Monatshefte für Chemie / Chemical Monthly最新文献

Sunlight-mediated water disinfection (SODIS) is an important technique, especially when applied in regions where the water treatment system is fragile because the SODIS process has a high capacity for inactivating pathogenic microorganisms. Although the intensity of solar radiation, exposure time, and turbidity of the water are relevant factors for the process, it has also been observed that the chemical composition of the water can interfere with the efficiency of the process. Some chemical species are able to capture radicals that are important for the disinfection process; therefore, the identification of these compounds would contribute to the optimization of the process and increase its efficiency. Thus, the present study aims to evaluate the influence of bicarbonate and carbonate anions using concentrations of Na₂CO₃ (5, 10, 20, 50, 75, 100, 150, 200, and 300 mg dm⁻³) on the solar disinfection process in surface water using total coliforms (C₀ = 10⁴ UFC.100 cm⁻³) and Escherichia coli (C₀ = 10³ UFC.100 cm⁻³) content as performance parameters for disinfection efficiency. It was observed that in all samples exposed to solar radiation (4 and 5 h), there was a reduction in E. coli and total coliform content when compared to a sample that was not exposed to radiation. However, the addition of carbonate and bicarbonate anions negatively interferes with the disinfection process, reducing the efficiency of SODIS by approximately 0.1 log for E. coli and 0.3 log for CT from a Na₂CO₃.

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The current study presents the analysis of tinidazole with the aid of electrochemical analysis by utilizing 0.2 M of phosphate buffer saline and a modified carbon paste electrode. Poly(L-arginine) fabricated carbon paste electrode (PLAMCPE) was obtained by polymerizing L-arginine (L-agn) onto a bare carbon paste electrode (BCPE) by applying electropolymerisation method at pH 6.5. To examine the electrochemical response and characterization of the developed PLAMCPE, differential pulse voltammetry (DPV), cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscope techniques were implemented. The PLAMCPE shows significantly enhanced electrochemical sensitivity for the reduction of tinidazole compared to BCPE. At optimal working circumstances, the consequences of several parameters like scan rate, pH, concentration variation, and active surface area were analyzed. By examining the scan rate, the reaction was found to be diffusion controlled. The attained values of limit of detection was 0.0841 μM, and limit of quantification was 0.2803 μM at a linear range of 0.2 to 9.0 μM for DPV method. Moreover, PLAMCPE shows great selectivity and sensitivity at sensing tinidazole in the occurrence of other interfering organic dyes and metal ions. In addition, it demonstrates commendable repetitiveness, stability, and reproducibility. The developed electrode has a remarkable recovery rate indicating its applicability to the real sample.

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A proficient technique utilizing core–shell structured Fe₃O₄@MgO nanocatalyst for the synthesis of β-naphthol condensed 1,3-oxazinone derivatives through a one-pot condensation reaction of aldehyde, urea, and β-naphthol in the presence of K₂CO₃ and Fe₃O₄@MgO nanoparticles in PEG-400 is presented. This technique provides numerous benefits, such as high yields, unaltered reactions, quick responses, reusability of the catalyst, and an uncomplicated workup technique. PEG-400 was the most effective solvent among the variety of solvents investigated for this system. In addition, polyethylene glycol (PEG) can enhance the stability of nanoparticles against oxidation, improving catalyst efficiency. This results in a more ecologically sound and sustainable protocol.

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Cellulosic fibers spun from 1,3-dialkylimidazolium ionic liquids are effectively stabilized against cellulose degradation by the addition of antioxidants, but this protective effect comes at the expense of chromophore generation from the degradation products of the stabilizers. In this study, we identified the oxidation and degradation products of four natural antioxidants, α-tocopherol, N-methyl-α-tocopheramine, propyl gallate, and hydroxytyrosol, formed upon accelerated ageing of the fibers. Ageing was performed according to standard protocols under either dry or moist conditions and the extraction was done with supercritical carbon dioxide. Chromophore formation in spinning dope, upon dry ageing and moist ageing were compared. In total, 16 different oxidation/degradation products were isolated, their structure confirmed by comprehensive analytical characterization with full NMR resonance assignment in the ¹H and ¹³C domains as well as by comparison with authentic samples, and their formation pathways discussed. Knowledge of the chemical structures of the degradation products originating from the stabilizers now provides a good starting point for optimization of the fiber bleaching stage.

