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A series of novel benzimidazole derivatives 1-alkyl-2-(2’-tosylaminophenyl)-5-nitrobenzimidazoles with common formulas HL (1–3) (R = C2H5 (1); R = n-C3H7 (2); R = n-C4H9(3)) and their mononuclear zinc(II) complexes ZnL2 (4–6) have been synthesized in a molar ratio Zn: HL = 1:2 in methanol solutions. Formulation of 1–6 is based upon satisfactory C, H, N, S elemental analyses, IR and 1H, 13C NMR spectroscopies, while the structures of 2, 3, 5, 6 were determined by X-ray single-crystal diffraction. The optical properties of 1–6 were investigated.

Interaction of [Cu2(Piv)4(HPiv)2] (Piv− = pivalate) with tetrabutylammonium salt of 1,1-cyclohexanediacetate (Chda2−) and 2,2-bipyridine (2,2′-bpy) in acetonitrile led to formation of the trinuclear homometallic complex [Cu3(2,2′-bpy)2(Chda)2(Piv)2]·2MeCN·0.4H2O (1·2MeCN·0.4H2O). In similar conditions but in presence of [Ln2(Piv)6(HPiv)7] tetranuclear heterometallic complexes [Ln 2 III Cu 2 II (2,2′-bpy)2(Chda)2(Piv)6] (Ln = SmIII, 2·2MeCN, or GdIII, 3·2MeCN·5H2O) and [Gd 2 III Ni 2 II (2,2′-bpy)2(Chda)2(Piv)6] (4) were synthesized. Carboxylic groups in Piv− and Chda2− act as bridges between the metal ions in all complexes. Temperature dependencies of magnetic susceptibilities and room-temperature solid-state ESR spectra of compounds 2·2MeCN, 3·2MeCN·5H2O, 4 were studied and analyzed.

A new cocrystal of 2-hydroxybenzamide (A) with 4-acetamidobenzoic acid (B) has been obtained by the DSC screening method. Thermophysical analysis of the aggregate [A:B] has been conducted and a fusion diagram has been plotted. Cocrystal formation from melts was studied by using thermomicroscopy. A cocrystal single-crystal was grown and its crystal structure was determined. The pattern of noncovalent interactions has been quantified using the solid-state DFT computations coupled with the Bader analysis of the periodic electron density. The sublimation processes of A-B cocrystal have been studied and its thermodynamic functions have been calculated. The classical method of substance transfer by inert gas-carrier was chosen to investigate sublimation processes experimentally. The lattice energy is found to be 143 ± 4 kJ/mol. It is lower than the sum of the corresponding values of the cocrystal pure components. The theoretical value of the lattice energy, 156 kJ/mol, is in reasonable agreement with the experimental one. A ternary phase diagram of solubility (A-B-ethanol) has been plotted and the areas with solutions for growing thermodynamically stable cocrystals have been determined.

We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to � 2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to � 80 m 2 /g) and simultaneously to decrease in sulfate content and total acidity of

The reaction of potassium dimethylmalonate (K2Me2Mal) and cobalt(II) pivalate [Co(Piv)2]n under various conditions resulted in {[K2Co(H2O-κO)(μ-H2O)(μ6-Me2Mal)(μ5-Me2Mal)]·2H2O}n (1) and {[K6Co36(H2O-κO)22(μ-H2O)6(μ3-OH)20(μ4-HMe2Mal-κ2O,O′)2(μ6-Me2Mal-κ2O,O′)2(μ5-Me2Mal-κ2O,O′)8(μ4-Me2Mal-κ2O,O′)12(μ4-Me2Mal)6]·58H2O}n (2) (where Me2Mal2− is the dimethylmalonate dianion). Coordination polymers 1 and 2 were characterized by X-ray diffraction and magnetochemical studies. Analysis of the magnetic behavior indicates that 1 is characterized by an extremely high anisotropy of magnetic susceptibility and very weak spin coupling between CoII centers through malonate groups; compound 2 contains a highly symmetric, spherical-like Co36 metal core that exhibits low magnetic anisotropy and antiferromagnetic interactions between CoII centers. Theoretical aspects of anisotropic magnetic properties of orbitally-degenerate CoII ions in polynuclear cobalt(II) complexes are discussed.

