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We have obtained a new water-soluble form of boron(III) dipyrromethene luminophores using the example of 3,3',5,5'-tetraphenyl-ms-aza-2,2'-dipyrromethenate boron(III) (BODIPY) and Cremophor® (polyethylene glycol, PEG-40). The results of a study of the spectral-luminescent properties of the studied BODIPY–Cremophor®–aqueous–alcohol medium system are presented. It is found that Cremophor® is the only one of a series of investigated excipients (PEG-400, PEG-1000, polyvinylpyrrolidone, bovine serum albumin, sodium carboxymethylcellulose) providing solubilization of BODIPY in an aqueous medium, while maintaining its intense spectral characteristics, including fluorescence and luminophore, in the red region of the spectrum. The BODIPY–Cremophor® system is tested on two mouse cell lines: metastatic breast cancer and non-metastatic skin cancer. It is shown that the introduction of the BODIPY–Cremophor® system into both cell lines of mice leads to the detachment of cell cultures from the substrate and suppression of the development of cancerous tumors. The results obtained show that immobilization of BODIPY in PEG-40 in an aqueous-alcoholic medium makes it possible to obtain preparations with prolonged action, which can be used as photosensitizers (PSs) in photodynamic therapy and for bioimaging in cell biology.

The spectral luminescent and electrophysical properties of polymer films based on poly-N-vinylpyrrolidone with the stabilized derivatives of tetraphenylporphyrin in various aggregation states (monomers, J- and H-aggregates) were investigated. Films containing a monomolecular form of porphyrins are characterized by intensive fluorescence. For films with J-aggregates an electric response that was not practically observed in the case of H-aggregates was detected. The films obtained are also characterized by optical and electric response to pH change, particularly in the presence of ammonia and hydrogen chloride vapors. The obtained data allow polymeric films with immobilized porphyrins to be considered as potential material for the creation of film systems for sensor applications, photovoltaics, molecular electronics, and photocatalysis. The variability of the film synthesis methodology allows the aggregation state of the immobilized porphyrins to be changed directionally, which provides the possibility of obtaining films of hybrid organic materials with the desired photophysical properties.

New hybrid graphene and aluminum phthalocyanine structures are synthesized (graphene is prepared with the sonochemical method in N,N-dimethylformamide). The physicochemical properties of these hybrid systems are studied with transmission electron microscopy, Raman spectroscopy, and optical spectroscopy. We show that graphene in the system prevents the aggregation of aluminum phthalocyanine and leads to its stabilization in monomeric form. The results may be used to obtain new materials for various sciences and technologies.

The effect of the filler content on the optical absorption spectra, electroconductivity, and surface morphology of thin nanoocomposite films based on poly(n-xylylene)–tin (PPX–Sn) has been studied. The films under study are prepared in vacuum by cryochemical synthesis on polished quartz, glass-ceramics, and silicon substrates. After completing the preparation, the samples are exposed to air for some time prior to measurements. With an increase in the filler content, a nonmonotonic change in both surface morphology of films (by atomic force microscopy) and adsorption spectra is found. An analysis of the spectra shows that, at the filler concentration C ≤ 9 vol %, tin in the composite is in the oxidized form of SnO2, while at C = 12 vol % it is in a metal state, respectively. With an increase in C from 4 to 12 vol %, the increase in conductivity of nanocomposites is more than 7 decimal orders, with a sharp change in the region of C ≈ 9–12 vol %. The conductivity of the film consisting of nanoparticles (C = 100 vol %) is found to be low and comparable with that for composites with C = 4–5 vol %. With a decrease in the temperature from 300 to 15 K, the resistance of the sample with C = 12 vol % is found to decrease, while that for all other samples increases by the activation law. The activation energy with an increase in the filler concentration to 9 vol % is found to decrease, while that for the sample with C = 100 vol % increases by almost an order of magnitude. The most significant changes in the properties and morphology of the surface of nanocomposites are observed at a concentration of ~9 vol %, which apparently is the percolation threshold.

