Russian Journal of Physical Chemistry B最新文献

For the first time in Russia, a clearly expressed functional effect of supercritical fluid of carbon dioxide in the presence of alcohol as a cosolvent is demonstrated on 12 species of paper-degrading micromycetes. To estimate the possibility of further use of this method for disinfection treatment of library and museum collections by pure supercritical carbon dioxide and with the addition of ethanol as a cosolvent in concentrations of 2 and 4%, the efficiency of various modes is analyzed using paper samples with foci of biodamage caused by the micromycete Aspergillus niger. It is shown that pure supercritical carbon dioxide leads to a minimal decrease in the content of microorganisms on the surface of samples. Treatment in supercritical carbon dioxide with the addition of 4% ethanol in the stirring mode allows for a high degree of reduction in sample contamination and can be considered as a promising method for processing paper documents.

Dimethyl sulfoxide (DMSO) is proposed as a solvent at the gelation stage for obtaining transparent aerogels (AGs) based on tetramethyl orthosilicate and 3-aminopropyltrimethoxysilane (APTMS). The transparency of the AGs varies depending on the content of the aminopropyl fragment. The textural characteristics of the AGs are studied. It is shown that the use of DMSO instead of isopropanol, a standard solvent for obtaining the gel, makes it possible to significantly increase the specific surface area of the AGs. Using DMSO as a solvent, transparent AGs based on APTMS modified with residues of perfluorononanoic acid and L-phenylalanine are synthesized. It is shown that it is possible to obtain transparent AGs containing amino complexes of transition metals, namely, copper and palladium.

The leafy moss Common Haircap (Polytrichum commune) is widespread in nature, actively used in folk medicine, and is a promising renewable raw material for obtaining valuable biologically active substances. In this study, a method for extracting lipophilic secondary metabolites from P. commune biomass using supercritical fluid extraction with a mixture of carbon dioxide and acetone (9 : 1) is proposed. The implementation of an experimental design with varying temperature, pressure, and duration of extraction makes it possible to establish the optimal process conditions to achieve maximum values of the yield of extractive substances (>1.5%), the total polyphenolics content, and antioxidant activity. According to a high-performance liquid chromatography–high-resolution mass spectrometry analysis, the main constituents of the obtained extracts are stilbene flavonone communin A, diterpenoids and pentacyclic triterpenoids, polyunsaturated fatty acids, and pheophytin A, which possess high antioxidant and biological activity.

This article aims to indicate the behavior of trapping of main group cations of Cr(III), Co(II), Cu(II), Ni(II) by gallium nitride nanocone for sensing the water metal cations. The partial density of states (PDOS) can also evaluate an appointed charge group between Cr(III), Co(II), Cu(II), Ni(II) and GaN which indicate the most stable complex of metallic visage and a certain degree of covalent specifications between heavy metals cations and gallium nitride nanocage. Furthermore, the NMR analysis indicated the notable peaks surrounding metal elements of Cr(III), Co(II), Cu(II), Ni(II) through the trapping in the GaN during ion detection and removal from water; however, it can be seen some fluctuations in the chemical shielding treatment of isotropic and anisotropy tensors. Finally, the selectivity of metal ion adsorption by gallium nitride nanocage (ion sensor) has been approved as: Ni(II) >>> Cu(II) > Co(II) > Cr(III). Theoretical calculations revealed that the unique electronic interaction and the excellent geometric-matching structure between GaN and transition metals enabled an ideal electron-migration channel for high charge carrier extraction efficiency, leading to outstanding performance.

A novel cationic complexes, [Cu₄Ce₂·(H₂L)₄(NO₃)₄(H₂O)₃](NO₃)₂·5H₂O·2MeOH was synthesized, characterized, and studied using XRD, TG/DTG/DSC techniques, as well as measurement of both AC & DC magnetic susceptibility. Analyzing of the results exhibited that this complex crystallize as (NO₃)-bridged structures, whereas Cerium ion of lanthanide(III) family acts as a linkage connecting two [CuH₂L] coordination subunits. In each hetero-tri-nuclear section, asymmetry structure was created in the degree of planarity of the bridging CuO₂Ln segments. In contrast of Cu(II) ions, which are mostly six-coordinate with octahedral geometry and occasionally are five with distorted square pyramidal, Ln(III) ions including Ce(III) are nine-coordinate. In addition, through AC and DC magnetic susceptibility it was confirmed temperature dependence of the magnetic susceptibility for these complexes. Finally, the field-dependent magnetization of the ferromagnetic interaction between centers Cu(II) and Ce(III) was discussed through both experimental and DFT calculation.

