Russian Chemical Reviews

The review addresses the prospects of global hydrogen energy development. Particular attention is given to the design of materials for sustainable hydrogen energy applications, including hydrogen production, purification, storage, and conversion to energy. The review highlights the key role of oxide-supported metal or alloy nanoparticles as catalysts in the hydrogen production via the conversion of natural gas or alcohols. An alternative approach is the pyrolysis of hydrocarbons giving hydrogen and carbon. The direct production of high-purity hydrogen can be performed using electrolysis or membrane catalysis. Apart from conventional hydrogen storage methods such as the compression and liquefaction, the hydrogen alloy absorption and chemical conversion to liquid carriers (ammonia and toluene cycles) are considered. Fuel cells, containing catalysts and proton-conducting membranes as the key components, are used for hydrogen energy generation. Binary platinum alloys or core – shell structures supported on carbon or oxides can be employed to facilitate the oxygen electroreduction and CO electrooxidation in low-temperature fuel cells. High conductivity and selectivity are provided by perfluorinated sulfonic acid membranes. The high cost of the latter materials dictates the development of alternative membrane materials. A crucial issue in high-temperature fuel cells is the necessity of reducing the operating temperature and ohmic losses. This problem can be solved by designing thin-film materials and replacing oxygen-conducting ceramic membranes by proton-conducting membranes.

The bibliography includes 290 references.

The interest in functional supramolecular systems for the design of innovative materials and technologies, able to fundamentally change the world, is growing at a high pace. The huge array of publications that appeared in recent years in the global literature calls for systematization of the structural trends inherent in the formation of these systems revealed at different molecular platforms and practically useful properties they exhibit. The attention is concentrated on the topics related to functional supramolecular systems that are actively explored in institutes and universities of Russia in the last 10–15 years, such as the chemistry of host–guest complexes, crystal engineering, self-assembly and self-organization in solutions and at interfaces, biomimetics and molecular machines and devices.

The bibliography includes 1714 references.

The review presents state-of-the-art data on the influence of catalysts (mainly transition metal complexes) on the regioselectivity of a number of reactions. The most important addition reactions to unsaturated bonds are considered, in particular, hydroformylation, hydrosilylation, hydroboration and hydroxy-, alkoxy- and aminocarbonylation, which give predominantly one product. Particular attention is given to reactions with divergent regioselectivity. The reaction conditions, the structures of metal complexes and the ligands involved are indicated and, in some cases, the reaction mechanism is discussed. Examples of industrial processes using homogeneous catalysis are given.

The bibliography includes 203 references.

Dedicated to the memory of V.V.Markovnikov.

The review is devoted to modern trends in the chemistry of nitrogen-, oxygen-and sulfur-containing monocyclic, polynuclear and benzo(hetero)annulated heterocyclic compounds. Methods for the synthesis and chemical reactivity of furazan, furoxan, thiazole, thiadiazole, dithiazole, thiophene, glycoluril, imidazotriazine, diaziridine and other heterocycles are discussed. Characteristic features of reactions depending on the structure of the starting compounds, intermediates and reaction medium (organic solvents, ionic liquids) and mechanistic aspects of the most interesting transformations are considered. Data on the biological activities and prospects for practical applications of the indicated heterocyclic systems are presented.

The bibliography includes 383 references.

The state of the art and the major trends of development of world energy engineering are analyzed. It is concluded that throughout the 21st century the role of alternative sources will remain rather modest. Fossil fuel will still be the major source of energy until the end of the century. Because of depletion of accessible oil resources, the proportion of crude oil in the world energy balance will constantly decline, while the proportion of natural gas will grow. It is shown that energy production from any source, including alternative sources, cannot be environmentally benign if the scale of production is large. In the long term, humanity has no sources other than fusion energy, but transition to this source would not solve the problem of the planet's heat balance.

The bibliography includes 70 references.

