Novel metal-organic frameworks with high stability for selectively sensing nitroaromatics

A critical review on the synthesis of NH2-MIL-53(Al) based materials for detection and removal of hazardous pollutants

Nowadays, emerging hazardous pollutants have caused many harmful effects on the environment and human health, calling for the state of the art methods for detection, qualification, and treatment. Metal-organic frameworks are porous, flexible, and versatile materials with unique structural properties, which can solve such problems. In this work, we reviewed the synthesis, activation, and characterization, and potential applications of NH₂-MIL-53(Al). This material exhibited intriguing breathing effects, and obtained very high surface areas (182.3-1934 m²/g) with diverse morphologies. More importantly, NH₂-MIL-53(Al) based materials could be used for the detection and removal of various toxic pollutants such as organic dyes, pharmaceuticals, herbicides, insecticides, phenols, heavy metals, and fluorides. We shed light on plausible adsorption mechanisms such as hydrogen bonds, π-π stacking interactions, and electrostatic interactions onto NH₂-MIL-53(Al) adsorbents. Interestingly, NH₂-MIL-53(Al) based adsorbents could be recycled for many cycles with high stability. This review also recommended that NH₂-MIL-53(Al) based materials can be a good platform for the environmental remediation fields.

A Zr-Based Metal-Organic Framework with a DUT-52 Structure Containing a Trifluoroacetamido-Functionalized Linker for Aqueous Phase Fluorescence Sensing of the Cyanide Ion and Aerobic Oxidation of Cyclohexane

A zirconium (Zr) metal-organic framework having a DUT-52 (DUT stands for Dresden University of Technology) structure with face-centered cubic topology and bearing the rigid 1-(2,2,2-trifluoroacetamido) naphthalene-3,7-dicarboxylic acid (H₂NDC-NHCOCF₃) ligand was prepared, and its solid structure was characterized with the help of the X-ray powder diffraction (XRPD) technique. Other characterization methods like thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy were applied to verify the phase purity of the compound. In order to get the solvent-free compound (1'), 1 was stirred with methanol for overnight and subsequently heated at 100 °C overnight under vacuum. As-synthesized (1) and activated (1') compounds are thermally stable up to 300 °C. The Brunsuer Emmett-Teller (BET) surface area of 1' was found to be 1105 m² g^-1. Fluorescence titration experiments showed that 1' exhibits highly selective and sensitive fluorescence turn-on behavior toward cyanide (CN^-) anion. The interference experiments suggested that other anions did not interfere in the detection of CN^-. Moreover, a very short response time (2 min) was shown by probe 1' for CN^- detection. The detection limit was found to be 0.23 μM. 1' can also be effectively used for CN^- detection in real water samples. The mechanism for the selective detection of CN^- was investigated systematically. Furthermore, the aerobic oxidation of cyclohexane was performed with 1' under mild reaction conditions, observing higher activity than the analogous DUT-52 solid under identical conditions. These experiments clearly indicate the benefits of hydrophobic cavities of 1' in achieving higher conversion of cyclohexane and cyclohexanol/cyclohexanone selectivity. Catalyst stability was proved by two consecutive reuses and comparing the structural integrity of 1' before and after reuses by the XRPD study.

Luminescence sensing and photocatalytic activities of four Zn(ii)/Co(ii) coordination polymers based on a pyridinephenyl bifunctional ligand

Four Zn(ii)/Co(ii) CPs act as bifunctional materials in the detection of Fe(iii) cation, Cr(vi) anion, and nitrofuran antibiotics and removal of methylene blue in aqueous media.

Coordination polymers with salicylaldehyde ligands: structural diversity, selective sorption and luminescence sensing properties

Five new coordination polymers with salicylaldehyde ligands were obtained. They show diverse structures, selective dye adsorption and fluorescence sensing properties.

Coordination polymers with a pyridyl–salen ligand for photocatalytic carbon dioxide reduction

Fe(iii) and Mn(iii) coordination polymers with a pyridyl–salen ligand were constructed and have shown photocatalytic activity for CO₂reduction under visible-light irradiation.

NH2-MIL-53(Al) nanocrystals: a fluorescent probe for the fast detection of aromatic nitro-compounds and ions in aqueous systems

Fluorescent NH₂-MIL-53(Al) nanocrystals used for the fast detection of ANCs and ions in aqueous systems were fabricated by a solvothermal route.

[2 + 2] cycloaddition reaction and luminescent sensing of Fe3+ and Cr2O72− ions by a cadmium-based coordination polymer

A cadmium-based coordination polymer can produce the corresponding photoproduct via [2 + 2] cycloaddition reaction, and can detect both Fe³⁺ and Cr₂O₇²⁻ ions.

Metal–organic frameworks with 5,5′-(1,4-xylylenediamino) diisophthalic acid and various nitrogen-containing ligands for selectively sensing Fe(iii)/Cr(vi) and nitroaromatic compounds

Four Zn(ii) complexes are applied in selectively sensing Fe(iii)/Cr(vi) and nitroaromatic compounds.

Luminescent metal organic frameworks for sensing and gas adsorption studies

Two three-dimensional metal organic frameworks (LZn and LCd) were synthesized solvothermally for sensing of nitro phenolic explosives and gas adsorption studies. LZn showed selectivity towards N₂ gas at 77 K.