Volume 92, Nº 8 (2023)
Articles
Recent advances in lignins: fundamentals and applications
Resumo
Lignin, one of the most abundant biopolymers on Earth, is a constant object of numerous fundamental and applied studies. Lignin processing is a challenging task of biorefining. Recent publications mainly concern various directions of valorization of technical lignins, as well as applications of lignin in medicine and pharmacology, 3D printing, synthesis of carbon fibres and biofuels. In the field of fundamental research, studies on lignin biosynthesis are of special attention. The review is devoted to the latest advances in the chemistry of lignin. The currently available data on the structure and biosynthesis of lignin are discussed.The trends in lignin valorization, such as pyrolysis and carbonation, production of composites,copolymers and nanoparticles, synthesis of practically valuable low-molecular-weight substances, production of hydro- and aerogels, etc., are analyzed in detail. It is noted that at present, the practical application of lignin is developing in two directions: valorization of technical lignins per se, without prior depolymerization, and valorization via low molecular weight compounds, mainly monomers, formed through lignin degradation by various methods.The bibliography includes 130 references.
Uspehi himii. 2023;92(8):RCR5082
RCR5082
Progress in single-atom methodology in modern catalysis
Resumo
The review addresses the development of the methodology of single-atom catalysts ranging from single-site to single-atom alloy systems. The preparation and characterization of single-atom catalysts and their use in a number of key catalytic reactions, including alkyne hydrogenation, are considered. The possibility of finetuning of the surface structure of single-atom alloy catalytic systems using the adsorbate-induced segregation is analyzed for the first time.The bibliography includes 312 references.
Uspehi himii. 2023;92(8):RCR5087
RCR5087
Catalytic properties of peroxidase mimicking nanozymes
Resumo
Herein is the first attempt to critically review the catalytic properties of peroxidase mimicking nanozymes. For this aim the main factors affecting nanoparticles activity are discussed, and the catalytic properties are normalized allowing true comparison of different nanomaterials. The highest catalytic activities in hydrogen peroxide (H2O2) reduction have been recorded for nitrogen-coordinated iron atoms (FeN4, FeN5). However, the main disadvantages of metal/metal oxide as well as "single atom" nanozymes are their additional activities in oxygen reduction and H2O2 dismutation, impairing their application abilities. Nanoparticles catalytically synthesized from the most advantageous electrocatalyst (Prussian Blue) display enzymatic selectivity in addition to the highest catalytic activity. This may indicate simultaneous electron donation to H2O2 from different iron atoms. Accordingly, perspective synthesis of "single atom" nanozymes can be carried out considering bi-metallic (Fe–Fe like) structures in addition to the presently synthesized ones.The bibliography includes 121 references.
Uspehi himii. 2023;92(8):RCR5088
RCR5088
Advances in the chemistry of 1,2,3,4-tetrazines
Resumo
The experimental and theoretical chemistry of 1,2,3,4-tetrazines have been actively studied in the last 20 years. The increasing interest in this class of compounds is due to the fact that the 1,2,3,4-tetrazine ring is a promising building block for the development of energetic and physiologically active compounds. The reviewconsiders various types of 1,2,3,4-tetrazines including completely unsaturated nonannulated tetrazines and their N-oxides; nitrogen-substituted tetrazines; annulated tetrazines with a nitrogen atom common to two heterocycles; 1,2,3,4-tetrazine 1,3-dioxides fused to benzene, pyridine, 1,2,3-triazole or 1,2,5-oxadiazole ring; and also 1,2,3,4-tetrazine 1,3-dioxide fused to one more 1,2,3,4-tetrazine 1,3-dioxidering. Methods of synthesis and reactivity of these compounds, their crystallographic features, spectral characteristics and thermal stability are described. The results of quantum chemical studies for 1,2,3,4-tetrazine derivatives are presented. The prospects of using 1,2,3,4-tetrazines as energetic compounds are discussed.The bibliography includes 189 references.
Uspehi himii. 2023;92(8):RCR5089
RCR5089