Highly Cr-substituted barium hexaferrite (BaFe12–xCrxO19, x = 5, 6, 7) is prepared by the solid-phase synthesis at the isothermal temperatures of 1400 °C, 1500 °C, and 1600 °C. The optimal synthesis temperatures are determined from the obtained powder XRD and electron microscopy data. Correlations are established between chemical composition and synthesis temperature on the one hand and unit cell parameters, particle size, Curie temperature, and electrical resistivity on the other hand.

Гексаферрит бария с высокой степенью замещения хромом (BaFe12-xCrxO19, при х = 5, 6, 7) был получен методом твердофазного синтеза при температурах изотермической выдержки 1400, 1500 и 1600 °С. На основе результатов рентгенофазового анализа, электронной микроскопии определены оптимальные температуры синтеза. Установлены корреляции между химическим составом/температурой синтеза и параметрами элементарной ячейки, размером частиц, температурой Кюри и удельным электрическим сопротивлением.

This study presents the results of the synthesis and examination of indium-substituted barium hexaferrite samples with the formula BaFe12–xInxO19. The ferrites were obtained via a solid state synthesis method. The substitution level of indium, represented by x(In), was varied from 0 to 1 in 0.25 increments. The stoichiometric formulas of the compounds were calculated using the EDS data. The powder X-ray diffraction analysis indicated that all samples form a single crystalline phase with the M-type hexaferrite structure. Parameters of the crystal unit cell were calculated from powder diffraction data. An expansion of the crystal lattice parameters was observed as iron was substituted with indium, from x = 0 to x = 0.84. The Curie temperatures of the synthesized ferrites were determined using differential scanning calorimetry (DSC) method. It is established that the Curie temperature decreases from 452 to 292°C with In content growth from x = 0 to x = 0.84 in the BaFe12–xInxO19.

The work presents the results of the synthesis and study of hexaferrite of barium, which is substituted with chromium within limits. The method of obtaining samples of the BaFe12–xСrxO19 system for a wide range of x from 0 to 4, with a step x = 0.5, has been worked out. It has been found that the optimal parameters of the synthesis mode are: temperature 1400°C and exposure time 5 h. The chemical composition was monitored using an energy dispersion analyzer. The phase composition was monitored by powder diffractometry. Lattice parameters for single-phase samples were calculated on the basis of obtained diffractograms. A monotonous change in the unit cell parameters was revealed, which was to be expected for isomorphic replacement of iron in the initial matrix with a magnetoplumbite structure. The temperature stability regions of the created samples were studied by differential scanning calorimetry. The influence of the degree of chromium substitution on the Curie temperature due to weakening of the inter-exchange interaction has been established.

This work is a continuation of the study of ligand exchange in the synthesis of the platinum complexes in the presence of dialkyl sulfoxides. Tetraphenylphosphonium hexachloroplatinate (I) is synthesized by the reaction of pentaphenylphosphorus with hexachloroplatinic acid in acetone. In order to study a possibility of incorporating dimethyl sulfoxide into the coordination sphere of platinum, complex I was recrystallized from dimethyl sulfoxide (DMSO). As a result, tetraphenylphosphonium pentachlorodimethyl sulfoxidoplatinate (II) is synthesized. The compounds are characterized by IR spectroscopy and X-ray diffraction (XRD) (CIF files CCDC nos. 1865783 (I) and 829586 (II)). The crystals of complexes I and II are formed from tetrahedral tetraphenylphosphonium cations and octahedral anions. In the tetraphenylphosphonium cations, the phosphorus atoms have a slightly distorted tetrahedral environment (CPC 107.8(3)°–113.2(3)° (I), 105.9(3)°–112.9(3)° (II)), and the P–C bond lengths are 1.785(6)–1.805(6) Å (I) and 1.783(7)–1.791(6) Å (II). The platinum atoms in the anions of complexes I and II are hexacoordinated. In complex II, the DMSO ligand coordinates to the platinum atom via the sulfur atom (2.290(2) Å).

— Since the discovery of a platinum compound containing the organic ethylene ligand by William Zeise in 1827, organic platinum compounds have attracted the attention of scientists all over the world. With the discovery of new properties of platinum compounds, the areas of their application have expanded: from catalysts of chemical reactions to use in medicine in the treatment of malignant tumors. This review analyzes the methods of synthesis, structural features, and the possibility of their practical use, published from 2020 to 2023. Due to the large amount of literature data on this topic, this review attempts to piece together and systematize the methods of synthesis and properties of organic platinum compounds containing one platinum–carbon bond in their composition. The main tendencies and directions of research into organic platinum compounds are revealed. The most efficient methods of synthesis, the chemical properties, and some reaction mechanisms are presented. Information on biological activity and catalytic and photoluminescent properties is presented.

