A novel Zn(II)-based metal-organic framework as a high selective and sensitive sensor for fluorescent detections of aromatic nitrophenols and antibiotic metronidazole.

A novel fluorescent Zn(II)-based metal-organic framework (Zn-MOF), [Zn2(oba)4(4,4'-bpy)2]n, was successfully synthesized through a simple solvothermal route at 130 °C for 48 h, employing Zn(NO3)2·6H2O, 4,4'-Oxybis(benzoic acid) (oba) and 4,4'-Bipyridine (4,4'-bpy) as the initial reactants, dimethylacetamide (DMA) as the reaction medium. The as-obtained Zn-MOF was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR), Thermogravimetric analysis (TGA) and elemental analysis. The fluorescence tests showed that the as-obtained Zn-MOF emit a strong violet light centered at 445 nm under the excitation of 323 nm UV light. Intriguingly, the above strong violet emission could be highly selectively quenched by aromatic nitrophenols or antibiotic metronidazole (MET) in aqueous systems with fairly low detection limits. Other substituted phenols and antibiotics, as well as some cations, anions, amino acids and small organic molecules hardly affected the violet emission of the as-obtained Zn-MOF, indicating that this novel Zn-MOF could be prepared as a selective fluorescent probe for detections of aromatic nitrophenols and MET antibiotic in water solutions.