Tunable rare-earth metal-organic frameworks for ultra-high selenite capture

Linkers and clusters with various conformations present challenges for the design and prediction of highly porous and stable rare-earth metal-organic frameworks (RE-MOFs) for trapping toxic ions in aqueous solutions. Herein, we designed and synthesized a series of RE-MOFs based on a malleable ligand to explore the effects of ligands, clusters, and configurations on structural stability. The results showed that the nonanuclear high-connected UPC-183 exhibited better stability than the hexanuclear low-connected RE-MOF (UPC-181/182 series). Due to the syngenetic effect of chemi- and physisorption, the adsorption capacity of UPC-183-Eu for selenite (SeO₃^2-) is as high as 308.39 mg/g, recorded one of the highest ever reported for MOFs. Furthermore, we accurately analyzed the adsorption site of UPC-183-Eu for SeO₃^2- through single-crystal structure and theoretical simulation. The ultra-high selenite adsorption capacity and removal efficiency endow UPC-183-Eu an excellent porous adsorbent for removing pollutants.