Applied Organometallic Chemistry最新文献

MXenes, a unique family of two-dimensional (2D) transition metal carbides, have attracted growing interest due to their outstanding electrical, mechanical, and catalytic properties. However, traditional synthesis methods often rely on hazardous chemical etchants and complex procedures, limiting their scalability and environmental feasibility. In this work, we introduce a simplified, etchant-free two-step method for transforming tungsten carbide into MXene-like materials, utilizing basic laboratory equipment and moderate temperature conditions. This novel approach involves the initial synthesis of metal carbide nanoparticles followed by their successful delamination in ethanol through a sonication-assisted method. The prepared WC nanoparticle and its MXenes were characterized using FTIR, XRD, Raman, SEM with EDAX, TEM, and XPS analysis. FTIR analysis confirmed the formation of MXenes through the appearance of a new peak at 1232 cm⁻¹ and the weakening of characteristic carbide peaks at 1112 and 832 cm⁻¹. XRD patterns revealed distinct reflections at 32.3°, 35.0°, 41.2°, and 48.0°, alongside a notable reduction in crystallite size from 48.52 nm in carbide to 35.67 nm in MXene. Elemental analysis showed a shift in the tungsten-to-carbon ratio from 1:4 to 1:12, while tungsten signal intensity dropped from 3.2 to 1.8 counts per second, suggesting encapsulation by carbon layers. Morphological transitions were evident in SEM images, evolving from amorphous particles to layered sheet-like structures. TEM imaging further revealed clear lattice fringes at the 2-nm scale. Raman spectroscopy exhibited a blue shift in the A₁g mode from 802to 798 cm⁻¹, indicating enhanced layering. XPS results confirmed surface functionalization and changes in tungsten oxidation states, affirming this method as an efficient, scalable, and environmentally friendly approach to MXene synthesis.

Herein, a porous NH₄Cl-C₃N₄/BiOCl heterojunction is constructed via a facile two-step route: NH₄Cl-assisted thermal exfoliation of g-C₃N₄ and the subsequent in situ deposition of BiOCl nanosheets. The 270NH₄Cl-C₃N₄/BiOCl composite, selected as the optimal photocatalyst, displays Rhodamine B (RhB) degradation rate constants that are 39-fold higher than those of pristine g-C₃N₄ and ninefold greater than those of BiOCl. The corresponding constants for ciprofloxacin (CIP) exceed those of g-C₃N₄ and BiOCl by a factor of 28 and 3, respectively. The robust activity (90.0% retention after five cycles) and sunlight-driven operation within minutes highlight its practical potential. Comprehensive characterization reveals that the thermal decomposition of NH₄Cl generates gases in situ, and their violent release directly enlarges the specific surface area and creates abundant mesopores, intensifying light harvesting and providing rich active sites. The cooperative promotion of photon harvesting within the visible spectrum and efficient segregation of photogenerated carriers was realized through interfacial heterojunction construction and enlarged surface area, which has been confirmed by SEM, TEM, BET, DRS, PL, RIS, and photocurrent response. In addition, radical-scavenging investigations conducted throughout RhB degradation demonstrate that h⁺ is the dominant oxidative species, whereas •O₂⁻ and •OH fulfill a secondary function. This was further confirmed by band gap analyses and Mott Schottky. This study presents a straightforward and efficient approach for modulating 2D carbon-nitride architectures and provides insights for designing high-performance heterojunction photocatalysts.

In recent years, graphitic carbon nitride (g-C₃N₄) containing nitrogen vacancies has been widely used as a photocatalyst in CO₂ reduction reactions. The introduction of transition metals into this system helps to improve its photocatalytic performance, but regulating the synergistic effect of nitrogen vacancies and metal sites has always been a challenge. In this work, we synthesized a composite material featuring metal Co species anchored on g-C₃N₄ with nitrogen vacancies (Co/Nv-WCN) through the molten salt method combined with the simple chemical reduction method, achieving a sea urchin-like morphology. The experimental results reveal that the concentration of nitrogen vacancies in the composites was successfully controlled by trace H₂O during the molten salt synthesis system. The as-prepared Co₁₀/Nv-WCN-L sample (by trace-H₂O-derived) with optimal nitrogen vacancies achieves a CO production rate (252.2 μmol g⁻¹ h⁻¹), demonstrating one-fold activity as much as that of Co₁₀/Nv-WCN-M with excessive vacancies (by free-H₂O-derived, 132.2 μmol g⁻¹ h⁻¹), and surpassing the performance of the corresponding reference materials. The excellent photocatalytic activity is attributed to the synergistic effect between the appropriate concentration of nitrogen vacancies and Co species, which is also proved by the photoelectrochemical characterization. This study provides new insights for designing efficient, low-cost, and durable CO₂ reduction photocatalysts.

