Applied Organometallic Chemistry最新文献

The construction of cobalt-based nanozymes (e.g., “nanostructured Co₃O₄ catalysts with enzyme-mimicking activity”) with highly efficient peroxidase (POD)-like activity remains a challenging task, due to the insufficient active sites and inefficient electron transfer. Herein, the flower-like Ni-doped Co₃O₄ (Ni-Co₃O₄) nanozyme was synthesized by a two-step method involving solvothermal and thermal treatment. The uniform doping of Ni improves the dispersibility and specific surface area of Co₃O₄ nanoparticles, and induces the generation of more oxygen vacancies (O_vac) by regulating the surface Co²⁺/Co³⁺ ratio. Compared with Co₃O₄, Ni-Co₃O₄ nanozyme shows much enhanced POD-like activity in buffer (pH 5) and water under ambient temperature (25 ± 2°C). After repeated use for six times, Ni-Co₃O₄ retains more than 80% of the highest activity, proving the excellent reusability. Based on Ni-Co₃O₄, practical colorimetric sensors were constructed for specific detection of H₂O₂ and phenol. Ni doping effectively reduces the formation energy of O_vac on the surface of Co₃O₄ and enhances electron mobility for fast electron transport. The introduction of more O_vac not only lowers the adsorption energy but also changes the dissociation pathway of H₂O₂ on Co₃O₄ nanozyme. This work provides a theoretical basis and experimental reference for the development and application of highly efficient nanozymes.

Herein, we report that directed C–H silylation of indoles and a pyrrole derivative with hydrosilanes in aqueous media under air was achieved under iridium catalysis. This reaction enables the introduction of a silyl group at the C2 position of a wide range of indoles. The protocol represents the first example of a transition metal-catalyzed C–H silylation in aqueous media as a sustainable solvent for C–H functionalization of indoles.

This work focuses on two chiral Ru(II) polypyridyl complexes, Λ-[Ru(bpy)₂(bipp)]²⁺ (Λ-1) and Δ-[Ru(bpy)₂(bipp)]²⁺ (Δ-1, bipp = 2-benzimidazoyl-pyrazino[2,3-f][1,10]phenanthroline) were developed. The stabilizing effects and structural influence of two enantiomers on the RNA triplex were investigated by spectroscopy and viscometry. The results of the UV–vis absorption spectroscopy titration experiments indicate that both enantiomers may bind to the triplex RNA via an intercalation mode, as evidenced by the hypochromic and red shifts observed in the absorption spectrum. Further quantitative analysis demonstrated that, under identical experimental conditions, the Δ-enantiomer exhibited a marginally stronger interaction than its Λ-counterpart. These conclusions were further supported by luminescence spectroscopy and viscosity experiments. Circular dichroism (CD) spectroscopy results indicate that both enantiomers significantly induce conformational changes in RNA triplex complexes, revealing strong intermolecular binding to the RNA triplex. Thermal denaturation analysis demonstrated that both enantiomers significantly and preferentially stabilized the RNA triplex third-strand. However, no significant chiral selectivity was observed in the thermal denaturation data of the present work. This work elucidates the interaction mechanism between chiral ruthenium(II) complexes and RNA triplex, providing a critical theoretical basis for stabilizing RNA triplex.

Ethylene oligomerization, a reaction of significant industrial relevance, was effectively catalyzed by Ni(II) immobilized within two distinct zirconium-based MOFs, namely, UiO-67 and UiO-67bpydc (bpydc = (2,2′-bipyridine)-5,5′-dicarboxylic acid). These frameworks differ in the nature of their anchoring sites, which in turn influences their catalytic performance. Under identical reaction conditions—1730 eq. of Et₂AlCl as co-catalyst, 10 bar of ethylene, 24°C, 1 h, and toluene as solvent—Ni(II) coordinated to the zirconium clusters of UiO-67 exhibited superior catalytic activity compared to Ni(II) bound to the bpydc linkers of UiO-67bpydc (1578 vs. 196 mmol Ni⁻¹ h⁻¹, respectively). Variation in the amount of Et₂AlCl co-catalyst and the applied ethylene pressure revealed that reducing the co-catalyst concentration to 870 eq. enhanced its catalytic activity (1930 mmol Ni⁻¹ h⁻¹) relative to 1730 eq., whereas further reduction led to complete loss of activity. In addition, the optimal ethylene pressure for achieving maximum activity was identified as 10 bar, while reactions conducted at 5 and 20 bar afforded lower activities of 1077 and 1464 mmol Ni⁻¹ h⁻¹, respectively.

