Antibiotics and organic explosives are among the main organic pollutants in wastewater; their detection and removal are quite important but challenging. As a new class of porous materials, metal-organic frameworks (MOFs) are considered as a promising platform for the sensing and adsorption applications. In this work, guided by a topological design approach, two stable isostructural Zr(IV)-based MOFs, Zr6O4(OH)8(H2O)4(CTTA)8/3 (BUT-12, H3CTTA = 5'-(4-carboxyphenyl)-2',4',6'-trimethyl-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic acid) and Zr6O4(OH)8(H2O)4(TTNA)8/3 (BUT-13, H3TTNA = 6,6',6″-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(2-naphthoic acid)) with the the-a topological structure constructed by D4h 8-connected Zr6 clusters and D3h 3-connected linkers were designed and synthesized. The two MOFs are highly porous with the Brunauer-Emmett-Teller surface area of 3387 and 3948 m(2) g(-1), respectively. Particularly, BUT-13 features one of the most porous water-stable MOFs reported so far. Interestingly, these MOFs represent excellent fluorescent properties, which can be efficiently quenched by trace amounts of nitrofurazone (NZF) and nitrofurantoin (NFT) antibiotics as well as 2,4,6-trinitrophenol (TNP) and 4-nitrophenol (4-NP) organic explosives in water solution. They are responsive to NZF and TNP at parts per billion (ppb) levels, which are among the best performing luminescent MOF-based sensing materials. Simultaneously, both MOFs also display high adsorption abilities toward these organic molecules. It was demonstrated that the adsorption plays an important role in the preconcentration of analytes, which can further increase the fluorescent quenching efficiency. These results indicate that BUT-12 and -13 are favorable materials for the simultaneous selective detection and removal of specific antibiotics and organic explosives from water, being potentially useful in monitoring water quality and treating wastewater.

This review summarizes research advances in photocatalytic organic pollutant degradation in metal–organic frameworks.

Guided by a top-down topological analysis, a metal-organic framework (MOF) constructed by pyrazolate-based porphyrinic ligand, namely, PCN-601, has been rationally designed and synthesized, and it exhibits excellent stability in alkali solutions. It is, to the best of our knowledge, the first identified MOF that can retain its crystallinity and porosity in saturated sodium hydroxide solution (∼ 20 mol/L) at room temperature and 100 °C. This almost pushes base-resistance of porphyrinic MOFs (even if MOFs) to the limit in aqueous media and greatly extends the range of their potential applications. In this work, we also tried to interpret the stability of PCN-601 from both thermodynamic and kinetic perspectives.

A base-resistant porphyrin metal-organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni(OH)(HO)Pz] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F, CO, and PO ions. Interestingly, the Mn-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C-H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOF was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.

Introducing functional groups into pores of metal-organic frameworks (MOFs) through ligand modification provides an efficacious approach for tuning gas adsorption and separation performances of this type of novel porous material. In this work, two UiO-67 analogues, [Zr6O4(OH)4(FDCA)6] (BUT-10) and [Zr6O4(OH)4(DTDAO)6] (BUT-11), with functionalized pore surfaces and high stability were synthesized from two functional ligands, 9-fluorenone-2,7-dicarboxylic acid (H2FDCA) and dibenzo[b,d]thiophene-3,7-dicarboxylic acid 5,5-dioxide (H2DTDAO), respectively, and structurally determined by single-crystal X-ray diffraction. Notwithstanding skeleton bend of the two ligands relative to the linear 4,4'-biphenyldicarboxylic acid in UiO-67, the two MOFs have structures similar to that of UiO-67, with only lowered symmetry in their frameworks. Attributed to these additional functional groups (carbonyl and sulfone, respectively) in the ligands, BUT-10 and -11 show enhanced CO2 adsorption and separation selectivities over N2 and CH4, in spite of decreased pore sizes and surface areas compared with UiO-67. At 298 K and 1 atm, the CO2 uptake is 22.9, 50.6, and 53.5 cm(3)/g, and the infinite dilution selectivities of CO2/CH4 are 2.7, 5.1, and 9.0 and those of CO2/N2 are 9.4, 18.6, and 31.5 for UiO-67, BUT-10, and BUT-11, respectively. The selectivities of CO2/CH4 and CO2/N2 are thus enhanced 1.9 and 2.0 times in BUT-10 and 3.3 and 3.4 times in BUT-11, respectively, on the basis of UiO-67. The adsorption mechanism of CO2 in BUT-11 has also been explored through computational simulations. The results show that CO2 molecules locate around the sulfone groups in pore surfaces of BUT-11, verifying at the molecular level that sulfone groups significantly increase the affinity toward CO2 molecules of the framework. This provides thus an efficient strategy for the design of CO2 capture materials.