The Soviet atomic project, also known as the nuclear shield, is a true triumph of the Periodic Law. Unlike other global projects, it covers the entire Periodic Table of chemical elements: from the first element of the table (hydrogen) to the last one at the time of the project’s completion (plutonium). The article, based on rare open publications, describes the main stages and chemical-technological issues surrounding the creation of atomic and thermonuclear weapons - the main goal of the nuclear shield New fundamental results of the chemistry and technology of isotopes of hydrogen, lithium, beryllium, polonium, uranium, and plutonium have been obtained that could significantly expand the Periodic Table of chemical elements.

The article was written for the 150th anniversary of the D.I. Mendeleev’s Periodic Law. The history behind the discovery of dvi-manganese - rhenium by D.I. Mendeleev has been explained. Rhenium as well as its compounds’ fields of application has been indicated. In addition, potential sources of rhenium in Russia have been identified.

This article provides information on one of the most interesting elements in the D.I. Mendeleev Periodic Table - ruthenium, discovered 175 years ago by the outstanding Russian chemist Karl Karlovich Klaus. Its most important physical properties, a variety of oxidation states, and a tendency to form countless compounds have been noted, mocking it unique and indispensable in all areas of science, technology, and in society. We have taken into consideration the structure of ruthenium consumption today as well as a few prospects for its future use.

Ancient sources indicate that aluminum was known at Ancient Rome. The article attempts to reconstruct the ancient technological process of production of metallic aluminum based on the currently available information about the properties of aluminum and modern production methods.

The general results of the 2018-2019 Mendeleev competitions for chemistry students have been presented and a detailed analysis of technological work of the last few years are given from the point of view of compliance of their subject and content to modern representations about chemical technology as science. An increased interest by representatives of leading companies, scientific organizations, and enterprises in the Mendeleev competition has been demonstrated. This is largely determined by the request of the chemical industry to train motivated chemical and technical specialists that possess research and implementation competencies. The possibility of forming the topics and content of students' scientific research based on the hierarchical structure of the chemical-technological system, the achievements of the theoretical foundations of chemical technology, and the principles of technology creation is shown.

The article is dedicated to the 125th birthday of Yakov Kivovich Syrkin - Academician, Doctor of Chemical Sciences, Professor, Laureate of the Stalin Prize, and founder of the school of quantum chemistry in Russia. He was the head of the departments of Physical Chemistry at the M. V. Lomonosov Moscow Institute of Fine Chemical Technology and of Simple and Complex Compounds at the N.S. Kurnakov Institute of General and Inorganic Chemistry of the USSR Academy of Sciences, and the Laboratory of the Structure of Molecules at the L.Ya. Karpov Institute of Physical Chemistry. Yakov Syrkin was a world-famous scientist in the field of physical chemistry, who has addressed many issues of quantum chemistry, molecules structure, chemical bonds; the mechanism of chemical reactions, kinetics and catalysis. He was a brilliant teacher and lecturer, the initiator of many scientific ideas and directions, the author of more than five hundred scientific works, a responsive man of many talents. The chronological outline of his scientific, pedagogical and life path is presented, some less well-known fa.cts about his biography has also been highlighted.

Objectives. The first allylpalladium complex was synthesized and characterized 60 years ago at the Department of Physical Chemistry of M.V. Lomonosov Moscow State University of Fine Chemical Technology (MITHT). This discovery was an important stage in the development of a new direction in chemistry - metal complex catalysis, which subsequently led to understanding the strategy for studying the mechanisms of catalysts action, and gave a powerful impetus to the study of intermediates of catalytic reactions. The key sta.ge in many catalytic processes involving transition metal complexes is the oxidative addition stage. The study’s aim was the quantum chemical modeling of the oxidative addition stage of allylic carboxylates to the Ni(0) and Pd(0) complexes.

Methods. Quantum chemical calculations were carried out under the Kohn-Sham method for the density Junctional theory using the PBE exchange-correlation Junctional and all-electron L11 basis set.

Results. As a result of theoretical study, we showed that the oxidative addition of allyl acetate to the triisopropylphosphite complex of nickel(0) and allyl formate to the triphenylphosphine complex of palladium(O) can proceed along two routes. In the first of them, in the coordinated breaking of the С-О bond and the formation of the metal-O bond, the same oxygen atom is involved, thus forming a three-center transition state. In the second route, the restructuring of relations is carried out in a five-center transition state. The chelating effect in the five-centered transition state of the second route reduces the reaction’s activation barrier by 12.7 kcal/mol for allyl acetate and the nickel(0) triisopropylphosphite complex Ni(P(QPr)₃)₂ and by 9.9 kcal/mol for allyl formate and the palladium(O) triphenylphosphine complex Pd(PPh₃). The presence of the second triphenylphosphine ligand in Pd(PPh₃)₂ reduces the activation barrier by only 2.6 kcal/mol.

