bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of zinc(ii) and manganese(ii) (1-hydroxyethylidene)diphosphonates with aqueous solution of 3-aminopropyltriethoxysilane
Authors: Kulikova T. I , Zolotareva N. V , Lopatina T. I , Razov E. N , Semenov V. V
Published: April 2024

An aqueous solution of 3-aminopropyltriethoxysilane reacts with suspensions of crystalline zinc(II) (1-hydroxyethylidene)diphosphonates H2ZnL·2H2O and manganese(II) H2MnL·3H2O to give heavy precipitates of amorphous bis(3-aminiumpropylsilsesquioxane)(1-hydroxyethylidene)zinc(II) diphosphonate tetrahydrate and bis(3-aminium propylsilsesquioxane)(1-hydroxyethylidene)manganese(II) diphosphonate trihydrate. Structure of the prepared compounds was studied by elemental, thermal, X-ray phase analysis, IR spectroscopy, and scanning electron microscopy. The specific surface areas of the initial xerogels and products of their thermal decomposition were measured.
Synthesis of tetrazinyl biradicals containing a p-phenylene fragment
Authors: Kostryukov S. G , Burtasov A. A , Dolganov A. V , Kozlov A. Sh. , Konushkin I. A , Malov N. A , Krasnov D. A , Asfandeev A. Yu.
Published: April 2024

3,3′-(1,4-Phenylene)bis[1-(4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium] perchlorates were transformed into stable tetrazinyl biradicals by the action of D-glucose in slightly alkaline medium (NH4OH) in the presence of air oxygen. The tetrazinyl biradicals were isolated in individual state and characterized by cyclic voltammetry, elemental analysis, IR, UV, EPR spectroscopy methods.
Synthesis of diethyl 6-amino-1,4-diaryl-2-oxo1,2,3,4-tetrahydropyridin-3,5-dicarboxylates based on the reaction of arylmethylidenecyanoacetic esters with N-arylamido esters of malonic acid
Authors: Avagyan K. A , Sargsyan M. S , Badasyan A. E , Sargsyan A. A , Manukyan A. G , Panosyan G. A , Ayvazyan A. G , Khachatryan A. Kh.
Published: April 2024

The reaction of arylmethylidenecyanoacetic esters with N -arylamides of malonic acid led to the formation of previously unknown diethyl 6-amino-1,4-diaryl-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxylates in 15-83% yields. Antibacterial activity of some obtained compounds was studied.
Selective oxidation of the 4-ethyl-3-methylcinnoline methylene group by al2o3-supported chromium oxide
Authors: Chikunov S. Yu. , Balakina E. A , Kulakov I. V
Published: April 2024

The optimal conditions for the oxidation of the methylene group in 4-ethyl-3-methylcinnoline to the corresponding ketone, 3-methyl-4-acetylcinnoline, were selected. It was shown that preliminary deposition of 4-ethyl-3-methylcinnoline on some inorganic substrates has a significant effect both on the selectivity of the oxidation of only the methylene group and on a high degree of conversion to the target product.
Spectrophotometric study of basic properties of glycosylated tetraphenylporphin derivatives
Authors: Ivanova Yu. B. , Pukhovskaya S. G , Lyubimtsev A. V , Syrbu S. A
Published: April 2024

The paper presents the results of spectrophotometric study of the basic properties of glycosylated substituted derivatives of 5,10,15,20-tetraphenylporphyrin, namely 5-(4′- O -galactosylphenyl)-10,15,20-tris( N -methylpyridin-3-yl)porphine, 5,15-bis(4′- O -galactosylphenyl)-10,20-bis( N -methylpyridin-3-yl)porphine, 5,10,15,20-tetra( N -methylpyridin-3-yl)porphin, 5,10,15,20-tetra(4- O -galactosylphenyl)porphin. The basic properties of the studied ligands in acetonitrile at 298 K were studied by spectrophotometric method. The effect of glycosylated fragments, as constituents of a macromolecule, on protolytic equilibria during acid-base interactions of the ligand in basic media and the change in the reactivity of porphyrin ligands depending on the nature of the peripheral substituent was analyzed.
A practical synthesis of 1-[3-(trimethoxysilyl)propyl]-1H-imidazole
Authors: El'kov N. A , Konshina Dz. N. , Konshin V. V
Published: April 2024

A simple and effective method for the synthesis of 1-[3-(trimethoxysilyl)propyl]-1 H -imidazole was proposed by alkylation of sodium imidazolyl obtained from imidazole and sodium hydroxide with (3-chloropropyl)trimethoxysilane at reflux in toluene for 15 h. The target imidazole was obtained with a yield of 82%.
Reactivity of olefin functions of dicyclopentadiene in the Diels-Alder reaction with thionylaniline
Authors: Ilyushkina E. K , Veremeychik Ya. V. , Lodochnikova O. A , Plemenkov V. V
Published: April 2024

The sulfonamide with a benzothiazine moiety was synthesized by a Diels-Alder reaction of thionylaniline with dicyclopentadiene. The prepared adduct was oxidized to the appropriate sulfonamide with a benzothiazine moiety. The molecular and crystal structure of the sulfonamide obtained was determined by the single crystal X-ray diffraction analysis. A higher reactivity of the the olefin function of the norbornene fragment was found; and the formation of two structural isomers was revealed.
Extraction properties of 4-[(hexylsulfanyl)methyl]3,5-dimethyl-1-phenyl-1H-pyrazole in the palladium(II) recovery from nitric acid solutions
Authors: Anpilogova G. R , Baeva L. A , Nugumanov R. M
Published: April 2024

