Transition Metal Chemistry最新文献

A wide range of niobium-based materials is described in the literature as efficient catalysts. The versatility of niobium catalysts prepared by different synthesis methods results in diverse compounds with unique characteristics that are active in producing high-added value compounds such as agrochemicals, fragrances, solvents, and building blocks in organic synthesis. Moreover, niobium catalysts have been used to convert biomass resources to biofuels. In this review, recent advances achieved in niobium-catalyzed reactions to add value to renewable feedstocks are discussed. The main goal was to explore how the physicochemical properties of niobium-based solid materials, prepared through various methods, influence their performance in acid-catalyzed reactions and oxidative processes. This understanding can help meet the industry’s increasing demand for sustainable and efficient processes to produce high-value chemicals from inexpensive, abundant, and renewable raw materials. The review covers processes using unsupported niobium catalysts (such as niobium oxide, phosphate, and sulfated forms) and solid-supported niobium catalysts (such as mesoporous silica, zeolite, carbon, alumina, and mordenite).

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Niobium catalyzed biomass conversion to platform molecules.

A dinuclear Cu(II) complex, [LCu₂(CH₃COO)₂]•[LCu₂(CH₃COO)₂(H₂O)]•H₂O is produced when the resorcinol bridged Schiff base ligand (H₂L) reacts with the Cu(II)–acetate salt. The complex was isolated in its pure form and was characterized by elemental analysis, single crystal X-ray crystallography and UV/Vis spectroscopy. The complex, which is dinuclear according to X-ray analysis, is formed by the tridentate ligand (H₂L) coordinating to Cu(II) through its two N donor atoms and one O donor atom in the equatorial locations. Four of these dinuclear units are joined by hydrogen bonds mediated by water to form supramolecular rhomboid structures. To gain quantitative, molecular-level insight into the intensity and energetic contribution of these complex, water-mediated hydrogen-bonding interactions DFT simulations combined with QTAIM energy analysis were rigorously employed.

Gold mineralization in low-sulfidation epithermal systems is strongly controlled by vein-hosted quartz mineralization and associated hydrothermal alterations. This study evaluates the mineralogical and geometallurgical characteristics of ore samples using petrographic analysis, ore microscopy, X-ray diffraction (XRD), and analytical spectral device (ASD), with gold recovery assessed through carbon-in-leach (CIL) testing. The ores are characterized by low sulfide contents (< 5%), dominated by pyrite with minor sphalerite, where visible gold was absent due to its submicroscopic nature. CIL testing on 49 samples (25 veins, 24 wallrocks) yielded average recoveries of 79.94% in quartz veins (range 56.53–95.44%) and a broad range of 27.42–94.64% in wallrock samples. Vein-hosted ores contained up to 6.11 ppm Au compared to ≤ 1.64 ppm in wallrock. Recovery efficiency varied systematically with alteration type: Type I (well-crystallized kaolinite) exhibited the lowest recoveries (< 50%), Type II (poorly crystalline kaolinite–smectite) achieved higher values (60–90%), and Type III (chlorite–kaolinite assemblages) showed wide variability (30–80%). Geochemical analysis demonstrated that sulfur content, primarily from pyrite, negatively correlated with recovery (r = − 0.763; R² = 58.3%), whereas Au grade exerted a strong positive influence on CIL recovery in vein samples (r = 0.94; R² = 88.3%). These findings underscore the critical roles of clay mineralogy and sulfide abundance in governing CIL performance and highlight the necessity of detailed geometallurgical characterization to optimize processing strategies in epithermal gold systems.

Reaction of cobalt(II) acetate with neocuproine (neoc, 2,9-dimethyl-1,10-phenantroline) and Schiff base H₂(samphe) (Schiff base formed by condensation of salicylaldehyde with 2-amino-4-methylphenol) afforded complex [Co(neoc)(samphe)] (1) which was chemically and spectroscopically characterized. Crystal structure of 1 is composed of neutral complex molecules in which the Co(II) atom is pentacoordinated and its coordination sphere is formed by one chelating neoc ligand and one tridentate dianionic chelating ligand samphe^2- (ONO-donor). Calculated τ₅ value of 0.435 indicates that the coordination polyhedron can be viewed as an intermediate shape between a square pyramid and a trigonal bipyramid. The complex 1 displays enhanced thermal stability up to 330 °C. The magnetic study of 1 has shown that Co(II) is in a high-spin state S = 3/2 and exhibits easy-axis magnetic anisotropy with parameters D = -48.7 cm^-1 and E/D = 0.166. The AC magnetic study indicates the presence of field-supported slow magnetic relaxation with a maximum of the imaginary component above 10 kHz. The results of the magnetic study are supported by theoretical calculations.

