title: Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures.
abstract: 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, TriNOx3-, featured a size-sensitive aperture formed of its three η2-(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)]2species. Differences in the equilibrium constants Kdimerfor 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.
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bogart
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Bren E
authors.initials: BE
authors.lastname: Cole
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Boreen
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Connor A
authors.initials: CA
authors.lastname: Lippincott
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Manor
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Carroll
authors.affiliation: P. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 schelter@sas.upenn.edu.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Schelter
keywords: coordination chemistry; critical materials; lanthanides; rare earth elements; separations