Home – Home – Jornals – Chemistry for Sustainable Development 2025 number 5

A method to synthesis new hybrid derivatives of α-pinene with α-aminophosphonate fragment has been developed to obtain an additional centre of metal coordination in the molecules of potential extractants for heavy metals. It has been shown that O-alkyl ethers of α-amino oximes of the pinane series can be converted according to the two-stage version of Kabachnik-Fields reaction with dimethylphosphite and benzaldehyde into new chiral α-aminophosphonates with a satisfactory preparative yield (40-42 %). According to this scheme, terpene aminophosphonates are obtained as highly lipophilic products in the form of a pair of stereoisomers with a diastereomeric purity of 49-66 %.

A method for modifying nopinane-annelated 4,5-diazafluorene by introducing butyl groups and an additional amide group is proposed. Stereoselectivity of the formation of a single isomer by the substitution of a benzyl methylene group of pinane system is demonstrated. The structure of the new substances is established using a set of physicochemical methods. The synthesised substances can be promising tridentate ligands and extractants for d- and f-elements.

Triarylmethyl radicals (TAM, trityls) presented in the form of water-soluble tricarboxylic acids are widely used in biomedical, chemical and spectroscopic studies. In most applications, trityl radicals demonstrate high stability against various redox agents. An exception is the oxidative degradation of TAM to diamagnetic quinone methides. A typical active form of oxygen in biological environments, superoxide (O₂^·- or HO₂^·) is involved in this reaction. The details of this process have been studied in order to identify the factors controlling the channel of TAM consumption. The study has been performed using quantum chemical calculations (by means of the density functional theory) on a model trityl - triphenylmethyl radical presented in the form of a monocarboxylic acid. Alternative routes differing in the nature of protonation of key reagents in the aqueous medium have been considered. It has been established that protonation/deprotonation of reagents controls the barrier of the rate-limiting stage and, thus, the rate of the observed decarboxylation. This conclusion is in good agreement with the experimental data on the dependence of the reaction rate on pH. Among the reaction pathways considered, the most favourable one is the interaction of TAM anion, containing deprotonated carboxyl group, with protonated superoxide (neutral hydroperoxide radical HO₂^·). Taking into account the identified features, an analysis of alternative oxidation routes of another TAM derivative was carried out, for which the role of the key stage is assigned to proton elimination.

The reaction of 2-R-5,5-diethyl-2-ethynylpyrrolidin-1-oxyls (where R = Et, i-Pr) with esters of azidoacetic and p-azidobenzoic acids in the presence of copper(I) salts has been studied. It was found that the presence of the bulky isopropyl substituent prevents the reaction with ethyl ether of p-azidobenzoic acid and decreases the yield of the corresponding triazole in the reaction with methyl ester of azidoacetic acid. The resulting nitroxides demonstrated a high degree of resistance to reduction by ascorbic acid, which was comparable to the stability of 3,4-bis-hydroxymethyl-2,2,5,5-tetraethylpyrrolidin-1-oxyl.

Results obtained in the studies of living systems using chemical fingerprinting methodology are presented. Gas chromatography - mass spectrometry and the tools of chemical fingerprinting were applied to obtain the chromatographic profiles and to determine the isomeric-homologous series of characteristic target metabolites of various classes of the objects of plant origin and cuticular lipids of insects at different stages of ontogenesis and living in different climatic conditions. The main target metabolites considered herein are hydrocarbons, ketones, alcohols, fatty acids and their hydroxy-derivatives, esters, alkylresorcinols, di- and triterpenoids, phenol acids, and lignans. The approach used in the work makes it possible to establish the composition of characteristic target metabolites in various living systems and their changes in the processes occurring under the influence of abiotic and biotic factors, targeted gene mutations, which can be used both in fundamental and applied research, including the improvement of approaches to biological control of economically important insect pests in agriculture.

