A dual functional turn off florescence sensor using metal-organic framework for sensitive detection of aluminum(III) in aqueous solution.

Aluminum, classified as one of the toxic heavy metals, has a recommended daily consumption limit of 3-10 mg, as specified by the World Health Organization (WHO). Herein, the selective and sensitive aluminum(III) fluorescence sensor based on TMU-16 metal-organic frameworks (MOFs) in aqueous medium, is reported. A sensing pathway was found via the cation exchange between aluminum(III) and zinc(II) ions, and caused selectivity and sensitivity detection of aluminum(III) with a 5-100 ppm linear range and 1.99 ppm limit of detection (LOD). This sensor offers the advantage of accurately determining the concentration range of aluminum(III) ions. At low concentrations, only fluorescence quenching was observed, while at higher concentrations, fluorescence emission not only undergoes quenching but also exhibits a blue shift in wavelength. Notably, the sensor demonstrates no interference from cation solutions of mercury(II), zinc(II), nickel(II), lead(II), cobalt(II), cadmium(II), silver(I), chromium(III), and iron(III). Another significant feature of this sensor is its selectivity toward copper(II) and aluminum(III) ions, due to quenching fluorescence in the presence of copper(II) ion. The results presented the sensor's selectivity toward copper(II) at low concentrations and aluminum(III) at high concentrations.