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Vol 99, No 6 (2025)
- Year: 2025
- Published: 15.06.2025
- Articles: 16
- URL: https://journals.rcsi.science/0044-4537/issue/view/20423
CHEMICAL THERMODYNAMICS AND THERMOCHEMISTRY
Thermodynamic characteristics of protolytic equilibria involving tyrosyl-proline
Abstract
The enthalpies of interaction of Tyr-Pro hydrochloride solution with HCl at 298.15 K and ionic strength values of 0.25 M, 0.5 M and 0.75 M (background electrolyte KCl) were measured by calorimetric method. The step dissociation constants of Tyr-Pro were determined by the potentiometric method at a temperature of 298.15 K and a solution ionic strength value of 0.2 M (background electrolyte KCl). The following values of pK1 = 2.87 ± 0.05, pK2 = 7.51 ± 0.05 and pK3 = 9.79 ± 0.05 were obtained. The enthalpies of stepwise dissociation of the dipeptide were calculated using the universal HEAT program. Standard thermodynamic characteristics (Δ rH°, Δ rG°, Δ rS°) of acid-base interaction reactions in aqueous solutions of Tyr-Pro were calculated. The influence of the background electrolyte concentration on the enthalpies of peptide dissociation is considered.
Russian Journal of Physical Chemistry A. 2025;99(6):831-836
831-836
SYNTHESIS, RENTGENOGRAPHICAL AND THERMODYNAMIC PROPERTIES OF FERRO-TELLURITE LuCaFeTeO6
Abstract
Ferro-tellurite of composition LuCaFeTeO6 was synthesized from oxides Lu2O3(grade «o.p.»), TeO2 («h.p.»), Fe2O3, calcium carbonate (qualification «p. d. a.») by ceramic technology. The identity was confirmed by X-ray phase analysis method, the syngony type was determined, and the unit cell parameters, X-ray and pycnometric densities of the compound were determined. The isobaric heat capacity of tellurite was investigated by the method of dynamic calorimetry in the temperature range 298.15—673 K, and the equations of Cp (T) dependence were derived. Temperature dependences of thermodynamic functions S(0)(T), H0(T) — H(0) (298.15), Fxx(T) and heat capacity Cp0(T) have been calculated.
Russian Journal of Physical Chemistry A. 2025;99(6):837-844
837-844
CHEMICAL KINETICS AND CATALYSIS
INFLUENCE OF THE NATURE OF THE CARRIER ON THE Al2O3 BASE ON THE PROPERTIES OF THE CATALYST FOR LIQUID-PHASE HYDROGENATION
Abstract
The influence of crystalline modification of aluminum oxide-based substrates for nickel catalysts on the activity in the reaction of liquid-phase hydrogenation of multiple carbon bonds in molecules of various classes of organic compounds is considered. The basic physicochemical and textural properties of the applied nickel catalysts obtained by the impregnation method are presented. The influence of textural properties of the carrier on the main kinetic regularities of the hydrogenation reaction is shown. The presence of individual forms of adsorbed hydrogen on the studied catalyst samples has been established, and the possibility of using the IR spectrometry method to solve this problem has been shown.
Russian Journal of Physical Chemistry A. 2025;99(6):845-852
845-852
Theoretical Study of the Reaction Amber Anhydride with Benzocaine
Abstract
Possible reaction pathways of aminolysis of succinic anhydride by benzocaine — concerted and two-step — have been investigated by the density functional theory method (level ωB97M—V/ma-def2-QZVPP//r2SCAN-3c). For each mechanism three variants are considered: without catalysis, self-catalysis by the reagent molecule (benzocaine) and autocatalysis by the product (succinamide). Thermodynamic and activation parameters of all elementary stages in the gas phase are calculated. It is shown that different mechanisms are involved in the course of the reaction: at early stages, both concerted and two-stage pathways of self-catalysis can be realized with equal probability; as the product is formed, the preferred route of reaction becomes stage autocatalysis with the limiting first stage.
