Transition Metal Chemistry最新文献

The mechanical, thermodynamic, and electronic characters of TiFe intermetallic compounds were examined on basis of density functional theory. The stability of TiFe at 0–100 GPa was proved by phonon spectrum and the born mechanics stability criterion. Firstly, the results of Poisson’s ratio, B/G and Cauchy pressure showed TiFe is a ductile material under high pressure. The elastic anisotropy index A^U indicated TiFe is an anisotropic material, and its degree of anisotropy decreases with increasing pressure. Furthermore, empirical formulas were employed to calculate the Debye temperature, minimum thermal conductivity, and melting point of TiFe. Finally, the band structure illustrated that TiFe maintains stable metallic properties under 0–100 GPa. These calculated results might have important reference significance for the industrial application in the future.

Refractory transition metal carbides are of interest due to their high melting point and hardness. This work demonstrates the synthesis of transition metal carbides, such as TiC, VC, ZrC, NbC, HfC, and TaC, by vacuumless electric arc method. Numerical simulation of heat transfer processes in the reaction zone was implemented to predict the parameters (temperature and reaction duration) ensuring synthesis and dominance of the corresponding metal carbide phases over by-products. The obtained parameters were used for a series of experiments conducted to confirm the production of transition metal carbides under specified conditions during arc discharge plasma synthesis. The fabricated materials were analyzed by X-Ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy techniques in order to assess the parameters of the structure, chemical composition, and particle morphology of the synthesized products. The oxidation properties of each monocarbide were studied by differential thermal analysis, thermal gravimetry and differential scanning calorimetry.

Two new metal complexes containing the ligand thiobenzamide (TBz), with the formula cis-[RuCl(TBz)(L)₂]PF₆, where L = 2,2’-bipyridine (bpy) or o-phenanthroline (phen), were synthesized and characterized by cyclic voltammetry and spectroscopic techniques (UV–Vis, IR, ¹H and ¹³C NMR). These compounds showed cytotoxic activity in all cancer cell lines studied. The HL-60 strain was the most sensitive to both metal complexes, with IC₅₀ ranging from 1.5 µmol L⁻¹ to 5.7 µmol L⁻¹. Interestingly, [RuCl(TBz)(bpy)₂]PF₆ exhibited a significant selectivity index of 6.6 for the cytotoxicity ratio between normal cells (MRC-5) and cancer cells (HL-60). In addition, this metal complex promoted mitochondrial membrane depolarization and increased mitochondrial superoxide production. Finally, synergism was observed between [RuCl(TBz)(bpy)₂]PF₆ and doxorubicin in combination against a cell model with HL-60 cells. A combinatorial index of 0.27 was observed in this study. In addition, an isobologram study showed points below the isobolographic line, indicating a synergistic effect. These results show promising pharmacological potential for these compounds which deserve further biological investigation.

Electrocatalytic hydrogen production holds great promise as a means of generating green energy. In order to achieve the large-scale industrial application, low-cost and highly efficient electrocatalysts are the key factors. The open mesh nanosheet array structure and doping can expose more active sites and effectively enhance electron transport during the hydrogen evolution reaction. Herein, a simple nanostructured electrocatalyst consisting of nitrogen-doped NiS₂ nanosheets array grown on carbon fiber cloth (N-NiS₂/CF) has been constructed. Benefiting from its nitrogen-doped, nanosheets array and intrinsic pyrite like structure, the optical N-NiS₂/CF electrode exhibits relatively excellent catalytic activity and long-time stability in both alkaline and acidic media. Especially, to drive the current density of 10 mA cm⁻², only an overpotential of 96 mV and 163 mV were needed in 1.0 M KOH and 0.5 M H₂SO₄, respectively. The as obtained N-NiS₂/CF can be a promising non-noble-metal electrocatalyst for practical hydrogen production application.

In this study, a nickel iron-titanate (NiFeTiO₃) perovskite composite was prepared newly and its photocatalytic activity was evaluated under visible light irradiation. The composite material was prepared by a synthetic method combining the sol–gel method and the solvothermal method. The physicochemical and optical properties of the prepared NiFeTiO₃ perovskites were investigated. In this study, a newly prepared NiFeTiO₃ perovskite composite was evaluated for its photocatalytic activity under visible light irradiation. The composite material was synthesized using a combination of the sol–gel method and the solvothermal method. The physicochemical and optical properties of the prepared NiFeTiO₃ perovskites were investigated. The perovskite composites with the NiFeTiO₃ structure had excellent absorption ability for visible light above 800 nm. Its bandgap energy was found to be approximately 1.8 eV. The photocatalytic activity of the NiFeTiO₃ composite was evaluated under visible light irradiation. The NiFeTiO₃ had superior visible light absorption ability compared to NiTiO₃. It had excellent decomposition performance for methylene blue and formaldehyde. In addition, the photocatalytic activity for sterilizing pathogenic bacteria was much higher than that of NiTiO₃ perovskite. In the water splitting by solar energy, the NiFeTiO₃ catalysts produced hydrogen through a photocatalytic decomposition reaction. The NiFeTiO₃ composite was considered a perovskite composite with significantly improved photocatalytic function due to its high sensitivity to visible light.

Two novel 2,5-diketopiperazine-N,N′-diacetic acid-based (H₂DPDA) metal complexes [Mn(DPDA)_0.5(phen)₂H₂O]₂Cl₂·2H₂O (1) and {[Cu(DPDA)(phen)H₂O]·4H₂O}_n(2)(H₂DPDA = 2,5-diketopiperazine-N,N′-diacetic acid, phen = phenanthroline) have been hydrothermally synthesized, and the relationship between magnetism, fluorescence and structure was investigated. Crystal structure analysis shows that (1) 1 and 2 belong to the triclinic crystal system, the p-1 space group; (2) 2 shows a 1-dimensional zigzag chain structure. Thermogravimetric analysis shows that the complex 1 has better stability than 2. Magnetic measurements show that 1 exhibits antiferromagnetism but 2 exhibits ferromagnetism. Fluorescence test shows that 1 and 2 have luminescent properties and emits blue fluorescence.

Among the various peroxides that are available, meta-chloroperbenzoic acid (mCPBA) is an effective oxidizing reagent that is used in a variety of oxidative transformations, including rearrangements, oxidation of different functional groups, and the formation of carbon–carbon and carbon–heteroatom bonds. This mini-review aims to emphasize on properties, structures, and reactivities of intermediate species involved in the representative metal-assisted contributions of mCPBA in organic synthesis and catalysis along with its scope, merits, and demerits of the reaction from mid-2015 to date.

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