Research on Chemical Intermediates最新文献

We report a new series of isatin-oxime-based Schiff base derivatives (p–H, p–Cl, p–CH₃). Structural analyses of the compounds were conducted through FTIR, ¹H NMR, UV–Vis, and elemental analyses. X-ray crystallography demonstrated that compounds 1 and 2 adopted an orthorhombic crystal system with a P bca space group. Hirshfeld surface (HS) analysis indicated that hydrogen bonding and van der Waals interactions were predominant in the crystal packing. The volumes of the crystal voids and the percentages of free spaces in the unit cells were calculated as 293.87 ų and 10.63% (for 1), 320.34 ų and 11.04% (for 2), respectively. The evaluations of energy frameworks showed that stabilization was dominated by electrostatic energy contributions in compounds. In silico investigations on the DNA binding activity showed that the binding activity of the compounds was mediated via intercalation. The anticancer activity of the compounds was also tested via an MTT assay using HepG2 (liver cancer), Caco-2 (colorectal adenocarcinoma), A549 (lung cancer) and HEK-293 (normal cell) cell lines. The MTT assay demonstrated significant cytotoxic activity of compound 1 across HepG2, Caco-2, A549, and HEK-293 cell lines, with IC₅₀ values of 5.07 µM, 5.19 µM, 4.01 µM, and 5.63 µM, respectively, after 24 h, surpassing cisplatin in efficacy at all tested time intervals. The data indicate that substituents play a significant role in modulating cytotoxicity, with compound 1 (p–H) demonstrating the highest activity. These findings demonstrate the high cytotoxicity and cancer cell selectivity of isatin-oxime-based Schiff base derivatives, especially compound 1, suggesting their potential as strong alternatives to traditional chemotherapy agents.

In the present study, a versatile biomaterial of chitosan polymer/ginger (Zingiber officinale Roscoe) extract/ZnO bionanocomposite (CS/GE/ZnO) was formulated. The physicochemical characteristics of the CS/GE/ZnO were examined using a variety of techniques, including Brunauer–Emmett–Teller (BET), elemental analysis (CHN), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), and field emission scanning electron microscopy (FESEM). The elemental analysis indicated that CS/GE/ZnO comprised 22.82% carbon, 4.17% hydrogen, 2.32% nitrogen, and 70.69% oxygen. The BET analysis indicated that CS/GE/ZnO possesses a specific surface area of 11.41 m²/g and a total pore volume of 0.0596 cm³/g. The CS/GE/ZnO exhibits a mesoporous structure with a mean pore diameter (20.91 nm). By analyzing the cytotoxicity and antioxidant properties of the CS/GE/ZnO biomaterial on a breast cancer cell line (MDA-MB-231), its biological activity was determined. In contrast to the standard ascorbic acid (78.08%), the CS/GE/ZnO biomaterial demonstrated an exceptional DPPH radical scavenging efficiency of 78.66%. An IC50 value of 103 μg/mL was determined through MTT assay research on breast cancer investigations involving CS/GE/ZnO and the MDA-MB-231 cell line. The CS/GE/ZnO biomaterial demonstrates efficacy as a chemotherapeutic agent against breast cancer cells, as evidenced by the results. The performance and structure of the CS/GE/ZnO biomaterial indicate potential advancements in nanomaterials for biomedical applications.

The application of diesel, which is a key energy source, in cold climates is limited by its poor low-temperature flowability. Addressing this critical issue, this study designed and synthesized a series of novel comb shaped pour point depressants. This work showed how to synthesize and characterize three innovative copolymers: binary systems comprising tetradecyl methacrylate (C₁₄MC) with either dioctyl maleate (DOM) or vinyl benzoate (VB), and C₁₄MC-DOM, C₁₄MC-VB and C₁₄MC-DOM-VB were synthesized by integrating the three structural units mentioned above. The outcomes of the experiment show that adding the ternary copolymers(C₁₄MC-DOM-VB), particularly with a molar composition of 15:1:1 and the addition amount of 2000 ppm, improves the cold flow characteristics of diesel significantly, as shown by a decrease of 21 °C in solidification point and 12 °C in cold filter plugging point, respectively. Mechanistic investigations suggest that the comb-like structure and inclusion of benzene rings within the ternary copolymers furnish a multitude of nucleation sites, thereby more effectively disrupting the formation of extensive wax crystals. These mechanistic insights are substantiated by an array of analytical techniques, including rheologic analysis, differential scanning calorimetry and polarizing optical microscopy.