Palladium(II) extraction from nitric acid solutions with a complex-forming reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1 H -pyrazole, was studied using chloroform as a diluent. The reagent extracts Pd(II) with high efficiency from 0.5-5 M. HNO3 solutions. It has been established that palladium(II) is extracted from 2 M. HNO3 solutions by a coordination mechanism with the formation of the extracted compound [Pd(NO3)2μ-L] n ( n > 2). Palladium(II) is quantitatively stripped with a nitric acid solution of thiourea. The reagent is promising for the concentration of Pd(II) from nitric acid solutions and its highly selective separation from Fe(III), lanthanides(III), Al(III), Cu(II), and Ni(II).
Features of complex formation of native and polymeric β-cyclodextrins with sulfasalazine
Authors: Agafonov M. A , Terekhova I. V
Published: April 2024

The work is devoted to the study of the complex formation of sulfasalazine with native and polymeric β-cyclodextrins in buffer solutions with a physiological pH value using isothermal saturation and 1H NMR methods. It was established that sulfasalazine forms two types of complexes when interacting with the cyclodextrins under consideration, but only the process of formation of inclusion complexes determines the observed increase in drug solubility, which is more pronounced in the presence of polymeric β-cyclodextrin. It was determined that complexation with β-cyclodextrin and its polymeric derivative leads to a decrease in the permeability coefficients of sulfasalazine through the model membrane, which is determined by both the stability constant of the complexes and their ability to pass through the membrane.
Reactions of arylaldimines of glycine ethyl ester with halo-substituted arylideneacetones
Authors: Kostryukov S. G , Kalyazin V. A , Petrov P. S , Bezrukova E. V
Published: April 2024

The reaction of 1,3-dipolar cycloaddition of para -halosubstituted mono- and diarylideneacetones and azomethine ylides generated in situ from N -arylimines of glycine ethyl ester in the presence of silver acetate and a half time excess of triethylamine afforded tetrasubstituted ethyl pyrrolidine carboxylates. For para -halogensubstituted dibenzyledeneacetone, a minor product with a different regioselectivity was observed. The selectivity of the reaction and the structure of the products were determined using NMR correlation spectroscopy. The regioselectivity of the cycloaddition was interpreted using DFT/PBE calculations of the transition state energies of the reactions.
Intramolecular noncovalent interactions in bis-imidazolium dications with short aliphatic spacers
Authors: Zarechnaya O. M , Mikhailov V. A
Published: April 2024

Stretched all-trans conformations were found preferable in computed structures of bis-imidazolium dications with short aliphatic (С1-С4) and hydroxyl substituted -СН2-СНОН-СН2- spacers. Maxima of molecular electrostatic potential were established near С2Н imidazolium and spacer hydrogens, for α,ω-alkenyl spacers, and close to hydroxyl hydrogen for hydroxypropane spacer. Sufficiently higher rotational barrier around С1-C2 bond in -СН2-СНОН-СН2- spacer compared with polymethylene is supported with intramolecular hydrogen bonds С-Н···О-Н between imidazolium hydrogens and hydroxyl oxygen.
Copper(II) сomplexes with 2-hydrохy-5-ethylphenylphosphosphonic acid: synthesis, structure, cytotoxicity, and accumulation in HeLa cells
Authors: Rogacheva Yu. I. , Lapshina M. A , Baulin V. E
Published: April 2024

In order to study the physicochemical and biological properties of the coordination compounds of bioactive metal ions with 2-hydroxyphenylphosphonic acid derivatives, the reaction of 2-hydroxy-5-ethylphenylphosphonic acid (Н3L1) with copper(II) perchlorate, sulfate, nitrate, and acetate in water was studied for the first time. It has been established that, regardless of the ratio of reagents, in the case of copper(II) perchlorate, sulfate, and nitrate, a complex of the composition [Cu(H2L1)2(Н2О)2] is formed in high yield, while in the case of using copper(II) acetate a complex [Cu(HL1)(H2O)2] is formed, the composition of which is established on the basis of a combination of elemental analysis data, IR and electronic spectra. Quantum-chemical calculations of the structure of [Cu(H2L1)2(H2O)2] and [Cu(HL1)(H2O)2] complexes were performed for the first time by the density functional theory (DFT) method. The cytotoxic properties of H3L1 acid and copper complexes [Cu(HL1)(H2O)2] and [Cu(H2L1)2(H2O)2] with respect to HeLa tumor cells of human cervical adenocarcinoma were studied. The accumulation of the resulting copper(II) complexes in HeLa cells was proved by laser confocal microscopy.
Quantum-chemical study of еhe binding energy of lithium ion endofullerene li+@C60 with anion
Authors: Mikhailov G. P
Published: April 2024

The optimal geometry, binding energy Δ E ion pairs of type Li+@C60·A- (A = BF4, AsF6, PF6, FSI, TFSI, 4F-BB) in vacuum and chlorobenzene medium were calculated using the method of density functional theory. ΔE values were found to decrease significantly in chlorobenzene medium depending on the nature of the anion. In the structures of Li+@C60·A-, various contacts C···F, C···O, C···C, C···N and Li···C were established, which, within the framework of Bader’s theory, “atoms in molecules” were assigned to interactions of closed shells, and their energy is calculated.
Synthesis of aromatic and heterocyclic fumaropimaric acid triamides
Authors: Bei M. P , Yuvchenko A. P
Published: April 2024

A method was developed for the synthesis of previously unknown triamides of fumaropimaric acid by the reaction of anilide and 1-(piperidin-1-ylcarbonyl) derivative of fumaropimaric acid with aromatic and heterocyclic amines [4-toluidine, 4-pentylaniline, 4-biphenylamine, 4-methoxy-, ethoxy-, phenoxy-, bromoaniline, 2-picolylamine, 2-(aminomethyl)furan, 2-(aminomethyl)thiophene] under the action of propanephosphonic acid anhydride.
Synthesis of 5-[4-(arylsulfanyl)phenyl]-2,2′-bipyridines using aryne intermediates
Authors: Starnovskaya E. S , Krinochkin A. P , Rybakova S. S , Muzyka A. L , Slepukhin P. A , Kopchuk D. S , Zyryanov G. V , Chupakhin O. N
Published: April 2024

