A supramolecular lanthanide separation approach based on multivalent cooperative enhancement of metal ion selectivity

What is it about?

Multivalent cooperativity plays an important role in the supramolecular self-assembly process. Herein, we report a remarkable cooperative enhancement of both structural integrity and metal ion selectivity of metal-organic M4L4 tetrahedral cages self-assembled from a tris-tridentate ligand (L1) with an unprecedented variety of metal ions spanning across the periodical table, including alkaline earth (CaII), transition (CdII) and all the lanthanide (LnIII) metal ions (M). All these M4L14 cages are stable to excess metal ions and ligands which is in sharp contrast with tridentate (L2) ligand and bis-tridentate (L3) ligand, bearing the same coordination motif as L1. Moreover, high-precision metal ion self-sorting was observed during the mixed-metal self-assembly of tetrahedral M4L4 cages, but not on the M2L3 counterparts. Based on the strong cooperative metal ion self-recognition behavior of M4L4 cages, a supramolecular approach to lanthanide separation is demonstrated, offering a new design principle of next-generation extractants for highly efficient lanthanide separation.

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