Transition Metal Chemistry最新文献

DFT calculations were conducted to investigate bismuth–chalcogen di- and tri-iron carbonyl complexes: [E Bi Fen(CO)₆]⁻ (E = Se, Te, and n = 2, 3). The study employed the electron localization function and quantum theory of atoms in molecules to analyze the Fe–Fe, Fe–Se, Fe–Te, Fe–Bi, and Fe–CO bonding interactions. Additionally, a number of integral and local topological characteristics of the electron density related to these interactions were analyzed, along with the source function (SF). The topological properties and delocalization indices related to the Bi–Se and Bi–Te interactions, denoted as δ(Bi–E), suggest substantial direct Bi–E bonding in complexes 1 and 2, but only a minimal Bi–E interaction in clusters 3 and 4. The computed topological characteristics correspond well with the transition metal complexes documented in the existing literature. The topological parameters of the Fe–Fe bonds in complexes 1–4, where a localized bond has been identified, differ significantly from the Fe1–Fe2 interactions in clusters 3 and 4, where neither the bond critical point nor the bond path between the metal atoms could be identified. The SF contributions to the Fe–Fe bond critical points primarily arise from Bi atoms, which account for over 66.7%. Additionally, carbonyl O atoms contribute more than 15.7%, while E ligands contribute more than 7.6%. The topological properties and the delocalization indices associated with the Bi–Se and Bi–Te interactions, δ(Bi–E), imply significant direct Bi–E bonding in complexes 1 and 2, but only a very minor Bi–E interaction in clusters 3 and 4. The study also revealed notable π-back-donation from CO to Fe, as indicated by the Fe…OCO delocalization indices and SF calculations.

Tetracycline (TC) is a widely used antibiotic known for its significant antibacterial effects. However, its insufficient metabolism in living organisms and the accumulation of its residues have caused serious impacts on water sources and ecosystems. Photocatalytic technology, favored for its environmentally friendly, efficient, and non-polluting properties, has been applied to degrade TC. In this study, titanium dioxide nanoparticles (T6 and T32) were synthesized using titanium-oxo-clusters (Ti₆O₆ and Ti₃₂O₁₆) as the titanium source via a simple solvothermal method. Visible light degradation experiments revealed that the degradation rates of TC exceeded 92%, significantly outperforming commercial P25 (70%) and pure anatase TiO₂ (68%). Characterization by BET and XRD showed that the synthesized materials exhibited high specific surface areas (T6: 218 m²/g, T32: 207 m²/g) and good crystallinity. The surface complexes formed between the materials and TC enhanced the materials’ responsiveness to visible light (by broadening the absorption edge to 420 nm), playing a key role in the degradation process. Free radical trapping experiments and electron paramagnetic resonance (EPR) results indicated that ·O₂⁻, ¹O₂, and h⁺ were the primary reactive species involved in the degradation mechanism. Based on these findings, we propose a plausible degradation mechanism for the material. This study demonstrates that using titanium-oxo-clusters as a novel titanium source for TiO₂ synthesis can achieve highly efficient degradation of TC under visible light, offering innovative prospects for the development of future photocatalytic materials.

Considering environmental issues, which involve climate change and shortage of hydrocarbon resources, the usage of environmentally friendly technologies in energy generation has become essential worldwide. In this regard, water splitting is the best way of renewable energy source. Developing an efficient, high-performance and robust electrocatalyst became a significant goal to improve water splitting. For this purpose, we fabricated CdAl₂O₄@PANI (CAO@PANI) composite via hydrothermal approach for oxygen evolution reaction (OER). The CAO@PANI displayed varied morphologies, including nanoparticles of CAO affixed to PANI sheets, which enhance the surface area for adsorption of electrolyte ions. The electrocatalyst based on CAO@PANI nanostructure has enhanced efficiency relative to CAO as indicated by overpotential (η) of 192 mV at 10 mA/cm² j (current density) and remarkable durability (50 h). Additionally, CAO@PANI nanostructure exhibits an excellent Tafel plot (36 mV/dec) along with reduced charge transfer resistance (R_ct = 3.4 Ω). The fabricated catalyst also demonstrated notable double-layer capacitance (C_dl = 48 mF/cm²) and greater electrochemically active surface area (ECSA = 1200 cm²). The excellent outcomes may be associated to the combined effect of CAO and PANI, which has a distinctive π-conjugated framework and a variety of nitrogen species with lone pairs of electrons. This configuration facilitates a steady flow of OH⁻ ion and enhances its adsorption capacity on the surface of CAO@PANI, making it a remarkably effective and reliable catalyst for OER.