Впервые методом спонтанной кристаллизации из раствора получены крупные монокристаллы высокоэнтропийных оксидов со структурой гексаферрита М-типа, химический состав которых может быть описан формулой BaFe12-x(Ti,Mn,In,Ga)xO19. Определены фактические составы полученных образцов: BaFe1.20Ti0.22Mn0.76In0.58Ga0.23O19, BaFe8.71Ti0.44Mn1.16In1.25Ga0.44O19, BaFe7.14Ti0.57Mn1.77In1.79Ga0.73O19, BaFe5.6Ti0.64Mn2.48In2.52Ga0.76O19. Полученные кристаллы имеют характерную для гексаферритов форму и характеризуются достаточно равномерным распределением элементов в их структуре. Установлено существенное количественное различие в способности ионов различных металлов переходить из расплава в растущий кристалл. При этом изменение исходной концентрации ионов в растворе практически не оказывает влияния на способность ионов переходить в растущий кристалл. Изучено влияние состава кристаллов на параметры их кристаллической решётки. Некоторый рост значений этих параметров коррелирует с уменьшением содержания железа в образцах. Главным образом это объясняется повышением средневзвешенного ионного радиуса ионов, образующих кристаллы. Рассчитаны и сопоставлены значения конфигурационной энтропии смешения в рамках подрешётки, образованной Fe, Ti, Mn, In и Ga, для целевых составов и составов фактически полученных кристаллов.

Методом твердофазного синтеза получены ВЭО BaFe12-x(Ti,Mn,In,Ga)xO19(x=1, x=7). Исследована корреляция химического состава (степень замещения Fe), структурных параметров, магнитных характеристик. Магнитные характеристики ВЭО BaFe12-x(Ti,Mn,In,Ga)xO19 (x=1, x=7) были исследованы в широком диапазоне полей и температур. Измерены инфракрасные спектры коэффициента отражения образцов BaFe12-x(Ti,Mn,In,Ga)xO19 (x=1, x=7), содержащие особенности, связанные с фононными колебаниями. Выполнен качественный анализ зависимости характеристик фононных линий от концентрации x, а также сравнение спектров со спектрами монокристаллического образца состава BaFe12O19.

The BaFe12–x(Ti,Mn,In,Ga)xO19(x = 1, x = 7) HEOs are prepared by a solid-phase synthesis. Correlations between the chemical composition (degree of Fe substitution), structural parameters, and magnetic characteristics are studied. Magnetic characteristics of the BaFe12–x(Ti,Mn,In,Ga)xO19 (x = 1, x = 7) HEOs are studied in a wide range of fields and temperatures. The measured IR reflectance spectra of the samples contain features caused by phonon vibrations. The dependence of characteristics of phonon lines on the concentration x is qualitatively analyzed; the obtained spectra are compared with those of a single-crystal BaFe12O19 sample.

The purpose of this study is to obtain high-entropy oxides with the magnetoplumbite structure, in which the Pb cation is used as a divalent metal cation. The synthesis conditions were optimized, and a technique was developed to avoid the evaporation of lead oxide. For the first time, single-phase samples of high-entropy oxides with the magnetoplumbite structure were obtained, its chemical composition is reflected by the formula PbFe2.4X2.4Y2.4Ga2.4In2.4O19. The particle size of the high-entropy phase is about 100 nm, which makes it promising for a number of applications. The effect of preliminary grinding of the initial components on the results of synthesis was studied. A synthesis mechanism is proposed. The results pave the way to synthesis and study of the properties of a new large subgroup of high-entropy oxides with the magnetoplumbite structure, which expands the possibilities of controlling the properties of ceramic magnetic materials.