Fluorescent Gram-positive staining probes have become excellent and novel methods for flow cytometry and fluorescence microscopy. However, there are still few commercially available materials of this type. Recently, boron Schiff bases (BOSCHIBAs) have shown advantages such as low cytotoxicity, good cell staining capability, low-cost synthesis, tunable optical properties, and simple synthesis procedures. Herein, we report an effective multi-component synthesis of two new fluorescent molecular rotors (FMRs) derived from amino acids (1: phenylalanine and 2: tryptophan) and benzene 1,4-diboronic acid. The FMRs were fully characterized by nuclear magnetic resonance (NMR; ¹H, ¹³C, and ¹¹B), and high-resolution mass spectrometry (HRMS). The molecular structure by X-ray diffraction of rotor 1 is reported. Compound 1 exhibited higher fluorescence intensity compared with the tryptophan-derived compound 2. However, compound 2 showed high sensitivity to viscosity changes. Density functional theory (DFT) calculations were performed to understand the optical properties and photophysical mechanisms, considering changes in selected dihedral angles in the first excited state (S₁). According to time-dependent density functional theory (TD-DFT), molecular excitation promotes an intramolecular charge transfer (ICT) process that induces structural reorganization in the excited state. An increase in solvent viscosity affects the photoinduced conformational changes, favoring radiative deactivation in specific conformations. Both compounds showed low cytotoxicity in human and bacterial cells at concentrations ranging from 0.1 to 5 μg/mL and 2 μg/mL, respectively. Fluorescent bioimaging assays revealed that human cells (HUVEC, HeLa, and erythrocytes) did not show a staining pattern, in contrast to E. coli and B. subtilis, demonstrating that compounds 1 and 2 exhibited affinity and specificity for bacterial cells.

The catalytic conversion of CO₂ into industrially relevant chemicals offers a sustainable pathway for carbon mitigation, yet most existing methods require harsh reaction conditions. In this work, a series of substituted cobalt (II) dibenzoylmethane complexes (Co(x-dbm)₂) were applied to enable efficient CO₂ fixation with epoxides or aziridines at ambient pressure. Systematic substituent screening demonstrated that electron-donating groups (CH₃, t-Bu) significantly enhanced the catalytic activity in both CO₂/epoxide and CO₂/aziridine systems. For epoxide coupling, the optimized catalyst achieves up to 96% epoxide conversion and > 99% selectivity for cyclic carbonates at 40°C with only 0.5 mol% catalyst loading. Parallel experiments highlighted that electron-donating substituents simultaneously strengthen metal–ligand coordination and improve solubility, synergistically boosting catalytic efficiency. For aziridine coupling, 63% aziridine conversion with 92% oxazolidinone selectivity was attained at 40°C using tetrabutylammonium bromide (TBAB) as cocatalyst, whereas 86% aziridine conversion and 87% selectivity were achieved at 80°C with tetrabutylammonium chloride (TBAC) as cocatalyst. The balance between nucleophilicity (driving aziridine ring-opening) and leaving-group ability (facilitating ring-closure of the intermediate carbamate salt to form the oxazolidinone) of the halide anions (XCl, Br, I) in tetrabutylammonium cocatalysts (TBAX) influenced both activity and selectivity, demonstrating the comparable rates of the ring-opening and ring-closing steps.

The integration of catalysts with a dielectric barrier discharge (DBD) plasma reactor offers an efficient strategy for catalyzing CO₂ hydrogenation into C₂–C₄ hydrocarbons under mild conditions. The reduced Ni-based catalyst from perovskite has good metal dispersion, anti-sintering ability, and low cost, demonstrating significant potential for industrial applications. To further increase the yield of the target product, it is necessary to optimize the structure of the catalyst and improve CO₂ hydrogenation performance. Since the Ni content in highly ordered perovskites is relatively low, it is more likely to form small Ni particles after reduction. Therefore, we focus on preparing the Ni catalyst from the perovskite-like materials to increase Ni content and modify its morphology to improve the selectivity of C₂–C₄ hydrocarbons in the CO₂ hydrogenation process. A series of perovskite-like precursors with different La contents including LaNiO₃, La₅Ni₄O₁₃, La₃Ni₂O₇, La₇Ni₄O₁₅, and La₂NiO₄ were synthesized. The Ni-based catalysts derived from these precursors were investigated in a DBD plasma-catalysis system for CO₂ hydrogenation to C₂–C₄. Among them, the Ni-based catalyst from La₃Ni₂O₇ exhibited high reactivity at a discharge power of 55 W, achieving high CO₂ conversion of 69.2% and C₂–C₄ selectivity of 8.5%. Characterization results including XRD, N₂ adsorption–desorption, TEM, and H₂-TPR demonstrated that the superior CO₂ hydrogenation performance of La₃Ni₂O₇ is attributed to its enhanced surface area, high density of oxygen vacancies, abundant medium basic sites, and highly dispersed active metals. In addition, the catalyst exhibited exceptional thermal stability and sintering resistance, as evidenced by the fact that there was no significant difference in the structure and morphology of the catalyst after the reaction. This provides a promising pathway for converting carbon dioxide to value-added chemicals.