A convenient method for the preparation of 5-aryl-2,2′-bipyridines with para -arylsulfanyl group in an aromatic substituent was proposed. The synthesis was performed using in situ generated aryne intermediates without the use of complex experimental procedures and expensive reagents/catalysts. The structure of one product was confirmed by XRD data. This approach is a new variant for the preparation of 5-aryl-2,2’-bipyridines with an extended conjugation system.
Nucleophilic substitution in 4-bromo-5-nitrophthalodinitrile: XVIII. Synthesis and spectral properties of octasubstituted zinc phthhalocyanines with cyclohexylphenol moieties
Authors: Znoiko S. A , Kuzmina M. S , Maizlish V. E , Koshel G. N , Lebedeva N. V
Published: April 2024

Using 4-bromo-5-nitro- and 4,5-dichlorophthalonitriles, substituted phthalonitriles containing a fragment of 2-cyclohexylphenol and nitro- or 1-benzotriazolyl groups, as well as phthalonitrile containing two 2-cyclohexylphenoxy groups, were synthesized. Tetramerization of these precursors with zinc acetate hexahydrate gave the corresponding octa-substituted zinc phthalocyanines. Their spectral properties were studied.
Synthesis and analgesic activity of N-(1-aryl-3-oxo-2-azaspiro[3.5]nonan-2-yl)benzamides
Authors: Nikiforova E. A , Makhmudov R. R , Zverev D. P , Dmitriev M. V , Shurov S. N , Kirillov N. F
Published: April 2024

The Reformatsky reagent, derived from the methyl 1-bromocyclohexanecarboxylate and zinc, reacts with N′ -(arylmethylidene)benzohydrazides, to form, as a result of intramolecular cyclization of the initial addition products, N -(1-aryl-3-oxo-2-azaspiro[3.5]nonan-2-yl)benzamides. The structure of the latter was proved by X-ray diffraction analysis. In the case of p -tolualdehyde benzoylhydrazone, the adduct of the Reformatsky reagent to the double carbon-nitrogen bond of the substrate, which not underwent cyclization, was predominantly isolated. The resulting spiroazetidin-2-ones exhibit antinociceptive activity.
Morphology and luminescent properties of NaYF4 microcrystalline upconversion materials doped with ytterbium(III) and holmium(III) ions
Authors: Bulatova T. S , Betina A. A , Nosov V. G , Kolesnikov I. E , Bogachev N. A , Skripkin M. Yu. , Khairullina E. M , Mereshchenko A. S
Published: April 2024

Microcrystalline upconversion materials NaY0.8- x Yb0.2Ho x F4 ( x = 0-0.1) were synthesized by hydrothermal synthesis for the first time. All the synthesized compounds have hexagonal β-NaYF4 crystalline phase. Holmium(III) ions isomorphically replace yttrium ions. The maximum upconversion emission intensity is observed for NaY0.78Yb0.2Ho0.02F4 in the visible region of the spectrum upon excitation at a wavelength of 973 nm.
Morphology and luminescent properties of nanocrystalline NaGdF4 phosphors doped with neodymium(III) ions
Authors: Betina A. A , Bulatova T. S , Nosov V. G , Kolesnikov I. E , Bogachev N. A , Skripkin M. Yu. , Mereshchenko A. S
Published: April 2024

Nanocrystalline phosphors NaGd1- x Nd x F4 ( x = 0-1) were synthesized by hydrothermal synthesis for the first time. All the synthesized compounds have hexagonal β-NaYF4 crystalline phase. Neodymium(III) ions isomorphically replace gadolinium ions. NaGd0.96Nd0.04F4 compound has the largest photoemission intensity in NIR range upon 808 nm excitation; further doping with Nd3+ results in concentration quenching.
Synthesis and luminescent properties of Lu2O2SO4:Eu3+ spherical particles
Authors: Larionova K. A , Denisenko Yu. G. , Osseni S. A , Andreev O. V , Razumkova I. A
Published: April 2024

A study was conducted into the potential use of Lu2O2SO4: x Eu3+ as a contrast agent in multifunctional medical imaging. Spherical powders of solid solutions Lu2O2SO4: x Eu3+ ( x = 1-7 mol%) with a diameter of approximately 300 nm were synthesized through co-precipitation followed by calcination. The duration of synthesis was observed to impact particle morphology, with extended coprecipitation times leading to coarse particles that lost their spherical shape due to conglomerate formation. Exciting Lu2O2SO4: Eu3+ at a wavelength of 270 nm results in distinct peaks appearing in the 610-620 and 690-710 nm regions, with intensity varying depending on the concentration of Eu3+ ions present.
Synthesis, luminescent properties and antibacterial activity of new pyrazoline and pyrimidine derivatives of (2e)-1-biphenyl-3-arylprop-2-en-1-ones
Authors: Isakhanyan A. U. , Hakobyan N. Z. , Hovasyan Z. A. , Grigoryan G. S. , Mkhitaryan R. P. , Aracelyan H. G. , Safaryan A. S. , Muradyan R. E. , Panosyan H. A.
Published: April 2024

Substituted prop-2-en-1-ones were obtained by the condensation reaction of 1-biphenyl-4-yl-ethanone with aromatic aldehydes in the presence of sodium hydroxide in an aqueous ethanol solution. Subsequent cyclization of the latter with hydrazine hydrate, phenylhydrazine, and thiosemicarbazide in an acidic medium leads to the corresponding pyrazolines. The reaction of amidine hydrochlorides with chalcones in a KOH-ethanol system leads to 2,4,6-trisubstituted pyrimidines. The luminescent and antibacterial properties of the resulting systems was studied.
Addition of alcohols to 4-methylene-1,3-dioxolanes
Authors: Sokov S. A , Borisova Yu. G. , Raskil'dina G. Z , Zlotsky S. S , Golovanov A. A
Published: April 2024

