A Magnesium Organic Framework Fluorescent Sensor for Selective Detection of Nitrofuran Antibiotics and Inorganic Pollutants

A novel 3D magnesium-based metal organic framework (Mg-MOF) has been solvothermally synthesized using 5-(pyridin-4-yl)isophthalic acid. The ligand has demonstrated to preserve two types of coordination modes depending on the connection mode of the pyridine group. The uncoordinated pyridine groups provide Lewis base sites (LBSs), whereas the coordinated ones promote to form a rarely reported eight-connected tetranuclear Mg clusters. Benefiting from the multinuclearity with high number of connections, the framework keeps good performance of high thermal stability until 500 degrees C. Furthermore, the framework exhibits potential open metal sites (OMSs) benefiting from the terminal coordinated water groups of the metal clusters. Owing to the abundant active sites, the Mg-MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72-, with high KSV (at 104 M-1 level) and low limit of detection (LOD) values (similar to 10-6 M). Density functional theory (DFT) investigation reveals that the interchange of the HOMO-LUMO energy levels of the framework and antibiotics is responsible for the sensing activity. In addition, the Mg-MOF is greatly recyclable in five cycles while maintaining the structural rigidity and sensing activity, making it a promising luminescence probe material. A novel 3D magnesium-based metal organic framework (Mg-MOF) has been solvothermally synthesized by using 5-(pyridin-4-yl)isophthalic acid. The inorganic SBU is a rare eight-connected tetranuclear Mg clusters. Owing to the abundant Lewis basic sites (LBSs) and open metal sites (OMSs), the Mg-MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72-.image