Crystal structures of 10 spiro-derivatives of 1,3-thiazine were determined by X-ray diffraction technique. Molecular conformational states, packing architecture, and hydrogen bond networks were stu...

Bicyclic isoselenoureas (1-selena-3-azaspiro[5.5]undec-2-en-2-ylamines and 3-selena-1-azabicyclo[3.3.1]non-2-ylideneamines) were obtained by intramolecular cyclization of selenoureas leading to 1,3-selenazine ring formation and tested for antioxidant activity.

The reactions of CuSO4·5H2O, dimethylmalonic acid and Ba(OH)2·H2O (Cu: H2Me2mal: Ba=1: 2: 2) in aqueous and aqueous-ethanol solutions (H2O: EtOH=1: 1) resulted in formation of 3D-porous coordination polymers [(H2O)3(μ-H2O)2CuBa(μ3-Me2mal)(Me2mal)]n (1) and [(μ-H2O)CuBa(μ3-Me2mal)(μ4-Me2mal)]n (2), respectively. It has been shown that compound 2 was an intermediate in the thermal degradation of compound 1. Thorough studies of solid-state thermolysis of 1 and 2 allowed to detect formation of coordination polymer [CuBa(μ4-Me2mal)(μ5-Me2mal)]n (3), structure of which was determined by X-ray powder diffraction. It has been found that the channels in polymer 3 were accessible for guest molecules (MeOH). Theoretical estimation of methanol diffusion barrier was carried out. Complete solid-phase thermolysis of 1 and 2 leads to a mixture of BaCuO2, BaCO3, and CuO. Special conditions for obtaining of a crystalline phase of pure cubic BaCuO2 were determined.

New isostructural lanthanide cymantrenecarboxylates [Ln2(μ-О,η2-OOCCym)2(μ2-OOCCym)2(η2-ООССym)2(py)4]·2py, where Ln = Pr (1), Sm (2), Eu (3), Gd (4) and Cym = (η5-C5H4)Mn(CO)3, were synthesized and characterized by X-ray diffraction. The crystals of 1–4 are built of discrete binuclear molecules; the Ln atoms are nine-coordinate. The phases produced by thermal elimination of pyridine from complexes 3 and 4 are identical to the phases formed by elimination of THF from the THF-containing cymantrenecarboxylates prepared earlier. The magnetic properties of complex 4 indicate an enhancement of antiferromagnetic interactions between Gd3+ ions due to the substitution of THF for pyridine; in the product of ligand elimination from 4, ferromagnetic interactions were found. It was shown that the lanthanide cymantrenecarboxylates are virtually nonvolatile. The thermal decomposition of the complexes was studied by differential scanning calorimetry (DSC) and thermogravimetry (TGA). Thermolysis of 1–4 in air affords mixtures of LnMn2O5 and Mn2O3. For the earlier prepared complex [Nd2(μ2-OOCCym)4(OOCCym)2(THF)4] (5), standard thermodynamic functions were calculated from adiabatic calorimetry data. Cymantrenecarboxylate ligands appreciably suppress Eu3+ luminescence and determine the spectral and the fluorescent properties of the lanthanide cymantrenecarboxylates.

