Russian Journal of Inorganic Chemistry最新文献

Cyclic trinuclear silver(I) complex, [AgPz]₃ (Pz = 3,5-bis(trifluoromethyl)pyrazolate), serves as a versatile platform for binding to chelating N^N-donor aromatic ligands. In this work, we have proposed derivatives of pyrazolyl-1H-pyridine (L) as ligands of this type, including 2-(3-phenyl-1H-pyrazol-5-yl)pyridine (L¹) and 2-methyl-6-(3-phenyl-1H-pyrazol-5-yl)pyridine (L²). It has been found that complex of the composition [AgPzL₁] (1 : 1 : 1) forms in solution regardless of reactants stoichiometry. The crystallization of the prepared compounds from toluene results in binuclear complexes with the composition [AgPz₂Ln]₂ per one solvent molecule. The formation of these compounds is caused by hydrogen bonding between the NH groups of pyrazolylpyridines (Lⁿ) and the unshared electron pair of the nitrogen atom of the pyrazolate ligand. Shortened Ag…Ag contacts (3.143–3.197 Å) have been observed in the complex, which leads to additional stabilization of the structure. The prepared compounds exhibit ligand-centered phosphorescence in solid state at ambient temperature.

Hitherto undescribed copper(II) hexamethylenetetramine (HMTA) complexes of tungstophosphate metalates Rb₅[PW₁₁O₃₉Cu(H₂O)]‧9H₂O (I), Rb₅[PW₁₁O₃₉Cu(C₆H₁₂N₄)]‧10H₂O (II), Rb₅[PW₁₁O₃₉Zn_0.95Cu_0.05(H₂O)]‧9H₂O (III), and Rb₅[PW₁₁O₃₉Zn_0.95Cu_0.05(C₆H₁₂N₄)]‧10H₂O (IV) were prepared and characterized by IR and electronic spectroscopies, X-ray powder diffraction, and electron paramagnetic resonance (EPR). The copper-ion absorption peak in the spectrum shifts to the longer wavelengths in going from [Cu(H₂O)₆]²⁺ through [PW₁₁O₃₉Cu(H₂O)]^5– [PW₁₁O₃₉Zn_0.95Cu_0.05(H₂O)]^5–, and [PW₁₁O₃₉Cu(C₆H₁₂N₄)]^5–, to [PW₁₁O₃₉Zn_0.95Cu_0.05(C₆H₁₂N₄)]^5– because of the changing ligand-field strength in the inner sphere of the complex. Electron paramagnetic resonance showed a significant difference between the magnitudes of the ligand field around the octahedrally coordinated Cu²⁺ ions in complexes (III) and (IV): the height of the crystal field potential barrier at the location of the Cu²⁺ ion differs more than twofold due to the replacement of a water molecule by an HMTA molecule C₆H₁₂N₄. The results of the studies can be helpful in the preparation and structure determination of other tungstate polyoxometalates with inner-sphere paramagnetic ions.

New double complex salts [Co(NH₃)₅Cl][Cu(H₂O)(C₂O₄)₂] and [Co(en)₃]₂[Cu(H₂O)(C₂O₄)₂]₂[Cu(H₂O)₂(C₂O₄)₂]·10H₂O (en is ethylenediamine) have been prepared and their thermal properties have been studied. The compounds have been characterized by physicochemical methods of analysis (single crystal and powder X-ray diffraction, IR spectroscopy and elemental analysis). It has been found using thermal analysis and powder X-ray diffraction that decomposition of the complex salts leads to formation of metastable Co_xCu_1–x solid solutions with high mutual solubility of metals. Formation of metastable solid solutions in Co–Cu system has been shown.

New mixed-ligand organometallic frameworks based on zinc terephthalate (bdc), 2‑iodoterephthalate (bdc-I), and 1,4-diazabicyclo[2.2.2]octane (dabco) were obtained: [Zn₂(bdc)_1.67(bdc-I)_0.33dabco] (I), [Zn₂(bdc)_1.46(bdc-I)_0.54dabco] (II), [Zn₂(bdc)_1.12(bdc-I)_0.88dabco] (III), [Zn₂(bdc)_0.80(bdc-I)_1.2dabco] (IV), [Zn₂(bdc)_0.46(bdc-I)_1.54dabco] (V). Their structures and composition were determined by single-crystal and powder X-ray diffraction, as well as elemental analysis. Compounds I–V are isostructural with [Zn₂(bdc)₂(dabco)], but not with [Zn₂(bdc-I)₂(dabco)], which we have not described previously, which is confirmed by X-ray powder diffraction data. Experiments on the sorption of diiodine vapors are consistent with the idea that the presence of a larger amount of 2-iodoterephthalate in the MOF should lead to a decrease in pore volume: the greatest amount of I₂ is absorbed by I, and the smallest by is absorbed V.

