Volume 88, Nº 8 (2018)
- Ano: 2018
- Artigos: 34
- URL: https://journals.rcsi.science/1070-3632/issue/view/13700
Article
X-Ray Spectral and Theoretical Study of Electronic Structure and Features of Interatomic Interactions in Phenylaminosilanes HnSi(NHC6H5)4–n (n = 3–0)
Resumo
Electronic structure and features of interatomic interactions in a series of phenylaminosilanes HnSi(NHC6H5)4–n (n = 3–0) have been studied by means of computer-based simulation (electron density functional method) in comparison with experimental (X-ray and photoelectron spectroscopy). Distributions of density of electronic states of the valence band, correlation diagrams of the energy levels, and visualizations of the isosurfaces of molecular orbitals have been obtained. Major types of interatomic electronic interactions providing the Si–NH–C6H5 bonds in tetraphenylaminosilane have been elucidated.
Organic Catalysis: Synthesis of Propylene Carbonate by the Carboxylation of Propylene Oxide in the Presence of Phenols and Fluorinated Alcohols
Resumo
Phenol, polyphenols, as well as fluorinated alcohols actively catalyze the carboxylation of propylene oxide to form propylene carbonate in mild conditions (60°С, 7 at). The highest catalytic activity is characteristic of polyhydric phenols having neighbouring OH groups and alcohols with an enhanced acidity of OH protons. These catalysts in combination with tetrabutyammonium iodide exhibit activity at low concentrations (0.25 mol %) and ensure almost quantitative yields of propylene carbonate. The activity of the catalysts much increases with increasing ammonium salt amount (TOF up to 260), as well as temperature and initial СО2 pressure (TON up to 370).
Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural–Н2О2–Solvent
Resumo
General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer–Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and β-formylacrylic acid formed in a homogeneous reaction system furfural–Н2О2–solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with Н2О2 in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of β-formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.
Elementary Stages of Photochemical Reactions of Substituted 2,6-Diphenyl-para-benzoquinones with Thiols
Resumo
Using the effects of chemical polarization of nuclei, mechanism and elementary stages of photochemical reduction of 2,6-diphenyl-1,4-benzoquinone with thiols have been elucidated. The studied quinone is reduced with ethanethiol in two stages (transfer of electron followed by proton transfer). The final photolysis product is a derivative of dibenzofuran.
Reaction of 3,4,6-Triisopropyl-о-benzoquinone with 3,4,6-Triisopropylcatechol
Resumo
Formation of protonated 3,4,6-triisopropylsemiquinone radicals in solution of a mixture of 3,4,6- triisopropyl-о-benzoquinone and 3,4,6-triisopropylcatechol was shown using ESR spectroscopy. Heating the mixture to 110°С leads to the formation of the condensation products, additional amount of 3,4,6-triisopropylcatechol, and evolution of propylene. Mathematical simulation of the kinetics of the reaction was performed.
Synthesis of 2-Aminocarboxylic Acids on the Basis of Metalated Lithium Acylates
Resumo
2-Aminocarboxylic acids have been synthesized through the reaction of lithium acylate α-carbanions with alkyl nitrites to form α-hydroxyiminoacylates, followed by reduction of the latter with tin chloride. The reactions of lithium acylate α-carbanions, generated by the metalation of carboxylic acids with lithium diisopropylamide at 35–40°С in THF under argon, with alkyl nitrites at 45–50°С give 2-hydroxyiminocarboxylic acids in 55–97% yields. The reduction of 2-hydroxyiminocarboxylic acids with tin(II) chloride in conc. HCl at 20–25°С leads to 2-aminocarboxylic acid hydrochlorides in 52–94% yields.
Synthesis of Isomeric Dinitro and Diamino Derivatives of Polycyclic Crown Ethers: Dibenzo-18-crown-6 and Dibenzo-24-crown-8
Resumo
Specific features of the synthesis of polycyclic crown ethers dibenzo-18-crown-6 and dibenzo-24-crown-8 and their dinitro and diamino derivatives have been studied. A mixture of isomers of dibenzocrown ether derivatives was obtained and separated. The spectral and thermal characteristics of the synthesized compounds and the kinetics of synthesis of dibenzo-24-crown-8 by the two-component condensation of pyrocatechol with 1-chloro-2-[2-(2-chloroethoxy)ethoxy]ethane in an alcoholic medium in the presence of a KOH template agent were studied.
