A Simple yet Efficient Hydrophilic Phenanthroline-Based Ligand for Selective Am(III) Separation under High Acidity

Highly selective hydrophilic ligands were believed tobe an efficientway to overcome the massive amount of hazardous organic solvent usedin the liquid-liquid extraction process and stood as a newfrontier in the Lns(III)/Ans(III) partition. Current reported hydrophilicligands suffer from harsh preparation conditions, inferior extractionperformances, limited available chemical structures, and inabilityto carry out extraction under high acidity. In this article, we reporta simple yet efficient carboxylic group modified phenanthroline-diimideligand which displayed unexpected Lns(III)/Ans(III) and Ans(III)/Ans(III)separation capabilities in 1.5 M HNO3. Unique dimeric architecturesfor Eu(III) complexes were observed, which could be the origin ofthe outperforming selectivity and acid resistance. We believe thiscrystal engineering approach could inspire a renaissance in searchingfor new functional groups and coordination modes for efficient, high-acid-toleranceLns(III)/Ans(III) separation ligands. Elaboratedligand design by crystal engineering leads tohighly efficient and acid-tolerant hydrophilic Lns(III)/Ans(III) partitioningligands.