Russian Journal of Physical Chemistry A. 2025;99(6):853-865
853-865
STRUCTURE OF MATTER AND QUANTUM CHEMISTRY
SOME ASPECTS OF THE ENDOHEDRAL CLUSTER ORIENTATION IN THE EXOHEDRALLY FUNCTIONALIZED DySc2N@C80 AND Dy2ScN@C80 MOLECULES
Abstract
We present a computational study of the most energetically stable conformations and properties there of in the dysprosium endohedral compounds of the M3N@C80 type modified by exhohedral function alization. We report the most stable configurations of the endohedral cluster and demonstrate good perfor mance of the density functional theory (DFT) in combination with the large-core effective core potential (ECP) that incorporates the 4f-shell of the dysprosium ions.
Russian Journal of Physical Chemistry A. 2025;99(6):866-871
866-871
Conformations and types of coordination glutarate ions in f-metal complexes
Abstract
Crystallochemical analysis of all known compounds of f-metals containing glutarate ions C5H6O42– has been carried out. It was found that 154 crystallographically non-equivalent glutarate ions exhibit 11 topologically different types of coordination to f-metal atoms in crystal structures. It has been found out that for aliphatic dicarboxylate ions [O2C—(CH2)n—CO2]2– at n > 1 the types of coordination that lead to the formation of four-membered metallocycles are characteristic. Using glutarate ions as an example, a new method of quantitative evaluation of the conformation of chains consisting of five carbon atoms connected by single C—C bonds has been tested for the first time. It is shown that in the characterized structures 154 glutarate ions realize four different conformations, each of which corresponds to a certain «double» symbol: φ3/φ3, φ1/φ3, φ(1)/φ(1), or φ(1)/φ2.
Russian Journal of Physical Chemistry A. 2025;99(6):872-878
872-878
PHYSICAL CHEMISTRY OF NANOCLUSTERS, SUPRAMOLECULAR STRUCTURES, AND NANOMATERIALS
Influence of the method of catalyst production on the properties of synthesized carbon for electrochemical systems
Abstract
The results of investigation of the influence of the method of preparation on the properties of Co/Mo/MgO catalysts and carbon nanotubes (CNTs) synthesized on them by chemical vapor deposition are presented. The catalysts were prepared by modified precipitation method and glycine-nitrate method. The structure and properties of CNTs were studied by low-temperature nitrogen adsorption, scanning and transmission electron microscopy, and Raman spectroscopy. The effect of the addition of synthesized CNTs on the conductivity of NMC811 (LiNi0.8Mn0.1Co0.1O2) based cathode material was investigated.
Russian Journal of Physical Chemistry A. 2025;99(6):879-886
879-886
ХЕМОИНФОРМАТИКА И КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ
Modeling the influence of H2S and CO2 concentrations on hydrate formation of a mixture approximating natural gas
Abstract
The application of energy-efficient and environmentally safe technology of gas hydrate crystallization for purification of natural gas from hydrogen sulfide (H2S) and carbon dioxide (CO2) is considered. Thermodynamic modeling of the influence of H2S and CO2 concentrations from 1.00 to 20.00 mol. % on gas hydrate dissociation pressures and filling of gas hydrate cavities with the gas mixture CH4 — C2H6 — C3H8 — n-C4H10 — CO2 — H2S — N2 in the temperature range of 273.15—283.15 K has been carried out. It is obtained that increasing the concentration of H2S leads to a significant decrease in the dissociation pressures of gas hydrates. The filling of small gas hydrate cavities with H2S molecules reaches 0.91. Increasing the concentration of CO2 leads to a slight increase in the dissociation pressures of gas hydrates. It is found that CO2 is poorly concentrated in the gas hydrate phase of the considered gas mixture. To extract CO2 it is necessary to apply multiple gas hydrate crystallization or to use natural gas deposits with low concentrations of C3H8.