Condensation of 1,2,4-Butanetriol with Carbonyl Compounds and Reactions of Hydroxyalkyl-1,3-dioxacyclanes
Resumo
A mixture of isomers of 2-(1,3-dioxolan-4-yl)ethanol and 1,3-dioxan-4-ylmethanol was prepared by reaction of 1,2,4-butanetriol with paraformaldehyde. This mixture was subjected to O-alkylation, O-acylation, condensation with phenyl isocyanate, and substitution of OH groups for Cl. The relative activity of acetone derivatives of glycerol and 1,2,4-butanetriol in reactions with allyl chloride and benzyl chloride was estimated.
Synthesis, Physicochemical Properties, and Thermo-Oxidative Stability of Diesters of 5,7-Dimethyl-3-hydroxymethyl-1-adamantanol
Resumo
Synthesis of 5,7-dimethyl-3-hydroxymethyl-1-adamantanol with limited conformational mobility and of a series of esters based thereon has been performed. The physicochemical properties and thermo-oxidative stability of synthesized diesters have been studied.
2-Benzylidene-3-methyl-4-nitro-3-thiolene-1,1-dioxide and Its Analogs in Aza-Michael Reaction
Resumo
2-Benzylidene-3-methyl-4-nitro-3-thiolene-1,1-dioxide and its analogs have been introduced in the aza-Michael reaction with hydrazine derivatives. Novel polysubstituted nitrosulfolenes have been obtained; their structures have been confirmed using 1Н NMR and IR spectroscopy as well as X-ray diffraction analysis.
Synthesis and Biological Activity of 4-Aryl-N-(5,6-R-benzo[d]thiazol-2-yl)- 2-hydroxy-4-oxobut-2-enamides
Resumo
The interaction of 5-arylfuran-2,3-diones with 5,6-R-benzo[d]thiazole-2-amines has resulted in 4-aryl-N-(5,6-R-benzo[d]thiazol-2-yl)-2-hydroxy-4-oxobut-2-enamides. The products structure has been confirmed by means of IR, NMR, and 1H NMR spectroscopy as well as mass spectrometry. Analgesic and antimicrobial activities of the prepared compounds have been studied; acute toxicity of the most active compounds has been determined. The relationship between the structure and biological activity of the obtained compounds has been elucidated. The compounds acting comparably or better than the reference drugs have been found.
Synthesis of Cyclopenta[4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidine Derivatives. Dimroth Rearrangement of Triazolopyrimidines
Resumo
Methods of the preparation of 9- (methylsulfanyl)cyclopenta[4',5']pyrido[3',2':4,5]thieno[3,2-d]- pyrimidines and pentacyclic triazolopyrimidines derivatives were developed. The Dimroth rearrangement of these compounds was studied.
Synthesis and Structure of Tetraphenylphosphonium Carboxylates
Resumo
Hydrates of tetraphenylphosphonium carboxylates were synthesized by the reaction of equimolar amounts of pentaphenylphosphorus with 2-methoxybenzoic, 2-nitrobenzoic, and maleic acids in benzene. The product of the pentaphenylphosphorus reaction with tetrafluorophthalic acid (mole ratio 2: 1) is bis- (tetraphenylphosphonium) tetrafluorophthalate hydrate. According to the X-ray analysis data, crystals of tetraphenylphosphonim carboxylates are formed by tetraphenylphosphonim tetrahedral cations and single- or double-charged carboxylate anions. Structural organization of the crystals is determined by C–H···O weak hydrogen bonds formed with the participation of carboxylate groups and water molecules or manifold C–H···F interactions between cations and anions.
Synthesis and Estimation of Radical Scavenging Activity of Tetra(meso-aryl)porphyrins Containing 2,6-Dimethoxyphenol Unit
Resumo
Tetra(meso-aryl)porphyrins containing 2,6-dimethoxyphenol unit distant from the macrocycle and adjacent to it have been prepared. Radical scavenging activity of the obtained compounds has been estimated in the model reaction of ethylbenzene oxidation initiated by azobisisobutyronitrile. It has been shown that the phenol hydroxy group ability to inhibit ethylbenzene oxidation depends on the environment of phenol group.
