Russian Journal of Physical Chemistry A最新文献

The authors propose an algorithm for determining the reliability of physicochemical properties using zinc nitrate hexahydrate as a case study. This compound is a promising phase change energy-saving material at low temperatures. The approach underscores the need to verify the informational reliability of a vast amount of experimental data. Dubious experimental values are averaged or excluded in determining the reliability of such properties as enthalpy, temperature of melting, density in the solid and liquid phases, heat capacity in the solid and liquid phases, and viscosity. Reliable literature properties are identified, and experimental measurements are made of the characteristics of zinc nitrate hexahydrate of various classifications to find correlations between reliable literature and experimental data.

Adsorbents based on Silipore 200 silica noncovalently modified with complex compounds of nickel(II) with acetylacetone, benzoylacetone, and ethyl acetoacetate were obtained. The interaction of the vapors of aromatic compounds with the silica surface was studied by gas chromatography: the Henry constants were calculated, the thermodynamic characteristics of adsorption of the class of compounds under study were determined based on chromatographic data, and the contributions of modifying additives to the retention of adsorbates were calculated. The effects of the ligand functional groups in the chelate complex on the differential molar heat of adsorption and the change in the adsorption entropy were studied. The possibility of using the sorbents for gas chromatographic separation of complex mixtures of organic compounds was shown.

The paper presents the results of anticorrosion gravimetric studies of the quaternary nitrogen-containing derivatives of 2-allyl-4-isodecylphenol, namely, the quaternary ammonium salts 2-allyl-4-isodecyl-6-diethylaminomethylphenol (I) and 2-allyl-4-isodecyl-6-piperidinomethylphenol (II) on steel St.3 plates in a system consisting of a 3% aqueous NaCl solution and hydrocarbons (kerosene) at a ratio of 9 : 1 (vol/vol). The influence of the temperature and concentration of the compounds on the corrosion rate, metal surface coverage, and protective effect was studied (test time 5 h). Compounds I and II were found to have high inhibitory properties. The thermodynamic parameters of adsorption (ΔG, ΔH, ΔS) were determined, based on which the chemisorption blocking mechanism of steel St.3 surface protection was proposed. The chemisorption process is described by the Langmuir isotherm.

Thermodynamic modeling of the Ga–Ge binary system was carried out with the help of the CALPHAD (CALculation of PHAse Diagram) method. The liquid and diamond (Ge) phases have been described with the sublattice formalism and the excess model with the Redlich–Kister equation. The solution phase (Ga) was treated as a pure element. The most experimental data, including phase diagrams and thermodynamic information, gathered from the literature were employed to optimize the thermodynamic parameters. The resultant calculated phase diagram and the system’s thermodynamic properties are in satisfactory accordance with the majority of the experimental data.

The kinetic model of the synthesis of methyl-tert-butyl ethers by intermolecular dehydration of tert-butanol with methanol using HY zeolite with a hierarchical structure as a catalyst (HY_mmm), as well as a catalyst system based on CuBr₂ deposited on HY_mmm, is considered. A kinetic model was constructed and a multistage scheme of chemical transformations was developed based on the experimental data. The kinetic model is based on the law of acting surfaces with allowance for adsorption and desorption processes on the catalyst surface. The inverse problem was solved in the form of a global optimization problem, which made it possible to determine the parameters of the kinetic model—the kinetic constants and activation energies.

The linear Scofield–Litster–Ho (LM) model is used to obtain a representation of the scaling hypothesis (SH) similar in structure to the SH representation. The new representation follows from the phenomenological theory of the Migdal critical point and allows the construction of an equation of state in physical variables, in accordance with the requirements of the scale theory. As in the Berestov critical point model, isochoric heat capacity reduced to absolute temperature (({{C}_{{v}}})/T) is used as a scale factor in the proposed critical point model. Based on Benedek’s hypothesis, scale functions of Helmholtz free energy in density–temperature variables not inferior to the corresponding LM scale functions can be calculated using the proposed SH model. In contrast to scale functions calculated on the basis of Migdal’s SH representations, free energy scale functions calculated within the proposed critical point model do not contain integrals of differential binomials. A unified fundamental equation of state in the context of the new SH concept is proposed and tested by describing the equilibrium properties of methane in the 90.6941–620 K range of temperatures at pressures up to 600 MPa.

Cyclic voltammetry is used to study the electrocatalytic activity in the formation of molecular hydrogen with condensed heterocyclic compounds 1,10-phenatroline and its derivatives 2,9-dimethyl-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline using CF₃COOH. It is shown that the efficiency and mechanism of electrocatalysis depend strongly on the nature of the catalyst. Raising the number of methyl substituents in the heterocyclic framework improves the efficiency of the process (to more than the TOF value). Mechanisms of the processes are studied and key intermediates are identified via DFT within the context of the density functional theory (DFT) using the B3LYP hybrid functional in the 6-31++G basis.

Spinel type manganese oxide MnO₂⋅0.5H₂O (H_1.6Mn_1.6O₄) is considered one of the most promising precursors for lithium-ion sieves due to its high theoretical lithium adsorption capacity (72.3 mg/g), and is suitable for selectively extracting lithium from high magnesium lithium ratio brine. In this paper, the powdery lithium-ion sieve precursor Li_1.6Mn_1.6O₄ was prepared by two-step urea-assisted hydrothermal method combining with solid phase method, and the effects of urea/Mn ratios on the adsorption performance of lithium-ion sieves were explored. The results show that as the ratio of urea to Mn increases to 40, the particles tend to acquire a cubic morphology. Moreover, desorption of lithium during the acid leaching of the precursor becomes more favorable. The lithium-ion sieve pellets were prepared by the anti-solvent precipitation method. According to the calculated selectivity coefficient, the separation order by the pellets in the mixed solution is Li⁺ ( gg ) Na⁺ > Mg²⁺ > Ca²⁺, demonstrating the lithium-ion sieve has a high selectivity to lithium. The adsorption kinetics of lithium-ion sieve pellets in a solution containing lithium illustrates a chemical adsorption mode.

Detailed structural and computational studies of 2-((2-hydroxybenzylidene)hydrazineylidene)-2-phenylacetaldehyde oxime (1), using the DFT and molecular docking computations, are reported. The molecular structure of 1 is stabilized by a O–H⋅⋅⋅N hydrogen bond between the phenolic OH hydrogen atom and the nearest hydrazineylidene nitrogen atom, yielding a six-membered noncovalent ring, which, in turn, was found to be highly aromatic. Intermolecular O–H⋅⋅⋅N and C–H⋅⋅⋅N hydrogen bonds between molecules of 1 produce a 1D supramolecular polymeric chain of the zig-zag type. These chains are linked into a 2D supramolecular layer due to reciprocal π⋅⋅⋅π interactions formed between the phenylene and six-membered noncovalent rings. The reciprocal H⋅⋅⋅X (X = H, C, N, O) and C⋅⋅⋅Y (Y = C, N) contacts are the most prominent contributors to the crystal packing. The optimized molecule of 1 is a pronounced electrophile with the most nucleophilic sites found on the phenolic oxygen atom, oxime oxygen and nitrogen atoms, and one of the hydrazineylidene nitrogen atoms, while the oxime OH and some of the phenylene hydrogen atoms were revealed as the most eletrophilic sites. The discussed compound was found to be active against all the studied herein SARS-CoV-2 proteins. The best results were revealed against Papain-like protease (PLpro), nonstructural protein 14 (Nsp14_N7-MTase), and nonstructural protein 3 (Nsp3_range 207–379-MES), with the calculated ligand efficiency scores for complex PLpro–1 being within the recommended ranges for a Hit.