A reaction of (HPiv)2Cu2(Piv)4 with dimethylmalonic acid dipotassium salt (K2Me2mal) leads to the formation of a cage coordination polymer {(μ-H2O)6K8[(μ-H2O)Cu-(μ3,κ2-Me2mal)(μ6,κ2-Me2mal)]2[Cu2(μ5,κ2-Me2mal)2(μ5,κ2-Me2mal)2]}n (1). It was found that when 1 reacted with CdSO4·8H2O in a mixture of EtOH-H2O (3: 1), the potassium ions in 1 were displaced with cadmium(ii) ions with the formation of a heterometallic 1D-polymer [(κ1-H2O)4CdCu(μ,κ2-Me2mal)2]n (2). Compounds 1 and 2 were characterized by X-ray crystallography and ESR spectroscopy.

New dodecanuclear phenylphosphonate-bridged Co(II) complexes [(μ2-THF)5(η-HPiv)Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·THF·2С6Н6 (1·THF·2С6Н6), [(μ2-THF)6Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·3THF (2·3THF) and [(μ2-Hmhp)6Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·6.5MeCN (3·6.5MeCN) have been synthesized by the reaction of the cobalt(II) pivalate polymer {Co(Piv)2}n (Piv is the pivalate anion), as a source of metal fragments containing cobalt(II) atoms, with potassium phenylphosphonate (K2PO3Ph) in the presence of neutral O-donor additional ligands like molecules of THF or 6-methyl-2-pyridone (Hmhp). The structures of the dodecanuclear complexes 1–3 were determined by using single-crystal X-ray diffraction data. The magnetic properties of the compounds showed that complexes 1 and 3 exhibit antiferromagnetic exchange interactions between the magnetic centers. The stability of compounds 1 and 3 were studied using thermogravimetric analysis.

The micromorphology and catalytic properties of nanocrystalline TiO2/SO42− superacid systems prepared by a conventional sol-gel process, as well as hydrothermal (HT) and microwave-hydrothermal (MW-HT) processes, were analyzed. The samples prepared by the HT process have no developed surfaces and, as a consequence, have no high reactivity in isobutylene oligomerization. The TiO2/SO42− samples prepared by single-step MW-HT synthesis in their morphologic, acid, and catalytic properties are competitive with the systems prepared by the conventional multistage sol-gel process.

The change in physicochemical properties of sub� stances in transition to the nanocrystalline state has attracted considerable attention of researchers and engineers in the last decade. However, known exam� ples of change in catalytic properties in such a transi� tion are relatively few, and most of them involve an increase in the specific surface area and a correspond� ing increase in the number of active sites, whereas the issue of a possible change in the crystal structure of a catalyst with a decrease in the particle size remains vir� tually unstudied. Indeed, minor changes in the crystal lattice parameters of the active component of a cata� lyst are usually caused by introducing various modify� ing additives, which increase the number of defects [1]; meanwhile, a comparable result can also be achieved by transition to the nanocrystalline state, in which the crystal lattice parameters change because of a sharp increase in the contribution of the surface forces and the necessity of balancing them. Note that a decrease in the particle size of the active component may lead both to a desirable increase in the activity and to an abrupt decrease in it, which is also caused by structural changes [2].

For decades, it has been believed in Russian and foreign scientific and technical literature that conventional thin-layer chromatography (TLC) cannot be used for the determination of volatile compounds. Experiments have shown that the version of TLC with a closed adsorbent layer proposed recently at the Topchiev Institute, Russian Academy of Sciences, is applicable to the investigation of the group content of aromatic hydrocarbons in gasoline. It has been found that the best resolution of analyte groups of compounds can be achieved by means of circular chromatography and sample introduction into a chromatographic system, using the frontal variant of chromatography.

Two new salts based on heterocyclic organic cations and uranyl triacetate anion were obtained via reaction of zinc uranyl acetate with 2-substituted imidazoles in presence of an excess of acetic acid. Uranyl triacetate anion in [2-MeImH] + [UO 2 (CH 3 COO) 3 ] − and [2-PhImH] + [UO 2 (CH 3 COO) 3 ] − H 2 O has an expected bipyramidal structure with linear uranyl group and three acetate groups laying in equatorial plane. [2-MeImH] + [UO 2 (CH 3 COO) 3 ] − structure analysis reveals H-bonded 1D chains connected through N–H···O hydrogen bonds. 2-phenylimidazolium in [2-PhImH] + [UO 2 (CH 3 COO) 3 ] − H 2 O demonstrate planar geometry without any rotation of its rings, which was not registered before. H-bonds and π–π interactions of phenyl groups in this system lead to complicate 2D “sandwich” layer formation. The main features of IR- and luminescence spectrum of both compounds are also discussed.

