Doklady Physical Chemistry最新文献

This study is dedicated to exploring the electroless Pd–Ag plating process. The conditional formation constants of Pd and Ag ions with respect to the pH of the plating solution were determined. Leveraging the electrode potential equations of metals, the co-deposition conditions were investigated by altering the pH and Na₂EDTA concentration. Through this research, specific plating parameters were obtained, and a 78.7Pd-21.3Ag/α-Al₂O₃ film was successfully fabricated via electroless plating. The composition of the prepared film was analyzed using X-ray diffraction (XRD), providing experimental evidence for the research findings. This research not only deepens the understanding of the electroless Pd–Ag plating mechanism but also offers valuable parameters for the preparation of Pd–Ag alloy membranes with excellent performance.

Mitigating CO₂ emissions from mobile combustion sources has been recognized as a pressing need, as heavy-duty engines continue to serve remote and mission-critical applications. Capture systems for such sources faced rapidly fluctuating exhaust compositions, temperatures, and flows, under which solvent performance had been poorly characterized. The research gap concerned the limited availability of transient metrics and comparative evidence for hybrid amine–amino acid sorbents under realistic load changes. The objective was to determine how formulation influenced instantaneous capture efficiency, response time, and regeneration energy during stepwise engine operation. A bench-scale packed column was coupled to a diesel generator subjected to programmed load steps; six solvents—30% MEA, 8% PZ, an MEA+PZ blend, and lysine, arginine, and alanine salts—were evaluated. Efficiency and response time were determined from 1 Hz inlet–outlet CO₂ measurements using a 90% approach-to-steady criterion; regeneration energy was calculated from batch desorption duties normalized per mole of CO₂ released. The MEA+PZ blend achieved sub-minute response times across all steps and the highest cumulative uptake, while maintaining high capture as the Load increased. Lag times were reduced by 55–67% relative to MEA and by approximately 25% relative to PZ. Amino-acid solutions exhibited longer lags and lower uptake consistent with higher viscosity and reduced free-amine availability. Energy analysis indicated that a disproportionate regeneration penalty did not offset the blend’s kinetic advantage. These findings suggest that hybrid amine systems offer robust operation under dynamic exhaust conditions, potentially enabling smaller columns or reduced circulation rates. Future work should examine long-duration cycling, promoter optimization, and integration with real-world duty cycles and control strategies.

The study is devoted to the preparation and investigation of the luminescent properties of precursors of complex oxide systems containing rare earth elements obtained by electrochemical methods. The formation of precursors of oxide systems is based on the processes of anodic dissolution of aluminum in a chloride-containing electrolyte in the presence of Al(III), Zr(IV), Dy(III), and Nd(III) ions due to co-deposition by electrogenerated OH^– ions. The synthesised dispersed aluminozirconium oxide systems with REEs demonstrate clearly expressed luminescent properties. All dispersed oxide systems, when excited by UV light at a wavelength of 250 nm, demonstrated luminescence in the UV and visible regions of the spectrum with maxima at wavelengths of 360, 380, and 700 nm. When comparing the spectra obtained for systems doped with rare earth oxides with the bands of the base system Al₂O₃–ZrO₂, it was found that their character remained practically unchanged, but in the case of systems containing neodymium and dysprosium oxides, an increase in luminescence intensity (hypochromic effect) by 3.5–4.3 times was observed. In the system doped with dysprosium oxide, an increase in the peak shoulder in the 450–500 nm region was observed. Presumably, this is due to a change in the structure of the doped oxide systems compared to the base Al₂O₃–ZrO₂ system. In the IR region of the spectrum, the neodymium-modified alumina system exhibits distinct luminescence peaks at wavelengths of 1070 and 1340 nm, corresponding to the ⁴F_3/2→⁴I_J (J = 11/2, 13/2) transitions of the Nd³⁺ ion. In the case of a sample modified with dysprosium, luminescence similar to that of the base aluminozirconium oxide system is observed.

