Research on Chemical Intermediates最新文献

Pharmaceutical contaminants, particularly ciprofloxacin (CIP), pose significant ecological and health threats due to their persistence in aquatic environments and resistance to conventional water treatment methods. This study addresses the growing threat of pharmaceutical contaminants, specifically the antibiotic CIP, in wastewater. We developed a novel CQDs/N-WO₂ nanocomposite by coupling carbon quantum dots (CQDs) with nitrogen-doped tungsten dioxide (N-WO₂) via a synergistic hydrothermal-ultrasonication method. The key innovation of this work lies in the strategic electronic engineering of the material: nitrogen doping effectively narrows the band gap of WO₂ to enhance visible-light absorption, while the integration of CQDs creates a unique heterojunction that acts as an electron bridge, drastically improving charge separation and migration. This synergistic effect was confirmed through a combination of spectroscopic analysis, electrochemical measurements, and First-principles Density Functional Theory (DFT) calculations, which revealed enhanced light-harvesting and prolonged charge-carrier lifetimes. When applied to CIP degradation under ultraviolet–visible light (UV–vis), the optimized CQDs/N-WO₂ nanocomposite demonstrated exceptional performance, achieving a remarkable 98.3% removal efficiency, significantly outperforming its individual components. Mechanistic studies demonstrate superoxide and hydroxyl radicals as the primary active species, and a direct S-scheme charge transfer pathway was proposed to explain the superior photocatalytic activity. Furthermore, the composite exhibited excellent stability and reusability over multiple cycles. This work not only presents a highly efficient photocatalyst but also provides a fundamental understanding of interface engineering, offering a promising strategy for developing advanced materials for the remediation of pharmaceutical contaminants in water.

Graphical abstract

This study introduces a novel CQDs/N-WO₂ nanocomposite synthesized through a synergistic hydrothermal–ultrasonication approach for the efficient photocatalytic degradation of ciprofloxacin (CIP) in wastewater. Under optimized conditions, the composite achieves a high photodegradation efficiency of 98.3%, significantly surpassing the performance of its individual constituents. Exhibiting excellent reusability and structural stability, this photocatalyst offers a sustainable and effective strategy for the removal of persistent pharmaceutical contaminants from aquatic environments.

Graphitic carbon nitride (g-C₃N₄) was synthesized by applying a thermal treatment using waste melamine–formaldehyde product as a precursor. Photocatalytic antibiotic degradation performances of g-C₃N₄ was investigated. To enhance the photocatalytic activity of g-C₃N₄, the heat treatment temperature was varied as an experimental variable during the synthesis of g-C₃N₄, and different proportions of urea and silica template materials were separately mixed with the precursor before the heat treatment. A higher degree of crystallization was obtained as the heat treatment temperature was increased. According to FTIR analysis, it was understood that g-C₃N₄ was obtained more successfully at the heat treatment temperature of 650 °C. Mixing the precursor with urea and silica template did not significantly affect the chemical structure of the resulting g-C₃N₄. Mixing waste melamine–formaldehyde product with silica template gave rise to approximately sixfold expansion in the BET surface area of g-C₃N₄. It was determined that the g-C₃N₄ particles obtained by mixing waste melamine–formaldehyde product with urea and silica template turned from irregular blocks to spherical structures and the particle size decreased. By mixing waste melamine–formaldehyde product with urea and silica template, the photocatalytic antibiotic degradation efficiency of the resulting g-C₃N₄ was enhanced. The highest photocatalytic degradation efficiency (41.9%) was obtained on g-C₃N₄ synthesized from waste melamine–formaldehyde precursor containing urea and silica template under UV light irradiation for 120 min. It was attempted to produce high-value-added photocatalyst from waste melamine–formaldehyde material, reflecting the originality of the present study.

Inorganic micro- and nanoparticles are promising photocatalysts for removing toxic dyes from aqueous media. However, their dispersion in water and subsequent separation after the photocatalytic process remain challenging. In this study, MoS₂, a transition metal disulfide, was successfully dispersed in a water–ethanol mixture with the help of polyvinylpyrrolidone (PVP) and immobilized in a polyacrylamide (PAM) hydrogel to be easily separated from the medium after photodegradation. The resulting composite material was characterized, and its photocatalytic performance against methylene blue dye was studied. Optimal photocatalytic degradation was achieved at pH 9.0, using 40 mg of MoS₂ and 1.0 g of the composite hydrogel, resulting in a dye degradation efficiency of approximately 88.6% within 120 min. Kinetic studies indicated that the photodegradation of methylene blue dye followed second-order kinetics (R² = 0.989). Radical scavenging experiments revealed that superoxide radicals (left( { cdot {text{O}}_{2}^{ - } } right)), hydroxyl radicals (left( { cdot {text{OH}}} right)), and holes (h⁺) played predominant roles in the degradation process. Additionally, the composite hydrogel demonstrated promising reusability, retaining over 60% of its removal efficiency after four successive photocatalytic cycles.