Thermodynamic and kinetic analysis of the reaction of nonoxidative catalytic dehydrogenation of methanol into formaldehyde was performed with the aim of developing a scientifically sound approach to the technology of the coupled process. With allowance for the experimental data, a kinetic model of the reaction was proposed and the feasibility of the occurrence of the process at low temperatures with the use of conventional catalysts and chemical coupling was shown.

Based on a mechanistic study of the selective reduction of NOx by propane on NTK-10-1 and Ni-Cr oxide (NCO) catalysts, the reason for synergism in this process on a mechanical mixture of the catalysts was determined. On the NCO catalyst at temperatures higher than 250°C without NOx activation, C3H8 was oxidized with the formation of a considerable amount of hydrogen. This hydrogen migrated to the surface of NTK-10-1 through a gas phase and reduced this surface. On the reduced surface, H2 reacted with NOx by a mechanism characteristic of supported platinum group metals. In accordance with this mechanism, nitrogen atoms, which were formed by the dissociation of NO on metal atoms reduced by hydrogen, recombined to form nitrogen molecules in a gas phase, whereas oxygen atoms reacted with the hydrocarbon to form CO2 and H2O molecules in a gas phase. The positive effect of H2, which was formed on the NCO surface, on the reduction of NOx on NTK-10-1 is the main reason for synergism. An analysis of the experimental data demonstrated that an effectively working mechanical mixture of catalysts can be obtained if one of the mixture components is responsible for the effective activation of nitrogen oxides and the other is responsible for the activation of hydrocarbons.

Pd-CeO2 catalysts on a monolith support with a honeycomb structure have for the first time been prepared by surface self-propagating thermal synthesis (SSTS). Decomposition routes for the cerium precursors are deduced from TG-DTA data and from the mass spectra of decomposition intermediates. The Pd-CeO2/Al2O3 monoliths prepared by SSTS are more active in CO oxidation, total hydrocarbon oxidation, and nitrogen oxide reduction than the catalysts obtained by conventional impregnation. This is explained by the fact that the SSTS products have a larger specific surface area and their active component has a smaller particle size.

Chemisorption of propene and propane was studied in a pulse reactor over a series of cobalt silica-supported Fischer–Tropsch catalysts. It was shown that interaction of propene with cobalt metal particles resulted in its rapid autohydrogenation. The reaction consists in a part of the propene being dehydrogenated to surface carbon and CH x chemisorbed species; hydrogen atoms released in the course of propene dehydrogenation are then involved in hydrogenation of remaining propene molecules to propane at 323–423 K or in propene hydrogenolysis to methane and ethane at temperatures higher than 423 K. The catalyst characterization suggests that propene chemisorption over cobalt catalysts is primarily a function of the density of cobalt surface metal sites. A correlation between propene chemisorption and Fischer–Tropsch reaction rate was observed over a series of cobalt silica-supported catalysts. No propane chemisorption was observed at 323–373 K over cobalt silica-supported catalysts. Propane autohydrogenolysis was found to proceed at higher temperatures, with methane being the major product of this reaction over cobalt catalysts. Hydrogen for propane autohydrogenolysis is probably provided by adsorbed CH x species formed via propane dehydrogenation. Propene and propane chemisorption is dramatically reduced upon the catalyst exposure to synthesis gas (H2/CO = 2) at 323–473 K. Our results suggest that cobalt metal particles are probably completely covered by carbon monoxide molecules under the conditions similar to Fischer–Tropsch synthesis and thus, most of cobalt surface sites are not available for propene and propane chemisorption.