New bimetallic complexes of the composition [MHg(C₆H₆N₂O)₂(SCN)₄] have been synthesized, where M = Mn²⁺ (I), Fe²⁺ (II), Cd²⁺ (III) and C₆H₆N₂O is nicotinamide (NA). The compounds were obtained from aqueous solutions and studied by CHNS/O analysis, IR spectroscopy, inductively coupled plasma optical emission spectrometry (ICP-OES), and single-crystal X-ray diffraction. Compounds I–III are isostructural and crystallize in the monoclinic syngony (space group C2/c). The coordination environment of the M²⁺ atom is formed by two donor nitrogen atoms of two monodentately coordinated NA and four nitrogen atoms of the SCN groups, which form bridges between the M²⁺ and Hg²⁺ ions, connecting them into a three-dimensional framework. Hg²⁺ ions have a tetrahedral coordination environment consisting of four S atoms of four SCN groups.

A new method for obtaining K₂Ce(PO₄)₂·xH₂O (space group I4₁/amd, a = b = 6.8300(2) Å, c = 17.8488(4) Å, V = 832.63(4) ų, Z = 4) under hydrothermal conditions has been developed. It has been established that the thermolysis of this compound proceeds through three stages of mass loss with the formation of CePO₄ and K₄P₂O₇ as intermediate products, which upon further heating form a mixture of CePO₄ and K₃Ce(PO₄)₂. The calculated values of the sun protection factor and UV-A protection factor for K₂Ce(PO₄)₂·xH₂O were 2.1 and 2.0, respectively. In relation to the human keratinocyte cell line (HaCaT), a photoprotective effect of K₂Ce(PO₄)₂·xH₂O was recorded. For the first time, the photoactive properties of KCe₂(PO₄)₃ and K₂Ce(PO₄)₂·хH₂O in the decomposition reaction of methylene blue were evaluated. A significant slowdown in the decomposition reaction of an organic dye was demonstrated when using K₂Ce(PO₄)₂·хH₂O.

The paper discusses the results of a study of the structural and thermophysical characteristics of polycrystalline ceramics produced from the InFeZnO₄ nanoparticles. It was found that the bulk density of the resulting material is ~86% of the theoretical one. Scanning electron microscopy has shown that it has a dense microcrystalline structure consisting of randomly oriented grains with dimensions of 5–20 µm. The thermal diffusivity of InFeZnO₄ ceramics was studied using the laser flash method. It was found that as the temperature increases from 299 to 1273 K, it decreases from 1.29 to 0.44 mm²/s. Using adiabatic and differential scanning calorimetry, the temperature dependence of the heat capacity of InFeZnO₄ was studied for the first time. It was established that the measured curve has no signs of the existence of phase transitions in the range from 83 to 923 K. Using experimental data on thermal diffusivity, heat capacity, and density, an equation for the dependence describing the change in thermal conductivity of the material under study in the range from 299 to 1273 K was obtained. It was revealed that ceramics produced from InFeZnO₄ nanoparticles obtained by the polymer-salt method have a higher thermal conductivity compared to those synthesized by standard ceramic technology from a mixture of In₂O₃, Fe₂O₃, and ZnO oxides. The results obtained allow us to recommend InFeZnO₄ as a basis for the creation of thermally stable functional materials with low thermal conductivity at high temperatures.

Vanadium(V) oxide films doped with 10 mol % NiO and 10 mol % WO₃ were prepared by aerosol printing. In the case of nickel doping, the film crystallized in the tetragonal β-V₂O₅ modification with strong texturing along the {200} crystallographic plane, while tungsten doping resulted in an X-ray amorphous material. The nickel-doped film consisted of one-dimensional structures, whereas the V₂O₅–10 mol % WO₃ composition formed particles of irregular or nearly spherical shape. The electron work function values indicated high number of defects in the WO₃-containing film. Both samples exhibited anodic electrochromism, with the V₂O₅–10 mol % NiO demonstrating higher optical contrast and coloration efficiency. The results clearly show the influence of dopant nature on the functional properties of the obtained materials and demonstrate the potential of aerosol printing for fabricating electrochromic films.

Graphene oxide (GO) and composites based on it are often used to produce graphene-like materials by thermal or chemical reduction, and the reduction method strongly affects the properties of the materials. In this study, a new method was proposed to prepare a conductive composite based on reduced graphene oxide (rGO) with magnetite nanoparticles (NPs) with an average diameter of 18 nm dispersed on its surface. The method consisted of treating a GO-based composite with Fe₃O₄ on the its surface in supercritical isopropanol. The composites based on GO and rGO and magnetite NPs were investigated by FTIR spectroscopy, X-ray powder diffraction analysis, and scanning electron microscopy. It is shown that the sample compact film of the rGO-based composite has specific surface resistivity is 22 Ω cm^–2 and saturation magnetisation is 32.3 emu/g.

Efficient synthetic methods have been developed for hybrid compounds based on layered yttrium hydroxide (LYH) intercalated with malonate complexes of d-metals (Cr³⁺, Fe³⁺, Ni²⁺, Cu²⁺, or Zn²⁺) and f‑metals (Eu³⁺ or Tb³⁺). The influence of the anion-exchange reaction temperature and the nature of the intercalated metal cations on the orientation and coordination modes of malonate anions in the LYH interlayer space has been systematically studied. The amount of incorporated d- and f-metal cations increases in the following order: Tb³⁺ < Ni²⁺ < Zn²⁺ < Cu²⁺ < Cr³⁺ < Eu³⁺ < Fe³⁺. These findings demonstrate that malonate-intercalated LYH is a versatile platform for the design of novel d- and f-metal-based hybrid materials.