Conclusions. The quantum chemical modeling performed allowed us to determine the preference for the oxidative addition of allyl carboxylates to the Ni(0) and Pd(0) complexes through a five-center transition state. The reaction’s activation barriers through the “classical” three-center interaction are 9.9-12.7 kcal/mol higher, and the chelating effect is more noticeable for the Ni complex The presence in the coordination sphere of several bulky ligands, such as triphenylphosphine, practically eliminates the chelating effect in the oxidative addition of allyl carboxylates.

Objective. The work’s objective is to develop methods for the thermodynamic modeling of systems of liquid crystal - organic solvent.

Methods. Four binary systems of nematic 4-pentyloxybenzoic acid (5OBA) with n-alkanes (hexadecane, octadecane, icosane, and docosane) were investigated via thermal analysis methods (differential thermal analysis, polarization microscopy, visual polythermal analysis, and the polytherm solubility method). The accuracy in determining phase transitions temperatures is within 0.3 K. To describe the phase equilibria, models based on the Hildebrand and Hansen solubility parameters were used. Hansen solubility parameters were estimated using the Stefanis scheme. Hildebrand solubility parameters, molar volumes, and vaporization enthalpies were calculated using a group contribution scheme.

Results. Phase equilibria in the systems of 5OBA with n-alkanes were studied. Four T-x diagrams were obtained by thermal analysis methods, coordinates of invariant points (eutectics and metatectics) were determined in the systems. A linear dependence of the metatectic coordinate (х₁ is a fraction of 5OBA, mol. %) on the number of C atoms in the alkane (N) was established: x₁ = -0.3131 x N + 85.467. Solubility polytherms of 5OBA with solvents of different polarity were obtained: n-alkanes (hexane, octane), cyclohexane, aromatic compounds (benzene, toluene, and o-xylene), chlorobenzene, ethyl acetate, acetone, 1,4-dioxane, alcohols (propan-2-ol, propan-1-ol, butan-1-ol), and acetonitrile. The dependence of 5OBA’s solubility on the difference in the solubility parameters of the components and the distance Ra was established.

Conclusions. The model for regular solutions based on solubility parameters allows us to calculate the solubility polytherms of mesogens and to select solvents for the purification of mesogens by the mass crystallization method. The best solubility of 4-pentyloxybenzoic acid at 298 K appears in chlorobenzene.

Objectives. The objective of this paper was to compare acetylene oxidative dicarbonylation that leads to maleic anhydride with a side reaction of CO oxidation by oxygen in a PdBr₂-LiBr-H₂C-CH₃CN system and in the presence of insoluble (Co) and soluble (Co, Fe, and Mn) phthalocyaninates (PcM).

Methods. To study the oxidation of CO to CO₂, a kinetics method was used; UV and IR spectroscopy was used to determine the concentrations of initial and intermediate compounds.

Results. The knetics of CO to CO₂ oxidation were investigated and the reactivity series of PcM in CO oxidation and maleic anhydride synthesis was characterized. A satisfactory correlation was observed between reaction rates and PcM concentration, as well as the nature of metal, in both processes. The IR measurements of concentrations of Pd(II) and Pd(I) intermediate carbonyl complexes, and CO₂ concentrations, have made it possible to hypothesize the mechanism of CO₂ generation. The effect of PcM concentration on the concentrations of Pd(II)(CO) in CO oxidation has been shown.

Conclusions. Based on the data regarding CO oxidation and acetylene oxidative dicarbonylation, certain conditions have been proposed to effectively produce double-labeled maleic anhydride with ¹³C (from ¹³CO).

Objectives. Chlorin and bacteriochlorin photosensitizers are effective agents for cancer photodynamic therapy and fluorescence imaging. They are also excellent chelators forming stable metal complexes. Besides, ⁶⁴Cu and ¹⁰⁹Pd isotopes can serve as emitters for nuclear medicine. Chelation of these metals with cyclen conjugates with chlorin and bacteriochlorin photosensitizers can become a simple and universal strategy for the synthesis of diagnostic and therapeutic radiopharmaceuticals for nuclear medicine. This article reports on the synthesis of similar Cu and Pd complexes of cyclen conjugates with pheophorbide and bacteriopheophorbide and the study of their photophysical properties.

Methods. Metalation of cyclen conjugates was carried out with palladium and copper acetates. For bacteriochlorins, 6-O-palmitoyl-L-ascorbic acid was additionally used as a reducing agent. MALDI mass spectrometry, which was carried out on a time-of-flight mass spectrometer Bruker Ultraflex TPF/TOF and a Bruker Daltonics Autoflex II confirmed the structure of the compounds obtained Electronic absorption spectra were obtained on a Shimadzu 3101 spectrophotometer. Fluorescence and phosphorescence spectra were obtained on a FluoTime 300 PicoQuant spectrofluorometer.

