Speaker
Description
Lanthanide isotopes such as Pm-147, Gd-153, Tb-161, and Lu-177 are indispensable for nuclear medicine and materials research. Their domestic supply, however, is constrained by one of the toughest challenges: separating neighboring lanthanides whose chemical properties are nearly identical. Conventional cation‑exchange processes with α‑hydroxyisobutyric acid offer only modest separation factors and produce large volumes of acidic waste, while extraction‑chromatography resins containing di‑2‑ethylhexyl phosphoric acid (HDEHP) improve selectivity but are costly and have limited capacity. These limitations underscore the need for better separation strategies.
One promising approach is rational ligand design that takes advantage of the subtle size differences produced by the lanthanide contraction. We have developed a tetradentate “chemical chameleon” ligand that can switch its preference from heavy to light lanthanides based on medium acidity and contact time. This adaptability means the same ligand can perform multiple separations, reducing the number of stages and the amount of solvent required without compromising purity. Another approach pairs hydrophilic ligands with lipophilic extractants in a two‑phase “tug‑of‑war,” pulling light and heavy lanthanides into opposite phases. These strategies include diglycolamide complexes that harness the lanthanide contraction, rigid ligand architectures that enforce size selectivity, and stimuli‑responsive ligands that adapt to changing conditions. Collectively, these approaches demonstrate that high‑purity radiolanthanides can be produced more efficiently, with fewer stages and lower solvent volumes.