In recent years, the key principles of the electric power industry have radically changed and the number of studies on the development of devices for electrical energy storage in a different form such as mechanical or chemical energy has rapidly increased. This review gives a brief description of these devices. The attention is focused on redox flow batteries (RFBs), a promising type of energy storage devices capable of efficiently operating in distributed power grids, in order to eliminate the imbalance between the time-varying electricity production by 'unconventional sources' and electricity consumption. At the design level, RFBs combine the principles of fuel cells and chemical energy sources with solid electroactive materials: transitions between electrical and chemical forms of energy in these devices occur upon oxidation and reduction of redox-active electrolytes, which are stored in separate tanks and pumped into the electrode compartments of the membrane electrode assembly (MEA) separated by a semi-permeable membrane. This approach ensures an important advantage of these devices over other types of chemical energy sources, that is, the possibility of independent scaling of the energy storage capacity and power characteristics of the system. This review provides a systematic description of the main types of RFBs and analysis of their fundamental benefits and drawbacks, which determine the prospects for practical applications of RFBs.

The bibliography includes 149 references.

The preservation of DNA has attracted significant interest of scientists in diverse research fields from ancient biological remains to the information field. In light of the different DNA safekeeping requirements (e.g., storage time, storage conditions) in these disparate fields, scientists have proposed distinct methods to maintain the DNA integrity. Specifically, DNA data storage is an emerging research, which means that the binary digital information is converted to the sequences of nucleotides leading to dense and durable data storage in the form of synthesized DNA. The intact preservation of DNA plays a significant role because it is closely related to data integrity. This review discusses DNA preservation methods, aiming to confirm an appropriate one for synthetic oligonucleotides in DNA data storage. First, we analyze the impact factors of the DNA long-term storage, including the intrinsic stability of DNA, environmental factors, and storage methods. Then, the benefits and disadvantages of diverse conservation approaches (e.g., encapsulation-free, chemical encapsulation) are discussed. Finally, we provide advice for storing non-genetic information in DNA in vitro. We expect these preservation suggestions to promote further research that may extend the DNA storage time.

The bibliography includes 99 references.

Plant biomass is considered the main source of renewable carbon raw materials, which is a viable alternative to crude oil and natural gas and provides compounds with a low carbon footprint. The most promising direction for the conversion of biomass is the synthesis of 5-hydroxymethylfurfural, which is regarded as a platform chemical, the basis for the synthesis of valuable compounds, including monomers and polymers. The move of the polymer industry to renewable plant materials will contribute to solving global environmental problems and ensure the sustainability and environmental safety of plastics production. This review analyzes recent advances in the preparation of key C₆-furan platform chemicals, such as 5-hydroxymethylfurfural, 2,5-furandicarboxylic acid, 2,5-diformylfuran, 2,5-bis(hydroxymethyl)furan, levulinic acid, and their use for the production of monomers and polymers based on renewable plant biomass. Production processes of widely known furan polyesters and polyamides, such as polyethylene-, polypropylene-, polybutylene furanoates, polyhexamethylene furanamide, are considered, as well as developments towards novel promising materials that are furan copolymers and polymer mixtures. For the first time, studies have been systematized aimed at converting liquid and solid wastes of the synthesis of platform chemicals, known as humins, into a range of value-added products, including organic compounds, porous carbon materials, thermosetting binders, and anticorrosive coatings that can replace similar materials based on fossil raw materials. Economic and environmental prospects and problems of production and consumption of furan polymers are considered.

The bibliography includes 275 references.

The review addresses and highlights the main results of research on the physicohemical properties of single-phase and composite materials based on transition metal oxides in relation to their practical application as electrode materials for symmetrical solid oxide fuel cells. The electronic structures and thermodynamic stability of transition metal oxides with the perovskite structure are discussed. A detailed consideration is given to the thermal behaviour, chemical stability, electrical conductivity and electrochemical properties of a broad range of electrode materials based on iron-, chromium- and manganese-containing perovskite-like oxides and oxides that crystallize in other structure types. The analysis revealed the most promising compositions of electrode materials for symmetrical solid oxide fuel cells and effective approaches to the improvement of their functional characteristics.

The bibliography includes 202 references.

