Synthesis of new fluorescent metal-organic framework (4-sulfo-1,8-naphthalimide-UiO66) for detection of Cr(III)/Cr(VI) ions in aqueous media and its antimicrobial studies

Detection of toxic metals both rapidly and at low concentrations is of great importance. Researchers put a lot of effort to detect toxic metals and develop various detection systems. In recent years, fluorescent-based methods have been used for the detection of toxic metals such as chromium. Metal-organic frameworks (MOFs) are organic materials with unique properties such as excellent chemical-thermal stability, designable structure, well-defined pore structure, and high surface area. MOFs are used in the development of fluorescent-based sensor systems thanks to these advantages. In this study, 4-sulfo-1,8-naphthalimide immobilized UiO66-NH2 (UiO66-Nap) with fluorescent properties was synthesized and used for the detection of Cr(III) and Cr(VI). The structures of the synthesized compounds were elucidated using 1H-NMR, FTIR, PXRD, and SEM techniques. The MOF-based fluorescent sensor shows good sensing performances for Cr(III) and Cr(VI) ions including high selectivity, and great sensitivity (18.3 μM and 3.42 μM, respectively). Also, the antimicrobial potentials of these compounds were elucidated by a broth microdilution test against standard bacteria and yeast. Results showed that Ag-associated UiO66 had great antimicrobial potential with a MIC value of 0.019 mg/mL against Gram-positive and Gram-negative bacteria. In addition, this compound revealed very good antifungal activity against Candida at a dose of 0.039 mg/mL.