Russian Journal of Physical Chemistry A. 2025;99(6):887-894
887-894
Thermodynamic Modeling of Condensed Phase Composition during Decomposition of Iron(III) Acetylacetonate
Abstract
Thermodynamic modeling of the composition of condensed phases formed during the decomposition of the volatile precursor Fe(acac)3, iron (III) acetylacetonate, depending on the conditions (temperature, total pressure, amount of added oxygen) was performed. Selection and processing of initial thermodynamic data for gaseous and crystalline Fe(acac)3 (enthalpy and entropy of formation, temperature dependences of heat capacity) and for its sublimation process have been carried out. It is shown that the introduction of a set of consistent data on the precursor does not affect the modeling results, i. e., the initial substance is thermodynamically unstable in equilibrium with the possible components of the gas phase and the complication of the calculation model is not reasonable. The obtained diagrams can be useful for optimization of processes of chemical gas-phase deposition of materials containing iron oxide or carbide phases.
Russian Journal of Physical Chemistry A. 2025;99(6):895-900
895-900
PHYSICAL CHEMISTRY OF DISPERSED SYSTEMS AND SURFACE PHENOMENA
Study of hydrogen peroxide decomposition in the presence of mesoporous carbon material
Abstract
The process of hydrogen peroxide decomposition in the presence of mesoporous carbon material has been studied. The values of rate constants and activation energy of hydrogen peroxide decomposition reaction were determined. The change of the reaction rate in time from zero order to the first order was observed. It is shown that the activation energy of hydrogen peroxide decomposition reaction is 84 kJ mol¯1, and in the presence of mesoporous carbon material it decreases to 19 kJ mol¯1.
Russian Journal of Physical Chemistry A. 2025;99(6):901-911
901-911
Variation of Polymer Material of Walls as a Tool to Influence Mechanochemical Transformations Involving Molecular Crystals
Abstract
On the example of two polymorphic transformations in crystals of organic compounds (glycine and carbamazepine) and dehydration of carbamazepine dihydrate the influence of the material of the drum of a vibrating ball mill (steel or various polymers) on the result of mechanical impact on the sample is shown, as well as the possibility to use for studying this influence the method of manufacturing polymer liners in steel drums by 3D printing available in laboratory conditions.
Russian Journal of Physical Chemistry A. 2025;99(6):912-918
912-918
Thermodynamics of enantioselective adsorption of dipeptides on surface porous adsorbents with grafted antibiotics teicoplanin and vancomycin
Abstract
The effect of temperature on the retention and enantioseparation of dipeptides (DPs) with one and two chiral centers on surface-porous adsorbents Chiral-T and Chiral-V with grafted antibiotics teicoplanin and vancomycin by linear chromatography was studied. Multidirectional temperature dependences of the retention factor were revealed: decreasing — on Chiral-T and increasing — on Chiral-V. Adsorption of DP stereoisomers on Chiral-T is characterized by exothermic effect, and on Chiral-V — by endothermic thermal effect. It was found that the solvation effect and steric factors on Chiral-T have a greater influence on the retention and enantioseparation of the stereoisomers of the studied DPs than the energetic changes. The thermodynamic characteristics of adsorption were analyzed using extrathermodynamic relationships. Statistical analysis of the compensation effect revealed a different mechanism of retention and enantioseparation of DP stereoisomers on Chiral-T and Chiral-V. The mechanism of adsorption of DP stereoisomers on Chiral-T is more influenced by the spatial configuration of the DP molecule, and on Chiral-V — by the lipophilicity of DP.
Russian Journal of Physical Chemistry A. 2025;99(6):919-933
919-933
Sorption of La(III) and Er(III) ions on silica gel with fixed monoethanolamine
Abstract
The results of studying the sorption of lanthanum(III) and erbium(III) ions from model solutions on ASC silica gel modified with monoethanolamine are presented. The influence of solution composition (pH and salt background) on sorption equilibria was investigated. The sorption rate constants of La(III) and Er(III) ions for pseudo-first and pseudo-second order equations at 296, 303 and 313 K were calculated. The adsorption isotherms of the selected ions were treated in the coordinates of the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin equations. Using the sorption equilibrium constants of the Langmuir model, the thermodynamic parameters of sorption were calculated for different temperatures. According to the obtained values of thermal effects of the process, the sorption of lanthanum(III) and erbium(III) ions on the studied sorbent is mainly due to physical forces. With increasing temperature, the equilibrium for both ions shifts towards desorption. The kinetics of sorption of La(III) and Er(III) ions in their combined presence has been studied.
