Chemistry of new bismuth compounds

Article By:

Whitmire, Kenton H. Department of Chemistry, Rice University, Houston, Texas.

Last reviewed:2016

DOI:https://doi.org/10.1036/1097-8542.YB160008

Bismuth holds special interest for chemists because of its position as the heaviest stable element. It is monoisotopic in nature and exists as ²⁰⁹Bi. Technically, the atom is radioactive, but its half-life is a billion times longer than the age of the universe. Its chemistry is dominated by the +3 oxidation state, although +5, +2, and −3 are known. Because of its large size, it forms complexes showing very high coordination numbers, and the Bi³⁺ ion possesses considerable Lewis acidity. In contrast to its neighbors in the periodic table, which are known for their toxicity, bismuth compounds are relatively nontoxic to humans and have long been used to treat microbial infections, such as Helicobacter pylori, syphilis, and diarrhea. Its compounds have more recently been shown to have antitumor activity. Its compounds have been shown to act as a topical treatment for skin diseases such as Leishmaniasis. They offer considerable potential in treating a variety of illnesses that have developed drug resistance to normal organic compound–based pharmaceuticals. The inability of microbes to develop drug resistance to bismuth compounds may arise from ability of the metal ion to replace nickel, iron, and zinc ions in metalloproteins, because shutting down the metal absorption process of those ions as a means of developing drug resistance would also kill the organism. Additionally, ²¹³Bi, with a half-life of 45 min decaying by alpha-particle emission, can be produced from radium in a particle accelerator, and its compounds have been used to treat leukemia. See also: Acid and base; Bismuth; Coordination chemistry; Half-life; Helicobacter; Leukemia; Particle accelerator; Periodic table; Syphilis

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