Size Selective Ligand Tug of War Strategy to Separate Rare Earth Elements

[Image: see text] Separating rare earth elements is a daunting task due to their similar properties. We report a “tug of war” strategy that employs a lipophilic and hydrophilic ligand with contrasting selectivity, resulting in a magnified separation of target rare earth elements. Specifically, a novel water-soluble bis-lactam-1,10-phenanthroline with an affinity for light lanthanides is coupled with oil-soluble diglycolamide that selectively binds heavy lanthanides. This two-ligand strategy yields a quantitative separation of the lightest (e.g., La–Nd) and heaviest (e.g., Ho–Lu) lanthanides, enabling efficient separation of neighboring lanthanides in-between (e.g., Sm–Dy).