Transition Metal Chemistry最新文献

The present investigation deals with the synthesis and single-crystal X-ray analysis of Zu (II) coordination complex of ketimine ligand which was obtained by reaction of dehydroacetic acid with carbohydrazide (3) and characterized the title compound with elemental analysis, multinuclear (¹H and ¹³C) NMR, UV visible, and FTIR spectral data. It crystallized in orthorhombic crystal system with space group Pbcn and unit cell dimensions: a = 18.7959 (4), b = 11.2890 (2) and c = 13.4480 (3) Å, and α = β = γ = 90°. The suggested geometry obtained after experimental analysis was distorted octahedral due to some angle strain between axial homonuclear N donor atoms around central Zn, and it was very close to the expected geometry. The DNA co-relation analysis was carried out by using fixed concentration of Calf Thymus DNA against the solution of analyte using UV spectroscopy. The ligand and metal complexes were examined for antibacterial and fungal activities against E. coli, M. luteus, E. aerogenes, S. aureus, and C. albicans, and the titled complex was found to be active against all the tested strains.

Two vanadium complexes of mandelic acid having [Fe(bpy)₃]²⁺ as counterion, [Fe(bpy)₃][V₂O₄(rac-mand)₂]·4.9H₂O·0.1CH₃CN (1, FeV₂L₂) and (H₃O)[Fe(bpy)₃]₄[V₃O₇(S-mand)₂]₃·28H₂O (2, FeV₃L₂) (bpy = 2,2’-bipyridine, mand^2– = mandelato ligand, C₈H₆O₃^2–) have been synthesized and characterized by single crystal X-ray diffraction and spectral methods. The FeSO₄—bpy—KVO₃—H₂mand—H₂O—CH₃CN system exhibits a stereospecific behaviour: while from the system including racemic mandelic acid only the complex of the V₂L₂ type (1) could be obtained in crystalline form, the system with S-mandelic acid afforded the V₃L₂ (2) complex as the single crystalline product. All vanadium atoms exhibit tetragonal pyramidal coordination geometry with oxygen donor atoms of the oxido ligands and carboxylate anion. The stereospecific behaviour was investigated using the ⁵¹ V NMR spectroscopy, which revealed different composition of systems with racemic mandelic acid and S-mandelic acid after some preliminary period (≈ 15 days). The compound 2 is chiral non-racemic compound (space group P2₁2₁2), the structure of which contains Δ-[Fe(bpy)₃]²⁺ cations and [V₃O₇(S-mand)₂]^3– anions.

Graphical abstract

In this article, three iridium(III) complexes [Ir(bzq)₂(NPIP)](PF₆) (NPIP = 2-nitrophenyl-1H-imidazo[4,5-f][1,10]phenanthroline) (Ir1), [Ir(bzq)₂(MNPIP)](PF₆) (MNPIP = 3-nitrophenyl-1H-imidazo[4,5-f][1,10]phenanthroline) (Ir2) and [Ir(bzq)₂(PNPIP)](PF₆) (PNPIP = 4-nitrophenyl-1H-imidazo[4,5-f][1,10]phenanthroline) (Ir3) were synthesized and characterization. The cytotoxicity in vitro of the complexes Ir1, Ir2 and Ir3 toward human tibial osteosarcoma cell U2OS, human osteosarcoma cell HOS, human osteoblast-like cells MG-63, and non-cancer cell LO2 was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complex Ir1 displays high anticancer activity against U2OS cells with a low IC₅₀ value of 7.4 ± 0.04 μM, while Ir2 and Ir3 show no cytotoxic activity toward the above selected cancer cells. The colonies and wound healing show that Ir1 can effectively inhibit the cell proliferation and migration. The apoptosis was performed using Annex V/propidium iodide (PI) double staining and the obtained results show that Ir1 can induce apoptosis. The cell cycle distribution demonstrates that Ir1 prevents the cell growth at the G0/G1 phase. Ir1 locates at the mitochondria, causes an increase of intracellular ROS levels, induces a decrease of mitochondrial membrane potential. Additionally, Ir1 can cause autophagy, regulate the expression of Bcl-2 family proteins, inhibit the expression of PI3K, AKT, mTOR and p-mTOR. Taken together, Ir1 induces cell death through a ROS-mediated mitochondrial dysfunction and inhibition of PI3K/AKT/mTOR signaling pathway.

