Search

To find novel classes of potential fuel additives of multivalent activity, particularly antioxidants, a series of recently synthesized ethyl-6-amino-5-cyan-methyl-4-aryl-4H-pyran-3-carboxylates have been investigated using model oxidative reactions. The compounds studied appear to be prospective inhibitors of hydrocarbons oxidation. Some of them are antioxidants of combined action, breaking the chains of the oxidative reactions with cumene peroxide radicals and catalytically decomposing cumene hydroperoxide.

Functionalized graphene nanoplatelets (FGNPs) were synthesized through oxidative chlorophosphorylation (OxCh) reaction of graphite and subsequent hydrolysis of obtained chlorophosphonated graphite. Then FGNPs were used as a nanoscale filler to fabricate FGNPs/modified polybutadiene (MPB) hybrid composite (FGNPs/MPB). Fourier-transform infrared spectroscopy found that FGNPs have phosphonate functional groups and FGNPs/MPB has phosphonate and phosphate functional groups. X-ray diffraction showed that the thickness of FGNPs is 13.53 nm and the number of their layers is equal to 40, which are less than graphite’s thickness (37.08) and layers (111). FGNPs show high conductivity and dielectric permittivity than graphite, while FGNPs/MPB has improved electric properties than MPB without filler. Thermal properties of FGNPs/MPB also improve due to the fact that FGNPs achieve a high degree of dispersion with less agglomeration. As observed in the scanning electron microscope images, FGNPs/MPB displays a two-phase morphology with an MPB continuous phase and a dispersed FGNPs phase.

The sorption of Cu+2, Ni+2, Co+2, and Zn+2 ions onto the phosphorus-containing sorbent were studied as a function of the contact time, temperature, and concentration of the initial metal ions. The equilibrium studies are presented by the Langmuir, Freundlich, and Temkin isotherm models. The sorption data are well described by the Langmuir isotherm model, and they also can be simulated by the Freundlich isotherm model. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were applied to test the experimental data of the kinetic studies. The pseudo-second-order kinetic model provided the best correlation of the experimental data compared to the other kinetic models. The sorption capacity of the metal ions increased with temperature increasing. The positive value of enthalpy (ΔH°) and the negative value of Gibbs free energy (ΔG°) indicated that the sorption process was endothermic and spontaneous.

It was found that the coagulation of the Fe nanoparticles takes place when they are introduced into the polymer matrix. The increase in particle size depends on their concentration in the polymer matrix, the type and properties of polymer (polar, non-polar, viscosity, etc.), reaction mode, etc. Fe particles, coagulate when they are introduced into the polymer matrix, the oxidation of their surface layer not occur, and the magnetic size does not change, hence, does not change the magnetic characteristics. The magnetic hysteresis parameters depend on the size and concentration of the Fe particles. At the same time, have been shown that at low fields the theoretical and experimental dependence of M(H) correlate to each other very well. The hysteresis has been observed at the polarization of the nanoparticles. The increasing of nanoparticles size led to difference in theoretical and experimental values, that in the theory can be explained by acceptance of nanocluster as single domain particle and their interphase interactions are not taken into account.

The purpose of this study is to investigate the electret properties and charge states of the nanocomposites based on the polyvinylidenefluoride and titanium dioxide nanoparticles. It has been found that, large amount of charges are accumulated in the interface as a result of migration polarization and these charges create rather large internal local field in which the polarization of titanium-dioxide nanoparticles occurs. Calculated, the amount of the charges accumulated in the interfacial layer of nanocomposites, the intensity of the field created by them and the value of charge activation energy of PVDF/TiO2 nanocomposites after polarization from thermally stimulated depolarization (TSD) curves. As well as the thickness of the interphase layer of PVDF/TiO2 nanocomposites was calculated and it has been revealed that, as titanium dioxide content increases in the polymeric matrix, the thickness of the interphase layer increases and reaches at its highest value at 5% volume content of TiO2 nanoparticles, after this it commences to decrease.

