Functionalized MOF as a Sensitive Spectroscopic Probe for Hg(2+), Co(2+), and Al(3+) Ions Detection in Aqueous Media

[Image: see text] A modified metal–organic framework (MOF) named Al-MIL-53-N=SA-Br was synthesized via a Schiff-base reaction between the MOFs (Al-MIL-53-NH(2)) and 5-bromo salicylaldehyde. The robust functionalized Al-MIL-53-N=SA-Br was used as a novel spectrophotometric sensor for detecting Hg(2+), Co(2+), and Al(3+) ions. In a wide range of concentrations, the absorption spectral intensity of Al-MIL-53-N=SA-Br increased linearly upon increasing the concentration of Hg(2+), Co(2+), and Al(3+) ions. The limit of detection (LOD) of the proposed Al-MIL-53-N=SA-Br sensor reached 1.52 ppm of Hg(2+) ion (7.56 × 10(–9) M). Therefore, this study introduces a novel ratiometric Hg(2+), Co(2+), and Al(3+) ions chemosensor. Simple treatment using thiourea or ethylenediaminetetraacetic acid can remove the metal ions from the used sensor and use it many times with a high efficiency. In addition, the Al-MIL-53-N=SA-Br sensor has a high adsorption capacity for these metal ions. The design of the robust Al-MIL-53-N=SA-Br sensor provided high stability, reproducibility, selectivity, high sensitivity, and a facile sensing design. Furthermore, the good absorption spectral stability of Al-MIL-53-N=SA-Br in aqueous media, the broad linear in sensing, and the low LOD of the Hg(2+), Co(2+), and Al(3+) ions show its high potential in determining these ions in real water.