Neuromodulatory properties of two aza analogues of amantadine - 6-amino-5,7-dimethyl-1,3 -diazaadamantane 3 and 7-amino-1,3,5-triazaadamantane 4, as well as a synthetic precursor of compound 3 - 5,7-dimethyl-1,3-diazaadamantan-6-one 2, - were investigated in experiments on outbred male mice. Azaadamantanes and the reference drug amantadine hydrochloride 1 were administered intraperitoneally in an aqueous solution at a dose of 20 mg/kg. Control animals were administered water. In a model of neuroleptic haloperidol-induced parkinsonism, it has been shown that 2 and 4 are more potent agents in dopamine-stimulating activity than amantadine. In the model of arecoline tremor, azaadamontanes 3 and 4 were found to have higher M-cholinergic blocking activity than amantadine. All azaadamantanes have been shown to potentiate adrenergic neurotransmission but do not have GABAergic activity. The most promising agent is triazaadamantane 4, which has demonstrated pronounced dopamine-stimulating and M-cholinergic blocking properties with moderate adrenergic activity.

Conjugates of drugs and biologically active compounds with stable nitroxides are often used to study pharmacokinetics, the biochemical mechanisms of activity and distribution of the active substance in body tissues using electron paramagnetic resonance and magnetic resonance imaging. In this work, we synthesised a paramagnetic analogue of ibuprofen, a known cyclooxygenase inhibitor, retaining the free carboxyl group for critical interaction with the active site of this enzyme. For this purpose, ibuprofen was subjected to nitration into the aromatic ring, the nitro group was reduced, and the resulting amine was acylated with 2,2,5,5-tetramethyl-3-pyrroline-1-oxyl-4-carboxylic acid chloride.

A novel predictive model based on meta-learning algorithms for estimating the energy gap between the frontier molecular orbitals of aromatic p-conjugated molecules is presented. The main goal of the study was to develop a highly accurate and robust model capable of replacing computationally expensive quantum chemistry calculations, in particular the methods based on density functional theory, for screening organic compounds in optoelectronic applications. The filtered subset of the publicly available PubChemQC PM6 database was used as the primary dataset. Molecular structure was encoded using Morgan fingerprints, which served as input for training three base models: Random Forest, Gradient Boosted Trees, and a fully connected Neural Network. Among these, the Gradient Boosted Trees model achieved the best performance (the mean absolute error was 0.1795 eV). To improve prediction accuracy, a meta-model was implemented and trained on the outputs of the above-mentioned base models. This approach demonstrated improved accuracy: the final mean absolute error was 0.1744 eV, which is 8 % better than simple averaging and 3 % better than the best-performing individual model. The proposed approach can be further enhanced by expanding the dataset and incorporating additional models, which pave the way for more accurate and efficient prediction of the properties of organic conjugated molecules in optoelectronics.

2,7-Di(thiophen-2-yl)-9H-(4,5-diazafluoren)-9-one (TDAFO) was synthesised and its crystal structure, optical and electrochemical properties were studied. The target compound was obtained using the Stille reaction from 2-(tri(n-butylstannyl)thiophene and 2,7-dibromo-4,5-diazafluoren-9-one. Using X-ray diffraction analysis, the crystal structure of TDAFO was solved, and the formation of weak π-stacking interactions, C-H…N and C-H…O hydrogen bonds was revealed. The oxidation and reduction potentials of TDAFO were evaluated by cyclic voltammetry, and the possibility of TDAFO electropolymerisation on conductive coatings was demonstrated. The optical properties of both the monomer and the polymer obtained by electrochemical polymerisation were studied. The photoluminescence quantum yield of TDAFO was determined to be 7 % in solution and 13 % in the crystalline form.

