Journal of Structural Chemistry最新文献

Based on the literature analysis, we report the quantitative characteristics of the structure of the nearest environment of metal ions in dimethylsulfoxide, such as coordination numbers, interparticle distances, and ion association types.

In this work crystal structures of octa- and hexadecafluoro-substituted tin(II) and tin(IV) phthalocyanines are shown. Complexes were obtained by fusing of fluorinated phthalonitriles with SnCl₂ (Method 1) and refluxing the initial reagents in 1-chloronaphthalene (Method 2). In the case of octafluorosubstituted tin complexes it has been shown that during synthesis by the Method 1, Sn(II)PcF₈ complexes are formed. At the same time, during the synthesis by the Method 2, Sn(IV)Cl₂PcF₈ complexes are obtained. It was demonstrated that not only the synthesis method but also the number of fluorine substituents affects the composition and structure of the obtained complexes. Unlike octasubstituted derivatives, only tin(IV) complexes are formed during the synthesis of hexadecafluorosubstituted phthalocyanines using both methods. Thus, when fusing tetrafluorophthalonitrile with SnCl₂, halogen atoms are exchanged and a mixture of monomeric SnF₂(PcF₁₅Cl) and dimeric Sn₂F₃(PcF₁₅Cl)₂ complexes is formed. The synthesis in solution leads to the formation of SnCl₂PcF₁₆, which crystallizes together with 1-chloronapthalene solvate molecules. The effect of heating and vacuum sublimation on the transformation of Sn(IV) phthalocyanines is also studied.

A comparative analysis of the properties of bulk and aluminum oxide supported Ce_1–xNi_xO_y oxides (x = 0.2-0.8; y = 1.2-1.8) exhibiting catalytic activity in reforming reactions is performed using a complex of physical and chemical methods (thermal analysis, low-temperature nitrogen adsorption, powder XRD, Raman spectroscopy, electron microscopy, hydrogen temperature-programmed reduction). It is shown that the obtained samples are mesoporous materials with a specific surface area of 100±10 m²/g, containing substitutional solid solutions with fluorite cubic structure in their composition. In contrast to bulk Ce_1–xNi_xO_y complex oxide samples, the Ce_1–xNi_xO_y/Al₂O₃ material exhibits resistance to sintering during high temperature treatments in the course of activation and the subsequent reaction. At the same time, the formation temperature of metal Ni particles increases (540 °C vs. 350 °C) and the dispersion of the Ni⁰ phase after the reaction is preserved (6.5 nm vs. 50 nm). A relationship between characteristics of these materials and their functional properties is revealed.

The Na₃Nd(BO₃)₂-NdBO₃ phase diagram was investigated by the solid-state synthesis and DSC methods. Na₃Nd(BO₃)₂, Na₃Nd₂(BO₃)₃ and NdBO₃ were grown by spontaneous crystallization from the Na₂O-B₂O₃-NaF flux. Typical Nd³⁺ luminescence of ⁴F_3/2 → ⁴I_9/2 and ⁴F_3/2 → ⁴I_11/2 electron transitions at 875 nm and 1054 nm were registered. Maximum integral intensity of the luminescence was observed for Na₃Nd₂(BO₃)₃ crystals, more than twice that of NdBO₃, Na₃Nd(BO₃)₂.

Isostructural binuclear complexes [Ln₂L₂(hfac)₆] (Ln = Eu, Tb; hfac^– = hexafluoroacetylacetonate ion) are synthesized by the interaction of [Ln(hfac)₃(H₂O)₂] with 3,6-bis(diphenylphosphinyl)pyridazine (L). According to the single-crystal XRD data, two Ln(hfac)₃ moieties in the complexes are connected by two O,O´-bidentate-bridging ligands L, and the coordination polyhedron Ln@O₈ has the geometry of a triangular dodecahedron. The Eu³⁺ and Tb³⁺ complexes exhibit characteristic lanthanide-centered photoluminescence in the solid state at 297 K with luminescence quantum yields of 31% and 2% and excited state lifetimes of 707 and 30 μs, respectively, thus indicating that luminescence sensitization by the ligand environment is more effective for Eu³⁺ than for Tb³⁺.

By the condensation of 4-amino-5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones with anthracene-9- carbaldehyde, respective 4-[(anthracene-9′-ylmethylene)amine)]-5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones are prepared and structurally characterized by NMR, UV, IR spectroscopies, high-resolution mass spectrometry, and single crystal XRD. The effect of a substituent at position 5 in triazole moieties of azomethines obtained on their head-to-head or head-to-tail crystal packings is determined.

The molecular structure of 3-cyano-4-amino-1,2,5-oxadiazole-2-oxide (3-cyano-4-aminofuroxan, CAFO) in the gas phase is studied for the first time by gas-phase electron diffraction (GED) and quantum chemical calculations, and the equilibrium parameters of this molecule are determined. The data obtained are compared with those of related compounds analyzed by GED and single crystal X-ray diffraction. It is shown that the best agreement with the experiment is obtained at the B3LYP/aug-cc-pVTZ level of theory. The information on the molecular structure of free CAFO will be useful for the structural studies of compounds containing furoxan moieties.

Film heterostructures of compositions Ag/Au/Ti and Ag/Au/CFR-PEEK are obtained by thermal evaporation with subsequent deposition of metallic gold sublayers and silver nanostructures on modern biomaterials (Ti-6Al-4V alloy, polyether ether ketone CFR-PEEK). Silver concentration is varied within 2.1-20.8 µg/cm² by changing the initial metal portion (1.2-5 mg) and the number of successive depositions (1–3). According to SEM data, Ag nanofilms with a thickness up to 10-15 nm are formed on the surface of gold sublayers. According to XPS results, gold is present in the metallic state on the surface of biomaterials whereas along with metal, the Ag₂O oxide phase is detected for silver. The dynamics of silver dissolution from the Ag/Au surface is analyzed by ICP-AES (2-48 h). It is found that regardless of the silver concentration, the samples demonstrate moderate dynamics of releasing metal ions; some amount of gold is detected together with silver in the solution. The absence of cytotoxicity of the synthesized film heterostructures in vitro (L-929 cells, viability >95-98%) is shown. Heterostructures completely suppress the growth of colonies of Gram-negative (P. aeruginosa) and Gram-positive (S. aureus) bacteria after 6 h and 24 h action respectively.