Detection of Trace Amounts of Fe³⁺ and Cr⁶⁺ Ions Using a ZIF-8 Fluorescent Sensor with High Selectivity and Fast...

While zeolitic imidazole framework (ZIF)-based materials have shown promising metal ion detection performances, they did not achieve the same results as for pure ZIFs. Here, a highly porous ZIF-8 material is synthesized using a chemical method under stirring at room temperature, and characterized in terms of crystallinity and chemical state. The resulting ZIF-8 is employed as a multifunctional fluorescent sensor to detect Fe³⁺ and Cr⁶⁺ metal ions dissolved in water, exhibiting high luminescence with a broad wavelength band in the visible light region. The water-soluble metal ions are found to be very sensitive to a decrease in the luminescence intensity of ZIF-8, and can be detected at trace amounts with high selectivity. The detection limits of Fe³⁺ and Cr⁶⁺ ions are achieved to be 2.1 × 10^-6 and 7.6 × 10^-7 M, respectively. The intensity of luminescence decreases with increasing the concentration of both metal ions, thereby giving rise to the complete fluo>rescence quenching with a very fast response time using Fe³⁺ and Cr⁶⁺ ion concentrations higher than 1.0 × 10^-4 and 4.7 × 10^-5 M, respectively. These results may pave the way for the utilization of pure ZIF materials in the development of highly efficient fluorescent sensors in order to rapidly detect trace amounts of environmental pollutants.