In 1945, scientists first synthesized the element promethium, even though the Czech chemist Bohuslav Brauner had predicted its existence 43 years earlier. Brauner was renowned for his study of rare-earth elements.
Promethium is produced in the earth’s environment in two ways: when europium-151 breaks down by a rare alpha decay to promethium-147, or when uranium undergoes spontaneous fission. One unusual characteristic of promethium is that the radii of the atoms of elements 57 to 70 shrink rather than increase as the atomic number increases. This phenomenon is known as lanthanide contraction. Promethium, with atomic number 61, is a notable exception to this trend.
Bohuslav Brauner corresponded regularly with Dmitri Mendeleev, a Russian chemist famous for discovering that groups of chemical elements had the same number of regions around their atomic nuclei in which electrons could be present, and that they could be grouped in this way to reveal other similar properties. Mendeleev’s work greatly influenced Brauner’s own research on rare-earth elements.
On May 22, researchers from the Oak Ridge National Laboratory in the U.S. reported that they had managed to produce the first known lanthanide complex involving promethium by combining promethium ions with a ligand called bispyrrolidine diglycolamide. This discovery opens up new avenues for research into the properties and potential applications of lanthanides
