Excitation and luminescence spectra of UO2F2−4

The luminescence and excitation spectra of [(CH₃)₄]₂UO₂F₄, M₃UO₂F₅ (M = K and Rb) and Cs₂SnCl₆:UO₂Cl²⁻₄ have been recorded at temperatures down to 10 K. The excitation spectrum of [(CH₃)₄]₂UO₂F₄ is unique because the electronic origin is located at the lowest energy reported for any uranyl compound. The analysis of the excitation spectrum is consistent with a D_4h, but not a D_5h coordinated uranyl chromophore. A detailed interpretation of the vibronic structure of the spectrum enables the lower excited states of the uranyl ion to be located, and the symmetries of these are consistent with the model of Denning. A comparison with the excitation spectra of salts of the UO₂F³⁻₅ anion is made.     

Syntheses and Bioactivities of 4-Ar-2-oxo-glutaric Acids

Fourteen novel compounds were synthesized and characterized by using NMR and ESI-MS methods. The bioactivities of the four novel 4-Ar-2-oxo-glutaric acids were studied by using the LC-MS method. The experimental results show that 3-nitrobenzyl-2-oxo-glutaric acid is a mild inhibitor for the hydroxylation reaction catalyzed by PHD2. The decarboxylated peak for 3-fluorobenzyl-2-oxo-glutaric acid was observed by using the negative LC-MS method, indicating that it can be used as a mild cosubstrate to replace 2-OG, but this is possible only in the presence of the prime peptide CODD 19 mer.     

Reaction of 2-alkoxycarbonylmethyl derivatives of δ2-oxazoline and δ2-imidazoline and their tautomers with 4-nitrobenzonitrile N-oxide

It was established that 2-alkoxycarbonylntethylene derivatives of oxazolidine and imidazolidine react readily with 4-nitrobenzonitrile N-oxide; the reaction takes place at the methylidyne carbon atom to give intermediate oximes, which can then undergo cyclization to isoxazoles. Their tautomers —benzimidazole and ² -oxazoline derivatives —react with considerably greater difficulty; in the first case the reaction takes place at a different center, viz., the ring nitrogen atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–684, May, 1991.     

Preparation and Characterization of Nano-ZnFe2O4/TiO2 Films

The nano-ZnFe2O4/TiO2 films possess the functions of desulfurization and degradation for organic pollutants. The sols of ZnFe2O4/TiO2 were prepared by sol-gel method and coated on glass and porous ceramic by vertical coating and dipping-lift processes, respectively, and the samples were obtained after drying and sintering. The composition, appearance, absorption spectrum of the films, and the influence of the film on porous ceramic performances were analyzed using SEM, AFM, UV-Vis spectrometer, and mercury porosimeter, respectively, to determine the operation parameters of the multifunction porous ceramic elements for gas-purification.     

Structural and thermal characterization of Zn2−xCoxTiO4

In this work, spinels with the general formula Zn_2?xCo_xTiO₄ were synthesized by the polymeric precursor method and thermally treated at 1,000 °C. The powder precursors were characterized by TG/DTA. A decrease in the DTA peak temperature with the amount of zinc was observed. After the thermal treatment, the characterizations were performed by XRD, IR, colorimetry and UV/VIS spectroscopy. The XRD patterns of all the samples showed the presence of the spinel phase. Infrared spectroscopy showed the presence of ester complexes for Zn₂TiO₄ after thermal treatment at 500 °C, which disappeared after cobalt addition, indicating that organic material elimination was favored.     

Solubility and stability of (NH4)2SO4 · H2O2 in aqueous solutions and change in some crystallographic parameters of (NH4)2SO4 precipitates

Stability of (NH₄)₂SO₄ · H₂O₂ aqueous solutions and some structural changes in ammonium sulfate in the course of its solvation and subsequent desolvation were studied.     

