Zn-Based Three-Dimensional Metal-Organic Framework for Selective Fluorescence Detection in Zwitterionic Ions

Zinc-based MOFs exhibit significant advantages in ion detection due to their unique structure and chemical properties. They can efficiently and selectively recognize and detect specific ions, making them powerful analytical tools for applications in environmental monitoring, biomedical fields, and more. In this work, we used a simple ligand to improve the coordination environment of Zn²⁺ ions and successfully synthesized a 3D coordination compound Zn(all-bdc)(Py) MOF through a straightforward hydrothermal method at low temperature. Additionally, we explored the potential of this MOF as a bifunctional ion fluorescence probe for both cationic and anionic recognition. The results showed that this 3D porous MOF exhibited excellent recognition ability for trivalent iron ions (Fe³⁺) and potassium permanganate (KMnO₄^-) ions due to its highly porous structures and efficient ion recognition. When iron ions were added to 500 μL and potassium permanganate ions were added to 100 μL, the fluorescence of the compound was effectively quenched, and the detection limits for these two ions were 0.95 μM and 0.13 μM, respectively. The mixed-ion experiments also demonstrated that even in the presence of similar ions, this 3D MOF still maintained good selective recognition ability, specifically identifying Fe³⁺ and KMnO₄^- ions. This work provides a novel synthetic strategy for the design of MOFs capable of mixed-ion recognition and detection, expanding their application potential in ion sensing and analysis.