Water-stable 2-D Zr MOFs with exceptional UO22+ sorption capability

Abstract

Two new 8-connected 2-D MOFs, UCY-13 and UCY-14, based on Zr₆ secondary building units (SBUs) and angular dicarboxylate ligands are reported. UCY-13 and UCY-14 display remarkable stability in various types of aqueous media, an appreciable internal surface area of 925 m² g⁻¹ and 678 m² g⁻¹, respectively, and are the first examples of 2-D MOFs investigated for their uranyl sorption capability. They exhibit exceptional UO₂²⁺ sorption capacities of 984 mg g⁻¹ for UCY-13 and 471 mg g⁻¹ for UCY-14 and the ability to sorb UO₂²⁺ from various types of real-world aqueous media. Both sorbents were proven to immobilize UO₂²⁺ ions, thus being unique examples of MOFs that can be potentially employed as barrier materials for environmental application. Their exceptional sorption properties are attributed to the 2-D nature and structural features directly derived from it such as the presence of several easily accessible coordination sites in the Zr₆ SBUs.