Zirconium Metal-Organic Framework Bearing V-Shape Letrozole Dicarboxylic Acid for Versatile Fluorescence Detection

Metal-Organic Frameworks with both organic and inorganic components are widely used as fluorescent sensors due to their high thermal stability, special optical properties, etc. Current studies have shown that azole groups have rich nitrogen sites and optical properties, which can significantly improve the host-guest interaction sites and fluorescence sensing properties if the azole groups could be introduced into the backbone of MOF. However, it is still a great challenge to effectively introduce nitrogen-containing azole groups into the backbone of MOF and to explore their fluorescence sensing properties. In this work, a readily available precursor, letrozole, was selected, which could be converted into the dicarboxylic acid ligand by virtue of its angular structure, azole units and easily modified cyano groups. The connection of Zr6 cluster and V-shape letrozole dicarboxylic acid can form a stable MOF in water. The structural advantages of the resulted Zr-MOF as the certain porosity and abundant nitrogen-containing azole sites generate strong interactions for the adsorption and accumulation of analytes, and ensure sensitive fluorescence detection. The carefully constructed Zr-MOF can be adopted as the high sensitive fluorescent sensor for inorganic metal ions, aromatic nitro compounds and nitrofuran antibiotics (NFAs). Especially for NFAs, the established fluorescence sensor has a low detection limit, giving a KSV value of 3.28x102 M-1 and a detection limit of 9.15x10-5 mol L-1. The related results exhibit the expected potential application for the luminescent determination of pollutants in water.