Introduction: Machine learning methods, coupled with a tremendous increase in computer power in recent years, are promising tools in modern drug design and drug repurposing. Methods: Machine learning predictive models, publicly available at chemosophia.com, were used to predict the bioactivity of recently synthesized platinum(IV) complexes against different kinds of diseases and medical conditions. Two novel QSAR models based on the BiS algorithm are developed and validated, capable to predict activities against the SARS-CoV virus and its RNA dependent RNA polymerase. Results: The internal predictive power of the QSAR models was tested by 10-fold cross-validation, giving cross-R2 from 0.863 to 0.903. 38 different activities, ranging from antioxidant, antibacterial, and antiviral activities, to potential anti-inflammatory, anti-arrhythmic and anti-malarial activity were predicted for a series of eighteen platinum(IV) complexes. Conclusion: Complexes 1, 3 and 13 have high generalized optimality criteria and are predicted as potential SARS-CoV RNA dependent RNA polymerase inhibitors.

Large single crystals of high-entropy oxides with the M-type hexaferrite structure, the chemical composition of which can be described by the formula BaFe 12– x (Ti, Mn, In, Ga) x O 19 , are obtained for the first time by spontaneous crystallization from a solution. The actual compositions of the samples are determined: BaFe 1.20 Ti 0.22 Mn 0.76 In 0.58 Ga 0.23 O 19 , BaFe 8.71 Ti 0.44 Mn 1.16 In 1.25 Ga 0.44 O 19 , BaFe 7.14 Ti 0.57 Mn 1.77 In 1.79 Ga 0.73 O 19 , BaFe 5.6 Ti 0.64 Mn 2.48 In 2.52 Ga 0.76 O 19 . These crystals have a special shape for hexaferrites and are characterized by a fairly uniform distribution of elements in their structure. A significant quantitative difference in the ability of various metal ions to transfer from a melt to a growing crystal is found. A change in the initial ion concentration in the solution has practically no effect on this ability. The influence of crystal compositions on their unit cell parameters is considered. Some increase in these parameters correlates with a decrease in the iron content in the samples. This is mainly due to an increase in the weighted average ionic radius of ions forming the crystals. The configuration mixing entropies within the sublattice formed by Fe, Ti, Mn, In, and Ga for the target compositions and the compositions of actually obtained crystals are calculated and compared.

The BaFe12-x (Ti/Mn/Ga/In)(x)O-19 (x = 1-7) high-entropy oxides (HEOs) were obtained by solid-phase synthesis. The correlation of the chemical composition (the level of the Fe replacement), structural parameters, magnetic characteristics, and terahertz (THz) properties was investigated. All studied samples were single-phase (SG: P6(3)/mmc). Lattice parameters showed a monotonic increasing trend with an increase of (x). The key role in increasing the lattice parameters of HEOs may belong to the influence of In3+ ions, which are much larger in size than Fe3+ ions. As one of the possible reason for explanation of the lattice parameters behavior we hypothesized that partial charge transformation of the Mn3+ state to the Mn2+ state takes place in order to maintain electrical neutrality. Other cations (Ti/Ga/In) have stable oxidation state. The anisotropic nature of the increase in lattice parameters was demonstrated. No strong correlation between chemical composition and microstructural parameters of the investigated HEOs was observed. The magnetic characteristics of the BaFe12-x (Ti/Mn/Ga/In)(x)O-19 (x = 1-7) HEOs were investigated at broad intervals of magnetic fields and temperatures. The behavior of the magnetic characteristics was shown to be the result of the magnetic structure frustration. In addition, terahertz electrodynamic properties were studied by measuring spectra of complex dielectric permittivity at frequencies 0.2-1.2 THz in the temperature interval 20-300 K. The spectra indicate the presence of a higher-frequency infrared phonon resonance, whose damping decreases with cooling, as well as an excitation below 0.2 THz that freezes out at low temperatures, the origin of which is associated with the polycrystalline nature of the materials.

Introduction. One of the biological effects of platinum compounds is antibacterial action against Gram-positive and Gram-negative bacteria. Thus, some platinum compounds may inhibit the synthesis of DNA, RNA and proteins in Escherichia coli cells.Aim — to study the antibacterial effect of vinyltriphenylphosphonium hexabromoplatinate (VH) against E. coli and Staphylococcus aureus bacteria.Materials and methods. The antibacterial effect of VH was studied by the quantitation of the grown colonies of E. coli strain ATCC 25922 and S. aureus strain ATCC 6538 on a nutrient medium in test (suspension of microorganisms, solution of the test substance) and control (suspension of microorganisms). The significance of differences between the outcomes in test and control groups was estimated by two-sided Fisher's exact test.Results. The minimum inhibitory concentration of VH solution for E. coli strain ATCC 25922 was 14,0625 µg/ml, for S. aureus strain ATCC 6538 — 225 µg/ml.Conclusion. VH exhibits a more pronounced antibacterial effect against E. coli compared to S. aureus — the minimum inhibitory concentration of VH observed for E. coli (14,0625 µg/ml, 11,17 µM) is comparable to the effective concentrations of platinum antitumor compounds — therefore, further studies with this bacterium, including in vivo studies, are promising.