The effect of the size distribution of metal particles on the process kinetics was studied for the oxi- dation and reduction of cobalt nanoparticles (6-10 nm) in the Co/SiO 2 , Co/Al 2 O 3 , and Co/ZrO 2 systems in both isothermic and temperature-programmed regimes in the temperature range from 280 to 500 K. The average size of the cobalt particles was estimated by measurements of the coercive force and residual magnetization using a vibration magnetometer. It was found that the average particle size increases upon cobalt oxidation and decreases upon cobalt reduction due to changes in the fraction of nonsuperparamagnetic particles with sizes of at least 6.5 nm.

Processes occurring in the preparation of the Co/ZrO2 + 6% Y2O3 catalyst are studied by temperature-programmed reduction (TPR). The effects of the concentration of Co, the porosity of the support, and the calcination temperature on catalyst reduction were studied. As was shown by continuous magnetization measurements in the course of TPR, metallic cobalt appeared on the microporous support in two temperature ranges irrespective of the precalcination temperature and the concentration of supported cobalt. These factors affect the reduction rate but do not change the maximum temperatures of the corresponding peaks. It is suggested that the first maximum of the Co formation rate is due to the reduction of CoO particles on the surface of the support and within macropores, whereas the second maximum is due to the reduction of CoO particles located within support micropores. Only one temperature range of CoO reduction was found in the macroporous ZrO2 + 6% Y2O3. This effect is likely due to mass transfer in support micropores.

New bicyclic derivatives (IV) and (VI) can neither scavenge radicals nor affect the peroxide oxidation of lipids in rat brain homogenates.

A new one-step reaction between 1,1-difluoroazides and primary amines is reported as an efficient synthetic approach for tetrazole formation. Examples include the syntheses of fluorine-containing 1,5-substituted tetrazoles from three fluorinated azide precursors and various amines. Greater substituent diversity in comparison with conventional methods is achieved.

We outline the method for evaluation of the particle size distribution of the magnetic nanoparticles from the hysteresis loop measurements. We apply the method to study the ultrafine Co particles filling the porous silica gel matrix (SiO 2 ). The influence of the technological conditions of the sample preparation onto particle size distribution function is demonstrated.

The reaction of difluoroazides with primary amines provides an excellent access to tetrazole products.

Triphenylantimony and diphenyltellurium are readily oxidatively fluorinated by 2-hydroperfluoropropyl azide, CF 3 CHFCF 2 N 3 , to form appropriate difluorides from moderate to high yields.

Organoelement fluorides of group V and VI elements were found to be efficient catalysts for the synthesis of cyclic carbonates from oxiranes and CO2.

The effect of cobalt precursor and pretreatment conditions on the structure of cobalt species in silica-supported Fischer–Tropsch (FT) catalysts was studied with a combination of characterization techniques (X-ray diffraction, UV–visible, X-ray absorption, X-ray photoelectron spectroscopies, DSC-TGA thermal analysis, propene chemisorption, and temperature-programmed reduction combined with in situ magnetic measurements). The catalysts were prepared via aqueous impregnation of silica with solutions of cobalt nitrate or acetate followed by oxidative pretreatment in air and reduction in hydrogen. It was found that after impregnation and drying cobalt exists in octahedrally coordinated complexes in catalysts prepared from cobalt nitrate or cobalt acetate. Decomposition of the octahedral complexes results in the appearance of Co3O4 crystallites and cobalt silicate species. Cobalt repartition between crystalline Co3O4 and the cobalt silicate phase in the oxidized samples depends on the exothermicity of salt decomposition in air and the temperature of the oxidative pretreatment. Co3O4 crystallite is the dominant phase in the samples prepared via endothermic decomposition of supported cobalt nitrate. Significantly higher cobalt dispersion is found in the catalyst prepared via low-temperature cobalt nitrate decomposition. The uncovered enhanced cobalt dispersion is associated with lower cobalt reducibility. The high exothermicity of cobalt acetate decomposition leads primarily to amorphous, barely reducible cobalt silicate. A more efficient heat flow control at the stage of cobalt acetate decomposition significantly increases the concentration of easy reducible Co3O4 in the oxidized catalysts and the number of cobalt metal active sites after reduction. The catalytic measurements show that FT reaction rates depend on the number of cobalt surface metal sites; a higher concentration of cobalt metal sites in the catalysts prepared from cobalt nitrate or with the use of soft cobalt acetate decomposition results in higher catalytic activity in FT synthesis.

