A water-stable metal-organic framework Zn-MOF as a chemical sensor for efficient detection of Cr(VI) (Cr2O72-and CrO42-) anions in water

The luminescent three-dimensional Zn(II) metal-organic framework (Zn-MOF) was successfully synthesized via a hydrothermal method. The structure of the compound is denoted as [Zn3(mu 3-OH)(L)& sdot;(H2O)]n, where H5L rep-resents 3,5-bis(3,5-dicarboxyphenoxy)benzoic acid. Remarkably, this framework exhibits excellent stability in water and pH (3-13) conditions. Intriguingly, the compound shows high selectivity, sensitivity, and low detection limits (4.10 mu M for Cr2O72-and 6.63 mu M for CrO42-) in aqueous solution. Furthermore, the material proves to be easily regenerable. Additionally, the competition between analyte absorption and the excitation/ emission of Zn-MOF elucidates the fluorescence sensing mechanism of Cr2O72-/CrO42-ions. These findings un-equivocally establish Zn-MOF as a highly selective and recyclable fluorescence sensing material for the quantitative detection of Cr(VI) ions in aqueous solutions.