Vol 64, No 12 (2019)

Hierarchical nanostructures based on rodlike particles of the composition CeO₂–10% Y₂O₃ were obtained by programmed direct coprecipitation of metal hydroxides in the presence of polyvinyl alcohol. The effect of the concentration of the structure-forming polymer template on the morphology of the formed oxides was shown. The dependence of the particle size and microstructure of the products on the polyvinyl alcohol concentration in the reaction system was identified. Simultaneous thermal and X-ray powder diffraction analyses determined that the polymer during precipitation is incorporated into the structure of the produced nanopowder, preventing coarsening of particles during heat treatment.

Three solid solutions in the Pd–Bi–Te system were obtained by high-temperature ampoule synthesis from the elements at 700°C. The crystal structures of the solid solutions were determined using powder diffraction data by the full-profile Rietveld method. The solid solutions PdTe_0.33Bi_0.67 (a = 4.19816(8) Å, c = 5.6861(1) Å), PdTe_0.5Bi_0.5 (a = 4.18888(9) Å, c = 5.6778(1) Å), and PdTe_0.67Bi_0.33 (a = 4.17796(8) Å, c = 5.6733(1) Å) belong to the PdTe_{1 – x}Bi_x series: the structures of compounds are based on the statistical substitution of Bi atoms for Te atoms in the PdTe structure (NiAs type, hexagonal system, space group P6₃/mmc). The concentration limit for substitution in the PdTe_{1 – x}Bi_x series of solid solutions is in the 0.67 < x < 0.8 range. Band structure calculations demonstrate the metallic nature for all compounds and similar electronic structures for PdTe, PdTe_{1– x}Bi_x, and PdBi.

A novel scheme of multi-step synthesis for N-borylated dipeptide R-GlyPheOEt is proposed, which is based on the nucleophilic addition of amino acid derivatives to the [2-B₁₀H₉NCCH₃]^– anion. The products obtained at each step were studied by NMR, IR spectroscopy, and ESI mass spectrometry. The single-crystal structure of (NBu₄)[2-B₁₀H₉NH=C(NH₂CH₂COO^tC₄H₉)CH₃] was identified by XRD.

The interaction between tetrahydrofuran, tetrahydropyran, and 1,4-dioxane derivatives of the [B₁₀H₁₀]^2– anion and a number of amino acids (glycine, cysteine, serine, and p-aminobenzoic acid) has been studied. It has been shown that, during the reactions, the exo-polyhedral cyclic substituent is opened to form closo-decaborates containing the pendant amino acid group, while the nucleophilic reagent is attached via the oxygen atom. The nucleophilic reagents can be both amino acids (in water) and their sodium salts (in dimethylformamide). All the compounds obtained are effective polydentate ligands capable to be coordinated to the metal through the donor atoms of the amino acid moiety attached and by forming three-center two-electron bonds. The synthesized compounds have been studied by elemental analysis, IR spectroscopy, ¹¹B, ¹³C, and ¹H NMR spectroscopies, and ESI mass spectrometry. closo-Decaborates with pendant amino acid moieties are of interest for ¹⁰B neutron capture therapy of malignant tumors due to the high content of boron atoms and a convenient way to transport them to the cells affected.

The interaction of uranium(VI) with editionpanorama (2,6-dithiolphenol, 2,6-dithiol-4-methylphenol, 2,6-dithiol-4-ethylphenol, 2,6-dithiol-4-tert-butylphenol) and hydrophobic amines has been studied by absorption spectroscopy. Hydrophobic amines used are aniline, N–methylaniline, N,N-dimethylaniline, diphenylguanidine, triphenylguanidine, benzylamine, phenantrolin, dipyridyl, p-aninopyridin, 2‑(N,N-dimethylaminomethyl)-4-methylphenol, and 2-(N,N-dimethylaminomethyl)-4-bromphenol. The optimal conditions for the formation and extraction of ionic associates are found and the ratios of components in the complexes are determined. It has been found that associates are formed in a weakly acidic medium (pH_opt 3.5–7.1). The maxima in the light absorption spectra are observed at λ = 434–478 nm. Molar coefficient of absorption is equal to ε = (2.65–3.62) × 10⁴. On the basis of the obtained data, photometric methods of uranium determination in various objects have been developed.