4-{[Mono/dimethyl(1,1'-biphenyl)-4-yl]oxy}phthalonitriles and Phthalocyanines Based on Them
Resumo
4-{[Mono/dimethyl(1,1'-biphenyl)-4-yl]oxy}phthalonitriles have been obtained by nucleophilic substitution of nitro group in 4-nitrophthalonitrile. The prepared phthalonitriles have been used for the synthesis of tetra-4-{[mono/dimethyl(1,1'-biphenyl)-4-yl]oxy}phthalocyanines and their complexes with copper, cobalt, and zinc. Spectral characteristics and thermal stability of the prepared compounds have been investigated.
Synthesis and Aggregation of Cationic Zinc and Magnesium Phthalocyanines Containing 4-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy Groups
Resumo
Tetracationic metal phthalocyanines were synthesized by the quaternization of the Cs-regioisomers of tetrasubstituted zinc and magnesium phthalocyanines containing 3,5-dimethylpyrazole fragments. The individuality of the synthesized compounds was confirmed by HPLC‒mass spectrometry. The aggregation of the cationic metal phthalocyanines in water and aqueous-organic media, as well as in the presence of Triton X- 100 was studied. The dependence of the dimerization constant on the polarity of mixed solvents was determined.
Synthesis and Antimicrobial Activity of a Pyridine Complex of (Acetato)[5,10,15,20-tetrakis(N-methylpyridin- 4-yl)porphinato]manganese(III) Tetratosylate
Resumo
Aiming at preparation of new biologically active donor‒acceptor complexes, a water-soluble manganese(III) complex with 5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphine tetratosylate was synthesized and its reaction with pyridine was studied by spectrophotometry using the molar ratio method. In water a 1: 1 donor‒acceptor complex with pyridine is formed. The chemical structure of the compounds was established by spectral methods. (Acetato)[5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphinato]manganese(III) tetratosylate and especially its donor‒acceptor complex with pyridine showed an antifungal activity against Candida albicans.
Quantum-Chemical Simulation of Tetra-, Penta-, and Hexacoordinated Stereoisomers of Bis-Ligand Ni(II) Complexes based on Polydentate Heterocyclic Derivatives of Azomethines
Resumo
Molecular structures and relative energies of tetra-, penta-, and hexacoordinated stereoisomers of bis-ligand Ni(II) complexes based on polydentate heterocyclic derivatives of azomethines [coordination nodes of isomers NiN2O2, NiN2O2Y, NiN2O2Y2 (Y = S, Se)] were calculated using density functional theory. Within the framework of the proposed quantum chemical model of the mechanism of formation of NiL2 complexes (taking into account the possibility of subsequent stereoisomerization) the most probable product of complex formation was found to be the isomer with pentacoordinated central metal atom and nonequivalent ligands, tridentate and bidentate.
Complex Formation of 1,5-Bis(amidomethylsulfonyl)pentane with Copper(II) and Iron(III)
Resumo
The state of the new antitubercular agent 1,5-bis(amidomethylsulfonyl)pentane in aqueous micellar solution of the nonionic surfactant Bridge 35 and its complexing properties toward copper(II) and iron(III) ions have been studied by spectrophotometry, pH potentiometry (25°C, variable ionic strength), and mathematical modeling. In the concentration range from 5.00 × 10–5 to 1.00 × 10–3 M in the presence of Bridge 35, the title compound exists in a neutral monomeric form. It forms 1: 2 mononuclear and 2: 2 binuclear complexes with copper(II) and 1: 1 and 1: 2 mononuclear and 2: 1 binuclear complexes with iron(III). The most favorable structures of 1,5-bis(amidomethylsulfonyl)pentane and its complexes have been simulated in terms of the density functional theory.
Reactivity of Silver(I) Diethyldithiocarbamate and Ion-Polymeric Complexes {[Au(S2CNEt2)2][AgCl2]}n and {[Au(S2CNEt2)2]2[AgCl2]Cl·2H2O}n: Synthesis, Supramolecular Structures, and Thermal Behavior
Resumo
New ion polymeric gold(III)–silver(I) complexes, {[Au(S2CNEt2)2][AgCl2]}n and {[Au(S2CNEt2)2]2[AgCl2]Cl·2H2O}n have been synthesized and characterized by X-ray diffraction data and IR spectra. The structure of the first complex is represented by [Au{S2CNEt2}2]+ complex cations and polymeric silver chloride anion ([AgCl2]–)n; the second complex consists of isomeric cations, linear [AgCl2]– anions, chloride ions, and water molecules. Gold cations are involved in zigzag (AuAuAu angle 99.06°) and linear polymeric chains via secondary Au···S bond pairs. Thermal decomposition of the complexes with regeneration of gold and silver has been studied by simultaneous thermal analysis (STA).