Рiperidine nitroxides have found many applications in various fields of science and technology. The introduction of bulky alkyl substituents in an adjacent position to the N-O fragment imparts useful characteristics to such radicals, increasing their stability in biological samples, enhancing their protective antioxidant properties and making them valuable regulators of radical polymerisation. A sterically hindered nitroxide with a spiro-2-hydroxymethylcyclopentane moiety and two ethyl groups at positions 2 and 6 of the piperidine ring, respectively, was synthesised. For this purpose, the condensation of 2-(2-aminoethyl)-2-methyl-1,3-dioxolane with diethyl ketone under the conditions of acid catalysis was carried out. The resulting spirocyclic piperidine was oxidised to aldonitrone. Spiro-2-hydroxymethylcyclopentane moiety was assembled via the reaction with 4-pentenylmagnesium bromide, followed by oxidation and intramolecular 1,3-dipolar cycloaddition and reductive opening of the isoxazolidine ring. The resulting dispirocyclic piperidine was oxidised to the corresponding nitroxide, 8-[(hydroxy)methyl]-13,13-diethyl-1,4-dioxa-12-azadispiro[4.1.4.3]tetradecane-12-oxyl. The kinetics of reduction of the latter by ascorbic acid has been studied.

Structural modification of the Finland-type trityl core by replacing carboxyl groups by alkoxymethyl substituents (CH₂OCH₂CO₂H) resulted in new triarylmethyl radicals, which showed extremely high stability in the presence of superoxide.

The work is concerned with the synthesis of biologically active substances based on monoterpenoids through their chemical modification to increase the pharmacological potential of the synthesised compounds. The starting substances to synthesise urea derivatives were adamant-1-ylisocyanate and monoterpenoid amines with a perillyl or myrtenol fragment. These monoterpenoid substituents were chosen on the basis of literature data suggesting that the indicated compounds exhibit activity with respect to the nervous system in various animal models. On the basis of these ureas, imidazoline-2,4,5-triones were synthesised. These urea derivatives potentially possess lower lipophilic properties.

The structure of asphaltenes of oils sampled in various oil and gas provinces and differing from each other in chemical types and contents of asphaltene components has been studied using an oxidation reaction catalysed by ruthenium ions. Structural fragments, covalently bound through C_ar-C links with the aromatic rings of their molecules, and the compounds occluded in the hollow cells of macromolecular structures in asphaltenes are shown to be present in all the samples under investigation. The covalently bound fragments are represented by normal and branched alkanes, cheilanthanes, gopanes, and aromatic structures of the biphenyl type. Typical biological markers, n-alkanes and hopanes, have been identified among occluded compounds. n-Alkylbenzenes, n-alkyltoluenes, n-alkylxylenes, n-alkyltrimethylbenzenes, and alkylbenzothiophenes are additionally found in the composition of non-oxidised naphthenic aromatic oil compounds.

Two- and three-component systems of deep eutectic solvents (DES) based on polyatomic alcohol - pentaerythritol (PER), carbonic acid diamide - urea (carbamide, CA) and quaternary ammonium salt - choline chloride (CC) were synthesised: PER-CC, PER-CA, CC-CA, PER-CA-CC. Eutectic points in the obtained DES systems were determined. It is shown that the lowest melting point (-14.5 °C) is observed for the three-component DES system based on PER-CA-CC with the molar component ratio of 1.3 : 2.4 : 1, respectively. The solubility of this three-component system was determined by dissolution in water prior to precipitation. The density of the aqueous solutions of binary DES systems was determined to be within the range of 1.2158-1.2458 g/cm³. The presence of hydrogen bonds in binary and ternary DES systems was revealed by IR spectroscopy: CC acts as an acceptor of hydrogen bonds, while PER and CA act as donors. The presence of hydrogen bonds between DES components provides the formation of stable molecular complexes and lowering of the melting/crystallisation points of DES compositions due to intermolecular bond weakening and destruction of the crystal structures of initial substances.

