Russian Journal of Physical Chemistry A最新文献

A crystal-chemical analysis of o-halobenzene carboxylate-containing complexes of 3d metals has been performed using the stereoatomic model of crystal structure and the characteristics of the Voronoi–Dirichlet polyhedra. The coordination types of o-halobenzene carboxylate anions with respect to 3d metals are considered. The effect of the coordination type on the characteristics of M–O bonds (M = 3d metal) in the crystal structures was revealed. The electron donor capacity of o-halobenzene carboxylate anions with respect to 3d metals was quantified based on the 18-electron rule. It is shown that the o-halobenzene carboxylate anions are not planar, and the carboxyl groups are rotated relative to the plane of the benzene ring through an angle φ, and it was established that there is a linear relationship between the φ angle and the value of the solid angle of the face of the Voronoi–Dirichlet polyhedron corresponding to the Hal/C_COO contact.

Effects of the chemical polarization of nuclei are used to establish mechanisms and elementary acts of the photoreduction of diphenylmethanethione, bis(4-methylphenyl)methanethione, 2.6-dimethylcyclohexa-2.5-diene-1.4-dithione with triethylamine and 1,4-diazabicyclo-2,2,2-octane and 2-mercaptoethanol. Photoreduction proceeds in two stages (the transfer of an electron, and then a proton) or one (the transfer of a hydrogen atom). A mechanism for identifying intermediate particles is proposed.

The oxidation of sulfur dioxide to trioxide on a vanadium catalyst was simulated using the Priroda 6 quantum-chemical program. The active component of the catalyst is a complex compound containing vanadium pentoxide V₂O₅. This catalyst has found wide application in sulfuric acid technology at the stage of oxidation of sulfur dioxide. When studying sulfur oxides such as sulfur dioxide (SO₂) and sulfur trioxide (SO₃), it is important to evaluate their electronic states, low energy potential, and stability under the studied conditions. This can be useful for understanding the mechanisms of reactions involving these substances and predicting their behavior in different media. The probability of finding sulfur and its oxides in different multiplet states was taken into account in the calculations. The results of calculations prove the efficiency of using the vanadium catalyst, since the activation energy of the oxidation of sulfur dioxide to trioxide in the presence of a catalyst is one fifth the activation energy of the same process without a catalyst.

The evaluation of second order derivative thermodynamic properties of nonpolar gases is carried out by constructing the analytical formulae of the second virial coefficient (SVC) with Morse potential and its first and second derivatives for the first time in the literature without any parameter restrictions. The acquired analytical formulae are used for obtaining the (Delta {{C}_{{v}}}{text{/}}P) and (Delta {{C}_{p}}{text{/}}P) values at the temperature range of 500–5000 K and 1 atm pressure for the gases of He, Ne, Ar, Kr, Xe, H₂, N₂, O₂. Additionally, the speed of sound calculations are carried out for He and Xe gases for various temperature and pressure values. The Joule–Thomson coefficient (μ) and constant pressure heat capacities of a refrigerant gas of Ar are also obtained for six different temperature values for a temperature range of 193.15–383.15 K at 40 atm pressure. The (Delta {{C}_{{v}}}{text{/}}P) and (Delta {{C}_{p}}{text{/}}P) values of H₂, N₂ and O₂ indicated good consistency with analytical literature data using Lennard-Jones (12-6) potential. The speed of sound calculations demonstrated that the analytical approach utilizing the Morse potential provides closer results to experimental data compared to the Lennard-Jones (12-6) potential, particularly for heavier atom Xe at all pressure and temperature values, especially in the lower pressure region, and lighter atom He at only calculated higher pressure values greater than 10 atm. The calculations of the Joule–Thomson coefficient for Ar displayed good consistency with experimental data.

In this article, a novel configuration of a planar solid-state Si/Ag/AgCl/KCl reference electrode was designed and fabricated using different deposition techniques (screen-printing, chronoamperometry, and microdropping). The planar reference electrode was configured in a rectangular form, measuring 40  by 10 mm, through a layer-by-layer assembly process. The electrochemical performance and characteristics of the fabricated reference electrode were tested and compared to those of a commercially saturated Ag/AgCl reference electrode. The open-circuit potential of the fabricated electrode, compared to the commercial one, exhibits excellent stability in various KCl concentrations, reaching an ideal stable and constant value of approximately 0 V in a 3 M KCl solution. Additionally, the potential of the fabricated reference electrode remained stable for 15 days and was unaffected by pH variations. Cyclic voltammetry tests conducted in solutions containing K₃[Fe(CN)₆] and K₄[Fe(CN)₆] indicated that the electrochemical behavior of the fabricated electrode was similar to that of the commercial references.