Graphical Abstract

A palladium-catalyzed oxidative intramolecular cross-dehydrogenative coupling (CDC) strategy has been developed for the efficient synthesis of a novel class of polycyclic fused heterocycles, namely 9-tosyl-9H-indolo[3,2-c][1,2,3]triazolo[1,5-a]quinolines. This synthetic approach involves a sequential process consisting of Sonogashira coupling, cyclization, and oxidative C–H/C–H cross-coupling between indole and triazole moieties to deliver the desired fused products. The protocol proceeds under mild reaction conditions, utilizing palladium acetate as the catalyst, copper acetate hydrate as the oxidant, and acetic acid as an additive in DMF, enabling efficient annulation to construct complex molecular frameworks in moderate to good yields. A diverse range of substrates were explored to evaluate the scope and functional group tolerance of this method. The structures of the synthesized compounds were fully characterized by NMR spectroscopy, high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction analysis. This methodology offers several advantages, broad substrate scope, operational simplicity, and avoidance of pre-functionalized substrates. Overall, this work expands the synthetic utility of palladium-catalyzed CDC reactions for the efficient construction of structurally complex fused polycyclic heteroaromatic compounds, which are of potential interest in pharmaceutical chemistry, materials science, and optoelectronic applications.

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The design of cooperative catalytic systems inspired by nature represents a significant advancement in organic synthesis. In this research, the selective aerobic oxidation of primary and secondary alcohols to the corresponding carbonyl compounds was investigated using molecular oxygen as a green oxidant in the presence of a heterogeneous biomimetic catalytic system consisting of palladium, a sandwich-type polyoxometalate [(OCe)₃(PW₉O₃₄)₂]¹²⁻, and hydroquinone (HQ). In the first method, palladium nanoparticles were immobilized on siliceous mesocellular foam (MCF), while the polyoxometalate (POM) was supported on Nd-doped TiO₂ nanoparticles. Then, the aerobic oxidation of alcohols to the corresponding carbonyl compounds was investigated in the presence of the Pd@MCF/POM@TiO₂/HQ catalytic system in THF solvent at 40 °C. In the second method, both palladium and polyoxometalate were simultaneously immobilized on MCF and POM-Pd@MCF/HQ was used as an efficient biomimetic catalytic system. The second catalyst showed better performance with yields of 84–97% with TOF values up to 111 h⁻ ¹ in water as solvent at room temperature. Furthermore, the POM-Pd@MCF/HQ system showed the ability to be used for up to 8 consecutive applications with minimal decrease in its catalytic efficiency, indicating its structural stability and recyclability. The Pd@MCF, POM@TiO₂ and POM-Pd@MCF compounds were identified and confirmed by various techniques.

The green synthesis of nanoparticles using plant extracts has gained significant attention as a sustainable, efficient, and cost-effective route in modern nanotechnology. This study presents the green synthesis of ZnO and Cu-doped ZnO nanoparticles using Justicia adhatoda leaf extract via co-precipitation, achieving over 94% degradation of newly tested dyes. X-ray diffraction analysis confirmed that the nanoparticles exhibited a hexagonal wurtzite structure with crystallite sizes ranging from 21 to 22 nm. According to UV–Visible absorption measurements, the band gap of ZnO (3.1 eV) exhibited a noticeable reduction to 2.9 eV following Cu doping. Fourier-transform infrared spectroscopy showed that the functional groups in the leaf extract played a key role in nanoparticle formation. FE-SEM micrographs indicated nanosheet-to-spherical morphology for ZnO, while Cu doping resulted in predominantly spherical particles. HRTEM analysis confirmed the polycrystalline nature of the nanomaterials. X-ray photoelectron spectroscopy verified the presence of Zn²⁺ and Cu²⁺ oxidation states, demonstrating the successful incorporation of Cu into the ZnO lattice. Zeta potential analysis showed that the ZnO nanoparticles possessed a high negative surface charge. The photocatalytic degradation efficiencies of bromophenol blue and fast green dyes were 96% and 94%, respectively. Furthermore, Cu-doped ZnO exhibited significantly enhanced antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Rhizopus, and Penicillium compared to pure ZnO. Overall, this green synthesis approach demonstrates strong potential for wastewater treatment and offers a sustainable strategy for future household wastewater management.