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A novel NHC-mercury(II) transmetallating reagent [Hg(L)₂][BF₄]₂ (3), obtained from the proligand L·HBF₄ (1), lead upon reaction with [Pt(Cl)₂(cod)] to a novel platinum(II) diplatinamacrocycle of molecular formulae {[Pt(Cl)(L)][BF₄]}₂ (4) which structure was ascertained by single-crystal X-ray diffraction analysis. Oxidative addition of the C-H bond of the benzimidazolium moiety of the proligand L·HBF₄ (1) to [Pt(PPh₃)₄] occurs upon heating. As a result, a mononuclear platinum(II) hydride complex formulated as trans-[Pt(H)(L)(PPh₃)₂]BF₄ (5) could be characterized but the hydride ligand proved easy to hydrolyse.

Two new metal complexes 9-AIH-Co and 9-AIH-Zn, were synthesized using (Z)-2-(2-(anthracen-9-ylmethylene)hydrazineyl)-4,5-dihydro-1H-imidazole (9-AIH) as the ligand and evaluated as anticancer agents. Their structures were determined by single-crystal X-ray diffraction, elemental analysis and mass spectroscopy. The 9-AIH ligand crystallized in acetate form within the orthorhombic crystal system with space group Pna2₁. The cobalt complex, 9-AIH-Co, is a mononuclear complex with chloride counterions, adopting a tetrahedral coordination geometry and crystallizing in the monoclinic system with space group P2₁/n. Similarly, the zinc complex, 9-AIH-Zn, with acetate counterions, also exhibits a tetrahedral configuration but crystallizes in the monoclinic system with space group C2/c. Anticancer activity assays revealed that 9-AIH-Co demonstrated significant inhibitory effects against three representative tumor cell lines, MGC-803 (gastric cancer), SK-OV-3 (ovarian cancer), and HepG-2 (liver cancer), which were selected for their clinical relevance as models for prevalent and challenging solid tumors. The IC₅₀ values were 6.45 ± 0.78, 8.28 ± 0.80 and 8.87 ± 2.26 µM, respectively, showing superior activity compared to both the free ligand 9-AIH and the 9-AIH-Zn. In vitro antibacterial tests indicated that 9-AIH-Co possessed antimicrobial properties similar to those of 9-AIH against four common pathogenic bacteria, including Bacillus subtilis, with MIC values ranging from 3.9 to 7.8 µg/mL. Conversely, 9-AIH-Zn showed markedly diminished antibacterial effects, with the MIC value of 125 µg/mL. These findings collectively suggest that metal ions play a pivotal role in modulating the comprehensive biological activities of metal complexes. The coordination of imidazole with Co(II) synergistically enhances both anticancer and antibacterial activities, whereas Zn(II) appears more appropriate for developing complexes with lower cytotoxicity. This research provides fundamental insights into the metal-ion-specific behavior of anthrahydrazone complexes, highlighting cobalt coordination as a promising strategy for developing dual-functional metallodrugs.

In this work, a V-substituted Lindqvist polyoxotungstate, (C₇H₁₁N₂)₄[V₂.₁₂W₃.₈₈O₁₉]•4 H₂O (1), was synthesized via a solution-based synthetic methodology and comprehensively characterized. The identification of the characteristic functional groups was achieved through infrared spectroscopy, revealing distinct vibrational absorption bands representative of the hybrid polyoxometalate structure. UV-visible absorption spectroscopy was employed to investigate the optical properties of the material. Furthermore, computational studies were conducted to assess the stability of the compound. The binding stability is enhanced by strong hydrogen bonding, van der Waals forces, and electrostatic interactions occurring within the three-dimensional (3D) supramolecular network formed between the vanadotungstate polyanion and the organic moieties, as demonstrated by single-crystal X-ray diffraction and Hirshfeld surface analysis. In addition, density functional theory (DFT) calculations were performed to gain further insights into the electronic structure and stability of the compound.