The solvatochromic parameters (Nile red solvation energy E_NR, Kamlet–Taft polarizability π*, basicity β, and acidity α) of deep eutectic solvents (DESs) based on choline chloride as a hydrogen bond acceptor and carboxylic acids (formic, acetic, lactic, oxalic, malonic, malic) as hydrogen bond donors have been determined by UV-visible spectroscopy. A modified technique for determining the solvation energy in acidic media using Nile Red was proposed, and the β values obtained using different dyes were correlated with one another. The effects of the structure and physicochemical properties of the hydrogen bond donor (carboxylic acid) and the hydrogen bond donor/acceptor molar ratio on the solvatochromic parameters of DESs was studied.

Recently, “green fuel” based on highly concentrated hydrogen peroxide solutions has become increasingly popular for use in rocket and space production; its main advantages are low toxicity, versatility, and economic efficiency. With the development of modern technologies in the rocket and space industry, where high reliability and operational safety are of primary importance, the use of additive technologies (3D printing) is a challenge. In this regard, the study of compatibility of rocket fuel components (solutions of highly concentrated hydrogen peroxide) with finished products is very promising. The catalytic activity and chemical (corrosion) resistance of materials in hydrogen peroxide solutions has been analyzed. Various polymer materials with metal powder fillers, used in 3D printing, were considered and studied. These technologies are characterized, and their advantages are shown.

Mechanical activation (MA) of natural aragonite and calcite was performed to study the effect of fluid additives (1–10% aqueous solutions of dimethyl sulfoxide, DMSO, with 1–20 wt % in the MA batch) on the phase composition and particle sizes of the MA products. It was found that the formation of the final products occurs via the stages of dissolution and reprecipitation of CaCO₃ polymorph nanocrystals with sizes of ~20 nm from the fluid phase. During MA of aragonite, the calcite content increases and becomes comparable to that of aragonite. During MA of calcite, aragonite synthesis occurs only during the initial period of MA, and the final product is represented only by calcite. The correspondence of all samples to the standards was studied by powder and high-temperature X-ray diffraction, and the temperature dependences of the unit cell parameters of aragonite and calcite were measured. Thermal analysis of initial and MA samples of aragonite and calcite was performed with description of the specific features of the TG/DSC curves for MA aragonite. Using ultrasound treatment of MA samples with subsequent measurement of particle sizes by light scattering, the property of DMSO as a stabilizer of nanoparticle sizes was confirmed, and the mechanism of primary nanoparticle growth, consisting in their reversible aggregation, was discussed. The aging of colloidal solutions during their long-term storage was also studied.

The phase equilibria of the quaternary system Li⁺, Na⁺//Cl^‒, ({text{HCO}}_{{text{3}}}^{ - })‒H₂O at 313.15 K with CO₂ pressure at 0.3 MPa were studied with the isothermal dissolution method. According to the experimental results, the dry-salt phase diagram, the water content phase diagram, and the physicochemical properties (pH and refractive indexes) diagrams were plotted. In the dry-salt phase diagram, there are two invariant points, five solubility isotherm curves, and four crystallization fields corresponding to LiCl⋅H₂O, NaCl, LiHCO₃ and NaHCO₃. The crystallization region of LiHCO₃ is the largest, while that of LiCl⋅H₂O is the smallest. LiCl⋅H₂O has the highest solubility and exerts a strong salting-out effect on NaCl and NaHCO₃. A comparison between the phase diagrams of the systems Li⁺, Na⁺//Cl^‒, ({text{CO}}_{3}^{{2 - }})‒H₂O at 323.15 K and Li⁺, Na⁺//Cl^‒, ({text{HCO}}_{{text{3}}}^{ - })‒H₂O at 313.15 K shows that the crystallization zones of carbonate salts (LiHCO₃ and NaHCO₃) change to those of bicarbonate salts (LiHCO₃ and NaHCO₃).The change in area of the crystallization zones for bicarbonate salts can be used to separate NaHCO₃ from the lithium precipitation mother liquor with CO₂ carbonation method.

Abstract—Nitrogen, phosphorous, and silicon-doped few-layer graphite fragments (FGFs) are synthesized by pyrolyzing acetonitrile, triphenylphosphine, and tetramethylsilane, using a MgO template. The N, P, and Si-FGFs are consolidated using spark plasma sintering (SPS) at 1100°С and 30 MPa and also treated with the high-frequency induction discharge plasma. The materials are studied using transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. After the SPS treatment, the samples of N, P, and Si-FGFs are transformed into nonuniform materials with complex morphology, containing substantially lower amounts of heteroatoms compared to nonsintered samples. It is shown that the pressure applied during the SPS plays a less significant role as compared to the resistive heating. The latter induces a plasma breakdown, thus facilitating phase transitions. The treatment of N, P, and Si-FGFs with high-frequency induction discharge plasma facilitates their transformation into N-doped bulbous carbon structures (BCSs) ~10 nm in diameter, and amorphous P and Si-doped carbon.