Complexes (1–3) with nitrogen-based heterocyclic ligands were synthesized by reacting ruthenium precursor [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ and ligands L1, L2 and L3. Upon reacting the complexes 1–3 with sodium azide, azido complexes 4–6 were obtained. These complexes as well as ligands were tested for anti-cancer activity where, ligand L2 was found to have lowest IC₅₀ value with stable interaction of ROCK-1 protein suggesting one of the possible mechanisms for complex’s anti-cancer activity.

Graphical Abstract

Half-sandwich ruthenium complexes 1–3 were synthesized and upon further reaction with sodium azide (NaN3) in methanol yielded azido ruthenium complexes 4–6. All the ligands and complexes were studied for anticancer activity. Anticancer activity assessed in human lung cancer cell line (A549) revealed that ligand L2 has the highest anti-cancer activity amongst the others studied.

Azido Ruthenium Complex 4

In this study, eco-friendly synthesis of Cu/CuO nanoparticles (Cu/CuO NPs) and Ag/Cu based composites was described. The leaf extract of Dendrophthoe falcata (D. falcata) which is rich in phenolic and flavonoid content was used as green reducing agent for Cu and Ag ions in aqueous solution. The biosynthesis of Cu/CuO NPs is an appealing alternative to physical and chemical approaches due to its low cost, simplicity, and environmental friendliness. Biosynthesized Cu/CuO NPs were characterized by UV–Visible spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). Solid state UV–Visible analysis showed a broad band of absorption centered at 580 nm for Cu/CuO NPs. Powder XRD analysis confirmed the presence of FCC Cu(0) phase in the sample along with oxides of Cu and the crystallite size of Cu/CuO was 15.8 nm. Morphological analysis using TEM showed aggregated particles with size in range between 10–50 nm. Additionally, Ag/AgO NPs and Ag/Cu based composites were prepared using D. falcata leaf extract. All three biosynthesized materials were tested for inhibitory activity against Staphylococcus aureus, Bacillus thuringiencis, Escherichia coli, and Pseudomonas aeruginosa. In this study, Ag/Cu based composites showed activity against microorganisms classified as gram negative (Pseudomonas aeruginosa) and gram positive (Staphylococcus aureus and Bacillus thuringiencis). In contrast, Cu/CuO and Ag/AgO NPs were active against only a single species of gram positive bacteria. In conclusion, the biosynthesis of Cu/CuO NPs and Ag/Cu based composites described in this work is facile and the synthesized materials have the potential to be developed into antibacterial compositions that fight infectious microbes in the future.

Condensation of 8-hydroxy-2-quinolinecarbaldehyde and 3-bromoaniline, followed by reduction with NaBH₄, afforded a new potential tridentate ligand of 2-(((3-bromophenyl)amino)methyl)quinolin-8-ol (HL), which was characterized by NMR spectroscopies and mass spectrometry. Treatment of HL with zinc acetate or cadmium acetate using solvothermal method gave a dinuclear complex [Zn₂(κ²-N,O-L)₂μ-(κ²-N,O-L)₂]·2CH₄O (1) and a tetranuclear complex [Cd₄μ-(κ²-N,O-L)₄μ-(κ³-N,N,O-L)₂(κ²-O₂CCH₃)₂] (2), respectively. The crystal structures of complexes 1 and 2 were determined with single-crystal X-ray diffractions and powder X-ray diffractions, showing the good ligating property and rich coordination modes of the ligand L⁻. Moreover, the complexes 1, 2 were characterized by infrared, NMR, UV–vis spectroscopies and mass spectrometry.

In this work, four new aroylhydrazone-based Schiff base ligands (HL1-HL4) have been synthesized by the condensation of 2-(benzyloxy)benzoylhydrazine with four different aldehydes, namely cinnamaldehyde, 4-methylbenzaldehyde, 4-methoxybenzaldehyde, 4-allyloxybenzaldehyde. The correspondent bischelated Ni(II) complexes [Ni(L1)₂-Ni(L4)₂] were prepared in-situ by refluxing an ethanolic solution of 2-(benzyloxy)benzoylhydrazine with the aldehydes mentioned above in the presence of Ni(II) acetate tetrahydrate. The ligands and complexes were characterized by FT-IR, ¹H NMR, mass, and UV–visible spectroscopic techniques. The molecular structures of ligands HL1, HL2, and complex Ni(L3)₂ were determined by single crystal X-ray diffraction technique. In ligand HL1, the benzohydrazide moiety forms dihedral angles of 15.48 and 38.78° with the phenyl rings of the molecule. In contrast, the two independent molecules detected in the crystal of ligand HL2 slightly differ in their conformation, due to a different orientation of the benzyl ring that makes a dihedral angle of 29.54 and 49.25° with the benzohydrazide moiety. The metal ion in complex Ni(L3)₂ exhibits a distorted square-planar geometry with trans-configuration of the deprotonated benzohydrazide ligands coordinating Ni(II) through the azomethine-N and carbonylate-O atoms. The antioxidant activity of the ligands and complexes was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The ligands showed a low level of radical scavenging activity compared to the standard ascorbic acid, whereas the complexes did not show any activity. Moreover, the cytotoxicity of the synthesized compounds was tested in vitro against brine shrimp, and the results showed a promising cytotoxic effect of ligands and complexes.