The addition of alcohols to 2-methylene-1,4-dioxaspiro[4.5]decane under the conditions of CF3CO2H catalysis occurs with the selective formation of the corresponding alkoxy derivatives. The conditions that ensure the preparative isolation of target compounds in 63-94% yields are determined, and the relative activity of alcohols in the addition reaction at the exocyclic double bond of substrates is determined.
Synthesis of (2 E )-5-arylpent-2-ene-4-ynoates
Authors: Shakhmaev R. N , Ignatishina M. G , Blokhina Yu. S. , Zorin V. V
Published: April 2024

An effective method was developed for the synthesis of (2 E )-5-arylpent-2-ene-4-ynoates based on the olefination-dehydrobromination of (2 Z )-2-bromo-3-arylprop-2-enals obtained by bromination of commercially available cinnamaldehyde and its derivatives.
A new method for the synthesis of 2,3-aryl-5-arylideneimidazol-4-ones using N-trimethylsilylimidazole
Authors: Topuzyan V. O , Tosunyan S. R , Aleksanyan E. R , Hakobyan E. A , Hovhannisyan N. A , Makichyan A. T , Shahkhatuni A. A , Hovhannisyan A. A
Published: April 2024

A new method was developed for the synthesis of 5-arylidene-2,3-disubstituted 4 H -imidazol-4-ones by cyclization of N -substituted α,β-dehydroamino acid arylamides with N -trimethylsilylimidazole (TMSIM) in dimethylformamide. The process was carried out by both conventional and microwave heating. Target imidazol-4-one was also synthesized by a one-pot method based on the reaction of unsaturated 5(4 H )-oxazolone, arylamine, and TMSIM. The anticholinesterase and antiradical properties of synthesized both arylamides and 4-imidazolones were studied.
Phenalenyl-substituted stilbenes as the basis for spin switches: quantum-chemical modeling
Authors: Starikova A. A , Chegerev M. G , Starikov A. G
Published: April 2024

Isomers of stilbenes containing phenalenyl substituents in the para - and meta -positions of phenyl rings were studied by means of density functional theory method. Exchange coupling in structures with the trans -form of stilbenes is absent. In the cis -isomer of a meta -substituted compound, the state with a closed electron shell is stabilized due to two-electron multicenter interactions, which is confirmed by CASSCF calculations. The predicted transition between the triplet and singlet states as a result of trans-cis isomerization opens up prospects for using the discovered effect in the development of organic spin switches.
Synthesis of aromatic bishydrazones: new facets of a known reaction
Authors: Epishina M. A. , Kulikov A. S. , Fershtat L. L.
Published: April 2024

This work reconsiders the known condensation reaction of 1,2-diketones with arylhydrazines in the synthesis of the corresponding bishydrazones. It was shown that the reaction outcome significantly depends on the nature of the substituent of the aromatic ring of arylhydrazine. In addition, representatives of unsymmetrically substituted bishydrazones, rarely found in the literature, were obtained. The proposed approach is easy to carry out and isolate target bishydrazones, which opens the way to the preparation of various nitrogen-containing molecular systems based on them.
Acyl derivatives of 2,3,6,7-tetrahydro-1,4-diazepines: synthesis, structure, and tautomeric transformations
Authors: Anisimova N. A. , Melkova D. A.
Published: April 2024

The reaction of 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene with carboxylic acid chlorides afforded a series of N -and C -acylsubstituted 2,3,6,7-tetrahydro-1,4-diazepines, which in solutions of deuterated solvents (CD3OD, DMCO) undergo keto-enol and imino-enamine tautomerism. Structure of the obtained N - and C -acyldiazepines and their tautomeric transformations were characterized by 1Н and 13С NMR spectroscopy using two-dimensional experiments 1Н-13С HMQC, HMBC, 1Н-1Н COSY.
Routes of conversion of 2,2-di-(4-nitrophenyl)-1,1,1-trichloroethane into 4,4′-dinitrobenzophenone by reaction with nitrite ion: quantum chemical approach
Authors: Guzov E. A. , Kazin V. N.
Published: April 2024

Quantum chemical calculations of the transformation of 2,2-di(nitrophenyl)-1,1,1-trichloroethane into 4,4′-dinitrobenzophenone upon reaction with nitrite ion in aprotic polar solvents were performed. It was established that the dehydrochlorination reaction of 2,2-di(nitrophenyl)-1,1,1-trichloroethane proceeds via a synchronous E2H mechanism. A possible scheme for the subsequent formation of 4,4′-dinitrobenzophenone was proposed. For each stage of a multistage process, spatial structures were modeled and the energy parameters of pre-reaction, activated and post-reaction complexes were calculated.
Effect of the silicon atom on the electron density distribution in the organosilicon 1,2-hydroxyamines molecules
Authors: Khamitov E. M. , Konkina I. G. , Tsyrlina E. M. , Lobov A. N. , Ivanov S. P.
Published: April 2024