In this study, zinc vanadate nanocomposite (ZVNC-Zn₃V₂O₈) was prepared by hydrothermal method. SEM, UV–visible spectroscopy, PXRD, and TEM were utilized to analyze the morphology, crystal structure, particle size, and optical properties of the nanocomposite. The average crystallite size of synthesized nanocomposite was deducted ~ 24.48 nm. The measured energy bandgap was 3.4 eV, making the material suitable for degradation studies under ultraviolet (UV) light exposure. Notably, the degradation efficiency for malachite blue and malachite green was 87.15% and 92.64%, respectively. Additionally, the same compound was utilized for the detection of ascorbic acid, and charge–discharge studies revealed extremely low R_Ct and C_dl values of 82.4 C and 0.000125 F, respectively. These findings indicate that the charge transfer process in ZVNC is highly efficient, enabling rapid and effective energy transmission. These properties suggest that ZVNC hold significant potential for applications in energy and environmental fields, offering valuable insights into their material characteristics.

Graphical Abstract

The NH₃-SCR method is the most prevalent technology utilised for the removal of NOx. Among the numerous types of catalysts, minerals are composed of multiple metallic elements that produce natural synergistic catalytic effects when applied in the denitrification process. This phenomenon underscores the potential for their application in this field of research. In this study, rare earth tailings were modified using a hydrothermal method with Ce as the modifying agent. The impact of Ce-modified tailings catalysts on low-temperature denitrification performance and physicochemical properties was examined through a series of analytical techniques, including XRD, BET, SEM–EDS, XPS, NH₃-TPD, H₂-TPR, XPS, and in situ DRIFTS analyses. The findings indicated that the denitrification efficiency and N₂ selectivity of 7.5% Ce/rare earth tailings were 83% and 90%, respectively. The reaction temperature window was expanded from 250 °C to 425 °C. A mesoporous surface structure with highly dispersed active components, namely cerium and iron, was obtained. Concurrently, the combined effect of Ce and Fe resulted in an increase in oxygen vacancies, acidic sites, and acid activity strength within the catalyst. The denitrification reaction is governed by both the E-R and L–H mechanisms. The catalyst surface exhibits both Brønsted and Lewis acidic sites, with Brønsted acidic sites being more conducive to denitrification. The SCR reaction is predominantly influenced by NH⁴⁺ species adsorbed on Brønsted acidic sites, resulting in the formation of NH₃. Two active centres of Ce⁴⁺ and Fe³⁺ in the rare earth tailings, and NO as gaseous adsorbed NO₂, monodentate nitrate, and small amounts of bridged nitrate and bidentate nitrate participate in the SCR reaction.

This study is centered on the synthesis of NiO–Al₂O₃ catalysts using multiple preparation methods, which encompass mechanochemical, impregnation, sol–gel, co-precipitation, and combustion techniques. These various methods were employed to create catalyst samples, subsequently utilized in the carbon dioxide methanation process. Comprehensive characterization of the prepared samples encompassed H₂-TPR, XRD, BET, and FESEM analyses. The outcomes of the BET and XRD analyses unveiled that the 20NiO–Al₂O₃ catalyst, synthesized via the mechanochemical preparation approach, exhibited exceptional efficiency in relation to CO₂ conversion and selectivity of methane. This was especially pronounced at lower temperatures. Notably, this catalyst showcased a specific surface area measuring 240.7 m²/g, coupled with a reduced crystal size of 29.4 nm. The 20NiO–Al₂O₃ catalyst demonstrated a carbon dioxide conversion of 68%, coupled with a methane selectivity of 96% under the operational condition of 400 ℃. Notably, this catalyst demonstrated the highest degree of stability when compared to the other catalysts studied. To comprehensively assess the impact of varying nickel loadings, spanning from 5 to 25 wt. %, on both textural attributes and the catalytic efficacy of mechanochemically synthesized NiO–Al₂O₃, an in-depth investigation was undertaken. The experimental findings from this investigation unveiled that the augmentation of nickel loading up to 20 wt.% led to a discernible enhancement in CO₂ conversion efficiency. However, beyond this threshold, a decline in CO₂ conversion was detected. This can be linked to the phenomenon of particle sintering, which subsequently leads to a decrease in the dispersion of the active catalytic phase. Furthermore, the study thoroughly examined processing conditions and the temperature of calcination, assessing their influence on the catalytic efficiency of the chosen catalyst.