Magnesium oxalate is an important biomineral and coordination compound with potential relevance in materials science and optoelectronics. In this work, a comprehensive study combining experimental spectroscopic techniques and quantum chemical calculations was performed to elucidate the molecular structure and electronic properties of magnesium oxalate. The optimized geometry obtained at the B3LYP/6-31G(d,p) level confirms the bidentate coordination of oxalate ligands and the mixed ionic–covalent nature of Mg–O bonds. Vibrational assignments from FT-IR and Raman spectra, supported by DFT calculations, revealed characteristic stretching and bending modes of the oxalate framework and Mg–O linkages. Theoretical UV-Vis and NMR spectra further validated the electronic environment and structural symmetry of the complex. Frontier molecular orbital (HOMO–LUMO) analysis highlighted ligand-to-metal charge transfer processes and provided insight into electronic stability and reactivity. Natural bond orbital (NBO) analysis demonstrated strong donor–acceptor interactions, particularly between oxygen lone pairs and antibonding C–O orbitals, accounting for significant charge delocalization within the molecule. The molecular electrostatic potential (ESP) map identified oxygen atoms as preferred electrophilic sites and magnesium as the main electron-accepting center. Global reactivity descriptors, dipole moment, polarizability, and hyperpolarizability values indicate notable nonlinear optical (NLO) behavior, consistent with charge-transfer mechanisms. Overall, this integrated experimental and theoretical approach provides new insights into the bonding, electronic distribution, and optical properties of magnesium oxalate, underlining its potential applications in supramolecular chemistry and optoelectronic devices.

This study explores the molecular structure, stability, reactivity, and antibacterial activity of sulfamerazine, a sulfonamide derivative, using computational and experimental approaches. Density functional theory (DFT) at the B3LYP/6-311+G(d,p) level was used to optimize geometry, analyze vibrational modes, and evaluate electronic properties. Key interactions such as S–N bond length, N→π* delocalization, and hydrogen bonding were found to influence antibacterial efficacy. Vibrational analysis and scaled quantum mechanical (SQM) methods revealed functional dynamics supporting molecular stability. Docking studies showed strong binding of sulfamerazine to bacterial enzymes, corroborated by in vitro assays against Staphylococcus aureus and Pseudomonas aeruginosa. Electron localization function (ELF) and natural bond orbital (NBO) analyses confirmed significant charge transfer and delocalization. Pharmacokinetic and toxicity evaluations supported its drug-likeness and safety. These results highlight sulfamerazine’s potential as a versatile antibacterial agent and provide insights for designing improved sulfonamide-based therapeutics.

Changes in the composition of aluminum hypophosphite, calcium hypophosphite, and their mixtures with oxidizers after combustion in air under atmospheric pressure have been studied by X-ray photoelectron spectroscopy (XPS). It has been established that the formation of colored condensed combustion products is associated with the formation of the corresponding phosphides. A hypothesis is proposed that the source of phosphide formation is phosphine and its reactive decomposition products generated during the disproportionation reaction of hypophosphites.

Plasma-activated medium (PAM) is produced by exposing a liquid solution, consisting of hyaluronic acid gel and deionized water, to nitrogen plasma. Plasma exposure through fast pulsed discharge (FPD) generates reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the liquid. The goal of this work is to figure out how many of these reactive species are in PAM. To test the levels of hydrogen peroxide, nitrite, and nitrate right after treatment and after 96 h of storage, a DC high voltage of about 15 kV was used for 5, 10, 15, and 20 min. The discharge promotes the formation of reactive nitrogen species, leading to moderate RONS levels. These species decay rapidly in water, but the gel remains much more stable due to limited diffusion and a stabilized matrix. Results indicate that fast-pulsed nitrogen discharge is effective and that hyaluronic acid gel efficiently retains plasma-generated reactive species over an extended period.

