Dual-ligand Zn-based MOF as a fluorescent probe for the detection of HSO4−

The development of fluorescent probes for the recognition of HSO4− is important for social security and human health. In this work, Zn-MOF ([(Zn2+)(L+)2(H2O)2]∙6(H2O) ∙2(FDCA2−)) materials were synthesized using Zn2+ as the metal center and 1,3,5-triimidazolylbenzene (L) and 2,5-furan dicarboxylic acid (FDCA) as the bi-conjugate. The characterization was carried out by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TG), Zeta potential, and scanning electron microscopy (SEM). The fluorescence sensing experiments showed that Zn-MOF can be used as a fluorescent probe, which produces an obvious fluorescence burst in a short time, and has a good selectivity for the detection of HSO4−, with a low limit of detection (LOD) as low as 0.18 μM, and a good immunity to interference. The recognition mechanism of Zn-MOF was explored by electron transfer analysis methods and density functional theory (DFT) calculations, which indicated that the fluorescence burst mechanism was hydrogen bond formation.