Transition Metal Chemistry最新文献

Scientists and researchers are constantly striving to enhance the energy storage capacity, power density, and cycle life of supercapacitors. In this study, we comparatively analyse the electrochemical performance of molybdenum trioxide forming composites with graphite or tungsten trioxide or manganese dioxide for supercapacitor material application. The elementary behaviour is analysed using different characterization techniques like X-ray diffraction, FTIR, and SEM. The composites of MoO₃ with graphite and WO₃ demonstrate weaker performance while that with δ-MnO₂ shows excellent performance with a specific capacitance of 208 F/g at 10 mV/s. This enhancement is attributed to the synergistic effect between MoO₃ and δ-MnO2, stemming from the layered structure and faradaic redox activity of MnO2, which facilitates improved charge storage via pseudocapacitance. Moreover, δ-MnO₂ accounts for superior reversibility of the redox reactions compared to other samples, and the reduced Rct and ESR values suggest improved conductivity and lower internal resistance, which support fast electron and ion. The weaker performance of graphite and WO₃ is attributed to its irreversibility and the hindrance to the electrolytic ions. These findings underscore the potential of MoO₃/δ-MnO2 as a promising electrode material for advanced energy storage devices.

Reactions of ferrous or ferric sulphates with the chelating diamine ligands bpy (2,2'-bipyridine) and phen (1,10-phenanthroline) in methanol/water solution yielded two new complexes, a green Fe^III complex [Fe₂(bpy)₂(H₂O)₂O(SO₄)₂]·3H₂O 1 and dark red complex [Fe(phen)₃](SO₄)·8.4H₂O 2. Both complexes were characterized using chemical and spectroscopic methods (IR, UV–Vis). Single-crystal X-ray study showed that 1 exhibits molecular structure formed of dinuclear complex molecules comprising {Fe–O–Fe} structural unit with close distance between the deformed octahedrally coordinated Fe atoms (3.1857(8) Å) and the unit cell content is completed by water solvate molecules. The crystal structure of 2 is ionic and is formed of [Fe(phen)₃]²⁺ complex cation, sulphate anion and water solvate molecules. The temperature dependent magnetic study of dinuclear complex 1 revealed strong antiferromagnetic interaction between the two Fe^III atoms which both are in HS state at all temperatures. The theoretical calculations predict strong antiferromagnetic interaction in dimers, and the analysis of magnetic data yields J/k_B = −315.4 K. The thermal behaviour of both complexes 1 and 2 was studied in both oxidative (air) and inert (nitrogen) atmospheres. The thermal decomposition in all cases started with dehydration at 90 °C 1 and 80 °C 2; the dehydrations were followed by temperature dependent IR spectroscopy for complex 2. In both atmospheres, the solid residues consisted of nanosized oxides (α-Fe₂O₃), as corroborated by scanning electron microscopy, while energy-dispersive X-ray spectroscopy confirmed the homogeneity of the resulting oxides.

The present study effectively utilizes the Crassostrea angulata (oyster) marine waste shell to prepare biocompatible titanium (Ti) doped hydroxyapatite (Ti/HAp) through the most popular and widely researched precipitation technique. The prepared Ti/HAp sample was extensively characterized by FTIR, XRD, FE-SEM, EDX mapping, HR-TEM, together with SAED patterns. The extremely intense peak in XRD diffractograms and the absorption peaks in FTIR (groups such as PO₄³⁻, OH⁻, and CO₃²⁻) confirm the formation of crystalline hexagonal-shaped hydroxyapatite (35 nm) in the Ti/HAp matrix. The micrographs of FE-SEM and HR-TEM images at different magnifications portray the distinct rod-like structure of synthesized Ti/HAp. In addition to XRD results, the SAED pattern shows the crystalline nature of the synthesized Ti/HAp. The antibacterial properties and cell viability of the synthesized Ti/HAp composite were thoroughly investigated. The antibacterial activity of Ti/HAp was rigorously evaluated against two distinct bacterial strains: the gram-negative Escherichia coli and the gram-positive Staphylococcus saprophyticus. The cytocompatibility of Ti/HAp was thoroughly evaluated through an MTT assay, utilizing osteoblast cells, specifically the MG-63 cell line. The role of Ti in the antibacterial and cell viability activity of the product was assessed through suitable mechanisms. The cell viability decreases as Ti/HAp concentrations increase. It exhibits cell viability of 80% at the low concentration of 7.8 µg/mL. In both bacterial strains, Ti/HAp demonstrated good antibacterial activity at increasing doses. Consequently, the prepared Ti/HAp demonstrates excellent antibacterial activity and cell viability, making it suitable for various biomedical applications.