Graphical abstract

Degrading the organic compounds using the photocatalysis is a potential technology to control the environmental pollution. Concerned with this problem, a one-step hydrothermal approach was used to synthesise novel (1-x)Bi₂Sn₂O₇-xCuBi₂O₄ heterojunctions (where x = 0.05, 0.10, 0.15 and 0.20 wt.%). The compounds were investigated using XRD, FESEM, EDX, HRTEM, XPS, FTIR, UV-DRS, BET, EIS and PL techniques. The degradation of methylene blue (MB), rhodamine B (Rh B) and phenol were used to examine the photocatalytic activity (PCA) of Bi₂Sn₂O₇-CuBi₂O₄ heterojunctions. 0.90Bi₂Sn₂O₇–0.10CuBi₂O₄ heterojunction exhibited the highest PCA than pure Bi₂Sn₂O₇ and CuBi₂O₄. The enhanced specific surface area and the improved charge separations were primarily accountable for the enhanced PCA of these heterojunctions. The plausible mechanism of high PCA of these heterojunctions was comprehensively understood through the precisely computed energy band potentials and the performed free-radical trapping experiments. The trapping investigations showed that h⁺ and (O_{2}^{ cdot - }) play important roles, with (O_{2}^{ cdot - }) being the most prominent species. After four cycles, the heterojunction still effectively degraded the contaminants.

CeMn-rare earth tailings catalysts with wide temperature window and high denitrification were prepared by hydrothermal method. The results show that the optimum ratio of Ce/Mn is 1:1, and the NO_x conversion can reach 90% at the range of 100–300 °C. The introduction of Mn improves the dispersion of CeCO₃F on the catalyst surface, exposing more active adsorption sites. In addition, the interaction of MnO_x with Ce and Fe in the rare earth tailings promotes redox, which facilitates the oxidation of NO to NO₂. Meanwhile Mn also increases the abundance and stability of NO adsorption species and Lewis acid sites, forming important intermediates such as Mn⁴⁺-ONO₂, NH₄NO₃ and NH₂NO. But the strong oxidizing ability of Mn and the reaction between monodentate nitrate and adsorbed NH₃ results in N₂ selectivity decrease rapidly. Catalysts follow both E-R and L–H mechanism in the NH₃-SCR reaction. Moreover, the excellent redox performance and Lewis acid sites improve the NH₃-SCR catalytic activity together.

Addressing the dual challenges of environmental pollution and antibiotic resistance, this study investigates the synthesis and application of biosynthesized aluminum oxide nanoparticles (γ-Al₂O₃ NPs) and aluminum oxide/silver oxide nanocomposite (γ-Al₂O₃/AgO NC) using Ocimum basilicum plant extract. The green synthesis approach yielded stable NPs, characterized by XRD, SEM, TEM, FTIR, and UV–Vis techniques. The γ-Al₂O₃/AgO NC exhibited a band gap energy of 3.4 eV and an average particle size of 35 nm, compared to 3.6 eV and 30 nm for γ-Al₂O₃ NPs. Zeta potential measurements demonstrated good stability, with values of -24.5 mV for γ-Al₂O₃ NPs and − 28.6 mV for γ-Al₂O₃/AgO NC. The antimicrobial activity of γ-Al₂O₃ NPs and γ-Al₂O₃/AgO NC was evaluated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). E. coli exhibited an inhibition zone of 18.0 mm, while S. aureus showed a zone of 22.8 mm at a concentration of 5 µg/mL when treated with γ-Al₂O₃ NPs. Furthermore, using the γ-Al₂O₃/AgO NC, the inhibition zones increased significantly to 27.6 mm for E. coli and 23.8 mm for S. aureus, indicating enhanced antibacterial efficacy of the nanocomposite. In photocatalytic experiments, γ-Al₂O₃/AgO NC achieved 96.5% degradation of rhodamine B (RhB) dye within 90 min under sunlight, maintaining 93.05% efficiency after five cycles. These results underscore the dual functionality of γ-Al₂O₃/AgO NC as a sustainable material for environmental remediation and biomedical applications.

Graphical Abstract

This study investigates the impact of cerium promotion on NiMgAl catalysts for methane dry reforming (DRM) at 750 °C. A series of NiMgAl-Ce oxides with varying cerium content NiMgAlCe-x (x: rate of substitution of aluminium by cerium) were synthesized via co-precipitation method, aiming to enhance catalytic activity through the incorporation of nickel into hydrotalcite structures and cerium promotion. The obtained systems calcined at 800 °C, reduced at 750 °C and used catalysts were characterized by ICP, BET, XRD, SEM, H₂-TPR, TPO and O₂-TG analysis. The results demonstrate that cerium content influences specific surface area, with higher cerium promoting increased surface area but hindering catalytic activity and improved carbon resistance of the catalysts.. Activity improved with reaction temperature, with NiMgAl achieving the highest conversion, with CH₄ conversion dropping from 16% at 450 °C to 95.0% at 750°C. Stability tests at 750 °C, revealed decreased activity in cerium-containing catalysts. On the other hand in the case of catalysts without prior reduction, the catalytic activity of NiMgAlCe-1 and NiMgAlCe-2 catalysts are better, however, the NiMgCe solid presents a total catalytic inertia. This result suggests that the presence of aluminium is bringing a Lewis acidity favours this reducibility suggesting an influence on redox behaviour. Carbon fibers formation was observed, but it did not significantly affect reactor performance.