Optimization of cobalt deposition and textural properties of catalytic support represent two different but complementary approaches to enhance the performance of cobalt silica-supported Fischer-Tropsch catalysts. It is shown that low temperature decomposition of supported cobalt complexes involves formation of small Co3O4 crystallites. The exothermic effect due to the decomposition of cobalt precursor seems to be a major factor responsible of cobalt silicate formation. Gentle decomposition of cobalt precursor generally leads to Fischer-Tropsch catalysts with higher activity and selectivity to higher hydrocarbons. It was found that the sizes of supported cobalt particles prepared using cobalt nitrate depended on silica pore sizes. Narrow pore size distribution in periodic mesoporous silicas allows relatively high cobalt dispersion to be maintained at high cobalt loading. This leads to higher density of active sites and more active Fischer-Tropsch catalysts.

Copper- and iron-containing mesoporous silicas were synthesized using β-cyclodextrin as a template and characterized by XRD, SEM and N 2 -BET techniques; their catalytic activity in phenol monohydroxylation and CO oxidation was demonstrated.

This article represents a systematical investigation on the structures of silver(I) dicarboxylate incorporating secondary ligands, revealing that the secondary interactions could play an important role in interlinking low-dimensional entities to high-dimensional supramolecular frameworks. A new 2D silver(I) crystalline dicarboxylate, {[Ag(6)(ADC)(3)(H(2)O)(1.5)](2).5.18H(2)O}(n) (1) (H(2)ADC = 1,3-adamantanedicarboxylic acid), has been obtained by slow diffusion of corresponding precursors. To investigate the influence of the properties of pyridylic neutral ligands on the complex structures based on compound 1, five kinds of neutral ligands (bipy = 4,4'-bipyridine; bpa = 1,2-bis(4-pyridyl)ethane; bpe = 1,2-bis(4-pyridyl)ethene; bpp = 1,3-bis(4-pyridyl)propane; bpdap = N,N'-bis(3-pyridyl)-2,6-diaminopyridine) were selected, and a series of new silver(I) dicarboxylate have been synthesized: {[Ag(bpa)(HADC)]}(n) (2), {[Ag(bpp)(HADC)].CH(3)OH}(n) (3), {[Ag(4)(bpe)(3)(ADC)(2)].2H(2)O}(n) (4), {[Ag(bipy)(HADC)].H(2)O}(n) (5), {[Ag(2)(bipy)(2)(ADC)].6H(2)O}(n) (6), and [Ag(8)(bpdap)(4)(ADC)(4)].2C(2)H(5)OH.6H(2)O (7). Single-crystal X-ray structural analysis shows that complexes 1 and 4 are formed by hexanuclear and tetranuclear Ag(I) clusters with weak Ag-Ag interactions. Complexes 2 and 3 are dinuclear structures, 5 and 6 exhibit an infinite 1D chain structure, whereas 7 is a discrete octanuclear Ag(I) unit. The structures of 1-7 span from dinuclear, tetranuclear, hexanuclear, to octanuclear Ag(I) complexes, which indicates that secondary ligands do play important roles in the formation of such coordination architectures. Thermal stability, X-ray powder diffraction and luminescent properties of the compounds are also discussed.