Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

作者：Bogart Justin A; Cole Bren E; Boreen Michael A; Lippincott Connor A; Manor Brian C; Carroll Patrick J; Schelter Eric J^*

来源：Proceedings of the National Academy of Sciences of the United States of America, 2016, 113(52): 14887-14892.

DOI：10.1073/pnas.1612628113

• rare earth elements
• lanthanides
• separations
• critical materials
• coordination chemistry

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNO(x)(3-), featured a size-sensitive aperture formed of its three eta(2)-(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)](2) species. Differences in the equilibrium constants K-dimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation.

• 出版日期2016-12-27