In recent years, machine learning algorithms have become popular for predicting the physicochemical properties of polymers, including the glass transition temperature (T_g). Accurate T_g prediction is critical for developing polymers with desired properties. Traditional T_g prediction was based on semi-empirical methods, such as Askadskii’s method. The goal of this study was to develop a hybrid approach for predicting the T_g of organic homopolymers, combining Askadskii’s method and the QSPR model with machine learning (ML), which uses the advantages of theoretical analysis and the capabilities of ML to improve prediction accuracy. Random Forest, K-Nearest Neighbors, and a multilayer perceptron were used. The molecular structure of the polymers was represented by structural keys (MACCSKeys) and Morgan fingerprints. Optimization of the random forest algorithm hyperparameters enabled an R² of up to 0.77 to be achieved on the test set. A comparative analysis showed that Morgan fingerprints that consider the spatial arrangement of fragments provide higher prediction accuracy, especially for isomeric homopolymers, where the spatial arrangement of substituents is important. The results demonstrate the potential of using ML for predicting polymer T_g based on glass transition theories and highlight the need for further research into hybrid models.

Equipment in the chemical industry is susceptible to corrosion due to the low corrosion resistance of carbon steel in aggressive environments. Polymer coatings are used to enhance the corrosion resistance of equipment. The adhesive interaction strength between the polymers (adhesives) and the steel (substrate) is determined by the adhesion mechanism. This work explores adhesive interaction between an adhesive (polyethylene terephthalate, poly(methyl methacrylate), polystyrene, or polypropylene) and a substrate (steel St3) experimentally and theoretically. Experiments served to determine the acid–base surface properties of the adhesive and substrate using the Berger and van Oss–Chaudhury–Good methods. Polyethylene terephthalate, poly(methyl methacrylate), and polystyrene were found to have basic properties, while polypropylene and the substrate had acidic properties. The theoretical method consisted in the quantum-chemical modeling of adhesive interaction between the chosen adhesives and substrate. α-Fe₂O₃ was regarded as the substrate surface model. The adhesive interaction mechanism and energy characteristics of adhesive–α-Fe₂O₃ systems were determined by the B3LYP-GD3/6-31G(d,p) method. The adhesive interaction strength was assessed via the adhesion energy. The reactive sites in the adhesive–α-Fe₂O₃ systems were found to be the surface functional groups of the adhesives, the presence of which helps strong adhesion to the substrate surface. The strongest interaction was in the systems formed via the carbonyl oxygen atom. The experimental and calculated data are well consistent.

A new metal–organic coordination polymer (MOCP) {La₂(nBrTerPDC)₃DMSO₃} has been synthesized by a solvothermal reaction (in a DMSO/1,4-dioxane solution) between lanthanum(III) nitrate and a brominated terphenyl dicarboxylic acid derivative nBrTerPDC. The structure of this MOCP was solved for the first time by direct methods using X-ray diffraction data. Selected details of the structure solution and parameters of the experiment carried out on the Belok/RSA diffraction beamline at the Kurchatov synchrotron radiation source (λ = 0.7527) are as follows: C₃₆H₃₀Br₉LaO₉S₃, FW 1560.88; space group P(bar {3}), a = b = 26.822(4) Å, c = 8.6710(17) Å, α = β = 90°, γ = 120°, V = 5402.3(19) ų, F(000) = 1476.0, absorption coefficient μ = 4.399 mm^–1, crystal dimensions 0.2 × 0.02 × 0.02 mm, reflection index ranges –21 ≤ h ≤ 32, –32 ≤ k ≤ 32, –10 ≤ l ≤ 9; total reflections 17 717, independent reflections 6459, R_int 0.1072, residual electron density 1.31/–0.62 e/ų. The unit cell contains two structurally unrelated La³⁺ cations. The relatively high factor R₁ = 0.1942 is associated with disorder in the arrangement and degree of occupancy of bromine atoms. This is a consequence of that during the bromination of terphenyl dicarboxylic acid dimethyl ester, bromine attaches to both the central and peripheral aromatic rings of the acid, forming many homologues, presumably mono-, di-, tri-, tetra-, penta-, and hexabromo derivatives, including positional isomers.