New Journal of Chemistry最新文献

It is becoming increasingly challenging to develop environmentally friendly and safe methods for purifying water contaminated with dyes. In this work, we developed a cost-effective and secure strategy for creating an effective adsorbent for the adsorptive removal of RY 18 dye. A biopolymer, namely, tragacanth gum-based Cr-doped MnO₂ NP/clay (GCMC) composite, was fabricated using a one-pot approach for wastewater treatment. Various characterization techniques, including XRD, FTIR spectroscopy, SEM, BET analysis, and zeta potential analysis, confirmed the formation of the adsorbent. The strong diffraction peaks in the XRD pattern of GCMC indicated the high crystallinity of the composite, with the crystallite size estimated to be around 57.69 nm. SEM analysis revealed a well-defined structure consisting of distributed particles with a rod-like morphology having an average diameter of about 5.38 μm. The stability of the GCMC composite was confirmed by zeta potential analysis, which showed a value of −22.42 mV, indicating sufficient electrostatic repulsion between the particles. The adsorption capacity and percentage of removal of RY 18 dye were determined to be 418 mg g⁻¹ and 93.45%, respectively, as confirmed by a UV-visible spectrometer. The Temkin and intra-particle diffusion models were the best isothermal adsorption and kinetic models, with correlation coefficient values of 0.978146 and 0.99962, respectively. The recycling experiment suggested that the prepared adsorbent had high stability. In addition to expanding CO₂ adsorption capabilities, the developed GCMC composite showed outstanding consistency. With increasing CO₂ pressure and adsorption temperature, CO₂ adsorption exhibited endothermic reaction characteristics, as indicated by the higher R² values of 0.9994, 0.9883, and 0.9877. CO₂ adsorption followed the liquid-film diffusion model at 25 °C, 40 °C, and 55 °C. The GCMC composite is a viable option for the adsorptive removal of dyes from polluted water due to its affordable and effective adsorption process.

In the human body, vitamin C or ascorbic acid (AA) plays a vital role in maintaining a strong immune system; it serves as a cofactor for enzymatic reactions, supports collagen synthesis and neutralizes free radicals. However, an abnormal concentration of this antioxidant in the body can lead to serious health concerns. Thus, keeping the AA level within the safe concentration range is crucial for promoting good health. Since AA is not produced by the human body, its accurate quantification in food and pharmaceutical formulations (through which it is ingested) constitutes a golden opportunity to make necessary actions concerning AA concentration in the body. Herein, a nanocomposite consisting of graphitic carbon nitride (gC₃N₄) and pristine multi-walled carbon nanotubes (CNTs) is proposed as an electrode material for AA electroanalysis in vitamin C tablets and orange juices. Physical characterization confirmed the successful synthesis of gC₃N₄ and the distribution of CNTs over its layers. Various electrochemical studies revealed the strong affinity of gC₃N₄ towards AA, exhibited the great ability of CNTs to enhance the electron transfer kinetics at the sensor-electrolyte interface and indicated that the overall electrochemical kinetics at the sensor surface is diffusion-controlled. Under optimal conditions, the sensor calibration, carried out in the concentration range of 1 to 9 μM, revealed a sensitivity, LOD and LOQ of 5.16 ± 0.07 μA μM⁻¹, 1 nM and 2.5 nM, respectively. Interference study and real sample analysis evidenced the high potential of the sensor for AA electroanalysis in pharmaceutical formulations and fruit juices.

