Research on Chemical Intermediates最新文献

This study includes the synthesis of 11 different calixarene derivatives, the preparation of thin film sensors on quartz crystal microbalance (QCM) crystals, and the specification of sensor-analyte pairs by examining the sensing properties of these sensors against different phenolic compounds such as p-nitrophenol (PNP), phenol (PHE), p-chlorophenol (PCP), and m-nitrophenol (MNP) in the aqueous medium. For this purpose, calixarene derivatives with different structures were first synthesized and characterized using spectroscopic methods such as Proton nuclear magnetic resonance (¹H-NMR) and Fourier-transform infrared spectroscopy (FTIR). Detection studies were carried out for proposed phenolic compounds with calixarene-based QCM sensors obtained by electrospinning. At the beginning of the experiments, sensor-analyte pairs were determined according to the values at which the highest sensor frequencies were observed. Therefore, according to the highest sensor responses towards 5 × 10^–5 M analytes, the sensor-analyte pairs were determined as QCM-5 for PNP (17.8 Hz) and MNP (3.8 Hz). Also, for PHE and PCP, the highest responses were observed as 4.1 Hz and 4.0 Hz in the QCM-11 and QCM-1 sensors, respectively. In further experiments, determined sensor-analyte pairs were tested at different analyte concentrations. In addition, the limits of detection (LOD) of the sensors were calculated from different analyte concentration studies such as 0.580 (QCM-5), 0.659 (QCM-11), 0.490 (QCM-1), and 0.466 (QCM-5) mM against PNP, PHE, PCP, and MNP, respectively. Interactions between sensor-analyte pairs were evaluated in terms of adsorption kinetics. It was observed that the relationships between the sensor responses and the analyte concentration were highly consistent with the Freundlich isotherm. In addition, repeatability and stability tests of the sensors were performed, and it was observed that they exhibited good repeatability and stability properties. Finally, selectivity between analytes was assessed, and the highest selectivity was observed as with the QCM-4 sensor versus p-nitrophenol. It was found that the selectivity of the sensor to PNP was 21.1 times compared to PHE and PCP and 74 times compared to MNP.

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Three pyrrolo[3, 2-b]pyrrole compounds (Py–CF₃–H, Py–CF₃–CH₃ and Py–CF₃–OCH₃) were prepared as radical photoinitiators for visible light radical photopolymerization. Radical photopolymerization using the Py–CF₃–H initiator-induced TMPTA system achieved a peak conversion rate of 72% for C=C double bonds. The effect of changes in the electronic structure on the photoinitiation ability of the three photoinitiators was studied using spectroscopic measurements and theoretical calculations. The generated free radicals were detected using electron paramagnetic resonance (EPR). The synthesized photoinitiators matched the 405 nm LED. Under steady photolysis at 405 nm, the maximum absorption peaks decreased rapidly after exposure to light, and a new blue-shifted peak appeared. The end groups on the phenyl at 1,4 positions of the pyrrolo[3,2-b]pyrrole core considerably influenced the charge surrounding the central core, according to the electrostatic potential (ESP) results. The –H on 1,4-phenyl provides a less negative charge on the fused pyrrole core compared to the –CH₃ and –OCH₃. Thus, this work provides an experimental foundation for investigating pyrrole-based photoinitiators in polymer curing.

A copper coordinated L-ascorbic acid (Cu@AACP) metal–organic framework was synthesized and characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), wavelength dispersive X-ray spectroscopy (WDX), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The BET method was used to investigate the textural characteristics of Cu@AACP, including surface area, pore diameter and total pore volume. The SEM analysis was used to investigate the morphology and size of Cu@AACP particles. AAS, WDX and EDS techniques were used to investigate the elemental content of Cu@AACP. The TGA analysis was used to investigate the presence of solvents or moisture, thermal stability and organic–inorganic content of catalyst. The FT-IR spectroscopy was used to the characterization of functional groups in the structure of the materials. The XRD pattern was used to investigate the crystalline phase of the catalyst. The results of the analyses confirmed the successful synthesis of copper MOF of L-ascorbic acid (Cu@AACP). The catalytic performance of Cu@AACP was examined in synthesizing of 2, 3-dihydroquinazolin-4(1H)-ones (through condensation of aldehydes and anthranilamide in ethanol at 80 °C) and polyhydroquinolines (through condensation of aldehydes, dimedone, ammonium acetate and ethyl acetoacetate in ethanol at 80 °C). The reaction conditions for the synthesis of 2, 3-dihydroquinazolin-4(1H)-ones and polyhydroquinolines were optimized, where the best results were obtained in ethanol solvent at 80 °C in the presence of 6 mg of Cu@AACP as catalyst. The results show that an improved product yield is obtained between 84 and 95%. Recycle test of the catalyst confirmed that the heterogeneous catalyst exhibited good catalytic stability, efficiency and very high activity in successive runs because of its unique pore network. To show the stability of Cu@AACP nanocatalyst after recycling, the recovered catalyst was characterized by AAS, FE-SEM, EDS and FT-IR techniques.