The present study was undertaken to investigate and characterize the structure, the electrical conductivity in the temperature range 10-300 K, thermogravimetric analysis (TGA) data and micro-Raman spectroscopy data of pitch-based graphite fibers during the bromination process. All the results are explained by the structural changes, the appearance of bromine in two main states, namely, as an intercalated bromine and as a bromine bound to the carbon network by a C-Br bond, by the degradation of graphite network and by the growth of the content of the amorphous phase during the bromination.

The spectral-fluorescent properties of various supramolecular systems based on chlorin e6 (Ce6) are determined to facilitate the development of new medicines for photodynamic therapy and diagnostics. The effect of various excipients, such as poly-N-vinylpyrrolidone (PVP), polyethylene glycol (PEG), bovine serum albumin (BSA), chitosan, Triton X-100 (TX-100), sodium hexametaphosphate (SHMP), and poly(dimethyldiallylammonium chloride) chloride (PDDAC), on the optical absorption and fluorescence of Ce6 is demonstrated. In the Ce6−PVP, Ce6−PEG, Ce6−BSA, Ce6−TX-100, Ce6−SHMP, and Ce6−PDDAC systems, Ce6 molecules are disaggregated and complexes thereof with excipients are formed. The quantum yield of Ce6 fluorescence in supramolecular systems is close to that of the free-form photosensitizer, in the absence of excipients. The results suggest that supramolecular complexes of Ce6 are promising for the development of medicines with controllable photodynamic activity.

A geometric approach to revealing the characteristic signs of photoresponse from semiconductor sensor materials is presented. It is shown by the example of zinc chalcogenides that natural decomposition of the transient photoresponse into geometrically ordered components is performed upon transforming their transient photoresponse into first-order and second-order signatures. Universal differential-geometric parameters and other indices, which are also applicable for other characteristics of semiconductor sensor materials, are applied for the system analysis of ordering the dynamic structure of the photoresponse.

It is shown that the photophysical properties of chlorophyll a (Chl) depend on the nature and relative amounts of 2-methyl-1,4-naphthoquinone (MNQ) and nicotinamide adenine dinucleotide phosphate (NADP). Photoinduced charge separation occurs in aqueous ethanol solutions of Chl (1 × 10−5 M) and NADP (5 × 10−6–5 × 10−4 M), resulting in the dynamic quenching of Chl fluorescence. Coordination interaction between Chl and NADP is established at an NADP concentration of ≥5 × 10−4 M. The nonlinear Stern-Volmer dependence in this range is due to the input from static quenching. It is shown that the quenching of Chl fluorescence in an MNQ solution at Chl and MNQ concentrations of 1 × 10−5 M and 6.7 × 10−5–1 × 10−4 M, respectively, is described by a linear dependence in the Stern-Volmer coordinates; no complex formation is observed for Chl and MNQ under these conditions, and electron transfer is of the dynamic type. Static or mixed-type energy transfer from MNQ to Chl dominates at elevated MNQ concentrations.

The novel supramolecular systems based on chlorine e6 (Ce6) are presented, and their optical absorption and fluorescence have been investigated. The influence of different excipients as poly-N-vinylpyrrolidone (PVP), polyethyleneglycol (PEG), bovine serum albumin (BSA), chitosan, Triton X-100 (TX-100) on spectral characteristics of these systems has been studied. The obtained spectral-fluorescence characteristics of Ce6-PVP, Ce6-PEG, Ce6-BSA, Ce6-TX-100 indicate disaggregation of chlorine e6 molecules and their consecutive interaction with excipients in solutions and formation of molecular associates and molecular complexes. The system Ce6-chitosan is characterized by aggregation of pigments in solution that reduces photochemical activity of a photosensitizer. The fluorescence quantum yield k of mentioned above supramolecular systems has been calculated. The results can be useful during the new method of controlled aggregation of photosensitizers as a part of supramolecular complexes development as well as for the purposes of new medicines of predictable photodynamic activity creation. © 2016 Journal of Biomedical Photonics & Engineering.