Herein, the methods of co-precipitation and hydrothermal treatment were proposed to regulate the promotional effect of COS + CS₂ sulfation on the NH₃-SCR activity of Ce_0.5Fe_0.5O_x catalyst. The results indicated that the co-precipitation method contributed to the formation of Ce-Fe solid solution in Ce_0.5Fe_0.5O_x-CP catalyst, but the further hydrothermal treatment depressed the incorporation of Fe³⁺ into cubic fluorite CeO₂, promoting the formation of Fe₂O₃ crystals while decreasing the defective sites of catalyst. Furthermore, the different interaction of active components not only influenced the NH₃-SCR activity of Ce_0.5Fe_0.5O_x-CP and Ce_0.5Fe_0.5O_x-HT catalysts but also regulated the sulfation of COS + CS₂ on the catalysts surface. The further hydrothermal treatment decreased the concentration of iron species but increased the concentration of cerium species on the Ce_0.5Fe_0.5O_x-CP catalyst surface. COS + CS₂ sulfation increased the surface Ce³⁺/(Ce³⁺+Ce⁴⁺) and Fe²⁺/(Fe³⁺+Fe²⁺) molar ratios of Ce_0.5Fe_0.5O_x-HT effectively but decreased the calculated corresponding values of Ce_0.5Fe_0.5O_x-CP. Furthermore, Ce_0.5Fe_0.5O_x-HT-S exhibited larger deposited surface sulfate, stronger medium–strong acid sites, and more active oxygen than Ce_0.5Fe_0.5O_x-CP-S due to the better surface conversion of COS + CS₂.

Arsenate remediation remains a critical environmental challenge, motivating the development of efficient and scalable adsorbents. Here, we report a comparative study of monometallic Fe-MIL-88B and its bimetallic analogue Fe/Ni-MIL-88B synthesized via microwave-assisted methods, yielding crystalline frameworks with octahedral morphologies (~200 nm) and uniform metal distribution. Comprehensive characterization (XRD, FTIR, SEM, BET) confirms the integrity and porosity of both MOFs after synthesis. Adsorption experiments reveal rapid arsenate uptake for both materials, with equilibrium reached within 30 min. Kinetics follow a pseudo-second-order model, indicating an adsorption process dominated by chemisorption with additional contributions from physisorption, and equilibrium isotherms fit the Langmuir model, consistent with monolayer adsorption on homogeneous sites. Thermodynamic analysis at 298 K shows spontaneous adsorption for both materials: Fe-MIL-88B with ΔG° ≈ −20.6 kJ/mol, ΔH° ≈ −10.0 kJ/mol, and ΔS° ≈ +35.6 J/mol·K, and Fe/Ni-MIL-88B with ΔG° ≈ −24.5 kJ/mol, ΔH° ≈ −11.9 kJ/mol, and ΔS° ≈ +42.5 J/mol·K, indicating more favorable thermodynamics and a stronger entropic drive in the bimetallic framework. The monometallic Fe-MIL-88B exhibits a maximum arsenate capacity of 167.5 mg/g, while the bimetallic Fe/Ni-MIL-88B shows a superior capacity of 207.2 mg/g, demonstrating a clear synergistic enhancement from Ni²⁺ incorporation. Spectroscopic analyses (FTIR and XPS) corroborate the formation of Fe–O–As coordination bonds, supporting a chemically bonded adsorption mechanism, in addition to electrostatic interactions induced by Ni²⁺ sites. The presence of Ni²⁺ also improves structural stability against hydrolysis and maintains porosity after multiple adsorption–desorption cycles, highlighting the practical viability of the Fe/Ni-MIL-88B system for arsenate removal from water. Overall, the study underscores the advantages of integrating secondary metals into MIL-88B MOFs to boost adsorption performance through synergistic interactions, enhanced site diversity, and robust thermodynamic and structural features.