The methanol-to-olefins (MTO) process is a promising method for producing light olefins, which are essential intermediates in petrochemical processes. SAPO-34, a crucial catalyst for the MTO process, often suffers from compromised quality when synthesized using low-cost precursors. This study presents a novel and efficient gel preparation method to enhance the performance of amine-templated SAPO-34. Comprehensive characterization through XRD, SEM, EDX, XRF, N₂ physisorption, and FTIR analyses provided insights into the catalyst structure and composition. The results exhibit promoting nucleation, crystal growth, and silica incorporation while suppressing impurities. Notably, increased silica incorporation led to the formation of crystal cracks, significantly boosting the specific surface area. The optimized SAPO-34 catalyst exhibited improved catalytic performance, characterized by a short induction period and a sustained high light olefin selectivity of 84% for over 6 h, showcasing the potential of this approach for producing cost-effective, high-performance MTO catalysts.Kindly check and confirm the corresponding author of the article and the first/last name of the authors are correctly identifiedYes. The corresponding author of the article and the first/last name of all authors are correct.

Developing high-performance catalysts for NO_x reduction was a significant challenge. CWK catalysts modified with iron sources were synthesized using co-precipitation and impregnation methods. The CWK-F₃C and CWK-F₃S catalysts exhibited the superior catalytic activity at 250–350 ℃ and the excellent N₂ selectivity. The key reasons for the enhanced catalytic activity of CWK-F₃C and CWK-F₃S catalysts could be attributed to the higher Fe³⁺ concentration, more surface chemisorbed oxygen species and bigger relative fraction of Ce³⁺. More significantly, the adsorption of NH₃ and redox capability were both strengthened by the Fe³⁺ doping. The DRIFTS experiment results showed that the E-R and L–H mechanism were followed by CWK-F₃C and CWK-F₂C catalysts. Furthermore, the introduction of Fe³⁺ generated more surface acidic sites, which could facilitate the formation of key intermediates (-NH₂) (NH_3(ads) + O_(ads)/O²⁻(ads) → -NH_2(ads) + -OH_(ads)). The presence of Fe³⁺ was conducive to NO₃⁻ formation (NO₃⁻ + NO_(ads) → NO_2(ads)), resulting in the presence of fast reaction, causing the excellent low temperature catalytic performance. Hence, the production of -NH₂ and NO₃⁻ species was responsible for the outstanding catalytic activity of CWK-F₃C.

In this study, tetradecyl methacrylate-maleic anhydride-benzylidene acetone (C₁₄MC-MA-MCA) terpolymers were synthesized via free radical polymerization and evaluated as pour point depressants (PPDs) for coal-based diesel. The findings indicate that the C₁₄MC-MA-MCA (3:1:1) terpolymer exhibited the most effective inhibition of the solid point (SP) at 1500 ppm concentration. Specifically, it reduced the SP of coal-based diesel from − 4 to − 42 °C, marking a significant decrease of 38 °C. Furthermore, the crystallization behavior and SP reduction mechanism of C₁₄MC-MA-MCA in coal-based diesel were investigated using viscosity analysis and polarized optical microscopy (POM).

