Russian Journal of Physical Chemistry A最新文献

Single-walled ultrashort (BN–C) Janus nanotubes of (n,0) and (n,n) chirality were studied by the DFT6-31G/B3LYP method. It is shown that these molecular systems are stable with respect to dissociation into constituent parts. The (BN–C) Janus nanotubes possess emission molecular orbitals with electron density localized in the end regions of the nanotubes. The energy of the emission molecular orbitals is sensitive to a uniform constant electric field. The critical values of the electric field strength for the appearance of emission current were estimated qualitatively. The emission properties of (BN–C) Janus nanotubes depend on the direction of the external electric field strength vector. The best emission properties in an electric field are inherent in the “transverse” (BN–C) Janus nanotubes, whose peri-positions are occupied by pyrrole nitrogen atoms and the electric field strength vector is directed along the cylindrical axis of the nanotube to the carbon fragment of the nanostructure.

With growing interest in the use of molten salts in industry, the development of an equation of state for quantitative prediction of the density of liquid electrolytes under various conditions has become one of the most important problems in physical chemistry. This equation should include not only the basic repulsive and Coulomb contributions to pressure, but also second-order corrections due to the charge–dipole and dipole–dipole interactions between ions. A new version of the equation of state is considered here, which includes both of these additional contributions to pressure based on the charged hard spheres (CHS) model. The proposed equation of state was used to calculate the packing coefficients of the whole subclass of molten alkali metal halides (AMHs) at their melting points. It was found that inclusion of both charge–dipole and dipole–dipole interactions in calculations leads to better agreement with experimental data by an average of ~5%. The dipole–dipole contribution is an order of magnitude smaller than the charge–dipole correction in this case. An analysis of these effects on the packing coefficient in the series of alkali metal halides showed that inclusion of both charge–dipole and dipole–dipole interactions leads to a more noticeable increase in density in the systems containing larger and polarizable cations and anions.

The heat capacity of ultra-pure glasses of the (GeTe_3.76)(_{{100 - x}})(AgI)_x system is studied via differential scanning calorimetry in the 330–480 K range of temperatures at x = 10–50 mol %. Hydrostatic weighing shows the density of samples rises from 5.475 to 5.693 ± 0.005 g/cm³ as the content of silver iodide grows. Results from a dilatometric study are used to determine the coefficient of thermal linear expansion in the 295 to 385 K range of temperatures. Consistent standard caloric and volumetric functions are calculated in the 0 to 450 K range of temperatures. A way of predicting these functions for intermediate unexplored glass compositions based on parametric similarity is proposed within the context of the theory.

Correlation dependence ({{Gamma }_{0}} = {{Gamma }_{0}}(gamma ,omega ,{{Z}_{c}})) is established between critical amplitude ({{Gamma }_{0}}) of coefficient isothermal compressibility ({{K}_{T}}), acentric factor ω, critical compressibility factor ({{Z}_{c}}), and critical index (gamma ). A description of critical amplitude (Gamma _{0}^{{(e)}}) of 24 substances is used as an example to show that the correlations of Gerasimov (2003); Perkins et al. (2013); and Abbaci (2024) in the form ({{Gamma }_{0}} = {{Gamma }_{0}}(omega )), and of Ivanov (2008) in the form ({{Gamma }_{0}} = {{Gamma }_{0}}(gamma )), are vastly inferior to the proposed correlation ({{Gamma }_{0}} = {{Gamma }_{0}}(gamma ,omega ,{{Z}_{c}})) in their accuracy of calculation. Three intervals of the critical index (gamma ) are considered: (gamma in [1,1.242]) (interval I), (gamma in [1.1,1.242]) (interval II), and (gamma in [1.239,1.242]) (interval III). In intervals II and III, the dependence of (Gamma _{0}^{{(e)}}) on (gamma ) is close to linear, so it is described by others that are linear in respect to ω, ({{Z}_{c}}), and (gamma ). The dependence of (Gamma _{0}^{{(e)}}) on (gamma ) is nonlinear in interval I. The correlation for ({{Gamma }_{0}}) has the form (Gamma _{0}^{*} = {{C}_{0}} + {{C}_{1}}omega + ) ({{C}_{2}}Z_{c}^{{ - n}} + {{C}_{3}}{{gamma }^{{ - g}}}), where (g = 9.1) and (n = 2). It is established that in all three considered intervals of (gamma ), the accuracy of nonlinear correlation (Gamma _{0}^{*}) is superior to the others studied in this work for ({{Gamma }_{0}}). Deviations of ({{Gamma }_{0}}) from (Gamma _{0}^{{(e)}}) in, e.g., interval I for correlations of Gerasimov, Ivanov, Perkins et al., and Abbaci, and for linear correlations and correlation (Gamma _{0}^{*}) proposed in this work, are estimated using absolute average deviations 22.1, 8.5, 16.5, 21.6, 6.6, 5.5, and 2.7%, respectively.