An approach for preparing MoS2 films in mild conditions is described, which is based on producing the suspensions of nanocrystalline MoS2 particles in organic solvent via exfoliation of MoS2 crystals, followed by the deposition of these suspensions onto substrate. According to X-Ray diffraction data, acetonitrile suspensions yield highly oriented films with the basal planes of MoS2 crystallites being mainly oriented in the plane parallel to the substrate. Atomic force microscopy examination revealed changes in the film surface topography under variation of the film thickness, which varied in the range of 0.03–2.2 μm. The optical absorption spectra of the obtained MoS2 films were found to resemble those of thin natural MoS2 single crystals. Dark conductivity of the films with the thickness of d = 0.12–2.2 μm was determined to be ~ 10− 3 S∙cm− 1 at 300 K. Experimental data on the conductivity in the temperature range of 10–300 K were fitted to Mott function for 3D variable-range hopping. The synthesized MoS2 films were found to be photosensitive in the range of 300–800 nm. They provided the value of reduced photocurrent density of about 7∙10− 4 (A∙cm)/(WV) under photoexcitation at 575 nm.

The optical absorption spectra of molybdenum disulfide prepared by monolayer dispersion of a crys- talline precursor in a liquid medium were studied. On the whole, the three-dimensional structure of the crystalline analogue was reconstructed in disperse MoS 2 dried to a powder state. A substantial fraction of the material trans- formed into a nanosized state during dispersion and was stabilized in the form of nanoparticles in various sol- vents. The stabilizing action of the solvents studied decreased in the series acetonitrile, ethanol > chloroform > water. The data on the optical absorption of MoS 2 suspensions in various solvents were evidence of a broad par- ticle-size distribution. Along with nanoscale particles, the samples contained larger particles responsible for long-wave absorption (>600 nm). The size of nanoparticles was estimated using an empirical correlation between the position of maximum A (the long-wave maximum of the first allowed absorption band) in the absorption spectrum and the size of particles ( 2 R ). This correlation was obtained using the literature data on monodisperse particles and mixtures of particles. The number of particles showed a tendency to increase as the concentration of disperse MoS 2 in acetonitrile decreased.

Cyclopropylazoarenes containing methoxy groups in the aromatic ring give the corresponding N-arylpyrazolines on the reflux in o-dichlorobenzene or on SnCl2 catalysis at 80 °C in good yields. The products can be smoothly oxidized into the corresponding pyrazoles. Thermolysis of cyclopropylazoarenes containing hydroxy groups in the aromatic ring proceeds more complicated. Thus in the case of resorcin azo derivative, strong resinification of the reaction mixture is observed and the corresponding N-arylpyrazoline is isolated only in −40% yield. Under similar conditions, thermolysis of 1-cyclopropyl- and 1-(1-methylcyclopropyl)azo-2-naphthol proceeds otherwise and unexpectedly leads to naphtho[1,2-d]oxazole derivatives with degradation of the cyclopropane ring.

A reaction of cyclopropanediazonium ion, generated by decomposition of N-cyclopropyl-N-nitrosourea upon treatment with potassium or cesium carbonates, with various poly-hydroxyarenes and aminophenols has been studied. The reaction of azo-coupling proceeds with phloroglucinol, resorcinol, 3-methoxy- and 3-aminophenol giving rise to mono-, bis-, and tris(cyclopropylazo)arenes as the major products. Oxidizable phenols such as hydro-quinone, 2-methoxy-, 4-amino-, and 2-aminophenol give products of radical transformations with participation of cyclopropyl radical.