Photocatalytic reduction of O₂ to generate H₂O₂ has aroused more attention due to easily controlling H₂O₂ concentrations and relative green production process in comparison with conventional anthraquinone hydrogenation routes. Herein, an octahedral MIL-68-NH₂(In) modified with a hydrophobic surface was firstly designed and utilized in the visible-light induced photocatalytic H₂O₂ generation. Assisted by the -NH₂ groups of MIL-68-NH₂, the alkyl chain was able to covalently graft to the MIL-68-NH₂ via amidation reactions, and resulting MIL-68-NH₂-R_n demonstrate the hydrophobic nature being regulable through varying the alkyl chain. The hydrophobic surface was then proven to be essential in promoting H₂O₂ evolution in comparison with the unmodified MIL-68-NH₂. The enhanced photocatalytic mechanism analyses demonstrate that the hydrophobic interface is beneficial for H₂O₂ production at the immiscible benzyl alcohol (BA)/water interface. And by regulating the composition of BA and water, the generated H₂O₂ concentrations can be adjusted easily. It is well-known that the H₂O₂ concentration is a key factor to be controlled in the H₂O₂-assisteed reactions, especially in the enzyme catalytic processes. The good structure stability and the excellent photocatalytic activity under acidic conditions endow these MIL-68-NH₂-R_n, the possible applications in the efficient H₂O₂ production, and design the cascade reaction by utilizing the generated H₂O₂ in bio-enzyme catalysis.

Hydrodehalogenation is an important transformation in chemical synthesis and environmental protection. Current synthesis strategies are involved in the use of various additives and expensive hydrogen sources in both homogeneous and heterogenous catalysis system. Na-modified Silicalite-1 zeolite supported Pd catalyst (Pd/Na₃S-1) successfully mediated the dehalogenation reaction using water as a hydrogen source without any additives, outperforming its counterparts on Na-free Silicalite-1 (Pd/S-1) and Beta (Pd/Beta) zeolites in activity. This is because excess Na⁺ ions in S-1 zeolite led to the generation of numerous highly active, electron-deficient Pd^δ+ (0 < δ < 2) and Pd⁴⁺ sites in the Pd/Na-S-1 catalyst, due to the electron transfer from Pd species to nearby Na ion or framework O atom. While Pd/S-1 exhibited a predominance of low-active Pd²⁺ species, and Pd/Beta catalyst contained Pd⁰ species that was primarily responsible for the generation of dehalogenation-coupling product.

The utilization of natural products sodium alginate and L-arginine as raw materials is a facile and efficient route to fabricate supported catalysts for heterogeneous reactions. In this work, the dopant–evaporation–pyrolysis (DEP) strategy was employed to prepare Co incorporated into nitrogen-doped carbon aerogels (Co@CN-larg) from CoZn-MOF-polymer (Co/Zn-MOF@SA-larg), in which Co/Zn-MOF@SA-larg introduced L-arginine (larg) linker as N dopant. The Co/Zn-MOF@SA-larg in N₂ atmosphere enabled in situ evaporation of Zn nodes during pyrolysis process, which could facilitate the derived catalyst with high Co dispersity, large specific surface area, as well as abundant basic sites. All of these unique advantages endow Co@CN-larg with higher catalytic efficiency in comparison with traditional catalysts (Co@CN-mim and Co@CN-urea), along with well stability and recyclability. This DEP strategy may provide a new guideline to synthesize industrial organic catalysis for other catalytic reactions.