Methacrylate derivatives of methoxypolyethylene glycol (mPEG) (5 kDa) have been synthesized in supercritical carbon dioxide (SC-CO₂) using urethane formation reaction. The use of SC-CO₂ has been shown to allow one to effectively run the reaction in two steps (with the preparation of an isocyanate derivative of mPEG in the first step and a methacrylate derivative in the second step) or combine the two steps into one. We have examined the effect of the reactant ratio and reaction conditions on the composition of the reaction products. Running the reaction in two steps has made it possible to obtain a methacrylate derivative of mPEG with a yield of up to 80%. The preparation of the isocyanate derivative of the polyester and the attachment of methacrylate residues were carried out at different parameters of SC-CO₂: isocyanate groups were introduced under “harsh” conditions (65°C, 20–24 MPa), and methacrylate groups, under “mild” conditions (40°C, 12–13 MPa). The resultant monomers were polymerized to give three-dimensionally cross-linked systems based on both individual modified mPEG and its mixtures with methacrylated polylactide. In the future, such systems can be used as scaffolds for cell immobilization and fabrication of implants.

The solubility of a series of copper salts (carbonate, acetate, benzoate, and thiocyanate) in supercritical carbon dioxide at 308–328 K and 10–30 MPa is determined. The results are described using the Peng–Robinson equation of state and the Mukhopadhyay and Rao mixing rule. The results are required for developing technological approaches for the impregnation of polymeric materials and creating composite materials based on them.

We have proposed a new method for measuring solubility in multicomponent fluids, which relies on supercritical antisolvent precipitation in combination with UV spectroscopy (SAS–UVS). Using acetylsalicylic acid as an example, we have compared solubility measurement results obtained by the method proposed in this study to literature data. On the whole, the acetylsalicylic acid solubility data obtained by the SAS–UVS method agree with literature data: the values are on the same order independent of conditions. In the vast majority of our experiments, the solubility values obtained by the SAS–UVS method fall between those obtained by a dynamic method and SAS–SFC (supercritical fluid chromatography). These results provide indirect evidence for adequacy of our data.

The interaction of water-soluble fluorine-containing tetracarboranylchlorin (BFChl) with DNA was studied by absorption spectroscopy, fluorescence and flash photolysis techniques. The association constants of the BFChl –DNA complex were obtained: 4.2 × 10⁴ M⁻¹ (absorption spectroscopy data) and 4.8 × 10⁴ M⁻¹ (fluorescence spectroscopy data). The spectral and kinetic characteristics of BFChl excited singlet and triplet states in the presence of DNA were determined. The interaction of BFChl with DNA leads to the formation of a complex on the DNA surface by the sorption mechanism. The quenching rate constant for the BFChl triplet state by oxygen in aqueous solution corresponds to the diffusion constant (k_q = 2.0 × 10⁹ M⁻¹ s⁻¹). However, in presence of the DNA the quenching rate constant for the BFChl triplet state by oxygen decreases twofold (k_qDNA = 1.2 × 10⁹ M⁻¹ s⁻¹), which suggests the existence of dye’s weak steric shielding by the DNA molecule. The obtained data allow us to speak about the external binding of the BFChl in the major groove region of the DNA molecule.

Quinizarin has been used for the first time as a photocatalyst for the oxidation of organic compounds with molecular oxygen in supercritical carbon dioxide medium under visible-light irradiation. The choice of catalyst is justified by the availability and high efficiency of quinizarin compared to structurally related anthraquinone derivatives, namely 2-nitro-1,4-dihydroxyanthraquinone and 2,3-diamino-1,4-dihydroxyanthraquinone. Carrying out the photocatalytic process in scCO₂ not only enables the efficient synthesis of sulfoxides and sulfones from the corresponding sulfides but also enhances the safety and environmental sustainability of the oxidation reaction.