Two-layer heterostructures with a high yield of charged current carriers were obtained and investigated. The heterostructures comprised monolayer dispersions of MoS2 in polyvinyl alcohol as the lower layer and the upper p-, n-, or bipolar transport layer (TL). It was found that dark conductivity of the two-layer heterostructures increased considerably compared with the conductivity of reference samples based on TL but containing no MoS2. After excitation from the TL side, maximum photoelectric sensitivity was obtained where TL long-wave absorption decreased and there was a high concentration of TL excited states at the interface that interacted with the surface of MoS2 particles. This interaction quenched the luminescence of TL transport centers and led to the photogeneration of both positively and negatively charged current carriers at the interface. Luminescence quenching could be of 50–60% at high MoS2 contents in the lower layer (90–100 wt %). This was evidence that the contact area of MoS2 particles with the polymeric transport layer exceeded the geometric interface dimensions and the interface had a relief surface (was fairly thick). It was found that the donor-acceptor properties of both MoS2 and the polymeric TL were very important for the photogeneration of charge carriers at the interface. When the MoS2 content in the lower layer was maximum, the effectiveness of the accumulation of minority carriers increased because of the formation of an alternative transport network associated with MoS2 particles. The conclusion was drawn that the photogeneration of charges at the interface resulted from the phototransfer of electrons between MoS2 particles and TL excited states.

Methyl 2-cyclopropyl-2-diazoacetate was synthesized from acetylcyclopropane in few chemical steps in ∼55% total yield. Its copper or rhodium-catalyzed dediazoniation exclusively proceeds through the intramolecular isomerization of generated cyclopropyl(methoxycarbonyl)carbene to 1-methoxycarbonylcyclobutene, irrespective of the presence or the absence of unsaturated compounds. However, in the presence of acrylates or strained cycloalkenes, this diazo ester is being slowly involved into the 1,3-dipolar cycloaddition, giving cyclopropyl-substituted pyrazolinecarboxylates, which in case of 1-pyrazolines easily lose nitrogen molecule to selectively afford 1-cyclopropylcyclopropanecarboxylate derivatives.

A new way of generating cyclopropyl radicals in the base-catalyzed decomposition of N-cyclopropyl-N-nitrosourea in the presence of organic reducing agents (1-phenylpyrazolidin-3-one and 4-methoxyphenol) was developed. The cyclopropyl radical generated under these conditions can not only abstract a proton from the substrate to give cyclopropane but also form C-C or C-Br bonds in reactions with aromatic substrates or polybromomethanes.

The electronic structures and dissociation energies of diazocyclopropane (1), diazomethane (2), 2-diazopropane (3), and diazocyclobutane (4) were calculated at the density functional B3LYP and the ab initio MP2 levels using the 6-31G(d) basis set and at the G2(MP2,SVP)//B3LYP/6-31G(d) level. Distinctive features of diazocyclopropane 1 are the low energy of dissociation with loss of the nitrogen molecule; ΔE = 18.7 kcal mol−1, B3LYP; 9.2 kcal mol−1, G2 at 0 K) and a nonplanar structure, in which the C=N bond forms an angle of 115.7° with the plane of the cyclopropane ring. The behavior of molecules 1 and 2 in the 1,3-dipolar cycloaddition to ethylene (5), acrylonitrile (6), and methyl acrylate (7) was studied. The reactions of 1 with 6 and 7 have very low activation barriers (ΔE a = 4.7 and 4.4 kcal mol−1, respectively; at the B3LYP level). For these reactions, the G2 method gives even smaller activation parameters (1.8 and 0.3 kcal mol−1, respectively). The results of our calculations provide a good explanation for high reactivity of diazocyclopropane 1.

On the base of photo- and thermostable polyimides (PI) and carbazolyl-containing polymers (CzCP) possessing predominantly p-photoconductivity and doped with perylenediimide derivative (PDID) as an acceptor with n-conductivity, the efficient bipolar polymer nanocomposites are developed. The efficient bipolar transport is obtained for microsegregated triple composites (PI-CzCP-PDID and others) in which there are p- and n-microregions with efficient charge photogeneration (quantum yield up to 0.6) at the extended microphase interface and high photoelectrical sensitivity (up to 400 m2/J) in the UV and visible ranges. The photovoltaic effect is investigated for sandwich cells with (Al, ITO) electrodes. The best parameters are found for triple composite films (0.7–1 μm thickness).