In the framework of the theory of MO LCAO by the TPSS / cc-pVTZ, Hirshfield and NBO analysis methods in the molecules of 4-(dimethylamino)-1,1-diethylsilacyclopentan-3-ol and 2-(dimethylamino)- 5-trimethylsilylcyclohexan-1-ol the nature of the influence of the silicon atom on remotely located nitrogen and oxygen atoms has been studied. More pronounced in 4-(dimethylamino)-1,1-diethylsilacyclopentan-3-ol molecule, this effect is determined by the geometric parameters (endocyclic arrangement of the silicon atom), which favor the formation of MOs with a large Si contribution. According to NBO analysis, the interaction between the orbitals of the Si-C5 bonds and the orbitals of the C3-N and C1-O bonds in the silacyclopentane fragment of the 4-(dimethylamino)-1,1-diethylsilacyclopentan-3-ol molecule, has a donor-acceptor character. The calculated data are in qualitative agreement with the results of 1H and 29Si NMR spectroscopy.
Cyclization of l-leucyl-l-valine dipeptide in the crystal phase under non-isоthermal conditions
Authors: Larionov R. A. , Ziganshina S. A. , Klimovitski A. E. , Khayarov Kh. R. , Babaeva O. B. , Gorbachuk V. V. , Ziganshin M. A.
Published: April 2024

Thermal treatment of linear dipeptides in the solid phase makes it possible to obtain their cyclic analogues in high yield and without additional costs. At the same time, such reactions occurring under the constraints of a crystal lattice with the participation of molecules in the zwitterionic form have not been sufficiently studied. In this work, the cyclization reaction of the dipeptide L-leucyl-L-valine in the crystalline phase upon heating was studied. Using isoconversion kinetics approaches, a kinetic model describing this process is determined, and kinetic parameters are calculated, including activation energy, Arrhenius multiplier, and reaction order. The enantiomeric purity of the resulting cyclic product was assessed. The self-assembly of linear and cyclic dipeptides on a solid support was studied. The results of the study will be useful for establishing the mechanism of the cyclization reaction of dipeptides in the solid phase, and can also be used in the development of effective and cost-effective methods for the production of cyclic dipeptides.
Influence of production method on the structure and photocatalytic activity of CeO2/Au nanocomposite
Authors: Isaeva E. I. , Sizova A. A. , Boitsova T. B. , Staritsyn M. V. , Fedoseev M. L.
Published: April 2024

Two methods for preparing mesoporous CeO2/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, morphology of the obtained nanocomposites, as well as the specific surface area and pore size distribution were studied by a complex of physicochemical methods: X-ray phase analysis, X-ray spectral microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electron spectroscopy. The catalytic properties of the obtained nanocomposites were studied in methyl orange photodegradation reactions. It is shown that the CeO2/Au catalyst obtained by the photochemical modification method has the highest photocatalytic activity both under the action of UV and visible light.
First examples of phosphoric anhydride mediated O- and N-acylation
Authors: Shafran Yu. M. , Pospelova T. A.
Published: April 2024

It was shown that phosphoric anhydride can be used for the synthesis of esters and amides of carboxylic acids when they react with compounds containing hydroxyl and primary amino groups. A new method was proposed for obtaining paracetamol. An example of the reverse reactivity of these nucleophilic centers located in para -aminophenol molecule was revealed.
Oxidation of 4,6-dimethyl-2-thioxo-1,2-dihydropyridine3-carbonitriles with potassium hexacyanoferrate(III): synthesis and molecular docking of bis(pyrid-2-yl)disulfides
Authors: Dakhno P. G. , Kindop V. K. , Gordeev K. V. , Zimmer I. A. , Dotsenko V. V. , Temerdashev A. Z. , Vasilin V. K. , Aksenov N. A. , Aksenova I. V.
Published: April 2024

The reaction of 4,6-dimethyl-2-thioxo-1,2-dihydropyridin-3-carbonitriles with K3[Fe(CN)6] in an alkaline medium led to the formation of a mixture of oxidation products: bis(3-cyanopyridin-2-yl)disulfides and potassium 3-cyano-4,6-dimethylpyridine-2-sulfonates. Structure of the compounds was confirmed by NMR, IR spectroscopy and high-resolution mass spectrometry data. According to the results of molecular docking, 2,2′-dithiobis(5-butyl-4,6-dimethylnicotinonitrile) exhibits affinity for the zinc finger binding site of the HIV-1 p7 nucleocapsid protein.
Synthesis and properties of (+)-ketopinic and (-)-camphanic acids esters bearing a nitrogen-containing heterocycle
Authors: Sokolova A. S. , Yarovaya O. I. , Kuzminykh L. V. , Ilyina M. G. , Borisevich S. S. , Esaulkova Ya. L. , Zarubaev V. V. , Salakhutdinov N. F.
Published: April 2024

A three-stage method was proposed for the synthesis of (1 S )-(+)-camphor-10-sulfonic acid, (+)-ketopinic and (-)-camphanic acids esters containing a saturated nitrogen-containing heterocycle. It was found that (1 S )-(+)camphor-10-sulfonic acid esters undergo destruction with elimination of the sulfonic acid group in substitution reactions involving nitrogen-containing heterocycles. Esters of (+)-ketopinic and (-)-camphanic acids were formed during the proposed synthetic route, but undergo transesterification under column chromatography conditions. Quantum chemical calculations showed that the destruction of the ester bond in the case of (+)-ketopinic and (-)-camphanic acids requires less energy than the breaking of a similar bond in (-)-borneol esters. It was revealed that the internal bond strength index (IBSI) for the alkyl C-O bond in (-)-borneol esters is higher than in (+)-ketopinic and (-)-camphanic acid esters. Antiviral properties against the H1N1 influenza virus were studied for derivatives of (+)-ketopinic and (-)-camphanic acids.
4,7-(bis(octyloxy)-3-(quinoline-2-ylmethylene)isoindoline-1-one and its boronflouride complex. synthesis and spectral-luminescent properties
Authors: Nabasov A. A. , Rumyantseva T. A. , Aleksandriiskii V. V. , Galanin N. E.
Published: April 2024

