A sulfonate ligand-defected Zr-based metal-organic framework for the enhanced selective removal of anionic dyes.

In this work, we introduce a novel defective analogue of the representative 6-connected zirconium-based metal-organic framework (MOF-808), by employing 5-sulfoisophthalic acid monosodium salt (H2BTC-SO3Na) as a defect inducer via a mixed-linker approach. The structural integrity and different physicochemical properties were investigated by various characterization techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and nitrogen physisorption at 77 K. Additionally, proton nuclear magnetic resonance (1H-NMR), energy-dispersive X-ray (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES) were employed to confirm the presence of 6.9 mol% of the 5-sulfoisophthalate ligand within the highly crystalline MOF-808 structure. The defective material exhibited significant enhancements in the removal efficiency of various organic dyes, including approximately 64% and 77% for quinoline yellow and sunset yellow, and 56% and 13% for rhodamine B and malachite green, compared to its pristine counterpart. Importantly, the defective MOF-808 showed a remarkable selectivity toward anionic species in binary-component dyes comprising both anionic and cationic dyes.

Synthesis of 2-benzyl benzoxazoles and benzothiazoles via elemental sulfur promoted cyclization of styrenes with 2-nitrophenols and N,N-dialkyl-3-nitroanilines.

Herein we report a method for affording 2-benzyl benzoxazoles from substituted styrenes and 2-nitrophenols. The success of this method relies on the use of simple reagents, namely elemental sulfur and DABCO. A combination of identical reagents was utilized for the annulation of styrenes with N,N-dialkyl-3-nitroanilines to afford 2-benzyl benzothiazoles. Overall, benzoxazoles and benzothiazoles bearing useful functionalities such as halogens, amines, and heterocyclic groups were isolated in moderate to good yields. Our methods are a rare example of divergent transformations of substituted nitroarenes towards 2-benzyl benzoxazoles and benzothiazoles.

Efficient Removal of Chromium(VI) Anionic Species and Dye Anions from Water Using MOF-808 Materials Synthesized with the Assistance of Formic Acid.

This study presents a simple approach to prepare MOF-808, an ultra-stable Zr-MOF constructed from 6-connected zirconium clusters and 1,3,5-benzene tricarboxylic acid, with tailored particle sizes. Varying the amount of formic acid as a modulator in the range of 200-500 equivalents results in MOF-808 materials with a crystal size from 40 nm to approximately 1000 nm. Apart from the high specific surface area, a combination of a fraction of mesopore and plenty of acidic centers on the Zr-clusters induces a better interaction with the ionic pollutants such as K2Cr2O7 and anionic dyes. MOF-808 shows uptakes of up to 141.2, 642.0, and 731.0 mg/g for K2Cr2O7, sunset yellow, and quinoline yellow, respectively, in aqueous solutions at ambient conditions. The uptakes for the ionic dyes are significantly higher than those of other MOFs reported from the literature. Moreover, the adsorption capacity of MOF-808 remains stable after four cycles. Our results demonstrate that MOF-808 is a promising ideal platform for removing oxometallates and anionic dyes from water.

Quantitative Analysis of Colistin-Resistant Escherichia coli in Retail Meat from Local Vietnamese Markets.

The spread of drug-resistant bacteria via food has contributed to the dissemination of resistant bacteria among humans. However, the status of food contamination with resistant bacteria, particularly the quantitative level of resistant bacteria in food, has not yet been well elucidated. In this study, the abundance of colistin-resistant Escherichia coli in meat samples was quantified to understand the origin of the contamination of meat available in local Vietnamese markets. Fifteen samples each of chicken and pork meat purchased from local Vietnamese markets were assessed for the presence of colistin-resistant E. coli with the mobile colistin resistance gene, mcr. The results showed that 40% (6/15) and 66% (10/15) of the pork and chicken meat samples, respectively, were contaminated with colistin-resistant E. coli. The median quantitative levels of colistin-resistant E. coli in the contaminated pork and chicken samples were 1.8 × 104 and 4.2 × 103 CFU/g, respectively. The results of phylogenetic analysis of isolates from a chicken meat sample showed that the contaminated colistin-resistant E. coli was a mix of multiple phylogenetical clones of bacteria that may have multiplied during sale. This is the first study to quantify the abundance of colistin-resistant E. coli in meat samples.

Cobalt-catalyzed, directed arylation of C-H bonds in N-aryl pyrazoles.

We report a method for directed ortho-arylation of N-aryl pyrazoles with arylboronic acids. Reactions proceeded in the presence of a Co(hfacac)2 catalyst, CeSO4 oxidant, and HFIP solvent. Functionalities such as nitro, ester, bromo, and ketone groups were compatible with the reaction conditions. Using heterocycles including thiophene and carbazole was also feasible.

Correction: Cobalt-catalyzed, directed arylation of C-H bonds in N-aryl pyrazoles.

[This corrects the article DOI: 10.1039/D1RA00975C.].

Synthesis of primary N-arylthioglyoxamides from anilines, elemental sulfur and primary C-H bonds in acetophenones.

A simple method for coupling of anilines, acetophenones, and elemental sulfur to afford N-arylthioglyoxamides has been developed. Reactions proceeded in the presence of Na2SO3 and DMSO, thus eliminating the need for transition metals and external oxidants. Functionalities such as halogen, ester, methylthio, and heterocycle groups were compatible with the conditions. Electron-poor acetophenones sometimes gave isosteric glyoxamides.

Stepwise Methane-to-Methanol Conversion on CuO/SBA-15.

The direct partial oxidation of methane to methanol is a challenging scientific and economical objective to expand the application of this abundant fuel gas as a major resource for one-step production of value-added chemicals. Despite substantial efforts to commercialize this synthetic route, to date no heterogeneous catalyst can selectively oxidize methane to methanol by O2 with an economically acceptable conversion. Cu-exchanged zeolites have been recently highlighted as one of the most promising bioinspired catalysts toward the direct production of methanol from methane under mild conditions. In this work, Cu-based catalysts were prepared using mesoporous silica SBA-15 as an alternative support and their activity for this conversion was investigated. The results demonstrate that highly dispersed CuO species on SBA-15 are able to react with methane and subsequently produce methanol with high selectivity (>84 %) through water-assisted extraction. Furthermore, it was confirmed that the main intermediate formed after interaction of the catalyst with methane is a methoxyl species, which can be further converted to methanol or dimethyl ether on extraction with water or methanol, respectively.

Copper-catalyzed one-pot domino reactions via C-H bond activation: synthesis of 3-aroylquinolines from 2-aminobenzylalcohols and propiophenones under metal-organic framework catalysis.

A Cu2(OBA)2(BPY) metal-organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones. This Cu-MOF was considerably more active towards the one-pot domino reaction than a series of transition metal salts, as well as nano oxide and MOF-based catalysts. The MOF-based catalyst was reusable without a significant decline in catalytic efficiency. To the best of our knowledge, the transformation of 2-aminobenzylalcohols to 3-aroylquinolines was not previously reported in the literature, and this protocol would be complementary to previous strategies for the synthesis of these valuable heterocycles.