Monatshefte für Chemie / Chemical Monthly最新文献

Abstract

Nitrogen-containing heterocycles are an inseparable part of many biologically active compounds. Therefore, the synthesis of these structures is of great importance in the field of synthetic chemistry. Due to the presence of two nitrogen atoms in the amidine structure, this molecule can be considered as a dual nucleophile in the synthesis of various heterocycles. The current review highlights recent advances in the application of amidines, in particular, N-arylamidines, as versatile precursors in transition metal-catalyzed, and metal-free reactions for the construction of N-heterocyclic compounds.

Green synthesis of MnO₂ was carried out using natural extracts of Tilia cordata (TC) and Calendula officinalis (CO). Utilizing the transmission electron microscopy, powder X-ray diffraction, and UV–Vis spectra techniques confirmed the successful synthesis of α-MnO₂. The BET analysis showed that the CO-derived material has a larger surface area and appropriate mesoporous structure. The obtained synthesized materials were assembled in asymmetric supercapacitor test cell, with a polymer membrane serving as a separator and an electrolyte. The prepared CO-MnO₂ demonstrates excellent capacitance and energy characteristics and seems to be a promising electrode material for the development of environmentally friendly solid-state supercapacitors.

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The electrochemical properties of poly(l-asparagine) modified carbon nanotube paste electrode (PAMCNPE) were investigated for precise detection of methyl orange. Asparagine was electrochemical polymerized and deposited onto the carbon nanotube paste surface to develop the modified electrode, and comparing to the bare carbon nanotube paste electrode. Cyclic voltammetry measurements of the modified electrode at pH 7 in a 0.2 M phosphate buffer saline showed excellent oxidizing activity towards methyl orange. Various factors were studied, including the ionic strength of the buffer. The external morphology and conversion of the perception material were studied using field emission scanning electron microscopy and electrochemical impedance spectroscopy, respectively. High sensitivity and selectivity for detecting methyl orange were also achieved by optimizing experimental conditions such of pH, concentration variation, and scan rate. The concentration range spanned from 0.2 to 9.0 µM, with the lower limit of detection at 1.368 × 10^–7 M and the quantification limit of 4.562 × 10^–7 M, indicating its excellent analytical performance. Additionally, the PAMCNPE shows good stability, reproducibility, and repeatability. Its remarkable recovery in real samples underscores its potential for practical applications in environmental and clinical analysis.

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Recycling lithium-ion batteries (LIBs) have become increasingly important in response to expanding electromobility. This paper is focused on evaluating the environmental impacts (EIs) of recycling pre-treatment of three types of LIBs with black mass as its product. A detailed gate-to-gate Life Cycle Assessment study was conducted to obtain EIs of the recycling process. The benefits of LIBs recycling pre-treatment and significant recovery of secondary aluminum for compared battery types are highlighted in the analysis. This paper points out that the varying chemistry of the compared LIBs does not affect the resulting EIs of the recycling pre-treatment procedures.

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Abstract

Cotton textiles are mercerized with anhydrous ammonia liquefied at ca. − 33 °C to improve their mechanical performance, appearance, and handle. Similar effects may also be achieved with NaOH mercerization, but goods mercerized with liquid ammonia (L-NH₃) are judged qualitatively better (e.g., softer hand) and thus command a greater price. Therefore, it is of interest to be able to test and confirm whether cotton textiles labeled as L-NH₃ treated are indeed so. Building on previous work, we report on tests in collaboration with a process house on identifying ammonia-mercerized fabrics from a pool of cotton textiles treated with L-NH₃, NaOH, neither, or both––using FTIR-ATR spectroscopy. It is based on detecting the change in crystal lattice structure from type I (native cellulose) to type II (after NaOH mercerization) or type III (after ammonia mercerization). We could consistently differentiate the ammonia-mercerized fabrics from the untreated and those mercerized with NaOH, but the latter could not be differentiated from fabrics mercerized with both. It was also possible to detect evidence of ammonia mercerization in 4- and 14-year-old samples.

