Nitrogen-containing polyphenylene type polymers containing pyridine rings were synthesized. The polymer-forming reaction is based on the interaction of diacetylarylene and triethylorthoformate with the formation of a pyrylium salt and subsequent treatment of the intermediate product with ammonia. The optimal ratios of the reagents for the formation of the pyridine fragment were determined. The mechanism of the main reaction is discussed. The formation of the pyridine ring and phentriyl (1,3,5-triphenylsubstituted benzene) fragments was confirmed using 1H NMR data of the example of model reactions. After heating at a temperature of 450 °C, when a more complete polycondensation process occurs, the polymers reach high values of thermal characteristics—10% weight loss in an inert atmosphere corresponds to 600 °C. The structure of the synthesized polymers was confirmed using elemental analysis, IR, XPS, and EPR spectroscopy. The conjugation length in cross-linked polyphenylene pyridines can be controlled by varying the arylene bridge groups between the phentriyl fragments, which opens up opportunities for the development of new composite materials for electrical applications.

The process of complex formation between polyethylenimine and copper cations in an aqueous solution, followed by isolation of copper nanoparticles, has been studied by means of ESR spectroscopy. It has been shown that in excess of the polymer in the solution the copper cation forms complex containing three nitrogen atoms in the coordination sphere, with distorted tetragonal geometry. The increase in copper concentration has led to the formation of the copper cation complex with water. Addition of the reducing agent NaBH 4 to the studied solutions has led to the formation of copper nanoparticles accompanied by gradual disappearance of the ESR signal of Cu(II) and the appearance of the ESR signal typical of the mononuclear copper complexes with polyethylenimine.

Методом ЭПР-спектроскопии исследован процесс компексообразования полиэтиленимина с катионами меди в водном растворе с последующим выделением наночастиц меди. Показано, что в избытке полимера в растворе катион меди образует комплекс с тремя атомами азота в координационной сфере и искаженной тетрагональной геометрией. При увеличении концентрации меди начинает формироваться комплекс катиона меди с водой. Добавление в исследованные растворы восстановителя NaBH 4 приводит к образованию частиц Cu(0), вызывает постепенное исчезновение ЭПР-сигнала Cu(II) и возникает сигнал ЭПР, характерный для моноядерных комплексов меди с полиэтиленимином.

The results of studying the interaction of iogenic surfactant micelles with oppositely charged monomers using spin probe ESR spectroscopy were generalized to assess a possibility of using surfactant micelles as a template for radical polymerization. The electrostatic interaction of monomer ions with the studied surfactants was shown to lead to a decrease in the critical micelle concentration of the surfactant. The chemical nature of the monomer exerts a significant effect on its localization on the micelles. Quaternary salts of dimethylaminoethyl methacrylate are sorbed on the micelle surface, and high concentrations of the components do not prevent the interaction and, therefore, the polymerization of these monomers on the surfactant micelles via the template mechanism is possible. The optimum monomer/surfactant ratios for the implementation of the template mechanism of polymerization were determined. The template character of the polymerization of quaternary salts of dimethylaminoethyl methacrylate under these conditions was confirmed by light scattering data. The interaction of an anionic hydrophobic monomer, sodium styrenesulfonate, with dodecyltrimethylammonium bromide leads to the incorporation of the monomer ions into the surfactant micelles, which can prevent its polymerization via the template mechanism.

Interactions between meso-tetra(4-hydroxyphenyl)porphyrin (THPP) and anionic sodium n-dodecyl sulfate (SDS) in a wide surfactant concentration range (0.5-50 mM) have been studied by UV-vis absorption and fluorescence spectroscopy, resonance light scattering (RLS), spin probe EPR spectroscopy and dynamic light scattering (DLS). J-type aggregate formation has been observed for THPP within 2-5 mM surfactant concentration range, accompanied by a significant bathochromic shift of the absorption bands, fluorescence quenching and emergence of an intense RLS signal. Porphyrin binding to the surfactant micelles above the cmc and aggregate formation below the cmc have been observed in SDS solutions containing THPP by DLS and EPR spectroscopy. SEM and optical microscopy revealed a rod-like morphology of the microparticles crystallized from an air dried suspension of THPP J-aggregates. The results obtained contribute to understanding of the mechanism of porphyrin-surfactant interactions both below and above the surfactant cmc.

The possibility of using EPR spectroscopy to monitor the current concentration of polyaniline and control the kinetics of aniline polymerization is shown. Kinetic measurements were carried out for various temperatures, initial concentrations of reagents. Autocatalysis was detected in all cases. It was shown that the order of polyaniline-catalyzed oxidation of aniline changes from the first to the second as a result of a decrease in the monomer concentration. A new approach to deriving an equation for the rate of oxidative polymerization of aniline and its derivatives is proposed taking into account the physical adsorption and chemisorption of the monomer, and the reaction mechanism is considered.

The kinetic regularities of the initial stage of chemical oxidative polymerization of methylene blue under the action of ammonium peroxodisulfate in an aqueous medium have been established by the method of potentiometry. It was shown that the methylene blue polymerization mechanism includes the stages of chain initiation and growth. It was found that the rate of the initial stage of the reaction obeys the kinetic equation of the first order with the activation energy 49 kJ · mol−1. Based on the proposed mechanism of oxidative polymerization of methylene blue and the data of MALDI, EPR, and IR spectroscopy methods, the structure of the polymethylene blue chain is proposed. It has been shown that polymethylene blue has a metallic luster, and its electrical conductivity is probably the result of conjugation over extended chain sections and the formation of charge transfer complexes. It was found that polymethylene blue is resistant to heating up to a temperature of 440 K and then enters into exothermic transformations without significant weight loss. When the temperature rises above 480 K, polymethylene blue is subject to endothermic degradation and retains 75% of its mass up to 1000 K.

