Two Highly Water-Stable Imidazole-Based Ln-MOFs for Sensing Fe3+,Cr2O72–/CrO42– in a Water Environment

Developing highly stable materials for harmful ion detection in a water environment is of much importance and challenging. Here, two three-dimensional porous structures (termed as Eu-MOF and Tb-MOF) were successfully constructed by the strategy of anchoring Eu³⁺/Tb³⁺ and rigid 1,2,4,5-benzenetetracarboxylic acid (H₄BTEC) imidazole units (H₃ICA) onto its frameworks. The obtained Eu-MOF and Tb-MOF display high water stability and fluorescence stability up to 30 days. Furthermore, luminescent studies reveal that Eu-MOF and Tb-MOF show rapid, recursive, and simultaneous sensing Fe³⁺ and Cr₂O₇^2-/CrO₄^2- ions in water. In addition, the sensing function possesses remarkable cyclicity and selectivity even with the existence of other analogous ions.