MAIN SCIENTIFIC RESULTS
2004
GENERAL PROBLEMS OF CHEMICAL PHYSICS
ESR spectroscopy of XeF radicals in solid argon. Relativistic effects in chemical bonding of a heavy atom of noble gas (Xe).
For the first time the features of the chemical bond formed by a heavy atom of noble gas have been studied experimentally. Considerable delocalization of unpaired electron has been revealed, and spin density was shown to be mostly localized on atomic p-orbitals of fluorine and xenon, which contribute basically in the bond formation. It has been demonstrated that the relativistic character of the electron motion in the heavy atom results in a considerable growth (more than two times!) of spin density on the nucleus of Xe atom.
Microwave magnetic isotopic effect
Microwave magnetic isotopic effect is the influence of electro-magnetic field on chemical fractionating of isotopes with different magnetic moments and nucleus spins.
Microwave field was shown to differently affect the spin conversion and spin-related recombination of radical pairs with different isotopic composition. The dependence of chemical fractionating coefficient for such isotopes on frequency and amplitude of microwave field has been calculated. A huge potential efficacy of microwave magnetic isotopic effect as compared to conventional mass-related isotopic effect has been demonstrated.
Theory of diffuse attenuation of NMR echo signals with magnetic field gradient for amorphous solids, polymers and liquids.
The theory of diffuse attenuation of NMR spin echo signals with magnetic field gradient in amorphous solids, liquids and polymers has been suggested. The theory allows determining the diffusion shift of atoms in the process of self-diffusion in polymer nets with various supra-molecular structures in a wide temperature range assuming the observed echo signals.
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CHEMICAL PHYSICS OF COMBUSTION AND EXPLOSION
Non-uniqueness of modes of filtration burning
Theoretical study of carbon filtration burning in the mode of non-complete conversion of reagents revealed the area of governing parameters (carbon content in the solid phase and oxygen in the gaseous phase, gas flow speed) where, depending on the initial conditions, two stationary regimes can be realized, i.e., a low-temperature (with primary formation of carbon dioxide) and a high-temperature mode (yielding carbon monoxide).
Development of local disturbance of uniform distribution of the reagent concentration caused by diffuse instability
Numerical investigation of phenomenological model with thermal and kinetic nonlinearity describing the phenomenon of instability in the reactions of catalytic burning has been performed. These reactions include those of catalytic afterburning of automobile exhaust, neutralization of industrial outburst from organic dirt, ammonia conversion during the production of nitric acid. Features of auto-wave tuning of uniform modes of catalytic reactions occurring on the catalytic net have been studied. It has been shown that there is some area of parameters with non-uniqueness of auto-wave tuning patterns, which allows a possibility of transfer to a safer and more stable stationary regime with intermediate temperature depending on the initial conditions of initiation.
Study of reflecting properties of dense plasma
Study of the impact of electron density changes in plasma and the effect of extreme thermodynamic parameters on its reflecting properties in a short-wave region of the spectrum with the energy of photon-probing radiation Ept=2.33ev (the probing radiation wave-length λprob. = 532 nì, critical electron concentration nce = 3.9•10+21 cm-3) has been first performed. The reflecting coefficients of strongly non-ideal plasma with the electron density up to ne ~ 1022cm-3 have been determined. Analysis of new experimental data and those obtained earlier for λprob. = 694 nì and λprob. = 1064 nm reveals a strong dispersion of the reflecting coefficient, this being in favor of the model approach assuming the presence of non-equilibrium vibrations in plasma.
Numerical modeling of time-dependent gas-dynamic processes
Numerical modeling of a high-speed shock has been performed in a three-dimensional array using thermodynamic and rheological models of different complexity. The results of the modeling were analyzed and compared with the experimental data for various points of time. Multiphase equilibrium of the state was shown to provide a more correct description of the experiments from physical point of view. The final diameter of the hole in the obstacles was related to the rheological environment models being used.
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NEW MATERIALS
Photochromic and magnetic properties of hybrid materials based on SP+ and [MnIICrIII(OX)3]- salts.
Polyfunctional hybrid compounds of a new class have been obtained. They combine a cation phtochromic sub-lattice of spiropyrans (SP+) or mononitrosyl complexes Ru[Ru(NO)X]3+ and a magnetic anion sub-lattice of mono- or bimetal oxalate [Cr(III)M(II)(OX)3]-(MII=Fe, Mn, Cu) in the same crystalline lattice.
Both sub-lattices preserve the properties of the original salts and demonstrate a synergistic effect. Photochromic properties of crystals are reversible and do not change after a number of inter-conversion cycles. The stability of a colored form in such crystals grows by a factor of 10n as compared to the solutions. At ambient temperature the magnetic sub-lattice of bimetal oxalate yields weak interactions between paramagnetic metal centers. With the temperature decreasing a transfer into a regular ferromagnetic state is observed.
The creation of such polyfunctional crystal materials opens new possibilities for development of miniature electronic devices with new properties.
Carbocyanine dye in reverse AOT micelles and on the surface of AgHal NC
Light-sensitive materials of super-high resolution require hybrid organo-non-organic nanostructures "dye/NC" of super-small dimensions. It was discovered that such nanostructures could be formed directly in pools of reverse micelles during the dye adsorption in the form of trans-monomer on AgHal NC. At the same time, the dye performs not only the role of spectral sensitizing agent but also stabilizes the size of NC. An experimental sample of nano-composite material light-sensitive in the area of dye absorption was prepared using the obtained hybrid nano-elements of about 6nm in size.