4,7-Bis(octyloxy)isoindoline-1,3-dione was obtained by reacting 3,6-bis(octyloxy)phthalonitrile with sodium butoxide in butanol, followed by treatment with hydrochloric acid. Its condensation with quinaldine in the presence of zinc oxide leads to the formation of ( E , Z )-4,7-bis(octyloxy)-3-(quinolin-2-ylmethylene)isoindolin-1-one, which was treated with BF3۰Et2O in the presence of triethylamine in toluene to give a new unsymmetrical analogue of BODIPY - ( Z )-2-(difluoroboryl)-4,7-bis(octyloxy)-3-(quinolin-2-ylmethylene)isoindolin-1-one. The complex exhibits a Stokes shift of 25 nm and a high relative fluorescence quantum yield (0.68). To support the experimental data, DFT and TD-DFT calculations were performed.
Reaction of chloroethynylphosphonates with 1,3-diethyl 2-(acylamino)propanedioates
Authors: Viktorov N. B. , Dogadina A. V. , Stepakov A. V.
Published: April 2024

Reaction of 2-(acylamino)malonic acids esters with chloroethynylphosphonates yielded 2-substituted (5 E / Z )-5-(dialkoxyphosphoryl)methylidene-2-oxazoline-4,4-dicarboxylates, isomers of which could be separated. Following reaction of hydrolysis and decarboxylation affords 2-substituted 5-(dialkoxyphosphoryl)methyl-1,3-oxazole-4-carboxylates.
Optimal Boundary Control of a Distributed Heterogeneous Vibrating System with Given States at Intermediate Times
Authors: Barseghyan V. R.
Published: April 2024

The problem of optimal boundary control of a distributed heterogeneous vibrating system governed by the one-dimensional wave equation with piecewise constant characteristics is considered. It is assumed that each homogeneous segment is traveled by a wave over the same time. The control is performed via displacements of both ends. The cost functional is specified on the whole time interval. A constructive approach is proposed for finding an optimal control function that transfers the vibrations from an initial state through multipoint intermediate states to a terminal state over a given time interval. The results are illustrated by an example.
Quantum Markovian Dynamics after the Bath Correlation Time
Authors: Teretenkov A. E.
Published: April 2024

For a model of a multilevel system interacting with several baths at zero temperature, it is shown that its dynamics becomes Markovian after the bath correlation time. We take into account not only the contribution of the bath spectral density, which leads to a continuous correlation function, but also the ohmic contribution to the spectral density, which leads to a renormalization of both equations and initial conditions. An explicit Gorini–Kossakowski–Sudarshan–Lindblad equation describing the dynamics of the system after the bath correlation time is derived, and the form of initial conditions for this equation is obtained. They do not coincide with the exact initial conditions due to the renormalization associated with the ohmic contribution and due to the short initial non-Markovian time interval preceding the bath correlation time.
Functional Summation of Series
Authors: Varin V. P.
Published: April 2024

We consider a summation technique which reduces summation of a series to the solution of some linear functional equations. Partial sums of a series satisfy an obvious difference equation. This equation is transformed to the functional equation on the interval [0,1] for the continuous argument. Then this equation is either solved explicitly (to within an arbitrary constant) or an asymptotic expansion of the solution is computed at the origin. The sum of the original series is determined uniquely as a constant needed for the matching of the asymptotic series with partial sums of the original series. The notion of a limit is not involved in this computational technique, which allows summation of divergent series as well.
On Approximate Solution of One Class of Singular Integro-Differential Equations
Authors: Gabbasov N. S.
Published: April 2024

A linear integro-differential equation with a singular differential operator in the principal part is studied. For its approximate solution in the space of generalized functions, special generalized versions of the methods of moments and subdomains are proposed and substantiated. Optimality of the methods in order of accuracy is established.
A CLASS OF SINGULARLY PERTURBED EQUATIONS WITH DISCONTINUOUS RIGHT-HAND SIDE IN THE CRITICAL CASE
Authors: Liu Shitao , Ni Mingkang
Published: April 2024

In this paper, we investigate a class of singularly perturbed equations with discontinuous right-hand side in the critical case. An asymptotic expansion of a contrast structure solution for the system is contrasted. Moreover, results for existence of the solution and estimations of remainders are presented. Finally, an example is provided to verify the theoretical results.
Asymptotics of the Solution to the Cauchy Problem for a Singularly Perturbed Operator Differential Transport Equation with Weak Diffusion
Authors: Zaborskii A. V. , Nesterov A. V.
Published: April 2024

Formal asymptotic expansions of the solution to the Cauchy problem for a singularly perturbed operator differential transport equation with weak diffusion and small nonlinearity are constructed in the critical case. Under certain conditions imposed on the data of the problem, an asymptotic expansion of the solution is constructed in the form of series in powers of a small parameter with coefficients depending on stretched variables. Problems for determining all terms of the asymptotic expansion are obtained. It is shown that the leading term of the solution asymptotics is determined by solving Cauchy problems for a parabolic Burgers-type equation and, under certain conditions, for a Korteweg–de Vries–Burgers type equation. The remainder terms are estimated with respect to the residual.
Economic Growth Models with Heterogeneous Discounting
Authors: Borissov K. Yu. , Pakhnin M. A.
Published: April 2024

A survey of theoretical economic growth models with agents having different subjective discount factors is proposed. The structure of equilibrium paths in such models, their dynamics and convergence to stationary equilibria, and the relationship with Pareto optimal paths are described. Models with socially determined discount factors in which time preferences are formed endogenously are discussed, and the basic difficulties associated with social choice in the case of heterogeneous discount factors are examined. The models presented in the paper shed light on internal mechanisms of a market economy that lead to the division of society into the rich and the poor.
Inhomogeneous Problem for Quasi-Stationary Equations of Complex Heat Transfer with Reflection and Refraction Conditions
Authors: Chebotarev A. Yu.
Published: April 2024

The paper considers an inhomogeneous initial-boundary value problem for a nonlinear parabolic-elliptic system simulating radiative heat transfer with Fresnel matching conditions on the surfaces of discontinuity of the refractive index. Nonlocal-in-time unique solvability of the problem is proved.
A Model of Financial Pyramid with Quasi-Rational Participants
Authors: Kukushkin N. S.
Published: April 2024

