Russian Journal of Physical Chemistry A最新文献

Native, modified, and polymeric cyclodextrins are used for the first time to improve the solubility and bioavailability of synthetic immunomodulator fingolimod (FTY720). It is shown that the solubility of FTY720 grows in the presence of cyclodextrins. Constants of the stability of guest–host complexes and the index of efficiency of the solubilizing action of cyclodextrins are calculated from experimentally obtained phase solubility diagrams of FTY720. The effect the structure of cyclodextrin on the solubilization of FTY720 is considered.

Results are presented from developing a model for accurately predicting the wavelength of the absorption maximum of boron(III) dipyrromethenates (BODIPYs). The model is based on a graph neural network (GNN) and includes data for >2500 dyes of various natures. Statistical parameters of the model (MAE and R²) are 4 nm and 0.99 for the training set and 13.5 nm and 0.87 for the testing set. The developed model is available to the public in the GitHub repository (https://github.com/lukanov-9b/Abs_model.git).

Copper antimonides and phases based on them are of great interest as environmentally friendly functional materials for potential application in various areas of industry and technology. Present work demonstrates the results of thermodynamic study of Cu₄Sb and two polymorphic modifications of Cu₂Sb by low temperature electromotive force method (EMF) with a Cu⁺ conducting solid electrolyte RbCu₄Cl₃I₂ in 300–480 K temperatures range. Measurements were performed using equilibrium samples from the Cu₂Sb + Sb and Cu₄Sb + Cu₂Sb phase regions of the system. Phase compositions of samples were controlled using the powder X-ray diffraction (PXRD) method. Partial molar thermodynamic functions of copper in alloys, as well as, thermodynamic functions of formation and the absolute entropies of the RT–Cu₂Sb, HT–Cu₂Sb, and Cu₄Sb compounds were calculated. The enthalpy and entropy of the polymorph transition of Cu₂Sb were calculated based on the EMF data. A comparative analysis of obtained results with literature data was performed.

A comparative study is performed of the acid–base and optical properties of water-soluble porphyrin photosensitizers with meso-(3'-methylpyridyl) and meso-(β-D-galactopyranosyloxy)phenyl substituents. Due to the high hydrophilicity of these meso-substituents, the obtained compounds are quite soluble in water and have a linear concentration dependence of absorption and fluorescence in the working range. It is established that the photosensitizers are diprotonated on a porphyrin platform with close values of step constants, accompanied by a strong rise in the intensity of long-wave absorption, fluorescence, and fluorescence quantum yield. Introducing galactose fragments into the periphery of the macrocycle raises the observed rate of photodecomposition, testifying to the greater efficiency of singlet oxygen generation. It is shown that the studied cationic porphyrin photosensitizers can form effective charge-transfer nanoconjugates with colloidal quantum dots.

Donor-acceptor systems containing metalloporphyrin as an electron-donor component exhibit the property of photoinduced electron transfer (PET), which makes them promising in obtaining materials for optoelectronics. In a search for new perspective systems with PET we have performed experimental studies of interactions between the newly synthesized (5,15-bis(4,6-dichloropyrimidin-5-yl)-10,20-bis(2,4,6-trimethylphenyl)porphinato)cobalt(II) (CoPCl₄) and 1-methyl-2-(pyridin-4'-yl)-3,4-fullero[60]pyrrolidine (PyC₆₀) in toluene at 298 K. The process parameters were obtained, and a complete kinetic description is presented. The process occurs stepwise as reversible and irreversible reactions and ends with the formation of the donor-acceptor triad (PyC₆₀)₂CoPCl₄ via the formation of an intermediate product—the dyad (PyC₆₀)CoPCl₄. The composition and structure of the triad are substantiated using UV-visible, IR, and ¹H NMR spectroscopy and MALDI-TOF mass spectrometry data. A comparative analysis was performed of the quantitative parameters of the (PyC₆₀)₂CoPCl₄ formation reaction with those for structural analogs previously described in the literature; the formation constants of the triads were correlated with their structure, which is important for fine tuning of the properties of functional materials based on them.

Side interactions between the test substance and container were summarized and classified based on the experience of studying the thermodynamics of vaporization of metal oxides obtained by high-temperature or Knudsen effusion mass spectrometry (KEMS). The importance of identifying side interactions is emphasized and illustrated with examples. Practical experience in selecting the container material based on the available theoretical information and experimental testing is described.

Thermodynamic parameters of the formation of a silver(I) complex with 1-aza-18-crown-6 in mixed water–dimethyl sulfoxide solvents are determined calorimetrically at 298.15 K ((log K), ∆_rG°, ∆_rH°, ∆_rS°). The dependence of the constant of stability on the composition of the solvent is nonlinear, and the maximum stability of a complex particle is observed in a mixed solvent with x(DMSO) = 0.2 mol fraction (50 vol %). The exothermicity of complex formation grows monotonically upon raising the content of DMSO in the solvent. The solvation contributions from reagents to the change in the enthalpy of complex formation is analyzed from the viewpoint of the solvation–thermodynamic approach, along with the change in the stability of the complex upon moving from water to dimethyl sulfoxide. The thermodynamic parameters of the formation of a complex of silver(I) with 1-aza-18-crown-6 obtained in this work are compared to literature data for the complexation of silver(I) with crown ether 18-crown-6 and cryptands.

The structural and mechanical properties of hydrogels prepared from Pluronic F127 (20 wt %) are described and analyzed. The effects of nicotinic acid and nicotinamide (1 wt %) additions on the gelation process and the properties of Pluronic hydrogels are considered. The influence of the ionization state of nicotinic acid and nicotinamide molecules on interactions with the polymer matrix of the gel was studied by ¹H NMR spectroscopy. A kinetic study of the release and transmembrane transport of nicotinic acid and nicotinamide included in Pluronic hydrogels was performed. The influence of the acidity of the medium on the rate of release of drug compounds from hydrogels and on the transmembrane transfer was analyzed.

In this study, we conducted a comprehensive spectral analysis of the spatial structure of the anticancer drug compound bicalutamide, marketed under the trade name Casodex®, using a combination of one- and two-dimensional NMR spectroscopy methods in a deuterated dimethyl sulfoxide environment. The data from selective nuclear Overhauser effect experiments and quantum chemical calculations, performed within the framework of density functional theory, allowed us to quantitatively assess the conformer group fractions of the compound in deuterated dimethyl sulfoxide.

A way of processing thermochemical measurements is analyzed in respect to determining the enthalpies of combustion and the formation of ionic liquids (ILs). It is shown that the error in the difference between the heat of combustion of an IL in a polyethylene ampoule and that of polyethylene is ignored, and the error in the difference between the sum of the enthalpies of the formation of combustion products and the combustion of the IL is not considered when calculating the enthalpies of formation. It is proposed that the linear dependence of the heat of combustion on the mass of a sample passing through the origin of coordinates be used to increase the accuracy of calculating an IL’s heat of combustion. The heats of combustion of polyethylene ampoules and three ionic liquids are measured: trihexyltetradecylphosphonium bromide ([P₆₆₆₁₄]Br), butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N₄₁₁₁][NTf₂]), and 1-butyl-4-methylpyridinium tetrafluoroborate ([BMPy][BF₄]). A linear dependence of the heat of combustion on the mass of a sample is established and used to determine the standard enthalpies of combustion of the studied ILs. It is shown that the error in determining an IL’s heat of combustion grows as the mass of a sample shrinks, and the specific heat of combustion falls due to a reduction in the difference between the specific heats of combustion in a polyethylene ampoule and the ampoule itself.