Kinetics of the oxidative polymerization of aniline in toluene induced by manganese (IV) oxide deposited on the surface of silica gel was studied using ESR spectroscopy. The initial rate of an interfacial process decreases rapidly, and then polymerization proceeds as pseudo-first order reaction for the surface concentration of manganese (IV) oxide with an activation energy of 23 kJ x mol(-1). A low activation energy indicates that the overall rate is controlled by aniline diffusion into the reaction zone. The specific surfaces and the distribution of pore volume by radii of the silica gel samples before and after the deposition of manganese (IV) oxide on its surface, as well as after oxidative polymerization of aniline were determined. Oxidative polymerization of aniline causes a shift in the pore volume distribution along the radii to the region of larger pore radii, which indicates the predominant filling of pores of small diameter with polyaniline.

Using the method of inhibitors it was found that the reduction of H2O2 with natural thiols in aqueous solutions is accompanied by the formation of radicals. The reaction of the nitroxyl radical TEMPO with glutathione (GSH) and H2O2 was studied together and separately. It allowed us to determine the optimal conditions for using the spin trap method in the presence of thiols. In the case of 5,5′-dimethyl-1-pyrroline N-oxide the reaction of GSH and synthetic thiol N-acetylcysteine with hydrogen peroxide at pH < 7 leads to the formation of thiyl and hydroxyl radicals.

The properties of metallic titanium nanoparticles as dependent on the number of atoms in the shells-namely, ionization potentials, electronic affinity, melting point and energy characteristics-are studied on the basis of the shell theory of nanoparticles.

Spin probe EPR spectroscopy and UV spectroscopy have been employed to study the interaction between a hydrophobic anionic monomer, sodium styrene sulfonate, and micelles of a cationic surfactant, dodecyltrimethylammonium bromide. It has been shown that the interaction with the monomer decreases the critical micelle concentration of the surfactant in aqueous solutions. It has been found that the monomer is incorporated into micelles; therefore, the presence of the surfactant may hinder polymerization of the monomer.

The properties of PbTiO3 nanoparticles (NPs) are studied in the terms of the nanoparticle shell theory and are compared with those of BaTiO3 NPs. The effect of a(Pb) polarizability of the temperature of ferroelectric transition of PbTiO3 is discussed. The higher polarizability of a(Ba) and the considerably lower polarizability of a(Pb) determine the higher transition temperature of T c = 500°C in the case of PbTiO3 and the lower T c = 120°C in the case of BaTiO3. It is shown that the difference in the polarizability values of Ba and Pb atoms also affects the dimensional properties of NPs, at which the ferroelectric transition from the cubic phase to the tetragonal phase occurs: ≈30 nm for PbTiO3 NPs and 200 nm for BaTiO3 NPs.

Properties of BaTiO 3 nanoparticles, transition into the ferroand paraelectric BaTiO 3 phase, and dependence of Curie temperature T c (BaTiO 3 ) on the energy of excited states of a Ba atom are studied in the terms of the nanoparticle shell theory. Dimensional properties of ferroelectric BaTiO 3 and PbTiO 3 nanoparticles are compared.

The correlation between the electronic configurations of Au atom in the ground and excited electronic states and the E pl plasmon energies of gold nanoparticles is studied in the many-electron approximation, taking into account 5d, 6s, and 6p valence electrons. Relativistic effects are found to result in the E pl splitting in the visible and ultraviolet spectral ranges, and the splitting energies are predicted. The origin of low-energy plasmons with E pl = 1.14, 2.7, and 6.4 eV is determined by 5 d 9 6 s 2 ( 2 D 5/2 ), 5 d 9 6 s 2 ( 2 D 3/2 ), and 5 d 5/2 9 6 s 1/2 6 p 1/2 excited electronic configurations of Au atom. The bulk plasmon energy E pl = 25.4 eV is assigned to the mixed oxidation states of Au ions in the nanoparticle cores.

В рамках многоэлектронного приближения c учетом валентных 5d, 6s и 6p электронов изучено влияние электронной структуры атома Au в основном и возбужденном состояниях на энергию Epl плазмонов наночастиц золота. Установлено, что релятивистские эффекты приводят к расщеплению Epl в видимой и УФ областях спектра, предсказаны величины расщепления. Формирование низкоэнергетических плазмонов Epl=1.14, 2.7, 6.4 эВ обусловлено участием 5d 96s2(2D5/2), 5d96s2(2D3/2) и 5d 6s1/26p1/2 электронных конфигураций атома Au в возбужденном состоянии. Объемные плазменные переходы Epl = 25.4 эВ отнесены к смешанной степени окисления ионов Au в ядре наночастиц

The effects of the geometrical shape of silver nanoparticles and the electronic configurations of Ag atom in the ground and excited states on the plasmon characteristics of nanoparticles are considered. A relationship between the static polarizability of silver and gold atoms and the plasmon energies of nanoparticles is found. The Δ E excitation energy of a silver atom that corresponds to the 4 d 10 5 s ( 2 S 1/2 ) → 4 d 10 5 p ( 2 P 1/2 and 2 P 3/2 ) transition is shown to determine the plasmon energy of thin silver films. In the case of spherical silver nanoparticles in aqueous solution, the size effect—namely, the correlation between λ pl wavelengths of plasmon transitions and d diameters of nanoparticles—is discovered. With the increase in the diameter of nanoparticles, the plasmon transition peaks are red shifted. In the range of d = 9–120 nm, λ pl values are shown to change from 370 to 440 nm. The resonance splitting of plasmon bands determined by the mixed valence states of silver atoms is predicted.