Results. Photophysical studies of metal complexes showed that the introduction of palladium cations quenches fluorescence and increases the quantum yield of singlet oxygen generation to 0.98 for the chlorin conjugate. Besides, it decreases the quantum yield of fluorescence to 0.10 and increases the quantum yield of singlet oxygen generation to 0.72 for the bacteriochlorin conjugate. Introducing a copper cation to cyclen conjugates with pheophorbide and bacteriopheophorbide leads to photophysical characteristics quenching.

Conclusions. Due to the stability of the synthesized metal complexes in acidic media, as well as the short metalation time (5, 20, 10, and 15 minutes) it is reasonable to expect the successful development of effective imaging agents for positron emission tomography and radionuclide therapy. In addition, the residual fluorescence of bacteriochlorins makes it possible to use fluorescence diagnostics in combination with these methods.

Objectives. Determination of the influence of molecular weight on the modulus of elasticity, yield, strength, and retardation processes in polyethylene.

Methods. We used vane samples (thickness: 4 mm; length: 100 mm; width.: 10 mm) made by injection molding at p = 60 MPa, T = 210 °C, τ = 15 s from the following polyethylenes: HDPE 27773 (Stavrolen, Lukoil, Russia); BorSafe HE3490-IM (Borealis, Austria; black); CRP 100 Hostalen (Basell Polyolefins, Netherlands; black); Stavrolen PE4PP-25B (Stavrolen, Lukoil, Russia; black). The samples were in accordance with the defined standards for the AL 7000 LA-5 tensile testing machine. The study of relaxation characteristics was carried out in two modes: relaxation and retardation.

Results. We obtained stress-strain diagrams at various temperatures under isothermal conditions (T = const) and determined the influence of polyethylene molecular weights on the modulus of elasticity, yield, and strength of polyethylenes. We have shown that under isothermal conditions, when the stress equals the yield strength, the removal of the external action results in a two-stage response. The first stage is the stress relaxation. The second stage characterizes the elastic features of the studied materials under the external action ε = const.

Conclusions. We have established that temperature increase affects the physicomechanical characteristics of polyethylenes differently, depending on their molecular weights. The experiments have shown that when the stress exceeds the yield strength, at constant deformation, there is a complex response of the polyethylenes to external action. This response is characterized by two stress stages throughout the course of time. The first stage is characterized by asymptotic decrease in stress down to a constant value; the second stage is characterized by constant stress throughout the course of time. We have determined relaxation times for the relaxation stage (stage I) and calculated activation energy. We have also established that the activation energy depends on molecular weights of the polyethylenes. It has been shown that an increase in polyethylene molecular weight leads to a decrease in relaxation time and activation energy.

Objectives. Cationic surfactants are one of the classes of substances most commonly used in disinfectants. The trend in recent years has been the use of mixtures of several biocides, which poses new challenges for analytical chemistry. In this study, we describe a method for simultaneous determination in the disinfectants alkyldimethylbenzylammonium chloride (ADBAC), alkyldimethyl(ethylbenzyl)ammonium chloride (ADEBAC), chlorhexidine bigluconate (CHG), and polyhexamethylene biguanide hydrochloride (PHMB).

Methods. The proposed method is based on the use of reverse-phase and hydrophilic high-performance liquid chromatography with diode-array detection

Results. The best separation of ADBAC, ADEBAC, and CHG was achieved using a column filled with modified spherical silica gel (5 цт, 4.6 × 250 mm) in gradient elution mode. Acetonitrile and acetate buffer with a pH of 5.4 were used as eluents at a flow rate of 1 ml/min. For the determination of PHMB in the presence of the substances under consideration, hydrophilic high performance liquid chromatography was used. The best separation was achieved on an amine phase column (5 цт, 4.6 × 250 mm) using the same eluents. To determine all the substances under consideration, a diode array detector was used. 3D chromatograms were recorded in the wavelength range from 190 to 400 nm.

Conclusions. We have shown that the result of the analysis does not depend on the ratio of cationic surfactants in disinfectants. There is also no influence of N,N-bis-(3-aminopropyl)-dodecylamine (Triamine, TA) and the components most commonly used for the manufacture of disinfectants, which was confirmed by testing the method for analyzing real objects. The linearity range for ADBAC was from 0.0062 to 0.97%, for ADEBAC from 0.000726 to 0.201%, for CHG from 0.0128 to 0.111%, and for PHMB from 0.00311 to 0.0205%. The calculated relative errorfor all determined substances was about 4%.