This study identifies the novel palliated magnetic nanoparticles, Pd@CuFe₂O₄/BPMAEA, as an efficient and sustainable catalyst for Suzuki and Sonogashira cross-coupling reactions. The catalyst is synthesized by integrating palladium onto a magnetic CuFe₂O₄ support, which is functionalized with N,N-bis(2-pyridylmethyl)amine ethylamine (BPMAEA) as a ligand. This strategic design enhances palladium’s catalytic activity and stability while enabling easy separation and recovery of the catalyst from reaction mixtures. Comprehensive characterization techniques, including FT-IR, TEM, XRD, SEM, EDX, and VSM, confirm the successful synthesis of the Pd@CuFe₂O₄/BPMAEA nanoparticles, showcasing favorable structural and magnetic properties. The catalytic performance of the catalyst was assessed under various reaction conditions, demonstrating its remarkable efficiency in promoting both Suzuki and Sonogashira reactions with high yields and selectivity. Notably, the Pd@CuFe₂O₄/BPMAEA catalyst exhibits excellent reusability with minimal activity loss over multiple cycles, highlighting its potential for practical applications in organic synthesis. This research underscores the significance of developing sustainable catalytic systems that enhance reaction efficiency and minimize environmental impact using recoverable materials. Our findings contribute to advancing green chemistry practices in catalysis, paving the way for future innovations in sustainable organic transformations. The catalyst could easily and successfully be recycled up to six times with an E-factor as low as 29.48, a testament to its impressive efficiency and the potential it holds for the future of sustainable catalysis.

Graphical abstract

Efficient ammonia synthesis is a significant but challenging target. One of questions faced by Ru-based ammonia synthesis catalyst is the hydrogen poisoning of Ru. In this work, we developed a strategy to greatly alleviate the effect by regulating hydrogen acceptance capacity of support MgO, thereby promoting the ammonia synthesis rate. To this end, three kinds of MgO (i.e., MgO nanocube (MgO-c), MgO nanoplate (MgO-p) and MgO nanosphere (MgO-s)) were chosen as the support of Ru catalysts for ammonia synthesis. The ammonia synthesis rate of 4Cs–Ru/MgO-c is 4466 μmol g⁻¹_cat h⁻¹, higher than the 2Cs–Ru/MgO-p (3483 μmol g⁻¹_cat h⁻¹) and Cs–Ru/MgO-s (2080 μmol g⁻¹_cat h⁻¹) at 350 ℃ and 0.1 MPa. The kinetic analysis results show that the value of the hydrogen reaction order is 4Cs–Ru/MgO-c > 2Cs–Ru/MgO-p > Cs–Ru/MgO-s > 0, indicating that no hydrogen poisoning occurs. The H₂-TPR and in situ FTIR characterizations show that MgO-c support has more active sites which can accept hydrogen atoms from the Ru surface as compared to the other two kinds of MgO. Meanwhile, the active sites released from the Ru surface can be used for N₂ activation, which will reduce the reaction activation energy of ammonia synthesis. Therefore, MgO containing abundant active sites for accepting hydrogen atoms can be expected to be a promising commercial catalyst support for Ru-based ammonia synthesis.

A new Ni^II two-dimensional coordination polymer [Ni₂(CN₂N)₂L]_n (1) is rendered assimilating the metal salt, Ni(ClO₄)₂·6H₂O, H₂L [N,N′-bis(3-methoxysalicylidenimino)-1,3-diaminopropane] and the co-ligand, sodium dicyanamide [NaN(CN)₂]. In the asymmetric unit, one Ni^II ion belongs on a distorted octahedral framework, whereas, the distorted tetrahedral geometry is procured by the other Ni^II ion. The two CN₂N²⁻ anions bridge between nickel centers in adjacent molecules resulting in the formation of a two-dimensional coordination polymer with a (6³) topology. The magneto-structural concurrence with variation of temperature (T) divulges that a weak anti-ferromagnetic interaction endures between two adjacent Ni^II centers where the χ_MT value is 1.20 cm³ mol⁻¹ K. The electrochemical study is implemented that manifests the redox peaks concerning the reduction and oxidation potentials of Ni(II) system. Furthermore, complex 1 impedes the cell growth of human colorectal carcinoma cells (COLO 205 cells), human lung carcinoma cells (A549 cells), and human hepatocellular carcinoma cells (PLC5 cells). In human colorectal carcinoma cells (COLO 205 cells), the highest inhibitory activity with 46.00 ± 1.09 μM IC₅₀ is revealed.

The CoFe₂O₄/g-C₃N₄ (CF/GCN) heterojunction was successfully synthesized by a sol–gel auto-combustion method. In synthesis, cow urine was used as a stabilizing and chelating agent. Further, the synthesized CoFe₂O₄ (CF), g-C₃N₄ (GCN), and CF/GCN heterojunctions were characterized utilizing X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–visible diffuse reflectance spectroscopy (DRS) techniques. The findings show that the heterojunction is composed of spherical cobalt ferrite nanoparticles attached to the graphitic carbon nitride nanosheets. The synthesized photocatalysts' optical characteristics were examined, and the findings demonstrated that the heterojunction between CF and GCN enhanced light absorption, decreased the band gap, and separated the e⁻/h⁺ pairs. Photocatalytic efficacy of the CF/GCN was assessed by degrading of methylene blue (MB) and methyl orange (MO) under visible light irradiation. The photocatalytic efficacy of the CF15/GCN photocatalyst was higher than pure CF and GCN nanoparticles. Under stimulated visible light, it decomposed MB up to 93.61% and MO up to 88.42% in 90 min, which is greater than that of pure CF (49.71%; 44.12%) and GCN (37.14%; 31.21%). This substantial improvement can be attributed to synergistically enhanced electron/hole pair separation in CF15/GCN heterojunction. Also, the possible degradation mechanism has been proposed according to experimental results.

