbert Morgan, and HDK Drew in the year 1920 and is derived from a Greek word meaning the claws of a lobster. The term chelate thus refers to the dentate structure of the ligands that appears to be like the claws of lobster, also appearing like pliers. The structure is an advantage for binding with the central atom to form ring-like complexes.

Chelate Effect

The Chelate Effect can be explained as the affinity of the chelating agents or ligands to bind with a particular metal ion compared to the analogous non-chelating or monodentate ligands. The most simple explanation for this can be that holding anything with both hands is more powerful than with only one hand. There’ll be less possibility of dropping it. The strength increases as the ligands increase the donors through which they bind with the ion. The coordination complex, thus, formed by the binding of metal ions with chelating ligands is thermodynamically more stable than with the non-chelating counterparts. For example, the binding of a metal ion with the bidentate ligand, Ethylenediamine (C₂H₄(NH₂)₂). This binding is more powerful than the monodentate ligands like ammonia.

Characteristics of a Chelate

Chelate is considered a water-soluble complex formed between a metal ion and chelating ligands, also known as complexing agents. The complex thus formed is very strongly bound and inert and does not break down easily. The chelates of the complex are formed to increase their strength with the increasing number of donor points of ligands. They form a ring-like complex because of the position of the functional groups of the chelating agents that donate an electron to the metal ion.

Chelating Agents or Ligands

The ligands, also called chelating agents in Chelation, are usually organic atoms but not compulsorily. Ligands are often termed monodentate, bidentate, tridentate, and polydentate. It highly depends on the number of electron pairs they donate. However, the monodentate are not considered chelants. The ligands or chelates can be organic molecules like some proteins, polysaccharides, and nucleic acids. In the living system, there are numerous chelating agents found commonly, and water also can act as a chelating agent. There are natural chelating agents like steroids, amino acids, lipids, peptides, nucleotides, phosphates, phenolics, etc., as well as synthetic chelators like salicylic acid, tri ethanol-amine, 2,2′-Bipyridyl, etc.

Uses of Chelation

Chelation is an important phenomenon that happens naturally as well as used medically for the treatment of many diseases. It happens in the human body as a part of normal metabolism. The chemical weathering of rocks and minerals is due to the Chelation that the metal ions are extracted from them. In medical applications, Chelation is used with many nutritional supplements and dentists. Chelation therapy is essential for the treatment of metal toxicity as some chelating agents induced in the body bind with these heavy metals and forms an inert complex thus, nullifying the harmful effect of the metals. Chelating agents are also used in pharmaceutical industries to prepare many drugs.

Conclusion

From all the above, we learned the Chelation Phenomenon, which is the basis of all the research related to the physiology and toxicity of heavy metals. Chelation can be and is being used in the evaluation of the harmful effects of such heavy metals in the body and the treatment of many chronic diseases because of them. Moreover, the human body itself eliminates the effect of many metals during the normal metabolism with the help of the ligands like most biochemical ones. We can conclude that the phenomenon of Chelation is important in chemistry as many of the properties and physiologies included with the metal and their ions are studied through it.