The design and development of efficient catalytic systems for sustainable chemical reactions and transformations is an essential principle. In the present study, the synthesis and application of a magnetic nanocatalyst for biodiesel production from waste cooking oil via transesterification reaction were presented. The catalyst was prepared from silica-coated copper ferrite nanoparticles functionalized with amine groups (CuFe₂O₄@SiO₂-NH₂). The surface, structural, and functional group properties of the catalyst were carefully investigated using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrational sample magnetometry (VSM). Under the optimized conditions obtained (4 wt% catalyst, 1:12 oil to methanol molar ratio, 65 °C) without the need for high energy consumption and advanced equipment, the catalyst showed significant efficiency in biodiesel production. The catalyst is rapidly recovered by applying an external magnetic field and can be reused over several cycles with little activity loss, demonstrating its stability and practical applicability. This study increases the knowledge on the structure–activity relationship of metal oxide-based nanocatalysts and their performance as reaction intermediates in green catalytic processes, thus promoting the development of sustainable energy conversion systems.

This study presents a novel bimetallic iron–silver phosphate (FeAg(PO₄)₂) nanocatalyst. We detail a one-pot hydrothermal synthesis of FeAg(PO₄)₂, a hetero-structured composite dominated by silver phosphate (Ag₃PO₄) and iron (III) phosphate (FePO₄). Characterization techniques include X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV–Vis diffuse reflectance, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis, transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray mapping, revealing a mesoporous structure with a surface area of 55.60 m²/g and a pore size of 2 nm. Machine learning, particularly the Random Forest Tree model, predicted energy per atom of − 7.17 eV, and a band gap of 1.87 eV, indicating high stability and suitability for catalysis. The nano-catalyst showed high efficiency in synthesizing benzimidazole derivatives (up to 95% yield in 10 min at 60 °C in ethanol) and was reusable for five cycles. It also demonstrated selective fluorescence quenching for L-cysteine detection, with sulfur-containing amino acids exhibiting higher fluorescence. The study concludes with potential applications in pharmaceuticals and sensing, encouraging further research.

This study demonstrates the successful use of polyimide (PI) as a support material to fabricate hierarchical porous V₂O₅@PI composite materials via hydrothermal synthesis followed by calcination. PI support exhibited a distinctive honeycomb-like porous structure. V₂O₅ loading induced a remarkable morphology evolution. The VO50 catalyst (50 wt% V₂O₅ loading) exhibited a “flower-like” microsphere structure composed of assembled nanosheets. XPS analysis confirmed the coexistence of V⁴⁺ and V⁵⁺ species in VO50. Both specific surface area and pore volume were found to decrease gradually with increasing V₂O₅ loading, likely due to the blockage of pores by vanadium species. The developed V₂O₅@PI composite materials were applied to the ammoxidation of p-chlorotoluene for the synthesis of p-chlorobenzonitrile. The VO50 catalyst exhibited outstanding performance under optimized conditions, achieving a yield of 65.5% and a selectivity of 76.3% toward p-chlorobenzonitrile—both significantly higher than those obtained with the unsupported V₂O₅ catalyst. The excellent performance of the VO50 catalyst could be attributed to its stable flower-like morphology, high specific surface area, high dispersion of vanadium species, and full exposure of active sites. The present study demonstrates that PI can serve as an ideal support for high-performance vanadium-based ammoxidation catalysts. The developed VO50 catalyst shows great potential for industrial-scale aromatic hydrocarbon ammoxidation applications.

Graphic abstract

The development of efficient photocatalysts for nitrogen fixation is often hindered by limited visible-light absorption. In this work, a series of UiO-66 materials (UiO-66, UiO-66-Br, UiO-66-NH₂, and UiO-66-NO₂) with different functional groups were synthesized through solvothermal reaction, which showed diverse light harvesting ability. Among them, UiO-66-NH₂ exhibits the superior photocatalytic performance, achieving an ammonia production rate of 11.59 μmol g⁻¹ h⁻¹, which is 2.38 times higher than that of the pristine UiO-66. Comprehensive characterization reveals that the electron-donating –NH₂ group extends the light absorption into the visible region and significantly enhances the separation and migration of photogenerated charge carriers. This study highlights the efficacy of ligand functionalization in tailoring metal–organic frameworks for efficient solar-driven nitrogen fixation.

Graphical abstract

The introduction of –NH₂ group significantly enhanced the photocatalytic nitrogen fixation (transforming N₂ into NH₄⁺) activity of UiO-66.