Addressing environmental and biological issues requires the fabrication of multifunctional nanocomposites that provide photocatalytic and antibacterial functions. In this study, we report the successful formulation of a ternary nanocomposite composed of poly(para-phenylenediamine) (poly(pPD)) and Ag nanoparticles (NPs) synthesized from Nigella sativa seed extract, decorated on multi-walled carbon nanotubes (MWCNTs). The nanocomposite was characterized by spectroscopic and microscopic techniques, which demonstrated that MWCNTs and spherical Ag NPs were integrated into the polymer matrix. The ternary poly(pPD)/MWCNT@Ag NP nanocomposite exhibited greater antibacterial activities against Gram-positive and Gram-negative bacterial strains than the binary poly(pPD)/MWCNT nanocomposite. The enhanced antibacterial effect was due to the presence of Ag NPs in the ternary nanocomposite. The enhanced conductivity of the nanocomposite compared to pristine poly(pPD) indicates its improved interfacial compatibility with the nanofillers, potentially allowing efficient charge separation and transfer, and producing a degradation value of 89.6% for methylene blue under visible light. The ˙OH, ˙O₂⁻, and h⁺ species might synergistically contribute to this photocatalytic degradation. We evaluate the benefits of polymer isomerism, carbon nanotube support, and green-synthesized silver nanoparticles (Ag NPs) in developing a sustainable multifunctional nanocomposite for environmental remediation and antibacterial applications.

Supported metal catalysts exhibit excellent catalytic activity in N₂ activation and serve as crucial materials for NN triple bond cleavage. However, the mechanism of supports in facilitating this bond cleavage and its relationship with the N₂ activation energy barrier (E_a) at the atomic and electronic level remain unclear. In this study, we employed density functional theory (DFT) calculations to investigate the structures, energetics, orbital interactions, and electron transfer during N₂ activation on Ru single-atom catalysts (Ru-SACs) with and without supports. From the perspective of catalysts, we demonstrate that catalysts with electron-withdrawing supports are more conducive to N₂ activation. From the perspective of mechanism, the electronic metal–support interaction (EMSI) modulates the E_a of the N₂ activation on supported Ru-SACs by regulating the electron transfer (ET) between the Ru atom and supports. Furthermore, the synergistic effect of EMSI and N₂ adsorption controls the energy separation (E_d) between the d-band center (ε_d) and the Fermi level (E_f) of the Ru 4d orbits, thereby modulating the E_a of N₂ activation. The ET and E_d are two potentially important catalyst descriptors affecting the E_a value. Some key findings about the effect of the support in the Ru-SAC systems are rather consistent with those in the case of dual Ru and Os atom catalysts, which have much lower E_a. As a whole, this report provides deeper insights into the effect of the support on single and dual atom metal catalysts for N₂ activation, and can help design better ammonia-synthesis catalysts in the future.

The synthesis of uracil derivatives and their conversion to a number of potential compounds have drawn attention of researchers aiming to develop innovative materials. Therefore, a novel azo ligand, 1,3-dimethyl-5-(5′-methyl-3′-isoxazolyl-azo)-6-aminouracil (H₂L, 1), was synthesized from 1,3-dimethyl-6-aminouracil and 3-amino-5-methyl-isoxazole. Compound 1 was converted to an 8-azaxanthine derivative, 1,3-dimethyl-8-(5′-methyl-3′-isoxazolyl)azaxanthine (2), via its reaction with Cu(NO₃)₂·6H₂O in DMF solution. Alternatively, when 1 reacted with Cu(CH₃COO)₂·H₂O in the presence of NaN₃ in methanol, an antiferromagnetic Cu(II) complex (3) was formed, where Cu(II) is found to be coordinated with the in situ-generated novel ligand 1,3-dimethyl-5-(but-2-one-3-ene-4-amino-azo)-6-aminouracil (L¹) and azide ions. The structures of these compounds (1–3) were characterized using single crystal X-ray analysis. Complex 3 is a tetrameric assembly of Cu(II) with a nearly parallelogram shape. Its Cu(II) centers are interconnected through doubly end-on azide (μ_1,1-azide) bridges and doubly end-to-end azo (μ_1,2-azo) bridges. The theoretical study shows the presence of non-covalent interactions, including H-bonding and stacking interactions. Magnetic studies of 3, a nearly parallelogram tetranuclear Cu(II) unit with side lengths of 3.7839(6) Å and 4.7727(8) Å, revealed that it possesses strong antiferromagnetic interactions, as evidenced by its exchange coupling constant J₁ = −250 (1) cm⁻¹ through end-on azide bridging between the Cu(II) ions (Cu–N–Cu, 116°). Thus, the present study not only introduces a strong antiferromagnetic material, but also establishes a notable correlation between its structure and magnetic properties.

