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Vol 16, No 2 (2021)
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THEORETICAL BASES OF CHEMICAL TECHNOLOGY 

  • A nanostructuring method, in which the nanostructure material acts as a substrate, was implemented for the first time.
  • The replicas method allowed for creating nanostructured surfaces with controlled morphology and the ability to modify materials with nanoclusters in the process of their creation.
  • A nanostructured nickel material was obtained that surpassed smooth nickel in methanol oxidation reaction by 70–150 times.
105-112 129
Abstract

Objectives. Catalytically active materials are required in different chemical engineering processes. This makes the development of new materials with high efficiency and original ways in which to obtain them of significant interest. The present work investigates the synthesis of catalytically active material including electrode materials, as well as their improved efficiency due to the nanodecoration of their surface.

Methods. An aluminum folio was nanoperforated (nanoscalloped) by high-voltage anodization in an acidic medium. The effective electrode material was obtained as a metallic nickel replica rather than an oxide layer of the product. To study the surface state of aluminum obtained in this manner, a scanning electron microscope (Hitachi-SU8200) was used. The elementary composition of the aluminum was determined by back-scattered X-ray irradiation.

Results. The nickel replica obtained in the above-described process exceeded the catalytic activity estimated by methanol oxidation of the unprocessed nickel 70–150 times.

Conclusions. The present paper demonstrates the potential of creating effective catalytically active nanopillar materials using the metallic rather than metal-oxide part of a layer of anodized aluminum as a matrix template. 

  • Structural specific features and packing particularities of antipyrine and its derivatives.
  • Self-organization of molecules in the solid state: single crystal XRD studies and DFT calculations.
  • Hydrogen bonding contribution in the process of dimers formation.
113-137 111
Abstract

Objectives. The paper is devoted to the crystal structure characterization of 5-methyl-2-phenyl4H-pyrazol-3-one (compound I) and 2-(4-chlorophenyl)-5-methyl-4H-pyrazol-3-one (compound II).

Methods. Single-crystal X-ray diffraction studies and theoretical calculations: Density functional theory and quantum theory of atoms in molecules.

Results. In the solid state, the crystal structure of compound I is characterized by the alternation of OH and NH tautomers connected via O–H---O and N–H---N hydrogen bonds. For compound II, the existence of chains built from the NH monomers via hydrogen bonding can be explained by the peculiarities of cooperative effects. In the framework of quantum theory of atoms in molecules, the following topological characteristics are calculated for all dimers: electron density, Laplacian of electron density, density of kinetic, potential, and total energy in the critical point of the intermolecular hydrogen bond. It is concluded that the hydrogen bond in dimers 1–4, 7 (compound I), and 8–11 (compound II) can be assigned to the intermediate (between covalent and dispersion types) interaction owing to hydrogen bond formation with the participation of electronegative oxygen- (and/or nitrogen-) atoms, whereas H-bond in dimers 5 and 6 (compound I) can be attributed to the dispersion one (no hydrogen bond formation or weak H-bond formation), and it represents the weak interaction, being in agreement with length for intermolecular hydrogen bond in dimers. The electron density and total energy density values demonstrate that the strongest intermolecular H-bonds take place in dimers 1 (OH---O), 4 (OH---O), 7 (OH---N), 8 (OH---O), 9 (NH---N), and 11 (OH---N). The results obtained for compounds I and II are compared with data for antipyrine (1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one; compound III)

Conclusions. An important role of intermolecular hydrogen bonding in the crystal packing, molecule association and self-organization via dimer- or more extended species formation has been demonstrated. 