Effect of Preliminary Binding of HAuCl4 with DNA and Cetyltrimethylammonium Bromide in Aqueous Solution on Morphology of the Formed Nanoparticles
Resumo
Competitive interactions in the HAuCl4–DNA–cationic surfactant (cetyltrimethylammonium bromide) systems have been studied. Decisive role of the components binding on size and shape of gold nanoparticles obtained via reduction in these mixtures has been shown.
Specific Features of the Formation of Aqueous Nanodispersions of Interpolyelectrolyte Complexes based of Chitosan and Chitosan Succinamide
Resumo
Aqueous dispersion of particles of interpolyelectrolyte complexes based on chitosan hydrochloride and sodium salt of chitosan succinamide have been prepared and characterized. The size of the complex particles and the system stability are affected by the concentration of the polymers in the solution and the molar ratio of the components. In the studied disperse systems, steady aggregation of the particles has led to the precipitation of the insoluble complex, and the relative stability of the systems against aggregation has increased with the increase in the fraction of the lower-molecular component and concentration of the polymers in the solution.
Atomic Layer Deposition of Aluminum Nitride and Oxynitride on Silicon Using Tris(dimethylamido)aluminum, Ammonia, and Water
Resumo
Thin films of aluminum nitride and oxynitride were deposited by atomic layer deposition (ALD) in the temperature range from 170 to 290°C (optimal deposition temperature 200–230°C). Tris(dimethylamido) aluminum and ammonia were used as precursors for the atomic layer deposition of aluminum nitride (AlN). The average AlN film thickness per ALD cycle (deposition rate) at 200°C was ~0.8 Å. Films were deposited on a silicon <100> substracte with a native oxide layer. The N/Al atomic concentration ratio in the obtained films was ~1.3. Aluminum oxynitride films obtained by periodical dose of water vapor in the course of atomic layer deposition of AlN at 200°C. The composition of the deposited oxynitride films was Al0.5O0.43N0.07.
Complexes of Imino-1,2,4-triazole Derivative with Transition Metals: Synthesis and Antibacterial Study
Resumo
Biologically important triazole derived Schiff base ligand 2-[(1Z)-N-(1H-1,2,4-triazol-3-yl)- etanimidoyl]phenol (SR) is synthesized by condensation of 3-amino-1,2,4-triazole with 2-hydroxyacetophenone. The ligand forms the corresponding complexes upon reaction with salts of VO(IV), Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) in 2: 1 ratio. The Schiff base ligand coordinates to the metal atoms via nitrogen atoms of azomethine and triazole, and oxygen of acetophenone. Structures of the complexes are supported by physical and spectral data. Antibacterial activity of the synthesized triazole ligand and transition metal complexes is tested against several bacterial strains: Escherichia coli, Salmonella typhi, Bacillus subtilis, Klebsiella pneumonia, and Staphylococcus aureus. The complexes demonstrate substantial antibacterial activity.
Synthesis and In Vitro Antibacterial Evaluation of Some Novel Annulated Quinazolinone Derivatives
Resumo
A series of novel substituted quinazoline derivatives are synthesized. Antibacterial tests demonstrate their high activity against Gram-positive and Gram-negative bacteria. 3-[4-(2-Bromoacetyl)-phenyl]-2-phenylquinazolin-4(3H)-one 2 and 3-oxo-3-{[4-(4-oxo-2-phenylquinazolin-3(4H)-yl]phenyl}propanenitrile 3 are used as intermediates in the synthesis of functionalized heterocyclic derivatives such as 3-[4-(2-amino-thiazol-5-yl)phenyl]-2-phenylquinazolin-4(3H)-one 4, Schiff base 5, 3-{5-(4-[4-oxo-2-phenylquinazolin-3(4H)-yl]phenyl)thiazol-2-yl}-2-phenylthiazolidin-4-one 6, and N-phenyl acetohydrazonoyl derivatives 7a, 7b. The latter react with ethyl cyanoacetate with formation of 9a, 9b. Chalcone 10 is the key intermediate in the synthesis of N-acetylpyrazole derivative 11 and 1-thiocaramoyl pyrazole derivative 12. Treatment of 12 with chloroacetyl chloride and compound 2 leads to formation of compounds 13 and 14, respectively. Treatment of compound 3 with phenyl isothiocyanate affords the corresponding quinazolin-3(4H)-yl acrylonitrile derivative 15, which reacts with phenyl hydrazine to give the corresponding product 16. The synthesized compounds are characterized by IR, MS and 1H NMR spectra.
