Fluorescence/Electrochemical Dual-Mode Sensor Based on a Nickel Metal-Organic Framework

This study successfully developed a new dual-mode sensor material based on the nickel metal-organic framework (Ni-MOF) [Ni(tatrz)_1.5(5-MIA)·H₂O] (CUST-986) (tatrz = 1-(9-(1<i>H</i>-1,2,4-triazol-1-yl)anthracen-10-yl)-1<i>H</i>-1,2,4-triazole, 5-MIA = 5-methylisophthalic acid, CUST = Changchun University of Science and Technology) for a highly efficient detection of 2,4,6-trinitrophenol (TNP). In fluorescence sensing mode, CUST-986 demonstrates exceptional selective recognition capability for TNP, with a high quenching constant (<i>K</i>_sv) of 1.676 × 10⁵ M^-1 and an ultralow detection limit (LOD) of 69.3 nM. In electrochemical detection mode, the modified electrode achieves a TNP detection limit of 0.48 μM. Real environmental sample tests show spike recovery rates of 80.3-93.6%, indicating good potential for practical applications with long-term stability. Through characterization techniques including powder X-ray diffraction, UV-vis, DFT calculations, and fluorescence lifetime measurements, the mechanism of electron transfer and the inner filter effect was elucidated. This bifunctional MOF sensor provides a new detection solution for environmental monitoring and public safety applications.