A model of a financial pyramid is proposed in which each participant makes a decision about entering and exiting the pyramid based on the maximin principle using his (or her) ideas about the characteristics of other participants. If the pyramid organizers are able to carry out the whole process quickly enough (so that the payoffs to agents who participated in the pyramid and left it in time do not matter too much), then exactly those agents who overestimated the share of losers in the total mass of agents will lose.
Influence of the Shock Wave Intensity on Instability Development at Rough Interfaces of a Three-Layer Gas System
Authors: Zmushko V. V. , Razin A. N. , Sinel’nikova A. A. , Shcherbakov A. N.
Published: April 2024

The influence exerted by the intensity of a shock wave transmitted through rough interfaces on instability development in a three-layer gas system at Mach numbers M = 1.3 and M = 3 is studied. The three-layer system is obtained by placing two thin films (interfaces) across a shock tube. A heavy gas (sulfur hexafluoride) occupies the space between the interfaces (the central layer of the system), while the spaces to the left and right of the central layer are filled with air. The initial roughness of the interfaces is specified as a two-mode sinusoidal perturbation. The computations are carried out using the MIMOZA code based on implicit large eddy simulation (ILES) with the Euler equations integrated on a mesh with square cells. The numerical results are compared with each other and, at M = 1.3, with experimental data.
Results of Symmetry Classification of 2-Field Third-Order Evolutionary Systems with a Constant Separant
Authors: Balakhnev M. Yu.
Published: April 2024

The paper presents the results of the symmetry classification of nonlinear integrable 2-field evolutionary systems of the third order with a constant separant.
Aggregation Kinetics in Sedimentation: Effect of Diffusion of Particles
Authors: Brilliantov N. V. , Zagidullin R. R. , Matveev S. A. , Smirnov A. P.
Published: April 2024

The aggregation kinetics of settling particles is studied theoretically and numerically using the advection–diffusion equation. Agglomeration caused by these mechanisms (diffusion and advection) is important for both small particles (e.g., primary ash or soot particles in the atmosphere) and large particles of identical or close size, where the spatial inhomogeneity is less pronounced. Analytical results can be obtained for small and large Péclet numbers, which determine the relative importance of diffusion and advection. For small numbers (spatial inhomogeneity is mainly due to diffusion), an expression for the aggregation rate is obtained using an expansion in terms of Péclet numbers. For large Péclet numbers, when advection is the main source of spatial inhomogeneity, the aggregation rate is derived from ballistic coefficients. Combining these results yields a rational approximation for the whole range of Péclet numbers. The aggregation rates are also estimated by numerically solving the advection–diffusion equation. The numerical results agree well with the analytical theory for a wide range of Péclet numbers (extending over four orders of magnitude).
On Model Two-Dimensional Pressureless Gas Flows: Variational Description and Numerical Algorithm Based on Adhesion Dynamics
Authors: Klyushnev N. V. , Rykov Yu. G.
Published: April 2024

Weak solutions of the system of pressureless gas dynamics equations in two dimensions are studied. Theoretical issues are considered, namely, the general mathematical theory of conservation laws for the system is addressed. Emphasis is placed on an important distinctive feature of this system: the emergence of strong density singularities along manifolds of different dimensions. This property is characterized as the formation of a hierarchy of singularities. In earlier application-oriented works (e.g., by A.N. Krayko, et al., including more complicated cases of 3D two-phase flows), this property was studied at the physical level of rigor. In this paper, the formation of a hierarchy of singularities is examined mathematically, since, for example, the existence of a solution with a strong singularity at a point (in the 2D case) is rather difficult to prove rigorously. Accordingly, a special numerical algorithm is used to develop mathematical hypotheses concerning solution behavior. Approaches to the construction of a variational principle for weak solutions are considered theoretically. A numerical algorithm based on approximate adhesion dynamics in the multidimensional case is implemented. The algorithm is tested on several examples (2D Riemann problem) in terms of internal convergence and is compared with mathematical results, including those obtained by other authors.
Forward and Inverse Source Reconstruction Problems for the Equations of Vibrations of a Rectangular Plate
Authors: Sabitov K. B.
Published: April 2024

For the equation of vibrations of a rectangular plate, the initial-boundary value and inverse problems of finding the right-hand side (the source of vibrations) are studied. Solutions of the problems are constructed explicitly as sums of series, and the corresponding uniqueness and existence theorems are proved. When substantiating the existence of a solution to the inverse problem of determining the factor on the right-hand side, which depends on spatial coordinates, the problem of small denominators of two natural variables arises, for which estimates of the separation from zero with the corresponding asymptotics are established. These estimates made it possible to prove the existence theorem for this problem in the class of regular solutions by imposing certain smoothness conditions on the given boundary functions.
Determining the Height of Energy Barriers of the Cyclohexene Molecule Using Stochastic Approximation
Authors: Teplukhin A. V.
Published: April 2024

The Monte Carlo method (stochastic approximation) is used for calculating the relative values of density of the states of the cyclohexene molecule in the space of Cremer–Pople coordinates. Using this data, the heights of the energy barriers separating the molecule stereoisomers are estimated.
On Ranks of Matrices over Noncommutative Domains
Authors: Abramov S. A. , Petkovšek M. , Ryabenko A. A.
Published: April 2024