The paper deals with the measurement of the cell impedance parameters during discharging of the Li-ion NCR18650B cell. Re (Z) and Im (Z) of the battery were measured by PEIS method. The results of the impedance changes during discharging and charging were plot to Nyquist diagrams. The important values namely Rs, Rsei, Rct, Csei, Qsei, Cdl, α, and σ were found during discharging of the Li-ion cell with and without using CPE element.

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Films of heterostructure BiVO₄/WO₃, composite BiVO₄ with WO₃ and pure BiVO₄ were obtained by electrochemical deposition. Analysis of photoelectrochemical characteristics of such films showed that observed increase in photocurrent quantum yield and decrease in overvoltage of oxygen evolution on the photoanode in row from pure BiVO₄ films, than in heterostructure BiVO4/WO₃, after that—composite BiVO₄–WO₃. The reason of such positive effect of reducing the energy losses associated with the surface recombination of electrons and holes and reduction of losses at the stage of interfacial charge transfer in the BiVO₄–WO₃ composite compared with the heterostructure BiVO₄/WO₃ and pure BiVO₄.

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Abstract

The possibility of increasing the hydrogen release rate and reducing energy consumption was analyzed using a system in which the anodic process of metal (aluminum) dissolution occurred on one electrode and the process of H₂ release on the other (nickel) electrode. The possibility of generating hydrogen with a current density of ~ 400 mA cm^–2 in NaOH solutions with a concentration of 6–8 mol dm^–3 at a cell voltage of ~ 0.5 V was confirmed. When the electrodes were short-circuited, hydrogen was generated on nickel when aluminum was dissolved at a rate corresponding to current density ~ 100 mA cm^–2. The possibility of simultaneous hydrogen production and electricity generation in the system under consideration was shown. It was found that the maximum net power was generated in 6 mol dm^–3 NaOH. The specific power in such a solution can reach a value of 8 mW cm^–2 at a cell voltage of about 0.15 V. In this case, the hydrogen release rate corresponded to a current density of 60 mA cm^–2.

Synthesis of novel noscapine triazole tethered derivatives with γ-aminobutyric acid (GABA) linker is reported. Attachment of the linker was done by N-demethylation of noscapine followed by coupling with N-Boc protected GABA. The straightforward synthesis of the target molecules was made by a three-component reaction between GABA-noscapine, p-nitrophenyl azide, and commercially available ketones under metal-free conditions to produce a library with diverse functional groups. Anticancer activity of the synthesized derivatives was evaluated on MCF-7 cancer cell line. The best anticancer activity was demonstrated by a compound with an IC₅₀ value of 57.2 µM, close to that of noscapine (IC₅₀ = 55.2 µM).

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Conventional frontal polymerization processes for epoxy-based composites rely on cations and radicals generated by a short (and local) light or heat stimulus in the presence of an iodonium salt and a radical thermal initiator. However, due to heat losses, the propagation of the exothermic curing front is often limited by sample geometry and filler concentration. Redox cationic frontal polymerization (RCFP) is a promising approach to radically expand the composition and design options of frontally cured epoxy-based composites. By adding stannous octoate as reducing agent, a higher number of radicals and cations are generated at lower temperature, which yields highly cured composite even at elevated filler content. In the current study, RCFP was used to cure standard unidirectional carbon fiber-reinforced composites based on a commercially available epoxy resin and the properties were compared with its anhydride hardener-cured counterpart. Cure degree and thermal properties of the resins were determined by ATR FT-IR spectroscopy and DMA analysis. Subsequently, unidirectional composites with a fiber volume content of ~ 60% were produced via vacuum infusion and subjected to DMA, tensile, compression, and inter-laminar shear tests. The results showed a remarkable similarity between mechanical properties of RCFP and anhydride hardener-cured composites. The RCFP-cured composites exhibited even a higher damping resistance and compression strength than anhydride hardener-cured composites. The results show that RCFP allows for a significant reduction in the curing time (from several hours to 60 min), while it yields composites with properties comparable to classic anhydride-cured systems.