A series of metal-coordinated chromium–bis(diphenylphosphino)amine (Cr–PNP) catalysts were synthesized for highly selective ethylene oligomerization. Catalyst precursors were prepared by incorporating different metal additives (Fe(III), Fe(II), Co(II), and Ni(II)) alongside Cr(III) into PNP ligands, followed by activation with methylalumoxane (MAO) prior to catalytic testing. Structural characterization of the PNP ligand, Cr–PNP, and Ni–Cr–PNP complexes was conducted using NMR, FT-IR, UV-Vis, and ESI-MS spectroscopy to confirm coordination geometries. Comparative evaluation of ethylene oligomerization performance—including catalytic activity and 1-hexene/1-octene (1-C6/1-C8) selectivity—revealed that nickel doping significantly enhanced both total activity and C8 selectivity. Response surface methodology identified optimal process conditions, and reaction kinetics were modeled using the Ni–Cr–PNP catalyst. Density functional theory (DFT) simulations proposed a reaction pathway and exhibited alignment between the kinetic model's apparent activation energy (E_a) and DFT-calculated free energy barriers. This study establishes a bimetallic cooperative catalytic system, providing a foundation for developing advanced oligomerization catalysts.

Transition metal chalcogenides are promising electrode materials for electrochemical supercapacitors; however, their performance is often hindered by restacking issues during energy storage processes. Alternatively, integrating MXene nanosheets with chalcogens such as tellurides can effectively mitigate these issues. Thus, this study explores the potential of NiCoTe₂ (bimetallic tellurides) for energy storage applications, highlighting that the synergistic interaction existing between MXene (Ti₃C₂T_x) and NiCoTe₂ significantly enhances their electrochemical performance. Initially, NiCoTe₂ nanorod arrays were synthesized via a hydrothermal method, and the NiCoTe₂/MXene composite was subsequently developed using a sonochemical approach. Subsequently, electrochemical characterization of the composite, employing a graphite sheet (GS) as the working electrode, demonstrated a high specific capacity of 582 mAh g⁻¹ at a current density of 1 A g⁻¹ within the negative potential range. Moreover, the asymmetric supercapacitor device, NiCoTe₂/MXene||AC, delivered a specific capacity of 298 mAh g⁻¹ at 1 A g⁻¹, along with exceptional cyclic stability (94% capacity retention after 10 000 cycles), an energy density of 83.38 Wh kg⁻¹, and a power density of 577.24 W kg⁻¹. Thus, the results underscore the potential of this composite for application in practical energy storage systems.

A new route for the multicomponent construction of exclusively C3-unsubstituted iminocoumarin derivatives has been achieved in good yields using CaC₂ as a solid alkyne source along with o-hydroxyaryl aldehyde/ketone, and sulfonyl azide as precursors. The developed Cu(I)-catalyzed transformation proceeds efficiently at room temperature and is scalable up to the gram level. Experimental studies and DFT calculations were performed to assess the feasibility of critical steps in the reaction pathway. The reaction was found to proceed via a keteneimine intermediate, with dinuclear copper species playing a pivotal role in stabilizing the transition state over monomeric counterparts.

Vinylphosphonate scaffolds are found frequently in diverse functional molecules. Herein, a novel reaction of phosphite triesters with nitrocyclopropanes via in situ generated key intermediate allenes was realized. By this strategy, vinylphosphonate derivatives were synthesized in moderate to excellent yields (up to 95% yield) with regio- and E-stereo-selectivities. Moreover, the reaction is operationally simple, mild, and transition metal-free, uses a simple inorganic base, and can be carried out on a gram scale.

We synthesized fluorescent 10H-pyrido[1,2-a]-5-indolium salts and studied the variations in their optical and structural properties with different counteranions. Spectroscopic and crystallographic analyses revealed anion-dependent changes in absorption coefficients, fluorescence intensity, and intermolecular interactions. Furthermore, the compounds exhibited aggregation-induced emission (AIE) behavior. These findings highlight the potential of anion control for tuning the fluorescence behavior of advanced dyes and photofunctional materials