Russian Journal of Physical Chemistry A. 2025;99(6):934-941
934-941
ELECTROCHEMISTRY. GENERATION AND STORAGE OF ENERGY FROM RENEWABLE SOURCES
ESTIMATION OF FLUCTUATIONS OF ALUMINUM ELECTRODE POTENTIAL IN CHLORIDE-CONTAINING AT ANODIC POLARIZATION BY MICROCURRENTS
Abstract
The structure of integral curves obtained by processing chronopotentiograms (CPG) of an aluminum anode polarized by a weak (at the level of one to several μA/cm2) current in chloride-containing medium is self-similar. This universal property allows us to find their fitting function and calculate the reduced (compressed dependence; the initial number of points is 1000, described by the number of AFC-14 modes). The initial curve is invariant with respect to its transformed counterpart after five-fold compression. For two different types of data, obtained with open circuit and with metal polarization by microcurrent, a common fitting platform related to its parameters can be obtained. There are various methods of detrending: i. e., obtaining a trend from the original trendless noise. The simplest method of obtaining a trend that does not give computational errors is obtained from a numerical integration formula using the trapezoidal method. It is this trend, obtained from the original trendless sequence without additional data processing errors, that it makes sense to define as a clear trend. The approximation parameters can be used to compare various random processes, including those caused by reactions on the metal surface with changes in its microrelief during redox processes.
Russian Journal of Physical Chemistry A. 2025;99(6):942-951
942-951
PHOTOCHEMISTRY, MAGNETOCHEMISTRY, MECHANOCHEMISTRY
Photocatalytic oxidative degradation of diclofenac in water using iron-containing metal-ceramic composites under irradiation and ozonation conditions
Abstract
The photocatalytic activity of iron-containing silicon nitride-based metal-ceramic composites in the process of oxidative degradation of the pharmaceutical pollutant diclofenac (DCF) has been investigated. The composites were obtained by nitriding ferrosilicon without additives and ferrosilicon with shungite (modifier for SiC production) in combustion mode. It is noted that the use of urea allows to additionally modify the ceramic matrix of composites with semiconducting phases (Fe2O3, C3N4) capable of absorption in the region of near-UV and visible light. The phase composition has been established, morphological features and optical properties of the composites have been studied. The acid-base properties of the surface have been evaluated. Adsorption and catalytic activity of composites in the absence and with H2O2 addition under UV irradiation (Fenton photochemical process), under ozonation conditions under UV and visible light irradiation were studied. The highest degree of DCF degradation was found when heterogeneous photocatalysis and Fenton process were combined (84%) and under photocatalytic ozonation conditions (88%). The kinetics of photocatalytic degradation of DCF was investigated using a pseudo-first-order model. The degradation products of DCF were determined GC—MS.
Russian Journal of Physical Chemistry A. 2025;99(6):952-963
952-963
БИОФИЗИЧЕСКАЯ ХИМИЯ И ФИЗИКО-ХИМИЧЕСКАЯ БИОЛОГИЯ
Effect of copper(II) ions on physicochemical properties of lecithin liposomes in aqueous medium
Abstract
The interaction of copper(II) ions with natural lipids (soybean lecithin with different phospholipid composition) in aqueous medium has been studied. Using methods of thin-layer chromatography, dynamic light scattering and mathematical processing of UV-spectra by Gauss method, it was revealed that in aqueous medium lecithin forms rather large liposomes with a diameter of about 900 nm, the size of which decreases in the presence of copper(II) ions regardless of their concentration. It was found that copper(II) ions both initiate lipid peroxidation processes and form complexes with polar «heads» of phospholipids. It is shown that these processes depend on the composition of lecithin lipids and their ability to oxidation.
Russian Journal of Physical Chemistry A. 2025;99(6):964-970
964-970