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Since the industrial revolution the world economy has grown thanks to energy generated by cheap and abundant fossil resources. Today, due to climate change caused by human-induced CO₂ and other greenhouse gas emissions, we are in the midst of a shift away from fossil fuels and towards renewable energy. It remains to be seen how fast this shift will happen and whether the correlating economics are feasible. Increasingly, experts are asking: what role will catalysis play to help drive energy efficiency? With a 60-year history in industrial catalysis, Clariant’s Catalysts business has been a front runner in catalyst and technology development. For more than a decade we have been working in the catalytic Power-to-X segments. This paper presents our understanding on current developments around the important role of Power-to-X and Waste-to-X technologies to enable a worldwide transition of the energy sector to renewables.

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A mild and efficient method for the arylation of quinoxalinones are described using aryldiazonium tetrafluoroborates as aryl source. Reactions proceeds at room temperature in a short reaction time of 1 h without metal catalysts and bases. Broad functional group tolerance was observed with good yields of products even at gram scale reaction. Control experiments suggest that the reactions proceed through a radical pathway. Furthermore, the present protocol applied for the successive synthesis of three biologically active molecules. Overall, the method offers a convenient and versatile approach for the synthesis of arylated quinoxalinones.

We report a simple synthetic scheme for the preparation of several azido-derived analogues of N-acetylglucosamine (GlcNAc). The synthesis of GlcNAc analogues has been achieved through a straightforward approach starting from GlcNAc-OMe via an intermediate C6 azido derivative. Products reported in this work were then obtained respectively by azido-alkyne cycloaddition reactions and reductive derivatizations of the same azido-intermediate. This synthetic pathway presents different possibilities of functionalization that can be exploited for the preparation of novel GlcNAc-based drugs.

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1,5-Benzothiazepines represent key scaffolds in medicinal chemistry because of their applicability in a wide variety of pharmaceuticals. Many cardiovascular, antidepressant, and antipsychotic drugs on the market accommodate this privileged structure, but the biological effects of 1,5-benzothiazepines are much more diverse, including enzyme inhibitory, antimicrobial, central nervous system depressant, anti-inflammatory, and anticancer activity. The introduction of a heterocyclic substituent onto a chemical structure can be beneficial in terms of bioactivity and drug-like properties. In this review, the biological activities of 1,5-benzothiazepines with and without heterocyclic substituents are discussed and compared. In some cases, the addition of a heterocycle proved to be beneficial for enhancing activity, especially the introduction of a 2-thienyl group, and also the position of heteroatoms in the substituent can have an impact on the overall properties of the resulting compounds.

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Single-atom catalysts (SACs) have garnered considerable attention owing to their impeccable catalytic activity and unique ability to elucidate the active site. In this work, we synthesized iron-doped single-atom catalysts (Fe SACs) via a soft-template sacrificial approach, which exhibited peroxidase activity. Further investigations revealed that Fe SACs were capable of catalyzing the generation of highly reactive hydroxyl radicals (•OH) from hydrogen peroxide (H₂O₂), which facilitated the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB, resulting in a discernible color change from colorless to blue. According to the exceptional peroxidase activity of Fe SACs, we designed and fabricated a colorimetric sensor by combining uricase and TMB, achieving highly sensitive and selective detection of uric acid over a wide range of concentrations (0.1–50 μM), with a low detection limit of 0.039 μM (3σ/k). Finally, we demonstrated the feasibility of our sensor in detecting uric acid in real human urine samples, yielding satisfactory recoveries and low relative standard deviations.

Pyridoxine and riboflavin can be determined individually or together using a carbon paste electrode modified by electropolymerization method with aspartic acid (PAMCPE). Using scanning electron microscopy, electrochemical impedance spectroscopy, differential pulse voltammetry, and cyclic voltammetry, the electrochemical behavior of pyridoxine was examined. The results of the studies showed that PAMCPE facilitates pyridoxine oxidation. The technique made it possible to determine pyridoxine and riboflavin simultaneously using cyclic voltammetry. The pH study showed that the good current response was observed at 6.5 pH; hence, it was chosen as the optimum for the analysis. The electrochemical reaction of pyridoxine is adsorption controlled with two-electron transfer process. Pyridoxine has a linear working range of 2.5–8.0 μM, with detection limit of 2.95 μM and limit of quantification of 9.85 μM. The developed modified electrode exhibits a number of benefits, including an easy preparation process, good stability, easy surface modification procedure, excellent reproducibility and repeatability. The practical applicability of PAMCPE for the detection of pyridoxine in pharmaceutical sample shows good sensitivity and selectivity.

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