Mesoporous silicas of MCM-41 and MCM-48 types were synthesized and modified with copper by template ion-exchange (TIE) technique. A high dispersion of deposited copper species was managed by subsequent treatment of the samples with ammonia, urea, or acetonitrile solution. Copper-modified silicas were analysed in terms of their chemical composition (ICP-OES), ordering of porous structure (XRD), textural parameters (low-temperature N₂ sorption), dispersion and form of introduced copper species (UV–vis-DR, XRD, H₂-TPR, NH₃-TPD). Mesoporous silicas modified with copper exhibited promising catalytic efficiency in selective catalytic reduction of NO with ammonia (NH₃-SCR). The samples containing dispersed copper species (predominantly monomeric copper cations) presented enhanced catalytic activity compared to catalysts containing CuO aggregates. On the other hand, CuO aggregates showed greater catalytic activity in the side process of direct ammonia oxidation by oxygen present in the reaction mixture. It was demonstrated that TIE post-treatment of the samples with urea resulted in most effective improving dispersion of deposited copper and is less destructive for ordered porous structures of mesoporous silica comparing to treatment with ammonia solution.

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We report a novel magnetic ionic liquid (MIL) based on pyridine successfully prepared by a two-step reaction pathway. The prepared MIL was recognized by means of Fourier transform infrared spectroscopy (FT-IR), UV–visible and Raman spectroscopies, thermal analysis (TGA and DTG), magnetic susceptibility measurement, mass spectra (MS), proton NMR ((^{1}hbox {H},hbox {NMR})), carbon NMR ((^{13}hbox {C},hbox {NMR})), Hammett acidity, and CHN elemental analysis. The MIL was shown to be efficient in the synthesis of xanthenediones under solvent-free conditions. In addition, the antibacterial and antifungal activity of the MIL was investigated.

Viologen-based organic electrochromic materials have been extensively studied due to their excellent electrochromic performance. Nevertheless, the dimerization of the radical cation state will destroy the reversibility of viologens and result in poor stability of the electrochromic device (ECD). Herein, two π-extended viologen derivatives (Spr-MPTT and Sbu-MPTT) are synthesized by inserting a thiazolo[5,4-d]thiazole unit between bipyridine moieties and N-bisubstituted with alkyl sulfonate groups. All-in-one hydrogel ECDs are assembled using Spr-MPTT or Sbu-MPTT and ferrocene modified by a water-soluble group. The Spr-MPTT-based ECD exhibited alternating color change between yellow-green and violet, while the Sbu-MPTT-based ECD displayed alternating color change between yellow-green and purple at 1.0/0 V pulse voltage. The extended conjugation of the viologen chromophore confers these devices with visible-NIR absorption and good cyclic stability. Their optical contrasts at 535 nm are 54.85% and 60.17%, respectively, for Spr-MPTT or Sbu-MPTT based ECD. These results demonstrate their potential application in electrochromic hydrogel smart windows.

Ce-doped WO₃ nanoparticles were fabricated and characterized using powder X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman, SEM–EDX, UV–Vis, photoluminescence (PL), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS) analyses. The results revealed the formation of a highly crystalline monoclinic phase in Ce-doped WO₃ photocatalyst (abbreviated WCC), confirmed by Raman spectroscopy. The bandgap was tuned by increasing the percentage of Ce dopant, where the WCC (1 mol wt% Ce-doped WO₃) photocatalyst sample exhibited the highest photocatalytic activity towards synthetic methylene blue (MB) dye pollutant and biodegradation-resistant tetracycline hydrochloride (TC-HCl) antibiotic. The decomposition efficiency using the WCC photocatalyst against aqueous MB dye and TC-HCl antibiotic reached 95% and 51% after exposure to simulated sunlight irradiation for 180 min, with excellent stability after four recycling runs. The interfacial contact between Ce and WO₃ effectively shortened the charge transfer carrier process, enabling redox reactions to provide the best decomposition efficiency over the investigated pollutants. The photodecomposition rate constant of WCC was 0.017 min⁻¹ for MB dye, which is 3.6-fold higher performance than common literature photocatalysts. The results showed the significance of the environmental impact toxicity assessment by applying the treated water to finger millet plant growth. Based on the research feasibility, the synthesized photocatalyst demonstrated superior decomposition against dyes and antibiotics, making it highly suitable for applications in wastewater treatment. Moreover, the use of degraded water resulted in productive plant growth.

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