CHEMISTRY AND TECHNOLOGY OF ORGANIC SUBSTANCES 

  • The crystal structure of N-(4-n-butoxybenzylidene)-4'-methylaniline contains associates formed by orientational interactions between two independent molecules. Close length values of 4-n-pentyloxybenzoic acid dimers (270 nm) and associates of N-(4-n-butoxybenzylidene)-4'-methylaniline (250 nm) were noted.
  • The dielectric constant anisotropy of the of 4-n-pentyloxybenzoic acid changes its sign from positive to negative at the transition temperature of the high-temperature nematic subphase to the low-temperature nematic subphase.
  • The highest values of the electrical conductivity anisotropy are observed when the system content ranges between 30 and 60 mol % N-(4-n-butoxybenzylidene)-4'-methylaniline.
138-147 81
Abstract

Objectives. Our aim was to study the dielectric properties of the 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4’-methylaniline system and reveal how different concentrations of N-(4-n-butyloxybenzylidene)-4’-methylaniline additives affect the dielectric properties of 4-n-pentyloxybenzoic acid.

Methods. System properties were investigated using polarization thermomicroscopy and dielcometry.

Results. We found that dielectric anisotropy changes its sign from positive to negative at the transition temperature of the high-temperature nematic subphase to the low-temperature one. The anisotropy of the dielectric constant of N-4-n-butoxybenzylidene-4’-methylaniline has a positive value and increases as to the system approaches the crystalline phase. The crystal structure of the 4-n-pentyloxybenzoic acid contains dimers formed by two independent molecules due to a pair of hydrogen bonds. The crystal structure of N-(4-n-butoxybenzylidene)-4’-methylaniline contains associates formed by orientational interactions of two independent molecules. 4-n-Pentyloxybenzoic acid dimers (270 nm) and associates of N-4-n-butoxybenzylidene-4’- methylaniline (250 nm) proved to have approximately the identical length. Considering the close length values of the structural units of both compounds and the dielectric anisotropy sign, we assume that the N-4-n-butoxybenzylidene-4’-methylaniline associates are incorporated into the supramolecular structure of the 4-n-pentyloxybenzoic acid. The specific electrical conductivity of the compounds under study lies between 10−7 and 10−12 S∙cm−1. The relationship between the specific electrical conductivity anisotropy and the system composition in the nematic phase at the identical reduced temperature, obtained between 100 and 1000 Hz is symbatic. However, the electrical conductivity anisotropy values of the system obtained at 1000 Hz are lower compared to those obtained at 100 Hz. At N-(4-n-butoxybenzylidene)-4’-methylaniline concentrations between 30 and 60 mol %, the electrical conductivity anisotropy values are higher than those of the individual component.

Conclusions. A change in the sign of the dielectric constant anisotropy of the 4-n-pentyloxybenzoic acid during nematic subphase transitions was established. We showed that the system has the highest dielectric constant anisotropy value when components have an equal number of moles. Highest electrical conductivity anisotropy values are observed when the concentration of the N-4-n-butoxybenzylidene-4᾽-methylaniline system lies between 30 and 60 mol %. 

CHEMISTRY AND TECHNOLOGY OF MEDICINAL COMPOUNDS AND BIOLOGICALLY ACTIVE SUBSTANCES 

The substrate properties of the modified derivatives of purine and pyrimidine dNTPs were studied in enzymatic reactions: real-time PCR and PEX. In the experiments, we used four DNA polymerases of different families with no 3′–5′ correcting exonuclease activity. Both individual and joint pairwise insertions of unlike modified nucleotides into the growing DNA strand were conducted. The most effective nucleotide pairs found were 5-propynyl-2′-deoxyuridine-5′-triphosphate and 5-propynyl-2′-deoxycytidine-5′-triphosphate combined with the Vent DNA polymerase (exo-matric).

148-155 114
Abstract

Objectives. This study investigated the substrate properties of the modified derivatives of triphosphates of purine and pyrimidine deoxynucleosides (5-propynyl-2’-deoxyuridine-5’-triphosphate, 5-propynyl2’-deoxycytidine-5’-triphosphate, 5-methyl-2’-deoxycytidine-5’-triphosphate, and N6-methyl-2’-deoxyadenosine-5’-triphosphate) during their simultaneous incorporation in enzymatic reactions (polymerase chain and primer extension reactions).

Methods. The real-time polymerase chain and primer extension reactions were used to study the substrate efficiency of modified deoxynucleotide triphosphates. Various pairwise combinations of modified derivatives were used; specially designed synthetic DNA fragments and libraries for the Systematic Evolution of Ligands by Exponential Enrichment technology were used as templates. Reactions were conducted using DNA polymerases: Taq, Vent (exo-), DeepVent (exo-), and KOD XL.

