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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.