Reactions of pyridine (Py) with (5,10,15,20-(tetra-4-tert-butylphenyl)porphinato)trichloroniobium(V) (Nb(Cl)₃T^tBuPP) and H⁺-bonded Nb(Cl)₃T^tBuPP (Nb(Cl)₃T^tBuPP···H⁺···Cl⁻) in toluene have been studied using spectroscopy (UV-vis, IR, ¹H NMR, mass spectrometry, fluorescence), thermodynamics and kinetics. The process is a system of consecutive two- and one-way reactions of the two pyridine molecules bonding; the nature of this interactions is determined by the chemical structure of the initial niobium(V) porphyrin. The reactions have been completely quantitatively described, and the intermediate and final products spectral parameters used for the product chemical structure confirmation have been determined. It has been demonstrated that Nb(Cl)₃T^tBuPP and Nb(Cl)₃T^tBuPP···H⁺···Cl⁻ are good candidates for use as optical and fluorescent chemosensors of VOCs (volatile organic compounds) and nitrogenous bases—building blocks of pharmaceuticals, food components, and environmental pollutants—with the following parameters: the stability constant of the complex with pyridine K = (1.99 ± 0.3) × 10⁴ L²/mol² and (2.8 ± 0.5) × 10² L/mol, relative optical response A = 0.91 and 0.35, detection limit of Py 1.74 × 10^–3 and 4.05 × 10^–4 mol/L, respectively. The results are applicable for use in the design of dye-sensitized solar cells (DSSCs) since the reaction studied is a model for self-assembly of donor–acceptor systems based on metalloprorphyrins and pyridyl derivatives of carbon nanoforms.

This research aimed at exploring the stabilities of 2,2-di-tert-butyl-1,3-dioxane, 2,2-di-tert-butyl-1,3-dithian, and 2,2-di-tert-butyl-1,3-diselenan conformers at the B3LYP/6-311+G(d,p) theory level. To this goal, estimations of the total energies, dipole moments, Frontier Orbital Energies (FOEs), and HOMO/LUMO gaps of the chair and twist-boat conformations were first done for the mentioned molecules. The partitioning of the total electronic energy E(tot) into Lewis E(L) and non-Lewis E(NL) parts was performed using the concept of natural bond orbital (NBO) analysis. Then, the Natural Coulomb Electrostatic (NCE) potential energies, total energies into Lewis components, and total steric exchange energies were estimated. Finally, the hyperconjugative anomeric effects on the conformers were illustrated by NBO analysis and the interactions responsible for the effects were explored.

Isotherms of the T–x–y–z projection of the p–T–x–y–z phase diagram for the system Cd–Ge–Mn–As have been constructed by a topologic representation of phase states using fragmentary experimental data. In the absence of melt (below 320°C), 18 stable equilibria involving four crystalline phases were found to exist. For limited chalcopyrite solid solutions (Cd,Ge,Mn)As₂, eight crystalline phases affecting its cationic composition have been isolated, namely, Cd₃As₂, CdAs₂, GeAs, GeAs₂, Ge, MnAs, MnGeAs₂, and As. The (Cd,Ge,Mn)As₂ homogeneity area has been shown to be a 14-vertex nonahedron, and the transformation of the (Cd,Ge,Mn)As₂ polyhedron upon the appearance of melt has been considered. A model of the primary crystallization polyhedron has been presented for limited solid solutions (Cd,Ge,Mn)As₂ in equilibrium with the saturated vapor.

The synthesis scheme and properties of folates with compositions Li₂C₁₉H₁₇N₇O₆ ∙ 5H₂O, PbC₁₉H₁₇N₇O₆ ∙ 4H₂O, CdC₁₉H₁₇N₇O₆ · 4H₂O, and Eu₂(C₁₉H₁₇N₇O₆)₃ · 12H₂O are described. The solubility constants K_S are determined for lead(II), cadmium, europium(III) and folic acid C₁₉H₁₉N₇O₆ · 2H₂O at an ionic strength I = 0.1. The contemplations on using soluble europium(III) salts to extract folic acid from solutions at pH ~6 in the form of poorly soluble europium folate (logK_S = –24.68 ± 0.11), followed by regeneration of folic acid (by 99%) in an acidic medium, and on using folic acid or soluble sodium folate as an antidote of lead poisoning are presented.

A facile synthesis of CsPbI₃ perovskite nanoparticles (NPs) at room temperature is described. The results of characterization of the nanoparticles synthesized using a high-resolution transmission electron microscope and their optical characteristics are presented.

Visible-light-driven Gd-doped ZnO nanoparticles have been synthesized by tartaric-assisted precipitation method. The content of Gd dopant can play the role in morphology and photocatalysis. XRD patterns of ZnO and Gd-doped ZnO certified that all samples have hexagonal ZnO structure. TEM images of the samples showed that the particle size of products has been deceased with increasing in Gd content from 0 wt % to 5 wt % due to the inhibited growth of crystallite. The photocatalytic activities of Gd-doped ZnO samples with different contents of Gd dopant have been studied by measuring the degradation of methylene blue (MB) under visible light irradiation. In this research, 5 wt % Gd-doped ZnO nanoparticles with particle size of 20–30 nm showed the highest photocatalytic activity for photodegradation of MB at 100% within 45 min because Gd³⁺ ions acted as an effective electron scavenger to trap photo-induced electrons and inhibit electron–hole recombination.