The widespread use of nonbiodegradable synthetic dyes in various industries has led to significant toxic contamination and water pollution. The release of these dyes into aquatic environments poses serious risks to human health and ecosystems. To address this issue, rapid and efficient techniques for dye removal or transformation are required. In this article, we present a pioneering approach for the synthesis of a highly efficient photocatalyst material, PPAH/Ag@ZnO nanocomposites, for the degradation of organic dyes in wastewater. By integrating silver (Ag) and zinc oxide (ZnO) nanoparticles within the potassium polyacrylate hydrogel (PPAH) matrix, a two-step method was employed to create stable and effective photocatalytic nanocomposites. The successful formation of PPAH/Ag@ZnO nanocomposites was confirmed through comprehensive characterization using UV–visible spectroscopy, FTIR, XRD, and SEM techniques. The photocatalytic performance of the PPAH/Ag@ZnO nanocomposite was evaluated for the degradation of o-toluidine blue (o-TB) and 4-bromophenol (4-Bph) under sunlight. The experimental results demonstrate that the PPAH/Ag@ZnO nanocomposite effectively degrades 98.77% of o-TB and 98.05% of 4-Bph. Moreover, the kinetics of the photocatalytic degradation reactions were investigated, revealing apparent reaction rate constants of 0.0229 and 0.018 min⁻¹ for the degradation of o-TB and 4-Bph, respectively. Additionally, the reusability of the prepared PPAH/Ag@ZnO photocatalyst was evaluated over 5 consecutive cycles, demonstrating its exceptional effectiveness and stability. This innovative approach with hydrogel-based nanoparticles offers a potential breakthrough in the field of photocatalysis for addressing water contamination caused by organic dyes.

The synthesis of six new copper(II) nitrobenzoate complexes with N-methylnicotinamide, used as an auxiliary ligand for a supramolecular interaction study, is reported. Crystal structures of six novel compounds [Cu(2-NO₂bz)₂(mna)₂(H₂O)₂] (1), [Cu(2-NO₂bz)₂(mna)₂(H₂O)₂]∙2H₂O (2), [Cu(3-NO₂bz)₂(mna)₂(H₂O)₂] (3), [Cu(3,5-(NO₂)₂bz)₂(mna)₂(H₂O)₂]∙2H₂O (4), [Cu(4-NO₂bz)₂(mna)₂(H₂O)₂]∙2(4-NO₂bzH) (5) and [Cu(3,5-(NO₂)₂bz)₂(mna)(H₂O)₃] (6) (mna = N-methylnicotinamide, 2-NO₂bz = 2-nitrobenzoate, 3-NO₂bz = 3-nitrobenzoate, 4-NO₂bz = 4-nitrobenzoate, 3,5-(NO₂)₂bz = 3,5-dinitrobenzoate) were determined by X-ray analysis. Compounds 1–6 are mononuclear with a tetragonal-bipyramidal geometry around the Cu²⁺ ion. The molecules of the studied complexes are mostly linked by a combination of N–H…O and O–H…O hydrogen bonds between N-methylnicotinamide and water molecules into supramolecular hydrogen-bonded coordination chains and networks. Intermolecular interactions in the supramolecular structures were also studied using Hirshfeld surface analysis. In addition, the complexes 1–6 have been characterised by elemental analysis, IR, UV–Vis and EPR spectroscopy. Density functional theory calculations were performed in order to reproduce the EPR magnetic parameters. DFT calculations of the EPR parameters show a good agreement with the experimental results.

The conformation, geometry, and relative energies of bis (2,6-dimethylheptane-3,5-dionato)copper(II), (Cu(DIMHD)₂), and bis (5,5-dimethylhexane-2,4-dionato)copper(II), Cu(DMHD)₂ have been assayed through using calculated results from atoms-in-molecules (AIM) analysis, time-dependent density functional theory (TD-DFT), natural bond orbital (NBO), and density functional theory (DFT). The electronic and vibrational spectra of these compounds have also been studied using experimental infrared, Raman, and ultraviolet (UV) spectra. All theoretical and empirical vibrational frequencies of the mentioned compounds have been assigned. The DFT was used to characterize the conformers of the complexes mentioned above, as well as the observed vibrational and UV spectra. Similar complexes, including copper (II) acetylacetonate Cu(AA)₂, bis(3,5-heptanedionato)copper(II) (Cu(HPD)₂), and copper (II) 2,2,6,6-tetramethylheptane-3,5-dionate (Cu(TMHD)₂), have been chosen to evaluate the influence of isopropyl (iPr) and tert-Butyl (t-Bu) groups substituents instead of methyl and ethyl groups. All experimental, spectroscopic, and DFT results confirmed that the O-Cu bond strength in Cu(DIMHD)₂ and Cu(DMHD)₂ is between Cu(TMHD)₂ and Cu(AA)₂ and close to Cu(HPD)₂.

The preparation and characterization of a new unsymmetrical ligand on Fe₃O₄@SiO₂ with its cobalt complex including an ionic liquid (ILs) group by ¹H-NMR, ¹³C-NMR, FTIR, SEM, EDX, TGA, XRD, and VSM. The catalyst was used in the reaction to prepare chromene compounds from alcohol. Catalyst amount, temperature, solvent, and solvent amount were investigated as factors affecting the reaction. For the synthesis of chromene derivatives at optimum conditions, the alcohol derivatives were first oxidized by the catalyst, followed by malononitrile and diketone additions to the reaction vessel. Recovery and reusability of the catalyst were investigated, which showed excellent results. The presence of ionic liquid groups increased the solubility of the heterogeneous catalyst in green solvents, which increased the efficiency and reduced the reaction time.

