Moscow University Chemistry Bulletin最新文献

Solubility behavior of amlodipine besylate (ADB) was investigated in the binary mixtures of ethylene glycol + 2-propanol at five different temperatures (293.2–313.2 K). The solubility results obtained from the shake-flask method are correlated with some reported cosolvency models (i.e. the van’t Hoff, combined nearly ideal binary solvent/Redlich–Kister, the Jouyban–Acree, the Jouyban–Acree–van’t Hoff, the mixture response surface, the modified Wilson, and Buchowski–Ksiazczak models). The accuracy of these models is investigated with the mean relative deviations of the back-calculated solubility data.

This article studies the development of a simple chromatographic method for the simultaneous determination of well-known antiseptics—chlorhexidine and triclosan—in new-generation antiseptic liquids. The dependencies of the retention times of chlorhexidine and triclosan on the concentration of acetonitrile in the mobile phase (30 to 60%) and pH (in a range of 3–8 units) for Luna C18, Nucleosil CN, and Diasfer C4 sorbents are studied. Ideal separation of chlorhexidine, p-chloroaniline (the most toxic decomposition product of chlorhexidine), dibutyl phthalate (as a component of cosmetic alcohol), triclosan, and ionol (butylhydroxytoluene (BHT) and E321—an antioxidant agent) during 20 min in the gradient elution mode on a column with a domestic Diasfer C4 sorbent is demonstrated.

The structures of small silver clusters (Ag_n, n = 1–3, 13) and their complexes with molecules of the antibacterial drug 2,3-bis-(hydroxymethyl)quinoxaline-N,N′-dioxide–dioxidine (Dx) are calculated using the electron density functional method in the DFT/B3LYP5 version. The features of the geometric structure and energy of the metal cluster–dioxidine ligand interaction are considered depending on the size (nuclearity) of the metal cluster. For small clusters (n = 1–3), a tendency for the metal to be coordinated to only one of the oxygen atoms of the ligand molecule is revealed. The most stable complexes are the silver trimers Dx–Ag₃ and the icosahedral silver cluster Dx–Ag₁₃, which are coordinated simultaneously with two oxygen atoms of the hydroxyl groups of the dioxidine molecule. The difference between the obtained optimized structures of the silver–dioxidine complexes and the previously studied silver complexes with hydroxide ligands, for which the hydrogen atom of the ligand hydroxyl group is displaced during the interaction, is shown.

A spectrophotometric procedure for the quantitative determination of copper(II) by a reaction of complex formation with pyrogallol red in the presence of cationic and nonionic surfactants is proposed. The optimum conditions for the analysis are determined. The procedure is tested for the determination of copper(II) in a sample of a soil extract. The following metrological characteristics of the proposed procedure are assessed: the limit of detection is 0.12 mg/kg of soil and the relative standard deviation is <0.05.

The stability of aqueous dispersions of detonation nanodiamonds (NDs) in the presence of polyvinyl alcohol (PVA) is studied. It is found that PVA additives with a concentration above 0.1 wt % cause the formation of aggregates. To increase the stability of dispersions of NDs, it is proposed to add a stabilizer—an anionic surfactant sodium dodecyl sulfate (SDS)—into the system. As a result of the simultaneous stabilizing action of an SDS–PVA mixture, the aggregation stability of aqueous dispersions of NDs noticeably increases, while the particle size in the dispersions remains unchanged for several days.

Lattice tilings of a plane into polyominoes are constructed for N from 3 to 12, where N is the order of the packing space. A total of 5191 symmetrically independent lattice tilings of the plane with one polyomino in a reduced (primitive) cell are obtained, among which 122 variants belong to the structural class (SC) cm, Z = 2(m), with a rectangular conventional (centered) unit cell. Chain tilings of the plane are derived, for which both the SC and structural subclass (SSC) are identified. The results of the analysis of the lattice tilings of a plane into polyominoes are illustrated with examples of real molecular layers in crystal structures.

A new interpretation is proposed for the dependence of dynamic moduli on the strain amplitude in the course of shear vibrations at a fixed vibration frequency. The interpretation is based on a structural rheological model that includes kinetic equations for the formation and destruction of particles’ aggregates under the action of an oscillating shear flow. The rheological equations, which can be used for the approximation of rheological curves G'(γ₀) and G''(γ₀) in separate sections with different amplitudes of the shear strain, are obtained. The possibilities of the new rheological model are demonstrated through the example of two polymer systems with solid particle-based fillers.

As insecticides, fungicides, heavy metals, and aflatoxins enter the food chain, they cause adverse effects on living organisms and humans. Given that rice is a widely-consumed food in Iran, the present study aimed to investigate the probability of the existence of insecticides, fungicides, heavy metals, and aflatoxins, as well as the nutritional value of rice in Mazandaran province. To this end, four cultivars of rice, namely Tarom, Fajr, Neda, and Shiroodi rice were collected from farms in the region, and after preparation, the concentration of pollutants in rice was measured in different ways in the laboratory. SPSS 25 software was used to analyze data. Based on the findings, the average nutritional value of four cultivars of rice was high in terms of protein (8.575 ± 0.298 g), fiber (less than 1), fat (1.2 g), carbohydrates (81.725 ± 0.512 g), calcium (405.64 ± 0.81 ppm), and B vitamins, where the average of vitamin B1 was 2.775 ± 1.305 g, vitamin B2 was 3.5 ± 1.62 g, vitamin B3 and B6 were less than 0.2, and vitamin B12 was less than 5. Heavy metals (less than 0.1 ppm), arsenic (0.095 ± 0.338 ppm), and cadmium (less than 0.025 ppm) were lower than the standard level. Due to the proximity of heavy metals to the standard, its status was considered critical. The average concentrations of aflatoxins, insecticides, fungicides, and herbicides were standard in different cultivars of rice. Given the nutritional value, the standard level of pollutants, and the health of Iranian rice species, rice consumption is recommended in diets and exports.

We prepared a novel series of 1,3,4-oxadiazole and benzo[d]imidazolecontaining fi fteen new connections to develop potential antimicrobial agents (9a–9o). The structures of this new series were characterized by various spectral techniques like IR, ¹H NMR, ¹³C NMR, LC–MS, and elemental analysis. Using the Broth Dilution method, the hybrids were examined for antimicrobial activity against a variety of bacterial and fungal strains. Compound 9n (MIC = 50 μg/mL) exhibited good activity against gramnegative E. coli and compound 9m (MIC = 50 μg/mL) showed potent activity against P. aeruginosa. While compounds 9c, 9f, 9g and 9m indicated MIC = 250 μg/mL against C. albicans.

The results of studies in which the relationship of the self-organization, physicochemical properties, and bioeffects in dilute aqueous solutions of various biologically active substances sustained under natural and reduced levels of external physical fields (geomagnetic and low-frequency electromagnetic), as well as under exposure to ionizing radiation solutions studied by the complex of physicochemical methods, are considered. The established patterns can be used to create a scientific base related to the clarification of the mechanisms of the negative influence of hypomagnetic conditions on the functioning of living organisms necessary to ensure the normal operation of the ecosystem of spacecraft during flights.