Thin film titanium/poly-para-xylylene nanocomposites with controlled Ti content are prepared by vacuum coevaporation and cocondensation of Ti and paracyclophane. The structure and chemical composition of as-deposited samples and the changes of electrical resistivity, which they undergo upon heating, are studied by atomic force microscopy, optical absorption spectroscopy, and the temperature coefficient of the electrical resistivity. It is shown that vacuum coevaporation results in the production of nanocomposite thin films with average Ti particle size of 10–50 nm. The inorganic phase is shown to be amorphous Ti for the samples with high metal content, whereas for the low-filled nanocomposites it consists of amorphous titanium oxide. Two types of kinetics of the nanocomposite oxidation process have been found and modeled by (i) inverse logarithmic and (ii) logarithmic functions depending on the metal content within the thin film. After a long preconditioning period in air the electrical conductivity of the thin film nanocomposites was carefully investigated by two-probe DC measurements. A strong correlation between the concentration of Ti in the thin films and the electrical conductivity dependency on temperature is found and modeled by a heterogeneous model of conductivity.

Decomposition of a series of N-cyclopropyl-N-nitrosoureas (CNU) in CD3OD was studied. These decompose much more rapidly than N-methyl-N-nitrosourea, one of the decomposition pathways being denitrosation, which is atypical of alkylnitrosoureas under the reaction conditions used. The nature of substituents in the cyclopropane ring has a great effect on the stability of CNU and the product ratio. In the presence of H2 SO4, decomposition occurs much more rapidly. Possible pathways of the formation of the major decomposition products of CNU are proposed based on the experimental data.

Decomposition of N-nitroso-N-cyclopropylureas at 5—7 °C on treatment with K2CO3 containing 15—20% H2O allows simultaneous generation of both substituted diazocyclopropanes and cyclopropyldiazonium ions, which can react according to 1,3-dipolar cycloaddition or azo-coupling pattern with appropriate substrates. The nature of substituents in the cyclopropyl ring have a pronounced influence on the product ratio (and, probably, on the equilibrium between the diazo compound and the diazonium ion). Thus, on treatment with a base in the presence of equimolar amounts of methyl metacrylate as a trap for the diazo compound and 2-naphthol as a trap for the diazonium ion, N-cyclopropyl- and N-(2,2-dimethylcyclopropyl)-N-nitrosourea azo coupling products predominate. Conversely, N-(2,2-dichlorocyclopropyl)-N-nitrosourea is transformed predominantly into 1,3-cycloaddition products. A rationalization for the experimental data is proposed.

N-(1,3,3-Trideuterio-2-methylidenecyclopropyl)-N-nitrosourea was synthesized and its decomposition on treatment with K2CO3 in the presence of acrylonitrile and ethyl acrylate or on treatment with MeONa in the absence of unsaturated substrates was studied. The rate of decomposition of the nitrosourea is much lower than that of the nondeuterated analog. The use of acrylates for trapping the intermediate 3,3-dideuterio-1-diazo-2-methylidenecyclopropane results in the corresponding 2"-methylidenespiro[4,5-dihydropyrazole-5,1"-cyclopropanes] containing two deuterium atoms in the cyclopropane fragment. The resulting dihydropyrazoles are isomerized almost entirely over a period of 1—3 days to give a mixture (∼1 : 1) of isopropenylpyrazoles in which both deuterium atoms occur either in the methyl or in the methylidene groups of the isopropenyl substituent. A possible mechanism of this transformation is considered.

N-(2-Methylenecyclopropyl)-N-nitrosourea (2) was synthesized for the first time (yield 70%) and its decomposition induced by bases was studied. In particular, treatment with MeONa/MeOH at-30°C in the presence of methyl methacrylate gives the corresponding I-pyrazoline stereoisomers, the products of [3+2]-cycloaddition of diazo-2-methylene-cyclopropane (1) generatedin situ. Decomposition of2 on treatment with K2CO3 at 0–5°C in the presence of acrylonitrile also proceeds as [3+2]-cycloaddition: however, the expected 2-pyrazoline easily isomerizes into 5(3)-isopropenyl-3(5)-cyanopyrazole. Buta1,2,3-triene is the main product of base-induced decomosition of2 in the absence of unsaturated substrates.

