Probing promethium

Promethium—named for the mythological Titan who stole fire from the ancient Greek gods and gave it to humans—is a mysterious element. Proposed in 1902 and first identified in 1945, promethium has practical applications in radiotherapy and nuclear batteries. But because all its isotopes are radioactive, it is challenging to study. For the first time, scientists have made a promethium complex in solution ( Nature 2024, DOI: 10.1038/s41586-024-07267-6 ). "We know little about the chemistry of promethium," says Alexander S. Ivanov of Oak Ridge National Laboratory (ORNL), who led the work with ORNL's Ilja Popovs . In particular, the scientists were interested in promethium's behavior as part of the lanthanide contraction—a phenomenon in which the lanthanides' atomic and ionic radii decrease more than one would expect. "We wanted to test if this lanthanide contraction happens in solution," Ivanov says. The researchers used bispyrrolidine diglycolamide ligands to make a water-soluble coordination complex