The electrochemical behavior of tricyclic monoperoxide on a smooth gold electrode in an acetonitrile solution was studied by cyclic voltammetry (CV). It was found that the cathodic process involves the joint transfer of two electrons. In the anodic process, the electrode corrodes, forming gold nanoparticles. A mechanism for the reduction of monoperoxide to triketone was proposed.

The photocatalytic activity of a suspension of titanium dioxide with fullerenol-70 in the decomposition of a microplastic has been studied. The efficiency of decomposition of various types of microplastics was determined based on the obtained results: the degradation after 1 day of experiment was 25 ± 12% for low-pressure polyethylene; 27 ± 3% for polyethylene terephthalate; 42 ± 8% for polystyrene; and 44 ± 21% for nylon. The resulting suspension of titania with fullerenol-70 is 1.9 times more efficient than a suspension of individual titania in the decomposition of high-density polyethylene and polyethylene terephthalate, three times more efficient in the decomposition of polystyrene, and 3.1 times more efficient in the decomposition of nylon.

An analysis of experimental data for solutions of 150 binary systems establishes a pattern of changes in Helmholtz energy depending on the molar mass and concentration of the system’s components. The corresponding equation is obtained. The established pattern allows us to predict the thermodynamic properties of binary solutions with high accuracy with a limited amount of experimental data. An analysis of experimental data on solutions of 150 binary systems has established a pattern of changes in Helmholtz energy depending on the molar mass and concentration of the components of the systems. The corresponding equation is obtained. The established pattern allows us to predict the thermodynamic properties of binary solutions with high accuracy with a limited amount of experimental data.

The paper describes results of studying the composition, structure, and catalytic properties of heterogeneous hybrid composites composed of an imidazole ionic liquid and iron(III) chloride supported on silicas of various structures, namely, silica gel, synthetic opal, and mesoporous SiO₂ synthesized by treating sodium borosilicate glass. The composition and structure of the hybrid materials are determined by adsorption methods, X-ray fluorescence (XRF) analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The catalytic properties of the materials in model oxidation catalysis reactions are determined. The results show that composites based on silica gel and opal exhibit high activity in the hydrogen peroxide-assisted oxidation of sulfur- and nitrogen-containing compounds.

The processes of the thermo-oxidative destruction of biphenyloxy-substituted phthalocyanines with fragments of small nitrogen-containing heterocycles and their metal complexes, as well as of sulfonic acids synthesized on their basis, were studied. The influence of the nature of peripheral substituents and the complexing metal on the thermal stability of the compounds is shown.

The possibility of using potentiometric titration with a copper indicator electrode to determine the solubility product of copper(II) dicarboxylates and the stability constants of Cu(II) complexes with dicarboxylate ligands is explored. The “Cu(II)–succinic acid in an aqueous solution” system is studied. Although the titration curve depends on both the solubility product and stability constants of some complexes, solubility product is the only parameter that can be determined from the titration curve in actual practice. The determined solubility product (K_SP) of copper(II) succinate CuC₄H₄O₄⋅2H₂O in water is as follows: in a temperature range of 21–40°C, the common logarithm (log {{K}_{{{text{SP}}}}})(CuC₄H₄O₄⋅2H₂O) is −6.7 ± 0.1.