Nanomaterials include dispersing materials containing structural elements (grains, crystallites, blocks, clusters, etc.), due to their nano dimensions acquire qualitatively new functional and operational characteristics, offering several biomedical and technical advances over their bulk analogues. Taking into the consideration the fact that the impact of nanoparticles (NPs) to a living organism through the food chain is extremely important and have not been studied in detail yet, in this review we aimed to show the effect of different NPs towards terrestrial food chain, aquatic ecosystem, microorganisms and etc. Understanding and managing the potential risks associated with the use of nanoscale objects serves as a guide for developing new methods, tools, and concepts in order to determine how new engineering nanoparticles will interact with living organisms in the food chain and environmental systems. It is assumed that these methods will fundamentally differ and challenge the existing research and testing methodologies.

According to an X-ray diffraction study, pyridine-2-selenenyl chloride (1) characterized by unusually high stability both in solutions and in the solid state adopts a dimeric structure formed by two secondary intermolecular Se···N interactions. However, it slowly transforms into zwitterionic T-shaped pyridinium-2-selenenyl dichloride (2) in a dichloromethane solution. Conformational features, electronic structures, and reactivities of 1 and 2 are discussed on the basis of experimental and theoretical (quantum chemical calculations) data.

In this work we report of functionalization of magnetite nanoparticles by hydroxyl containing diazacrown ether—macroheterocycle (MC) that is able to mimic the properties of natural siderophores. The structure of synthesized crown ether was investigated by NMR, mass-, FTIR spectroscopy methods. The morphology of prepared MC@Fe3O4 nano-ensembles was analysed by scanning electron microscopy SEM, X-ray diffraction XRD analysis methods. The quantitative analysis of nanostructures was determined by atom absorbance spectroscopy as well as on the basis of Lambert–Beer law by UV spectroscopy method. It was found that the synthesized compounds were effective against gram-negative microorganisms Escherichia coli, Klebsiella spp. and gram-positive Staphylococcus aureus, having multi drug resistance properties.

Interaction of 1-phenylbutane-1,3-dione and chalcones in the presence of a base gives, in one step, good to high yields cyclic and unusual acyclic insertion products in ratios which depend on substrate, catalyst, and reaction conditions. All the synthesized compounds are characterized using IR, 1H and 13C NMR spectroscopies, ESI–MS, and single-crystal X-ray diffraction (for one compound) analysis.

Bis(4,6-dimethylpyrimidin-2-yl) diselenide, a new representative of dihetaryl diselenides, was obtained by successively treating selenourea with hydrochloric acid, acetylacetone, potassium hydroxide, and the system iodine—potassium iodide. The unusual planar trans-conformation of this compound (X-ray diffraction data) is stabilized by intramolecular attractive nonvalent Se…N interactions (Se…N, 2.926(1) A) and stacking of the π-systems of the aromatic heterocycles (the centers of the pyrimidine rings are spaced apart at 3.365(2) A). The energy parameters of the factors that make the molecular structure flattened were estimated by quantum chemical DFT calculations.

Reaction of binucleophiles with 1,4- and 1,3-bis(2-chloro-2-cyanovinyl)benzenes, synthesized using a catalytic olefination of terephthalic and isophthalic aldehydes, gave high yields of aminopyrazoles, 3-amino-5-arylthiophene-2-carboxylic acid esters, and 2,4-diamino-6-arylpyrimidines.

A reaction of 2-chloro-4,6-dimethylpyrimidine with sodium ditelluride in DMF afforded bis(4,6-dimethylpyrimidin-2-yl) ditelluride, a new representative of dihetaryl ditellurides. An X-ray diffraction study revealed an unusual planar trans-conformation of this compound, which is stabilized by both intramolecular attractive non-valent Te...N interactions (3.082(2) A) and π-stacking of the aromatic heterocycles (the centers of the pyrimidine rings are disposed at 3.421(3) ). The energy parameters of the factors that make the molecular structure flattened were estimated by quantum chemical DFT calculations.

