Abstract: A metal-organic framework complex {[Zn₂(OH)(TZI)·2H₂O]·6DMF}_n (1) (TZI=5-tetrazolylisophthalic acid) was successfully isolated under solvothermal conditions. The structure of the complex was characterized by single crystal X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction. Single crystal X-ray diffraction study reveals that 1 displays a 3D structure with channels, where exist uncoordinated carboxylate groups and coordinated water molecules. Subsequently, through post-synthesis method, a Eu(Ⅲ)@1 with red fluorescence emission was obtained by introducing Eu(Ⅲ) into framework of 1. Under 275 nm wavelength excitation, Eu(Ⅲ)@1 possesses two groups of fluorescence emission. In the first group, the wide peak at 418 nm is the fluorescence emission of 1, which origins from the absorption and emission of the organic ligand. While, the second group of five emission peaks is the red characteristic emission peak of Eu(Ⅲ) ion, with main peak of 619 nm. The results of anti-interference experiments of other components in urine show that Eu(Ⅲ)@1 fluorescent probe is very sensitive to the biomarker 1-naphthol, and can lead to red fluorescence quenching (619 nm), accompanies by cyan fluorescence enhancement (465 nm), and has high selectivity for 1-naphthol. Fluorescence titration results show that the detection limits of Eu(Ⅲ)@1 for 1-naphthol based on fluorescence emission peaks at 465 and 619 nm are 6.95 μmol/L and 1.75 mmol/L, respectively.

Key words: metal-organic framework, Eu(Ⅲ) functionalization, solvothermal synthesis, crystal structure, post-synthesis, fluorescence, 1-naphthol