Calorimetric study of 2′-methylacetophenone and 4′-methylacetophenone

Values of the condensed phase standard (p = 0.1 MPa) molar enthalpy of formation for 2′- and 4′-methylacetophenones were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The values of the standard molar enthalpy of vaporization, at T = 298.15 K, were measured by Calvet microcalorimetry. Combining these two values, the following enthalpies of formation in the gas phase, at T = 298.15 K, were then derived: 2′-methylacetophenone, –(115.7 ± 2.4) kJ · mol⁻¹, and 4′-methylacetophenone, –(122.6 ± 2.4) kJ · mol⁻¹. Substituent effects are discussed in terms of stability and compared with other similar compounds. The value of the standard molar enthalpy of formation for 3′-methylacetophenone was estimated from isomerization schemes.     

Effect of Na+, Li+, Pb2+, Ba2+, Si2+, and Ca2+ cations on force constants of W-O and Mo-O bonds of WO4 2− and MoO4 2− anions in melts

By a matrix method of successive approximations, using perturbation theory, the complete set of force constants has been calculated for the free anions WO,^2– and MoO₄ ^2– and for systems MEO₄ ^2–(M = Na₂ ⁺, Li₂ ⁺, Pb²⁺,Sr²⁺, Ca²⁺; E = W, Mo) on the basis of known frequencies of IR and Raman spectra of the corresponding individual melts. Analysis of the results indicates an increase in the force constants of E-O bond stretching and the bending force constants for AD- and MoO₄ ^2– with increasing specific charge of the cation in a field of singly or doubly charged cations.Deceased.Poltava Engineering Construction Institute. Institute of General and Inorganic Chemistry, Academy of Sciences of the Ukrainian SSSR, Kiev. Translated from Teoreticheskuya i ÉksperimentaI'naya Khimiya, No. 1, pp. 120–123, January–February, 1991. Original article submitted January 12, 1989.     

Crystal Structure and Properties of Rb4H2I2O10 · 4H2O

Single crystals of the Rb₄H₂I₂O₁₀· 4H₂O were synthesized for the first time and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 7.321(6) Å, b = 12.599(8) Å, c = 8.198(8) Å, = 96.30(7)°, Z = 2, space group P2₁/c. The H₂I₂O₁₀ ^4– anion is formed by the edge-sharing IO₆ octahedra. The anions are united by hydrogen bonds into a chain running along the x axis. The chains are combined by water molecules into a three-dimensional structure through hydrogen bonds. The compound is a proton conductor. The conductivity values measured at 20–60°C vary within 10^–6 to 10^–4 ohm^–1 cm^–1.     

FTIR spectra of the 2ν4, ν4 + ν6 and 2ν6 bands of formaldehyde

High resolution IR spectra of the overtones and the combination band of the ν₄ and ν₆ modes of formaldehyde (2ν₄, ν₄ + ν₆ and 2ν₆) were measured in the region of 2200–2650 cm⁻¹ using FTIR. The combination band ν₄ + ν₆, whose dipole transition is forbidden from molecular symmetry, was observed due to the intensity borrowed from the other bands. The observed frequencies were analysed by a Hamiltonian in which A-type Coriolis interactions and Darling—Dennison interaction were taken into account. The ratio and the relative signs of the transition dipole moments of the overtone bands, μ_2ν4 and μ_2ν6, have been determined by analysing the intensity distribution of the vibration—rotation lines.     

Synthesis and Characterization of a Novel Compound SnDy2O4

In recent years, the research on rare earth became a focus, and a lot of rare earth complex compounds with AB2O4 stoichiometry were prepared1-3. The compound SnDy2O4 is expected to spinel-type phase while it exhibits a new structure type. SnDy2O4 was prepared by the thermal decomposition of the oxalate precursor that was prepared by rheological phase reaction method. SnO(AR), Dy2O3(99.9%) and H2C2O4·2H2O are ground in molar ratio 1:1:4.1, and placed into the reaction apparatus. …     

α-Thioureidoalkylation of 4-alkyl- and 4-phenylthiosemicarbazides

Previously unknown 1,3-dialkyl-4,5-bis[4-alkyl(phenyl)thiosemicarbazido]imidazolidine-2-thiones and 4,5,7-trialkylperhydroimidazo[4,5-e]-1,2,4-triazine-3,6-dithiones have been synthesized by the α-thio-ureidoalkylation of 4-alkyl(phenyl)thiosemicarbazides using 1,3-dialkyl-4,5-dihydroxyimidazolidine-2-thiones.     