DNA Binding Studies and Evaluation of Electrochemical Parameters of New Tri-and Di-Organotin(IV) Complexes of 4-(1H-Indol-3-yl)butanoic Acid
Resumo
New triorganotin(IV) [R3SnL where R = Me (1), Bu (2), Ph (3)] and diorganotin(IV) [R2SnL2, where R = Me (4), Bu (5), Ph (6)] derivatives of 4-(1H-indol-3-yl)butanoic acid (HL) were prepared and characterized by FT-IR and 1H and 13C NMR spectroscopy. Interaction between DNA and selected compounds was studied by UV-Vis spectroscopy and viscometry. The binding constants calculated on the basis of the accumulated data reveal the following order of binding strength: compound 2 > 1 > 5 > 4. Electrochemical parameters such as diffusion coefficient and charge transfer coefficient are evaluated with cyclic voltammetry. The results demonstrate that diorganotin(IV) complexes are characterized by higher diffusion coefficient than triorganotin(IV) analogues. In case of triorganotin(IV) complexes, the lower coordination number allows a solvent to interact with Sn(IV) center and hence decreases the rate of diffusion.
Synthesis of New Tetrazole Derivatives and Their Biological Evaluation
Resumo
An operationally simple and efficient method of synthesis of novel 1,5-disubstituted tetrazoles with high yields from easily accessible 2-(2-benzamido-3-arylacrylamido)acetate under mild conditions is developed. Anticancer and anti-microbial tests of the new tetrazole derivatives have been carried out.
Synthesis and Anti-HBV Activity of Novel Substituted Pyrimidine Glycosides and Their Acyclic Analogues
Resumo
New aryl substituted uracil and thiouracil glycosides are synthesized by glycosylation at N1 in the pyrimidine nucleus using glycopyranosyl halides in basic medium. In addition C-linked hydrazinyl acyclic sugar derivatives exhibiting different sugar moieties, attached at C6, are also prepared. Antiviral activity of the newly synthesized compounds is studied against Hepatitis B virus (HBV). The antiviral tests data indicated high activity of compounds 6b, 6c and 12a–12c with mild cytotoxic effects. The influence of glycosyl moieties attached to the substituted pyrimidine system in addition to the substitution at the aryl fragment on activity is discussed.
Letters to the Editor
Thermal Decomposition of Triethylindium
Resumo
Thermal decomposition of triethylindium has been studied under static conditions. The temperature dependence of the thermal decomposition rate is described by the equation log k = 8.1 ± 0.4–(156 600 ± 5000)/2.3 RT. The composition of gaseous thermolysis products has been determined. The obtained data suggest radical chain mechanism of the process.
Synthesis and Antimicrobial Activity of Some New Isatins Containing Benzotriazole Fragment
Resumo
New isatin derivatives bearing benzotriazole substituent at the endocyclic nitrogen atom were synthesized. The resulting compounds and trimethylammonium acylhydrazones on their basis show a pronounced antimicrobial activity.
Synthesis of 2,3-Dihydro-1-benzofuran-2-ylmethyltellanes
Resumo
Tellurium tetrabromide readily reacted with 2-allylphenol at room temperature in acetonitrile to give previously unknown tribromo(2,3-dihydro-1-benzofuran-2-ylmethyl)-λ4-tellane in quantitative yield. The reduction of the product afforded bis(2,3-dihydro-1-benzofuran-2-ylmethyl)ditellane and benzyl(2,3-dihydro-1-benzofuran-2-ylmethyl)tellane.
Reaction of Benzylidene Chlorides with О-Methyl Diethylphosphinothioate
Resumo
О-Methyl diethylphosphinothioate reacts with benzylidene chlorides to form arenecarbthioaldehyde trimers and diethylphosphinoyl chloride. This result suggests that the reaction involves initial attack of the thione sulfur atom of the phosphinothioyl group on the methine carbon atom of the gem-dichloride.