Ultrasensitive Detection of Hg(II) Ions in Aqueous Medium Using Zinc-Based Metal–Organic Framework

Abstract

Here we describe, a simple solution and solid-state sensor for the ultrasensitive detection of Hg­(II) ions in both standardized and environmental samples through changes of fluorescence intensity of a zinc-based metal–organic framework (MOF). The MOF is highly water stable in a wide pH range from 4 to 11. The lower detection limit of Hg2+ is 10–11 M with a very high binding constant of 1.011 × 109 M–1 s–1. It also exhibits a high selectivity toward mercury ion in the presence of other interfering metal ions. The MOF is found to retain its efficiency in detecting mercury ion in spiked environmental water samples.

Recent advances in process engineering and upcoming applications of metal–organic frameworks

“…Metal ion sensors NH 2 -MIL-125(Ti) Pb 2+ 0.70 × 10 −2 nM 5 [405] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Fe 3+ 3.24 µM 5 [406] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Al 3+ 1.31 µM 5 [406] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Cr 3+ 1.84 µM 5 [406] MOF NU-902 Cd 2+ 0.3 ppb – [407] MOF NU-902 PVC membrane Cd 2+ – – [407] CAU-10-V-H Pd 2+ 110 nM 5 [408] MIL-53(Al)–NH2-MPA Fe 3+ 0.36 µM – [416] [[Zn(4,4′-AP)(5-AIA)]. (DMF)0.5] n Hg 2+ 0.01 nM – [409] b. Anion sensors TMU-41 Cr 2 O 7 2− 0.02 µM 4 [410] TMU-41 CrO 4 2− 0.03 µM 4 [410] TMU-41 MnO 4 − 0.03 µM 4 [410] ...…”

“…Mercury ions can cause fatal poisoning. For their detection, Mandal’s group developed a new Zn-based MOF, [Zn(4,4′-AP)(5-AIA)]·(DMF) 0.5 , that shows selective and sensitive detection of Hg 2+ in aqueous media [409] . The authors reported that the MOF could detect picomolar concentrations of Hg 2+ ions, with a LOD of 9.9 × 10 −12 M. This is one of the lowest values ever reported.…”

Recent Advances in Nanocomposite Luminescent Metal-Organic Framework Sensors for Detecting Metal Ions

“…(DMF) 0.5 ] n is highly water stable, which provides very low detection limit of Hg 2+ as low as 10 −11 M with a very high binding constant of 1.011 × 10 9 M −1 s −1. [103] Interestingly, the boric acid (BA)-functionalized lanthanide MOF, BA-Eu-MOF, provides an efficient sensor for detection of Hg 2+ and CH 3 Hg + ions Reprinted with permission from ref. [ 268 ] .…”

“…The soft acid Hg 2+ ion has a higher affinity toward a soft base like N. The above MOF is highly water stable, providing a lower detection limit of Hg 2+ as low as 10 −11 M with a very high binding constant of 1.011 × 10 9 M −1. [103] It also exhibits a high selectivity toward mercury ion in the presence of other interfering metal ions. [103] Furthermore, Zn-based MOF, Zn-APA (APA is 5-aminoisophthalic acid), features a 3-D supramolecular network with uncoordinated carboxylic oxygen atoms, exhibiting a fast fluorescence response to Hg 2+ ion over other metal ions in aqueous solutions.…”

“…[103] It also exhibits a high selectivity toward mercury ion in the presence of other interfering metal ions. [103] Furthermore, Zn-based MOF, Zn-APA (APA is 5-aminoisophthalic acid), features a 3-D supramolecular network with uncoordinated carboxylic oxygen atoms, exhibiting a fast fluorescence response to Hg 2+ ion over other metal ions in aqueous solutions. [104] Recently, a 3-D porous zinc(II) coordination polymer [Zn 2 (bbmb) 2 (tdc) 2 ]•2 H 2 O, where bbmb is 1,4-bis(benzimidazol-1-yl-methyl) benzene and H 2 tdc is 2,5-thiophene dicarboxylic acid, was hydrothermally synthesized.…”