Kinetic and thermal studies of removal of CrO 4 2− ions by ettringite

Ettringite was prepared in the presence of various dosages of CrO ₄ ^2? ions at three different temperatures. X-ray diffraction (XRD) and differential scanning calorimetery (DSC) results showed shift in the peaks characterized to ettringite as the result of formation of Cr-substituted ettringite. Substitution of SO ₄ ^2? by CrO ₄ ^2? ions in ettringite crystal resulted in delay in the rate of its formation, as well as reduction in the crystal diameters. However, the crystal diameters and rate of formation of both ettringite and Cr-substituted ettringite were increased by increasing temperature of preparation, and this was confirmed by scanning electron microscope (SEM) micrographs. The thermodynamic parameters: the enthalpy, entropy, and Gibbs free energy changes for substitution process were studied. It is concluded that the removal of chromate ions by ettringite is an endothermic spontaneous process. The positive value of ΔS° suggests increasing in randomness during the removal process.     

Separation of CO2/CH4 and CH4/N2 mixtures using MOF-5 and Cu3（BTC）2

In this paper we used MOF-5 and Cu3（BTC）2 to separate CO2/CH4 and CI-I4/N2 mixtures under dynamic conditions. Both materials were synthesized and pelletized, thus allowing for a meaningful characterization in view of process scale-up. The materials were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. By performing breakthrough experiments, we found that Cu3（BTC）2 separated CO2/CH4 slightly better than MOF-5. Because the crystal structure of Cu3 （BTC）2 includes unsaturated accessible metal sites formed via dehydration, it predominantly interacted with CO2 molecules and more easily captured them. Conversely, MOF-5 with a suitable pore size separated CH4/N2 more efficiently in our breakthrough test.     

Preparation and characterization of CoFe_2O_4/TiO_2 magnetic composite films

CoFe2O4/TiO2 magnetic composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting materials. The effects of heat treatment temperatures on micro- structures and on magnetic properties were studied. The microstructure and properties of the samples at different heat treatment temperatures were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, polarized microscopy and vibrating sample magnetometry. The results show that crystals of different substances grow up independently. Cobalt ferrite is evenly embedded into the titanium dioxide matrix in the prepared composite films. The magnetism of the composite films is enhanced with an increase of the heat temperature.     

Synthesis of sulfonyl chlorides and thiosulfonates from H2O2–TiCl4

A new method is described for the oxidative chlorination of thiols to sulfonyl chlorides using titanium tetrachloride in combination with the oxidant hydrogen peroxide. Direct conversion of thiols into their corresponding thiosulfonates is also reported. Good to excellent yields, short reaction times, high efficiencies, cost-effectiveness, and, facile isolation of the desired products make the present methodology a practical alternative.     

Simultaneous Molecular Recognition of Interleukins 2 and 4, and of Tumour Necrosis Factor-α in Biological Samples

Two 3D stochastic sensors based on single-walled carbon nanotubes and multi-walled carbon nanotubes decorated with gold nanoparticles and modified with 5,10,15,20-tetrakis (pentafluorophenyl)-21H,23H-porphyrin iron (III) chloride were constructed and utilized for the simultaneous molecular recognition of IL-2, IL-4, and TNF-α in biological samples. The proposed sensors present low limits of quantification, high sensitivity, and wide concentration ranges. Recoveries values higher than 98.2 % of analytes from whole blood and brain tumour tissue samples were obtained.