Natural mineral composite catalysts have attracted much attention due to their great potential in the fields of water treatment, air purification and energy conversion. In this study, porous TiO₂ materials were synthesized from ilmenite by a two-stage calcination and acid leaching process, and porous TiO₂/CdS composites were prepared by a hydrothermal method. The results of photocatalytic experiments indicate that the porous TiO₂/CdS composite (PTC-2) with a Ti/Cd molar ratio of 1:1 exhibits the highest photocatalytic activity, with the degradation rate of methylene blue achieving a maximum value of 96.6% at 80 min. Moreover, the composite maintains a degradation efficiency of 88.5% after five cycles. The findings demonstrate that the TiO₂/CdS heterojunction significantly enhances the photocatalyst's absorption of visible light while facilitating the effective separation and transfer of photogenerated electron–hole (e⁻/h⁺) pairs. The porous architecture of the composite facilitates superior electron transport pathways and effectively mitigates e⁻/h⁺ recombination. Furthermore, a mechanism for the photocatalytic degradation of organic dyes using porous TiO₂/CdS composites is proposed, wherein photogenerated superoxide radicals (^·O₂⁻) and hydroxyl radicals (^·OH) serve as the primary reactive species. This study explores the cost-effective synthesis of TiO₂/CdS heterojunctions and makes a significant contribution to the advancement and utilization of natural minerals for pollution degradation.

It is of great practical significance to explore and prepare cheap, high-performance, and stable catalysts for oxygen reduction reaction (ORR), but it is still in progress at present. Herein, a straightforward evaporation–pyrolysis strategy is designed for the preparation of 3D porous electrocatalysts (denoted as (textrm{Fe}-textrm{Co}-textrm{NC}), which represented carbonization products at °C) made of carbon nanoparticles combined with metallic Fe-Co-doped N-enriched bridged carbon nanotube by carbonization of a pristine ZIF8 as highly efficient and durable ORR electrocatalysts. The obtained Fe–Co–NC structure possesses 3D open porous texture, abundant active sites, desired nitrogen bonding type, and high specific surface area, providing them with excellent ORR activity. The optimal performing (textrm{Fe}-textrm{Co}-textrm{NC}) catalyst presents an outstanding ORR performance in terms of a high onset potential ((textrm{E}_{text{ onset } })) of 0.96 V (vs. RHE) and half-wave potential ((textrm{E}_{1 / 2})) of 0.86 V (vs. RHE), respectively, possible to rival those of the commercially available (textrm{Pt} / textrm{C}) in an alkaline electrolyte solution. Besides, the (textrm{Fe}-textrm{Co}-textrm{NC}) catalyst manifests better stability than those of commercially available (textrm{Pt} / textrm{C}), which is of importance for the optimization and characterization of novel electrocatalysts originated from non-precious metals.

The current work describes the synthesis of two Cu(II) complexes [Cu(LA_I)₂] complex-1 and [Cu(LA_II)₂] complex-2 based on σ-donating acylpyarazolone ligands. Both complexes were thoroughly investigated using FTIR, UV–Vis, TGA and ESR spectroscopy methods. Additionally, single-crystal X-ray diffraction analysis was employed to determine their structures. The analysis indicates that the Cu²⁺ ion in both complexes occupies a centre of inversion symmetry and exhibits square-planar geometry. The examined complexes [Cu(LA_I)₂] complex-1 and [Cu(LA_II)₂] complex-2 crystallize in the P2₁/c Monoclinic and P2₁/n Monoclinic space groups, respectively, according to the X-ray single-crystal investigation. In addition to the experimental and spectroscopic investigations, DFT calculations were performed using the B3LYP functional with the LANL2DZ basis set for optimization. The bond lengths and bond angles determined from the DFT calculations are consistent with the X-ray data. HOMO–LUMO energy, natural bonding orbital and spin density analyses were also conducted to provide the best possible correlation and comparison with the experimental data. Intermolecular and non-covalent interactions were examined using Hirshfeld surface analysis. Furthermore, a cytotoxicity assay of the synthesized [Cu(LA_II)₂] complex-2 was performed against three different cancer cell lines: NCI-H23 (lung carcinoma cell line—lung cancer), SH-SY5Y (neuroblastoma cell line—neuroblastoma cancer) and HepG2 (hepatocellular carcinoma cell line—liver cancer), where notable cell death was observed, demonstrating the effectiveness of the complex against cancer cells.

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