The divalent platinum complexes [Ph3PCH2OH]2[PtCl4] (I) and trans-[PtCl2(PPh3)2] (II⋅CHCl3) are synthesized by the reaction of hexachloroplatinic(IV) acid with (hydroxymethyl)triphenylphosphonium chloride in an acetonitrile–water (4 : 1) mixture. The dissolution of crystals of complex I in diethyl sulfoxide affords crystals of complex II. The structures of the complexes are determined by IR and NMR spectroscopy and X-ray diffraction (CIF files CCDC nos. 2055552 (I) and 2055809 (II⋅CHCl3)). The platinum atoms in complexes I and II⋅CHCl3 have a planar square coordination. The crystal structures of complexes I and II⋅CHCl3 are stabilized by interionic and intermolecular contacts. The thermal analysis of the crystals of complex I shows its instability and mass loss at 170 and 305°С. The thermogravimetric curve of the crystals of complex II⋅CHCl3 shows a mass loss of the solvent molecule at 170°C and a smooth descend of the thermogravimetric curve after the platform reaches 310°C.

The divalent platinum complexes [Ph 3 PCH 2 OH] 2 [PtCl 4 ] ( I ) and trans -[PtCl 2 (PPh 3 ) 2 ] ( II ⋅CHCl 3 ) are synthesized by the reaction of hexachloroplatinic(IV) acid with (hydroxymethyl)triphenylphosphonium chloride in an acetonitrile–water (4 : 1) mixture. The dissolution of crystals of complex I in diethyl sulfoxide affords crystals of complex II . The structures of the complexes are determined by IR and NMR spectroscopy and X-ray diffraction (CIF files CCDC nos. 2055552 ( I ) and 2055809 ( II ⋅CHCl 3 )). The platinum atoms in complexes I and II ⋅CHCl 3 have a planar square coordination. The crystal structures of complexes I and II ⋅CHCl 3 are stabilized by interionic and intermolecular contacts. The thermal analysis of the crystals of complex I shows its instability and mass loss at 170 and 305°С. The thermogravimetric curve of the crystals of complex II ⋅CHCl 3 shows a mass loss of the solvent molecule at 170°C and a smooth descend of the thermogravimetric curve after the platform reaches 310°C.

A series of compounds [Ph 3 PCH 3 ] 2 [PtBr 6 ] ( I ), [Ph 3 PCH=CH 2 ] 2 [PtBr 6 ] ( II ), [Ph 3 PCH 2 CH=CH 2 ] 2 [PtBr 6 ] ( III ) have been synthesized to extend the knowledge about ionic hexabromo-containing platinum (IV) complexes promising as catalysts of chemical reactions and bioactive components. Complexes I – III represent red crystals formed from potassium hexabromoplatinate and organyltriphenylphosphonium bromides in acetonitrile with a yield of 90–94%. The structure of the synthesized complexes was determined by X-ray diffraction and IR spectroscopy. Crystals of complexes I – III contain tetrahedral phosphonium cations. The tetrahedral configuration of cations approaches an ideal value. In hexabromoplatinate octahedral anions, the BrPtBr trans -angles are 180 ° and the cis -angles are close to the theoretical value of 90°. The structure of crystals is formed by weak hydrogen bonds Br … H–C between cations and anions.

Organyltriphenylphosphonium and -stibonium hexabromoplatinates were synthesized by the reaction of potassium hexabromoplatinate with organyltriphenylphosphonium and -stibonium bromides in acetonitrile or water. The complexes [Ph3PC2H5]2[PtBr6] and [Ph3PCH2Ph]2[PtBr6] were obtained by recrystallization from dimethyl sulfoxide; the complexes [Ph3PCH2Ph][PtBr5(Et2SO-S)] and [Ph4Sb·Et2SO-O]2[PtBr6], by recrystallization of benzyltriphenylphosphonium and tetraphenylstibonium hexabromoplatinates from diethyl sulfoxide. According to the X-ray data, phosphorus atoms in cations have a distorted tetrahedral coordination and antimony atoms, a distorted trigonal-bipyramidal coordination due caused by the Sb···O=SEt2 interaction.