Results. In each case, a pair of compounds (modified dUTP + dCTP, dUTP + dATP, and dCTP + dATP) was selected to study the simultaneous incorporation into the growing DNA strand. The most effective combinations of nucleotides for simultaneous insertion were dU and dC, having 5-propynyl substitution. The Vent (exo-) DNA polymerase was found as the most effective for the modified substrates.

Conclusions. The selected compounds can be used for the enzymatic preparation of modified DNA, including aptamers with extended physicochemical properties. 

O-alkylation of 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane 1 with 2 and cis-1,4-dichlorobutene-2 3 proceeded to give the corresponding ethers 46. Dichlorocarbenation of compounds 46 led to products 79. Exhaustive dichlorocarbenation of the compound 11 led to diester 12.

156-166 101
Abstract

Objectives. This study aimed to obtain ethers containing gem-dichlorocyclopropane and 1,3-dioxolane fragments and evaluate their cytotoxic properties against HEK293, SH-SY5Y, MCF-7, and A549 cell lines.

Methods. The qualitative and quantitative compositions of the reaction masses were determined using mass spectrometry (using a Chromatek-Kristall 5000M device with the 2012 National Institute of Standards and Technology, USA database) and nuclear magnetic resonance spectroscopy (using a Bruker AM-500 device with operating frequencies of 500 and 125 MHz).

Results. Ethers containing gem-dichlorocyclopropane and 1,3-dioxolane fragments were synthesized in the presence of a catamine AB catalyst. The structures of the obtained substances were confirmed using gas-liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The cytotoxicity of the esters was studied against HEK293, SH-SY5Y, MCF-7, and A549 cell lines.

Conclusions. Ethers containing gem-dichlorocyclopropane and 1,3-dioxolane fragments were obtained in quantitative yields; however, only 4-{[(2,2-dichloro-3-{[(2,2-dichlorocyclopropyl) methoxy]methyl}cyclopropyl)methoxy]methyl}-2,2-dimethyl-1,3-dioxolane exhibited cytotoxic activity against HEK293, SH-SY5Y, MCF-7, and A549 cell lines. 

SYNTHESIS AND PROCESSING OF POLYMERS AND POLYMERIC COMPOSITES 

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Abstract

Objectives. Due to the increasing number of oncological diseases, active research into developing new radiopharmaceuticals is underway. Thermosensitive copolymers have valuable physicochemical properties that can be harnessed to develop therapeutic radiopharmaceuticals for treating solid tumors. The aim of this study was to develop a method for producing thermosensitive copolymers that can find use as radionuclide carriers to create therapeutic radiopharmaceuticals for treating solid tumors.

Methods. Using radical copolymerization in polar solvents, we synthesized water-soluble copolymers based on N-isopropyl acrylamide and 2-aminoethyl methacrylate hydrochloride. The resulting copolymers were characterized in terms of molecular composition and hydrodynamic properties using gel permeation chromatography, IR spectroscopy, potentiometry, and viscometry. Changes in optical density during temperature scanning helped determine the phase transition temperature (PTT) of aqueous copolymer solutions.

Results. We developed a method for preparing copolymers of N-isopropylacrylamide with 2-aminoethyl methacrylate using radical copolymerization in water and isopropanol with a content of 2-aminoethyl methacrylate hydrochloride in a copolymer up to 23 mol %. We studied how the second comonomer affected the PTT of the aqueous copolymer solutions. An increase in the content of 2-aminoethyl methacrylate in the copolymer caused the PTT to increase. We found that the change in the PTT depending on the content of 2-aminoethyl methacrylate units in the copolymer had a straightforward relationship with its content up to 17 mol %. The use of physiological saline as a solvent led to a temperature decrease of the phase transition by two degrees.