This review deals with key methods of synthesis and characterization of metal-organic frameworks (MOFs). The modular structure affords a wide variety of MOFs with different active metal sites and organic linkers. These compounds represent a new stage of development of porous materials in which the pore size and the active site structure can be modified within wide limits. The set of experimental methods considered in this review is sufficient for studying the short-range and long-range order of the MOF crystal structure, determining the morphology of samples and elucidating the processes that occur at the active metal site in the course of chemical reactions. The interest in metal-organic frameworks results, first of all, from their numerous possible applications, ranging from gas separation and storage to chemical reactions within the pores.

The bibliography includes 362 references.

The formation of carbon–heteroatm bond is the key step of synthesis of numerous organic compounds, including socially important products such as pharmaceuticals, crop protection agents and organic functional materials. These reactions proceed most efficiently when catalyzed by compounds of transition metals, first of all palladium. However, this approach has considerable drawbacks, in particular, high cost and toxicity of transition metal compounds and harsh reaction conditions required in some cases, resulting in limited functional group tolerance. This review describes the recent advances in the development of methodology of transition metal-free carbon–heteroatom bond-forming cross-coupling. It is shown that single-electron transfer and homolytic bond cleavage result in the generation of highly reactive radical and/or radical ion intermediates, enable the formation of new carbon–heteroatom bonds. These intermediates are generated using either visible light or electricity as energy sources or simple organic compounds acting as electron donors. Methods for carbon–heteroatom bond formation based on radical reactions proceeding under mild conditions and in the presence of labile functional groups are considered. The key mechanistic aspects of the reactions are highlighted. The review mainly covers the original publications of the current decade.

The bibliography includes 302 references.

Alloys with high configurational entropy fundamentally differ from traditional alloys as they contain not one, but five or more basic elements with concentrations of 5 to 35 at.% each. Owing to the unique elemental composition, high-entropy alloys can have unusual functional properties such as high strength and wear resistance, exceptional heat resistance, good structural stability and good resistance to corrosion and oxidation. The review considers methods of synthesis of high-entropy alloys, methods and results of computer simulation of the high-entropy alloy structures and applications of such alloys as corrosion-, heat- and radiation-resistant materials and biomedical materials. Particular attention is paid to the prospects for the use of such alloys as protective coatings.

The bibliography includes 352 references.

The accumulation of advanced glycation end products (AGEs) is currently considered as one of the key factors in aging processes, the pathogenesis of late complications of diabetes mellitus, cancer and neurodegenerative diseases. This review is devoted to small synthetic molecules with antiglycation activity, i.e., compounds with the ability to inhibit AGE formation. Molecules with antiglycation activity in the low micromolar range (<10 μM), primarily fused heterocyclic systems containing oxygen or nitrogen as heteroatoms and (thio)ureas, have been discovered to date. The known scaffolds with antiglycation activity are analyzed, structural modifications to enhance antiglycation abilities are highlighted and the structure–activity relationships are discussed.

The bibliography includes 125 references.

Pickering emulsions are emulsions that are stabilized by solid micro- and nanoparticles. These emulsions are in most demand for applications where the use of surfactants is restricted. The review addresses stabilization of Pickering emulsions. The attention is focused on the flocculation, coalescence, sedimentation and Ostwald ripening processes taking place in these emulsions. The structures formed by particles in the emulsion dispersion medium and in thin interlayers between the dispersed phase droplets are analyzed. Methods for preparing colloidosomes, that is, microcapsules of assembled particles, from Pickering emulsions are considered. Colloidosomes are promising for the encapsulation and prolonged release of active substances. Conversely, Pickering stimuli-responsive emulsions provide intense release of encapsulated substances upon the change in the environmental parameters. This can be used not only in medicine and pharmacology, but also in sensors, food industry, paint and varnish industry, petroleum production, etc.

The bibliography includes 340 references.

This review generalizes diverse computational NMR studies of different natural products involving true alkaloids (indole, quinolizidine, pyrrolizidine, piperidine, indolizidine, quinoline, isoquinoline, indoloquinoline, and guanidine alkaloids), pseudoalkaloids (terpenes and steroids), quinones, lactones, lactams, flavonoids, and many others. The diverse computational protocols employed in each particular case are thoroughly discussed with a special emphasis on their structural and stereochemical applications.

The bibliography includes 165 references.