Supramolecular ligands for the extraction of lanthanide and actinide ions

Interest in the isolation and recovery of lanthanide and actinide metals has gained recent attention due to their increasing use in everyday materials (e.g. batteries, screens, sensors) as well as their application in alternative energy production (e.g. nuclear power). However, the purification of these metals, both from recycled materials and raw sources, is daunting due to the similar chemical properties of these elements. This review focuses on the use of supramolecular, preorganized organic ligands as extraction agents in liquid-liquid extraction systems to achieve the separation and recovery of f-elements. For the purposes of this review, "supramolecular ligands" are those that append two or more chelating groups to a scaffold. The synthesis of each ligand is presented, along with selections of the extraction results from each compound. When appropriate, the extraction results of the supramolecular, preorganized ligands are compared with their monomeric, commercial counterparts.