Conclusions. The method of producing thermosensitive copolymers by radical copolymerization in isopropanol does not allow creating a radionuclide carrier. Solutions of the obtained lowmolecular weight oligomers form coacervate solutions, which will inevitably cause the radionuclide to spread throughout the body. The copolymers obtained by radical copolymerization in water with the content of the second comonomer 2-aminoethyl methacrylate from 10–17 mol % can be used as a radionuclides carrier provided that a physiological solution of sodium chloride is used as a solvent. 

The introduction of high-molecular weight polyester increases the lifetime of the polyurea composition to the required values (up to 5 min) and increases its abrasion while the tensile strength and elongation are reduced to an acceptable level. With the help of the developed composition, it is possible to perform repair work of coatings based on polyurea without needing bulky equipment.

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Abstract

Objectives. Improvement of the technology for obtaining polymer-sprayed coatings based on polycarbodiimides (polyureas) with high chemical, hydrolytic, and abrasive resistance and improved physical and mechanical properties, as well as obtainment of polyurea compositions with a lifetime of at least 5 min without loss performance characteristics (i.e., “hand-applied” polyureas) suitable for repair of coatings already in use.

Methods. The reaction rate between isocyanate and amino groups is almost a hundred times higher than that between isocyanate and hydroxyl groups, necessitating the use of special highperformance and high-pressure installations equipped with self-cleaning mixing chambers and heating of components. The following are determined from the obtained materials: strength, elongation at break according to the standard method, Taber abrasion, and Shore hardness.

Results. Three methods of slowing down the reaction are investigated: 1) the synthesis of prepolymers with the content of NCO groups from 10.5% to 18%; 2) the addition of a plasticizer into the prepolymer in the amount of 1–10 mass parts; and 3) the introduction of polyesters into the composition and radiation of the so-called “hybrid” systems. When using 14% polyesters with a molecular weight of 2000 Da, only “hybrid” systems make it possible to obtain compositions with a lifetime of more than 5 min. At the same time, the tensile strength decreases by 20%, and the abrasion increases by 40%; however, such “hybrid” systems have a higher adhesion force and are cheaper than pure polyureas, allowing them to be used as “repair” systems.

Conclusions. The developed composition and technology of applying “hybrid” systems allow for the repair of existing coatings without using specialized devices. “Manual” polyurea is easy to use and does not require special training. 

CHEMISTRY AND TECHNOLOGY OF INORGANIC MATERIALS 

The dependence of the critical electric potential on the transmission coefficient was obtained and qualitatively matched the current-voltage characteristics of superconducting materials. The temperature dependences of many energy parameters for the Cooper pair in the Abrikosov vortex field were obtained, which can be used to construct a general theory of superconductivity and to describe the electrodynamics of superconductors.

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Abstract

Objectives. There is no general theory of superconductivity capable of fully describing this phenomenon, which imposes its own difficulties in the search for new superconducting materials, as well as in the study of their properties. In particular, the electrodynamics of a superconducting system is unexplored. With the aim of a possible further description of the electrodynamics of superconductors, the temperature dependences of the energy parameters of a Cooper pair in the potential field of Abrikosov vortex were analyzed.

Methods. The basis for the obtained results of the work was the consideration of the transmission coefficient for a superconducting particle in the approximation of the Wentzel– Kramers–Brillouin method, as well as the relationship between the critical temperature and the London penetration depth and the coherence length based on the model of plasmon destruction of the superconducting state.

Results. The dependences of the lifetime of a particle in a potential well, penetration depth, frequency of impacts of a particle against a potential barrier, blurring of the energy level, transmission coefficient, and potential and kinetic energy of a particle on temperature were obtained. The characteristic values of these parameters were obtained at absolute zero for various cuprate, organic, and other superconducting materials. The dependences of the critical electric potential on temperature, as well as the London penetration depth, coherence length, and electric potential on the transmission coefficient at different temperatures were obtained. The form of the dependences qualitatively corresponds to the experimental data.

Conclusions. The results obtained can be used to construct a general theory of superconductivity, describe the electrodynamics of a superconducting state, and develop new superconductors with higher critical currents. 



ISSN 2410-6593 (Print)
ISSN 2686-7575 (Online)