In this study, four metal complexes [VL (phen)], [RuL (phen)], [VL (bpy)] and [RuL (bpy)]—were synthesized and structurally characterized using comprehensive analytical and spectral techniques. Density functional theory (DFT) calculations (B3LYP) were employed to examine their electronic properties and reactive sites, while molecular docking studies revealed strong hydrogen-bonding interactions of the furan, thiazole, bipyridine, and phenanthroline moieties with Mpox and COVID virus receptor proteins. Key metal–ligand interactions, notably oxygen coordinated to vanadium and chlorine coordinated to ruthenium, exhibited high binding affinity. In silico ADMET profiling indicated drug-like properties but also highlighted potential limitations in oral bioavailability due to high molecular weight, lipophilicity and low solubility. To enhance predictive modelling, a molecular gradient evolution optimizer (MoGEO)—driven artificial neural network (ANN) framework was developed, integrating molecular energy shifts and docking interaction data into the learning process. The ANN-MoGEO approach achieved superior accuracy in predicting synthesis yields, docking scores and spectral peaks, outperforming conventional optimizers. These findings not only deepen the understanding of Ru (III) and V(V) complexes but also demonstrates ANN-MoGEO's potential as a powerful tool for molecular property prediction in drug design.

The C–F bond is one of the strongest single bonds in chemistry, making its activation a significant challenge in organic synthesis. Herein, we report a novel heterogeneous and base-free protocol for the site-selective arylation of indoles using fluorobenzene derivatives, enabled by a copper–zinc oxide–Schiff base nano–catalyst (Cu–ZnO–Scb). This strategy enables efficient C-2 and C-3 arylation of indole, yielding indole-aryl conjugates in good yield with broad tolerance to functional groups. FE-SEM, EDS with elemental mapping, HR-TEM, FTIR, XPS, P-XRD, UV, and BET were used to characterise the catalyst comprehensively. Notably, the development of a robust, reusable, and heterogeneous catalytic system for direct C–F bond activation under mild conditions represents a significant advancement in sustainable organic synthesis. This study highlights the growing importance of heterogeneous nanocatalysts as a versatile system for overcoming long-standing challenges in C–F bond activation and for streamlining the synthesis of structurally complex organic scaffolds.

Based on the policy of building a beautiful China and the increasing demand for natural gas, the technology of converting coal to natural gas is receiving more and more attention. The Ni-based methanation catalyst is prone to being poisoned and deactivated because coal-based synthesis gas contains sulfides. Therefore, it is urgent to develop a sulfur-tolerant methanation catalyst. MoS₂/CeO₂–Al₂O₃ sulfur-tolerant methanation catalysts were prepared with a DBD plasma fluidized bed. The effect of plasma atmospheres (Ar, H₂, and air) and promoters (Ni and Co) on catalyst structure and performance was studied. It was found that catalysts pretreated in an air atmosphere exhibited the highest CO conversion, which is over 10% higher than that in Ar and H₂, and CH₄ selectivity is also 8.94% higher than traditional calcination. Co doping resulted in more S vacancies in the catalyst, increasing its activity to 36.42%. Ni is more attached to the carrier in the form of oxides, forming Ni₃S₂ after sulfurization, which covers some of the hydrogenation active sites and leads to a decrease in activity.

Two new types of osmium complexes, PNN-osmium complex (Os1) and NN-osmium complex (Os2) have been developed and proven to be effective catalysts for the transfer-dehydrogenative (TDH) oxidation of various (hetero)aromatic, cycloalkyl, and aliphatic alcohols to the respective ketones (55 examples). Notably, both complexes have been fully characterized and their comparative performance as catalysts investigated; Os1 has been further proven more effective in TDH oxidation of alcohols with a high turnover number (TON) reaching up to 63,000. Comparative experiments and DFT computations indicate that PNN-complex Os1 exhibits higher reactivity in transfer-dehydrogenative reactions than its NN counterpart Os2 due to the steric hindrance of catalysts. A joint theoretical and experimental investigation further shows that the current osmium system follows an outer-sphere bifunctional mechanism, which involves the transformation between osmium hydride and amido-osmium species. Furthermore, these osmium catalysts show great potential promise for applications in atom-economic synthesis of ketonic fine chemicals.