Antibiotic identification in aqueous solution by a two-dimensional cadmium-based coordination polymer with excellent fluorescence properties

Over the past two decades, large amounts of antibiotics have been discharged into the aquatic environment, threatening human health and ecological balance. Meanwhile, numerous reports have documented coordination polymers as a fluorescent sensing material for detecting pollutants in aqueous environments. We successfully synthesized a two-dimensional coordination polymer using Cd2+ ions and the rigid ligand 1-(3,4-dicarboxyphenyl)-4-hydroxypyridin (H2L) and named it [Cd(L)]n (1). In this complex, each cadmium ion exhibits a six-coordinated pattern and forms a two-dimensional network structure with a (6,3)Ia-type topology according to the ToposPro software. In addition, the good stability and excellent fluorescence properties of the complex made it an excellent fluorescent sensor for the identification of ciprofloxacin and oxytetracycline in aqueous solution with low limits of detection (0.28 μM for ciprofloxacin and 36.5 μM for oxytetracycline). Finally, we investigated the detailed mechanism of the fluorescence sensing behavior of the complex by performing density functional theory calculations.