Water-Robust Zinc–Organic Framework with Mixed Nodes and Its Handy Mixed-Matrix Membrane for Highly Effective Luminescent Detection of Fe³⁺, CrO₄^2–, and Cr₂O₇^2– in Aqueous Solution

Abstract

Metal–organic frameworks (MOFs) and MOF-based composites as luminescent sensors with excellent economic practicability and handy operability have attracted much attention. Herein, we designed and fabricated a porous Zn-based MOF, [Zn­(OBA)2(L1)·2DMA] n [1; H2OBA = 4,4′-oxybis­(benzoic acid), L1 = 2,4,6-tris­(4-pyridyl)­pyridine, and DMA = N,N-dimethylacetamide], with mixed nodes under solvothermal conditions, and the pore size of 5.9 Å was calculated from N2 adsorption isotherms by using a density functional theory model. The as-synthesized compound 1 is stable in different boiling organic solvents and water solutions with a wide pH range of 2–12 and exhibits intense luminescence emission at 360 nm under excitation of 290 nm. Significantly, compound 1 shows high selective detection of Fe3+, CrO4 2–, and Cr2O7 2– in aqueous solution even under the interference of other ions. Compound 1 can quickly sense these ions in a short time and has a striking sensitivity toward Fe3+ with an ultralow limit of detection (LOD) of 1.06 μM. The relatively low LODs for CrO4 2– and Cr2O7 2– are 3.87 and 2.37 μM, respectively, compared to the reported works. Meanwhile, compound 1 can be reused to detect Fe3+, CrO4 2–, and Cr2O7 2– six times by simple regeneration. Considering the practicability, a mixed-matrix membrane (MMM) incorporated compound 1 and poly­(methyl methacrylate) has been constructed. This MMM displays quick detection of Fe3+, CrO4 2–, and Cr2O7 2– and prompt regeneration by lifting from the analyte. This useful MMM shows a comparable LOD below 4.35 μM for these ions. This work presents a cost-effective Zn-based MOF as a functional platform for simple but useful sensing of Fe3+, CrO4 2–, and Cr2O7 2– in aqueous solution.

A cadmium(II) coordination polymer with a fivefold interpenetrating diamondoid three-dimensional framework: synthesis, crystal structure, luminescence and photocatalytic properties

“…Since the Cd II ion is difficult to oxidize or reduce due to its d 10 configuration, the emissions cannot be assigned to either metal-to-ligand charge transfer or ligand-to-metal charge transfer. Hence, the emissive behaviour of compound (I) can be attributed to ligand-centred electronic transitions (Fan et al, 2021b;Qin et al, 2021).…”

Two bis-ligand-coordinated Zn(ii)-MOFs for luminescent sensing of ions, antibiotics and pesticides in aqueous solutions

“…[61][62][63][64] A common LMOF is constructed from carboxylic groups containing ligands and/or N-donor ligands (pyridines or imidazole groups, etc). 65 During a photoluminescent process, organic ligands oen function as 'antennae' to absorb incoming light thereaer, the interaction with metal centers or other auxiliary ligands affects the direct intrinsic emission properties, thereby producing a distinct luminescence spectrum of the LMOF. 66 The combination of the two types of ligands may enhance the advantages of both components and enrich the coordination environments of the center ions of the MOFs, thereby producing various novel topologies and fascinating uorescence properties.…”

Cationic Metal–Organic Framework-Based Mixed-Matrix Membranes for Fast Sensing and Removal of Cr2O72− Within Water

“…However, to the best of our knowledge, only two MMMs have been developed for the fluorescence sensing of Cr 2 O 7 2− in aqueous solution (Qin et al, 2021;Xu et al, 2021), MMMs for the removal and sensing of Cr 2 O 7 2− simultaneously within water have not been discussed yet. [Eu 7 (mtb)…”

“…However, to the best of our knowledge, only two MMMs have been developed for the fluorescence sensing of Cr 2 O 7 2− in aqueous solution ( Qin et al, 2021 ; Xu et al, 2021 ), MMMs for the removal and sensing of Cr 2 O 7 2− simultaneously within water have not been discussed yet. [Eu 7 (mtb) 5 (H 2 O) 16 ]·NO 3 8DMA·18H 2 O (Eu-mtb, H 4 mtb = 4-[tris(4-carboxyphenyl)methyl]benzoic acid)) is a hydrolytically stable cationic MOF that has been reported to have the lowest detection limit for Cr 2 O 7 2− ( Liu et al, 2017 ).…”