This study aims to explore the synthesis and structural characterization of nickel dithiolato complexes derived from thiolato ligands and phosphine co-ligands, with a focus on understanding their formation pathways and geometrical features. Treatment of nickel(II) chloride with thiolato anions afforded the known hexakis[di(alkylthiolato)nickel [Ni(SR)₂]₆, where R = CH₂Ph (1) or CH₂CH₂Ph (2). Cluster 1 reacts with bis(diphenylphosphino)alkane ligands {dppa = bis(diphenylphosphino)ethane (dppe) and bis(diphenylphosphino)propane (dppp)} to yield the corresponding mononuclear nickel dithiolato complexes, (dppe)Ni(SCH₂Ph)₂ (3a) and (dppp)Ni(SCH₂Ph)₂ (3b). Alternatively, complexes 3a and 3b can also be synthesized directly by the reaction of (dppe/dppp)NiCl₂ with lithium thiolates (RSLi). Complexes 3 were characterized by a combination of spectroscopic techniques, including UV–Vis, IR, and multinuclear NMR (¹H, ³¹P{¹H}), in addition to elemental analysis. Single-crystal X-ray diffraction studies of complexes 2 and 3a are presented.

In this study, two Pt(II)–8-hydroxyquinoline derivatives, [Pt(Rob)(DMSO)Cl] (RoPt), and [Pt(Ah)(DMSO)Cl] (AhPt), incorporating robustine (H-Rob) and 5-amino-8-hydroxyquinoline (H-Ah), respectively, were synthesized and characterized. RoPt and AhPt exhibited antiproliferative effects in human cisplatin-resistant ovarian SK-OV-3/DDP (3SKD) and ovarian SK-OV-3 (3SK) cancer cells, with RoPt showing the strongest activity (IC₅₀ = 6.42 ± 0.21 μM) compared with cisplatin, cis-Pt(DMSO)₂Cl₂, AhPt, H-Rob, and H-Ah. Notably, RoPt and AhPt induced apoptosis in 3SKD cells by triggering mitophagy pathways and inhibiting ATP and mitochondrial respiratory chain complex I/IV (MiRCC-I/MiRCC-IV) production. In vivo, RoPt displayed marked tumor suppression (ca. 37.1%) without causing notable body weight loss or mortality in 3SK tumor-bearing mice. These findings highlight the Pt(II)-robustine derivatives RoPt and AhPt as promising antiproliferative agents warranting further investigation.

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Complexes RoPt and AhPt exerted cell apoptosis via induction of mitophagy pathways, inhibition of ATP and mitochondrial respiratory chain production.

A novel Schiff base SBA1, was successfully synthesized and structurally characterized using UV-Vis, FTIR, and ¹H NMR spectroscopy. Its sensing capabilities were systematically investigated against a broad range of metal ions, including Cu²⁺, Co²⁺, Zn²⁺, Pb²⁺, Ag⁺, Cd²⁺, Mg²⁺, Ni²⁺, Ca²⁺, Fe³⁺, Mn²⁺, Hg²⁺, K⁺, and Na⁺. Among these, SBA1 exhibited a highly selective and distinct colorimetric response toward Cu²⁺ ions, marked by a visible color change from yellow to colorless. Fluorescence studies further revealed a substantial enhancement in emission intensity upon Cu²⁺ binding, indicating strong interaction and excellent sensing performance. The sensor demonstrated impressive sensitivity, achieving a limit of detection (LOD) of 0.0031 ppm (0.049 µM) and a limit of quantification (LOQ) of 0.0096 ppm, enabling trace-level detection of Cu²⁺ ions in aqueous media. To evaluate its practical utility, the SBA1 was tested in real environmental samples, including soil-extracted water, drinking water, lake water, river water, and pond water. Fluorescence titration with Cu²⁺-spiked samples showed outstanding recovery rates ranging from 91.0% to 102.0%, confirming the sensor reliability and accuracy in complex matrices. In addition to its sensing capabilities, the antibacterial potential of SBA1 was also assessed against selected bacterial strains. The compound exhibited notable antibacterial activity, indicating its dual functionality as both a highly sensitive Cu²⁺ sensor and an effective antimicrobial agent. These findings position SBA1 as a promising multifunctional material for environmental monitoring and biomedical applications.