Extrusion-based 3D printing methods are widely used to fabricate tissue-engineered constructs for regenerative medicine with specific dimensions, shapes, and properties tailored to the nature of the wound defect. High-viscosity solutions of the anionic polysaccharide sodium alginate show a potential as a base material for developing hydrogel inks for 3D printing. However, printing with sodium alginate solutions presents technical challenges due to the need for rapid gelation immediately after extrusion to form an elastic gel. This study demonstrates the possibility of controlling the viscosity of sodium alginate solutions by introducing a gelation modifier - ferulic acid, which participates in the formation of an entanglement network. Using IR spectroscopy, the nature of interactions in alginate-based materials obtained in the presence of ferulic acid was investigated. The conditions for producing highly hydrated gel structures based on an ionogenic polysaccharide solution and ferulic acid were optimised using piston-based 3D printing.

This article is concerned with the urgent problem of atmospheric air pollution in the post-industrial phase of the development of mining regions. Methodological approaches to the hygienic diagnostics of local aerosol pollution of the atmosphere have been elaborated. The modeling object was the Ursk dump of barite-pyrite loose material, formed in the 1930s after gold extraction by cyanidation in Ursk settlement, the Kemerovo Region. The field model of the dump was formed by the samples of sulphide-containing wastes collected from the object in summer. At the first stage, a theoretical analysis of the information presented in the literature on the physicochemical and toxic properties of aerosol particles in the submicron range, which pose risks to the environment and public health in mining areas, was carried out. At the stage of hazard identification, the application of the field modeling of atmospheric migration processes of target particles and mercury vapour from a sulphide-containing waste disposal facility was scientifically justified. At the modelling stage, which consisted of heating the waste samples to a temperature of 27.1±0.04, 33±0.1 and 50±0.3 °C, the trends of air concentrations of aerosol particles of various ranges and their correlations were estimated. At the design stage, the probability of accumulation of submicron particles and mercury vapour in the air basin, which poses a significant danger to the environment and public health, was determined. The data obtained from the results of simulation are intended for information provision of planning and implementation of measures for land reclamation and environmental improvement.

The effect of indium oxide additive on the properties of Pd-containing catalytic systems Pd/WO₃-ZrO₂ based on zirconia modified with tungstate anions (tungstated zirconia catalysts) and Pd/WO3-ZrO₂/Al₂O₃ catalysts in which the active component WO₃-ZrO₂ providing the acid properties of catalysts is introduced into the porous matrix of the alumina support is investigated. It is shown that the introduction of indium oxide additive in an amount of 0.5-1.5 wt% into the catalyst composition enhances their activity and also increases the yield of the target reaction products - octane isomers. The introduction of 0.5 wt% indium oxide into the composition of tungstated zirconia catalysts supported on alumina leads to an increase in octane conversion by 5.8 % and a rise in the yield of the target reaction products - octane isomers by 4.7 wt%. For Pd/WO₃-ZrO₂ catalysts, the introduction of indium oxide additive in an amount of 1.0-1.5 wt% leads to an increase in octane conversion by 28.0-38.7 %, with a rise in the yield of isomers by 17.0-21.3 wt%. The positive modifying effect of indium oxide additive to the Pd/WO₃-ZrO₂ catalysts is due to an increase in the proportion of the active tetragonal phase of zirconia from 33 to 43-63 %, a rise in the specific surface area from 28 to 38-40 m²/g and an increase in total acidity according to temperature-programmed desorption of ammonia from 113 to 122 μmol/g. The introduction of the active component into the porous alumina support causes an increase in the proportion of weak acid sites of the catalysts, which provides an increase in selectivity to octane isomers. The addition of indium oxide allows regulating the phase composition, textural characteristics and acid properties of palladium-containing tungstated zirconium catalysts, which determines their catalystic activity, and allows obtaining active and selective catalysts of octane isomerization - Pd/In₂O₃-WO₃-ZrO₂ and Pd/In₂O₃-WO₃-ZrO₂/Al₂O₃.