What Is the Meaning of Chelate?

A chelate is formed when an organic structure attaches itself to an already bonded metal atom in at least two points, solubilizing it. Chelation can be used to treat heavy-metal poisoning.

History

The term chelate was coined by two chemists, who derived it from "the great claw or chele (Greek) of the lobster... which... fasten to the central atom so as to produce heterocyclic rings."

Everyday Living

Life depends upon chelates. One chelate, heme, is the central component of hemoglobin, which transports oxygen in the blood. Another is chlorophyll, which harnesses solar energy for photosynthesis.

Description

The non-metal chelating agent is classified as a bi- or multi-dentate (or toothlike) ligand structure. By way of an example, ethylene diamine possesses the structure,

H2N-CH2-CH2-NH2

The -NH2 groups are like two teeth (bi-dentate) that close in on a metal atom. The ligand "bites" the metal atom in two places.

Medical Use

Chelation is used to treat heavy-metal poisoning. The chelated metal is excreted in urine. Some use chelation to treat atherosclerosis. The American Heart Association frowns on this "miracle cure."

Conclusion

Patients need to understand what is meant if they are offered chelation therapy.

References

• Gilbert T. Morgan, Harry D. K. Drew; CLXII.---Researches on residual affinity and co-ordination. Part II. Acetylacetones of selenium and tellurium; J. Chem. Soc., Trans. 117: 1456; 1920
• American Heart Association