Employing metal-organic cage for selective capture of UO22+ and Sr2

Selective capture of UO 2 2+ and Sr 2+ ions represents a key component in the nuclear fuel reprocessing, nuclear accident prevention, and environmental protection. We report herein a proof of concept, employing metal-organic cage (MOC) for the selective capture of UO 2 2+ or Sr 2+ ions, through using a C 3 -symmetrical multiple-carboxylate ligand (H 3 L) to fix uranyl ions together. By means of such MOC approach, we can facilitate the extraction of uranyl ions from a multiple metallic mixed solution by using the H 3 L ligands as an extractant, showing an ultrahigh extraction efficiency of 97% and UO 2 2+ selectivity of 19.4–97, suggesting its superior application in the UO 2 2+ capture. The mechanism for such outstanding performance is due to the formation of a polyoxouranyl-based MOC. Moreover, this MOC compound can be also used as a solid adsorbent to selectively capture Sr 2+ ions through a unique mechanism with the formation of a SrO 4 N 2 octahedral coordination.