Non-platinum (non-Pt) coordination compounds display great potential as antineoplastic drugs. Herein, two new 8-hydroxyquinoline-N-oxide (H-8QOL) non-Pt coordination compounds, [Co^II(8QOL)₂(biq)] (Yulin Normal University-2a, YNU-2a) and [Co^III(8QOL)₂(phe)]NO₃·CH₃OH (YNU-2b), bearing 2,2′-biquinoline (biq) and 1,10-phenanthroline (phe) as auxiliary ligands, respectively, were synthesized and evaluated for their potential anticancer efficacy. A third compound, [Co₂(biq)₂(NO₃)₂(OCH₃)₂] (YNU-2c), was used as the control. YNU-2a demonstrated superior antineoplastic activity compared to cisplatin (CCDP), YNU-2b, and YNU-2c against human cisplatin-resistant lung adenocarcinoma A549/DDP (A549C) cells. And YNU-2a–YNU-2c exhibited lower cytotoxicity towards normal embryonic kidney (HEK293) cells than that of CCDP. The different cytotoxicities of YNU-2a–YNU-2c against the A549C cells depended on auxiliary ligands, following the order phe < biq. Further analyses revealed that YNU-2a more obviously suppressed A549C cancer cell proliferation via triggering mitophagy, inhibiting the production of ATP and mitochondrial respiration complexes I (MR1) and IV (MR4), and inducing mitochondrial dysfunction compared with YNU-2c. This study demonstrates that YNU-2a facilitates targeted mitophagy, highlighting its potential as an anticancer drug.

Graphical abstract

Two novel polynuclear copper-based complexes, [(CH₃)₂NH₂]₂[Cu(II)₂Cu(I)₂(L¹)₄Bpy]·2H₂O (Complex-1) and [Cu₂(L²)₂(im)₂(H₂O)₂] (Complex-2), were synthesized . (H₂L¹: 4-chloro-5-(4-methylphenyl)-1H-pyrazole-3-carboxylic acid; H₂L²: 4-chloro-1H-pyrazole-3-carboxylic acid; Bpy: 4,4′-bipyridine; im: imidazole). The structures of the complexes were characterized by infrared absorption, X-ray powder diffraction, and single-crystal X-ray diffraction, with their thermal stability and Electrochemiluminescence (ECL) properties investigated. In Complex-1, Cu(I) and Cu(II) adopt planar trigonal and planar tetragonal coordination geometries, respectively, while Cu(II) in Complex-2 exhibits a slightly distorted trigonal pyramidal coordination geometry. Both complexes demonstrated good thermal stability below 260 °C. Complex-1 exhibited superior Electrochemiluminescence (ECL) performance, maintaining a maximum ECL intensity of 1447.20 a.u. even after removal of potential singlet oxygen interference.

Six new [Cu(XQ)₂] complexes (HXQ are derivatives of 8-hydroxyquinoline bearing methyl or aldehyde functional groups) were prepared with an emphasis on their preparation in a crystalline state using liquid-liquid, vapour-liquid and horizontal diffusions. Their composition is [Cu(dClMeQ)₂] (1), [Cu(dBrMeQ)₂]_n (2), [Cu(dIMeQ)₂]_n (3), [Cu(AQ)₂]_n (4), [Cu(dBrAQ)₂]_n (5) and [Cu(dIAQ)₂]_n (6) (HdClMeQ is 5,7-dichloro-8-hydroxyquinaldine, HdBrMeQ is 5,7-dibromo-8-hydroxyquinaldine, HdIMeQ is 5,7-diiodo-8-hydroxyquinaldine, HAQ is 8-hydroxyquinoline-2-carbaldehyde, HdBrAQ is 5,7-dibromo-8-hydroxyquinoline-2-carbaldehyde and HdIAQ is 5,7-diiodo-8-hydroxyquinoline-2-carbaldehyde). The complexes were characterised by infrared and UV-vis spectroscopy, elemental analysis and X-ray structural analysis (except 1). Deprotonated XQ ligands bind as bidentate chelates to the copper atom via the oxygen and nitrogen atoms of 8-hydroxyquinoline rings in all five compounds in the equatorial plane of an elongated tetragonal bipyramid. Oxygen (2c, 4c-6c) or iodine atoms (3c) of neighbouring [Cu(XQ)₂] molecules occupy axial positions and polymeric structures are thus formed, which are stabilised by hydrogen bonds and π-π interactions. This is a probable reason for their insolubility in a wide range of solvents. Crystal packing was further investigated by Hirshfeld surface analysis.