First supreme fullerene chloride [60] - C60Cl30 with a unique structure
Kinetics of high-temperature solvent-free chlorination of C60 has been studied, and new chlorine-derivatives C60Cl24 and C60Cl30 have been synthesized. Chlorofullerene C60Cl30 has a unique structure: 15 chlorine atoms are located on each hemisphere of fullerene frame; the spherical fullerene frame undergoes a strong deformation and becomes cylindrical. In spite of such drastic distortions of the frame, C60Cl30 chloride has a very high thermal stability. The method of the compound synthesis is relatively simple, which allows using C60Cl30 as a strong acceptor or as an original compound for synthesis of new materials on its base.
First trifluoromethyl derivatives of endohedral metal-fullerene
Solid-phase reaction between yttrium endometal-fullerene Y@C82 (DMSO extract) and silver tri-fluorine acetate has been studied, and tri-fluorine methyl derivatives Y@C82 have been first synthesized. The reaction was shown to be a selective and the main product to be a diamagnetic complex Y@C82(CF3)5, which was isolated as two isomers of chromatographic purity (I, II). Tri-fluorine methyl derivatives have been specified by means of liquid chromatography, mass-spectrometry, IR-, optic- and 19F NMR spectroscopy. Using the NMR spectroscopy data and quantum-chemical calculations, Y@C82(CF3)5 molecule structure has been suggested.
Proton-conducting membranes based on hetero-poly-compounds
Basing on polyvinyl alcohol - phosphorous-tungstic acid system, a new type of proton-conducting membranes for low-temperature fuel cells has been created. Due to specific features of proton-hydrate cover structure (formation of a mutual system of hydrogen bonds between the matrix and anion), such membranes are capable of effective functioning at humidity of 15-100% and temperature of 0-100°C, and their conductivity is the maximum among polymer electrolytes (~0.1 om-1cm-1). The interfaces of such membranes with electrode material are extremely tolerant to CO admixtures in hydrogen.
By their operating features these membranes surpass all the known low-temperature proton-conducting membranes.
New elastomer nano-composites - polyurethanes with fullerene cross-links
New fullerene derivatives, poly(hydroxylalkyl)fullerene containing five hydroxyalkyl groups in average, have been synthesized. These products can be considered as potential polyfunctional branching agents for obtaining new nano-materials, i.e. polyurethane elastomers with fullerene cross-links. Based on PHAF, new fullerene derivatives with various functional groups can be synthesized. Besides hydroxyl groups, other functional groups (such as isocyanate-, etc.) can be inserted into fullerene.
Elastomer nano-composites with fullerene cross-links are to demonstrate super physical-mechanical properties, in particular, strength due to:
a) polyfunctional character of linking agents (fullerenes with various functional groups),
b) absence of non-effective cycling as it is in case of using conventional polyfunctional compounds as linking agents,
c) strengthening effect of fullerene fragments as nano-fillers being in covalent bond with polymer fragments.
One can assume that with a certain content of fullerene fragments, it is possible to vary the electro conductivity of elastomer compositions during mechanical tests, i.e. these materials are likely to demonstrate sensory properties.
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CHEMICAL PHYSICS OF POLYMERS
Development of scientific bases for synthesis of hyper-branched polymers by TRP method
Scientific bases for synthesis of hyper-branched polymers (HBP) by the method of three-dimensional radical polymerization (TRP) have been developed. The method involves controlling of a side "cyclization" process due to co-polymerization with mono-unsaturated monomers and realization of a step (instead of chain) growth of the macromolecules, as well as the use of chain transfer catalysts to perform TRP in the mode of ultra-short chains (3 to 10 links).
Structural parameters of ω-polymer. Micro pictures of obtained by means of transmission and scanning electron microscopy
Structural-morphological investigations of ω-polymers have been first performed using optical and electron microscopy. ω-polymer was shown to have a nano-porous fracture structure with communicating pores. The formation of such a structure was shown to be tightly connected with the mechanism of ω-polymerization. Thus, ω-polymerization, though always considered as a harmful side process in chemical technology, can be used for development of highly effective sorbents and catalysts for various technical and biomedical applications.
Determination of the mechanism of hexene-1 to decene-5 metathesis and the ways to improve the process selectivity
The mechanism of alpha-olefins metathesis under the action of soluble (WCl6 - Sn n-C4H9)4) and heterogeneous (MoO3/SiO2 - Al(C2H5)3) catalysts has been studied, and the active sites of these processes were shown to have bifunctional carbene-hydride nature, i.e., R—CH2=Mo—H. The catalytic chain metathesis of olefins occurs under the action of the metal-carbene part of the active site, while the metal-hydride part is responsible for the catalytic isomerization of olefins and alkylation of aromatic hydrocarbons with a multiple re-activation of the initial parts of the active sites. Understanding of this mechanism will help to solve the problem of the stock expansion and processing hexene-1 and octene-1, which are not widely used.
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CHEMICAL PHYSICS OF BIOLOGICAL SYSTEMS
Electron transfer in the structure of the reaction centers
The adiabatic model for the electron transfer in proteins has been developed, which takes into account vibration and diffusion modes of dielectric relaxation of protein macromolecules. For the first time, the model describes quantitatively kinetics of the electron transfer in proteins in a wide temperature range, and it provides determination of their most important energetic and dynamic parameters. A drastic (by a factor of 105-106) change of the electron transfer rate appears when charges or protonation degree of individual groups change, this being a ground for efficient controlling of electron transfer in the structure of biopolymers and development of molecular electronic elements.
Formation of ozone in natural photo-synthesizing organisms and their chemical models
The reaction of six-electron water oxidation by chemical oxidizers has been found and studied in detail in the functional model of manganese co-factor of the active site in the photosystem-2 of natural photosynthesis. The search for natural photo-synthesizing organisms has been performed, which are capable of six-electron water oxidation to ozone. A new phenomenon has been determined, i.e., six-electron water oxidation to ozone by the active sites of the photosystem-2 of red sea algae.
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