Graphical abstract

The first molecular complexes of Cr(III) with chelating 2,6-diacetylpyridine-bis(thiosemicarbazone) Schiff-base ligand (H₂daptsc), [Cr(Hdaptsc)(H₂O)_1.4(CH₃OH)_0.6](NO₃)₂·1.4CH₃OH (1), [Cr(Hdaptsc)(H₂O)₂](NO₃)₂·1.3C₂H₅OH (2), [Cr(Hdaptsc)(H₂O)₂](NO₃)₂·H₂O (3), [Cr(H₂daptsc)(H₂O)₂](NO₃)₃·2h₂O (4), [Cr(Hdaptsc)(N₃)₂]·CH₃OH (5), [Cr(Hdaptsc)(N₃)₂]·1.25H₂O (6) have been synthesized, and their crystal structures have been studied. Structural analysis has shown that in all the crystals, the Cr(III) cation is seven-coordinated by N₃S₂ atoms of the pentadentate ligand in the equatorial plane and two O or N atoms of water/methanol or N₃‾ axial ligands. The pentadentate ligand is fully protonated in 4 and mono-deprotonated in one hydrazinic –NH group in all the other compounds. The degree of deprotonation depends on the pH of the reaction medium. The remaining proton in Hdaptscˉ is ordered and localized on one side of the ligand. As a result, the Hdaptscˉ ligand possesses a pronounced difference in Cr-S/N bond distances for the neutral protonated and negatively charged deprotonated halves due to the strong Jahn–Teller effect for the high-spin 3d³ configuration in the pentagonal bipyramidal (PBP) ligand field.

Graphical abstract

Heterostructures of metal-organic frameworks (MOFs) and metal oxides have currently been explored for their application in heterogeneous photocatalysis for wastewater remediation. We have developed two new heterostructures fabricated by integration of the [Zn(apca)₂]_n (Zn–MOF) and [CdCl₂(apca)]_n (Cd–MOF) over the hexagonal-faced surface of ZnO synthesized by template-assisted method and abbreviated as Zn/Cd–MOF@ZnO. The as-synthesized heterostructures were characterized by employing morphological (FE–SEM), thermal (TGA), and spectral techniques (FT–IR, UV–Vis, XPS, and PXRD). Their performance for the degradation of hazardous industrial dyes (methylene blue (MB), malachite green (MG), and methyl violet (MV)) has been explored. The response in terms of photodegradation efficacy, (89.4%, 90%) MB, (90.7%, 94.5%) MG, and (90.1%, 92.5%) MV was recorded in the presence of Zn–MOF@ZnO and Cd–MOF@ZnO heterostructures, respectively, at optimal conditions (pH–7, catalyst dose–0.6 g/L, and dye concentration–5 mg/L). The rate constant values for Zn–MOF@ZnO and Cd–MOF@ZnO heterostructures are (0.0247 min⁻¹, 0.0315 min⁻¹) MB, (0.0312 min⁻¹, 0.0359 min⁻¹) MG, and (0.0278 min⁻¹, 0.0372 min⁻¹) MV, respectively. These heterostructures are found to be promising photocatalysts as compared to pristine metal oxides owing to their synergistic effect. Moreover, the heterostructures have low band gap energy and high surface area which results in offering more active sites for carrying out photocatalytic reactions and enhancing the efficiency of catalysts. Furthermore, the fabricated photocatalysts demonstrate excellent stability and recyclability over five experimental cycles.

Graphical abstract

One of the most significant sources of copper metal is malachite ore. The world's demand for copper is being positively impacted by increased extraction. However, the chemical compositions of copper in the malachite ore, which vary depending on the region, determine how well copper may be extracted. This study evaluated hydrometallurgical processing of copper metal from malachite ore of Kola Tembein, Tigray, Ethiopia. Malachite ore was processed hydrometallurgical with sulfuric acid to leach copper, which was then recovered using a cementation process of zinc metal. The samples were examined with XRD, EDXRF, SEM, and FAAS. The rock ore sample examined by XRD contained a variety of minerals, including malachite (Cu₂CO₃(OH)₂), quartz (SiO₂), albite Ca-rich (CaAl₂Si₂O₈), albite disorder (NaAlSi₃O₈)m, etc., and the morphology of malachite ore was magnified by SEM. According to the EDXRF results, the malachite ores were dominated by metal oxides of CuO (58.21), SiO₂ (19.21), and Fe₂O₃ (5.32) by weight%. Similar spectroscopic results of malachite were shown for Turkey, China, Chile, and Nigeria malachite. The leaching experiments were optimized by BBD using the RSM to leach and extract malachite at 2.6130 M H₂SO₄, 133.919 µm particle size, 60 °C, and 600 rpm agitation speed, with 98.159% (68,850 mg/L) copper recovered. Using the cementation process, red–brown copper metal was obtained, and waste determined by AAS having very low concentrations of copper ions (1.74 mg/L) and high concentrations of zinc ions (68,850 mg/L). Both the leaching and cementation are best in environmentally and economically, and further purification will be needed to recover zinc from the waste.