We consider matrices with entries in some domain, i.e., in a ring, not necessarily commutative, not containing non-trivial zero divisors. The concepts of the row rank and the column rank are discussed. (Coefficients of linear dependencies belong to the domain ; left coefficients are used for rows, right coefficients for columns.) Assuming that the domain satisfies the Ore conditions, i.e., the existence of non-zero left and right common multiples for arbitrary non-zero elements, it is proven that these row and column ranks are equal, which allows us to speak about the rank of a matrix without specifying which rank (row or column) is meant. In fact, the existence of non-zero left and right common multiples for arbitrary non-zero elements of is a necessary and sufficient condition for the equality of the row and column ranks of an arbitrary matrix over. An algorithm for calculating the rank of a given matrix is proposed. Our Maple implementation of this algorithm covers the domains of differential and (-)difference operators, both ordinary and with partial derivatives and differences.
Reconstruction of Two Functions in the Model of Vibrations of a String One End of Which Is Placed in a Moving Medium
Authors: Andreyanova O. A. , Shcheglov A. Yu.
Published: April 2024

The paper considers an inverse problem of determining the coefficients in the model of small transverse vibrations of a homogeneous finite string one end of which is placed in a moving medium and the other is free. The vibrations are simulated by a hyperbolic equation on an interval. One boundary condition has a nonclassical form. Additional data for solving the inverse problem are the values of the solution of the forward problem with a known fixed value of the spatial argument. In the inverse problem, it is required to determine the function in the nonclassical boundary condition and a functional factor on the right-hand side of the equation. Uniqueness and existence theorems for the inverse problem are proved. For the forward problem, conditions for unique solvability are established in a form that simplifies the analysis of the inverse problem. For the numerical solution of the inverse problem, an algorithm is proposed for the stage-by-stage separate reconstruction of the sought-for functions using the method of successive approximations for integral equations.
Optimization of the Reachable Set of a Linear System with Respect to Another Set
Authors: Balashov M. V. , Kamalov R. A.
Published: April 2024

Given a linear controlled autonomous system, we consider the problem of including a convex compact set in the reachable set of the system in the minimum time and the problem of determining the maximum time when the reachable set can be included in a convex compact set. Additionally, the initial point and the time at which the extreme time is achieved in each problem are determined. Each problem is discretized on a grid of unit vectors and is then reduced to a linear programming problem to find an approximate solution of the original problem. Additionally, error estimates for the solution are found. The problems are united by a common ideology going back to the problem of finding the Chebyshev center.
The Problem of Complex Heat Transfer with Cauchy-Type Conditions on a Part of the Boundary
Authors: Mesenev P. R. , Chebotarev A. Yu.
Published: April 2024

The paper considers a boundary value problem for stationary equations of complex heat transfer with an undetermined boundary condition for the radiation intensity on a part of the boundary and an overdetermined condition on another part of the boundary. An optimization method for solving this problem is proposed, and an analysis of the corresponding problem of boundary optimal control is presented. It is shown that the sequence of solutions of extremum problems converges to the solution of a problem with Cauchy-type conditions. The efficiency of the algorithm is illustrated by numerical examples.
MULTIWAVE INTERACTION SOLUTIONS FOR A NEW EXTENDED EQUATION IN (4 + 1)-DIMENSION
Authors: Yang Yan , Liu Y.
Published: April 2024

In this paper, we present a new (4+1)-dimensional nonlinear evolution equation. We first verify its Painlevé integrability by the WTC–Kruskal method, then multiwave interaction solutions for this new equation are investigated by different approaches. It can be seen that this equation has very rich interaction wave solutions.
Stability Analysis of Nonclassical Difference Schemes for Nonlinear Volterra Integral Equations of the Second Kind
Authors: Botoroeva M. N. , Bulatov M. V.
Published: April 2024

A family of first- and second-order accurate noniterative numerical methods is constructed for solving systems of nonlinear Volterra integral equations of the second kind. The methods are examined for A-, L-, and P-stability. The conclusions are illustrated by numerical results obtained for test equations with stiff and oscillating components
A Modified Secant Method for Entropic Lattice Boltzmann Equations
Authors: Ilyin O. V.
Published: April 2024

Stability of lattice Boltzmann equations is governed by a parameter that is responsible for the relaxation time of the nonequilibrium system which, in turn, affects the viscosity of the flow under examination. In the entropic approach, the relaxation time is evaluated from the entropy balance equation in such a way that the entropy does not decrease at each time and spatial point. In this paper, a technique for solving the entropy balance equation using a modified secant method is proposed. It is shown that this approach provides high accuracy. As an application of the proposed method, numerical solutions of the two-dimensional double shear problem are considered. The simulation results are compared with the results obtained by other entropic methods.
MIXED VIRTUAL ELEMENT APPROXIMATION OF A FOURTH ORDER OPTIMAL CONTROL PROBLEM
Authors: Yang Minghui , Shen Yue , Zhou Zhaojie
Published: April 2024

In this article, we study mixed virtual element methods for a distributed optimal control problem governed by a fourth order partial differential equation. By introducing an auxiliary variable, the fourth order equation can be transformed into systems of second order equations. A mixed virtual element discrete scheme for the optimal control problem is established. Moreover, a priori error estimates for auxiliary, state, adjoint state and control variable in H2 and L2 norms are derived. Finally, the theoretical finding is verified by numerical experiments.
Sufficient Solvability Conditions for the Problem of Pursuit under an Impulse Action
Authors: Abdualimova G M. , Mamadaliev N. A. , Tukhtasinov M.
Published: April 2024

The article considers a linear differential pursuit game under the condition that an integral constraint is imposed on the evader’s control and the pursuer uses an impulse control. These impulse actions on the object are made at predetermined time points, and the corresponding control is represented using the Dirac delta function. The article studies linear conflicts described by a system of ordinary differential equations whose trajectories have jumps at certain times. The terminal set is represented by a cylinder in an n-dimensional Euclidean space. The problem is solved using the resolving function method. The fact that the lower bound is reached is proved using the theory of support functions. As a result, the quasi-strategy is replaced by an almost stroboscopic strategy and a method for building this strategy is presented. An example of a nonlinear right-hand side is given.