The interaction of norbornene with the di(2-pyridyl) ditelluride–antimony pentachloride system in methylene chloride proceeds with the formation of exo-9-telluro-3-azoniatetracyclo-[9.2.1.02.10.03,8]tetradeca-3(8),4,6-triene chloroantimonates(III), which are the products of polar cycloaddition of tellurium-containing electrophiles at the multiple bond. The structure of the heterocyclization products was established by X-ray structural analysis.

Sulfenylating reagents have been obtained by the action of sulfuryl chloride or antimony pentachloride on di(2-pyridyl) disulfide. Their interaction with alkenes proceeds as addition-cyclization with ring closure by the nitrogen atom of the pyridine fragment of the sulfur-containing electrophile with the formation of 2,3-dihydro[1,3]thiazolo[3,2-a]pyridinium derivatives.

Cycloalkenes react with di(2-pyridyl) diselenide in the presence of antimony pentachloride with the formation of products of the selenenylating electrophile cycloaddition at the multiple bond. The final products of heterocyclization, chloroantimonates(III) of 2,3-dihydro[1,3]selenazolo[3,2-a]pyridinium derivatives were isolated.

The thermodynamics of dissociation of 3-(2-hydroxyphenylhydrazo)pentane-2,4-dione (H 2 L 1 ), 5,5-dimethyl-2-(2-hydroxyphenylhydrazo)cyclohexane-1,3-dione (H 2 L 2 ), 5,5-dimethyl-2-(2-hydroxy-4-nitrophenylhydrazo)cyclohexane-1,3-dione (H 2 L 3 ), 1-ethoxy-2-(2-hydroxyphenylhydrazo)butane-1,3-dione (H 2 L 4 ) and 1-ethoxy-2-(2-hydroxy-4-nitrophenylhydrazo)butane-1,3-dione (H 2 L 5 ) and of their complexation with copper(II) was studied in aqueous–ethanol solutions by potentiometry and UV–vis spectrophotometry. It was found that the thermodynamic parameters of the proton dissociation in H2L1–5 and of their complexation with copper(II) depend on the substituents in the aromatic and β-diketone fragments of the molecules. Thus, the acidic properties of H2L increase from H2L1 to H2L5, reflecting the electron-acceptor character of the substituents, whereas all of the thermodynamic functions tend to decrease with increasing electron-withdrawing capacity of the substituents. The complexation of Cu(II) with H2L1–5 is exothermic, which is connected with the formation of two stable chelating cycles.

The action of 2-pyridinetellurenyl chloride on alkenes results in the polar cycloaddition of the tellurium-centered electrophile at the multiple bond with the formation of 2,3-dihydro[1,3]tellurazolo[3,2-a]pyridinium derivatives.

A reaction of styrene with the di(2-pyridyl) diselenide—antimony pentachloride system furnishes 2,3-dihydro[1,3]selenazolo[3,2-a]pyridinium chloroantimonates(III) and (V), the products of cycloaddition of the selenylating agent at the multiple bond.

The formation of hydrogen bonds and molecular dynamics of alkenylphenol derivatives has been investigated in solution using nuclear magnetic resonance. The results confirm formation of an N···H, O···H-type intramolecular hydrogen bond. The spin–lattice relaxation times (T 1) and activation energy of molecular dynamics have been investigated confirming the importance of relaxation times as a very sensitive tool for studying molecular mobility.

The synthesis and anion binding properties of a neutral macrocyclic receptor bearing H-bond donor coordination sites are described. The anion binding studies by use of UV-vis and 99Tc NMR methods revealed that the receptor can coordinate perrhenate and pertechnetate in dimethylsulfoxide and chloroform solutions with the relatively high binding constants, viz. log Ka > 4. The coordination mode of the perrhenate to the receptor was determined by a single-crystal X-ray diffraction analysis.

The alkylation of some representatives of β-dicarbonyl compounds by 1,4-dibromo-2-butene and ethyl 2,3-dibromopropionate was investigated.