2,2-Dimethyl- and 2,2-dichlorocyclopropyl-N-nitrosoureas were synthesized for the first time. Under the action of MeONa/MeOH at −10°C, these compounds generate the corresponding 2,2-dimethyl- and 2,2-dichlorodiazocyclopropanes, which are readily trapped by 3,3-dimethylcyclopropene to give the products of 1,3-dipolar cycloaddition,viz., isomeric substituted spiro(2,3-diazabicyclo[3. 1 .0] hex-2-ene-4,1 ′-cyclopropanes), in yields of about 70%

The series of monomethyne cyanine dyes as possible fluorescent probes for DNA and RNA analysis were synthesized and their optical properties were studied. Two dyes interacted with native DNA and RNA with strong fluorescence enhancement (up to 350 and 1550 times for Cyan 3 and Cyan 6, respectively). The complex of Cyan 4 with nucleic acids had extremely large Stokes shift (154 nm). Methylenoxybenzthiazole residue seems to be perspective structural fragment for the synthesis of new nucleic acid binding cyanine dyes. Досліджено спектральні характеристики семи синтезованих монометинових ціанінів як мож­ливих флюоресцентних зондів, специфічних до нуклеїнових кислот (НК). Два барвники Cyan 3 та Cyan 6 у комплексі з НК значно підвищували власнуфлюоресценцію (у 160 i 800 разів з ДНК та в 350 і 1550 разів з РНК відповідно). Cyan 4 при взаємодії з НК показав аномально великий (154 нм) Стоксів зсув. Метиленоксибензтіазоловий структурний фрагмент виявив перспективні вла­ стивості для конструювання нових НК-специфічних барвників серед досліджених ціанінів. Исследованы спектральные характеристики семи синтезированных монометиновых цианинов как возможных флюоресцентных зондов, специфичных к нуклеиновым кислотам (HК). Два кра­сителя Cyan 3 и Cyan 6 в комплексе с НК значительно повышали собственную флюоресценцию ( в 160 и 800 раз с ДНК и в 350 и 1550 раз с РНК соответственно). Cyan 4 при взаимодействии с НК показал аномально больиіой (154 нм) Стоксов сдвиг. Метиленоксибензтиазоловый структурный фрагмент проявил перспективные свойства для конструирования новых НК-специфических красителей среди исследованных цианинов.

IR spectroscopy showed that in nitrile copolymers and fibres containing units based on itaconic acid, these units can exist in different modifications. The formation and set of modifications are a function of the conditions of preparation of the copolymer and fibre, especially their hydrophilicity. The existence of different modifications of itaconic acid fragments (in both the initial samples and in the samples formed in the initial stages of heat treatment) affects the rate of the subsequent processes of thermooxidative decomposition of the objects and the set of polyconjugated systems formed and consequently also the supermolecular structure. These findings should be taken into consideration both in the analysis of the corresponding copolymers and in the technology of their fabrication and processing.

Cyclopropylazoarenes containing methoxy groups in the aromatic ring give the corresponding N-arylpyrazolines on the reflux in o-dichlorobenzene or on SnCl2 catalysis at 80 °C in good yields. The products can be smoothly oxidized into the corresponding pyrazoles. Thermolysis of cyclopropylazoarenes containing hydroxy groups in the aromatic ring proceeds more complicated. Thus in the case of resorcin azo derivative, strong resinification of the reaction mixture is observed and the corresponding N-arylpyrazoline is isolated only in −40% yield. Under similar conditions, thermolysis of 1-cyclopropyl- and 1-(1-methylcyclopropyl)azo-2-naphthol proceeds otherwise and unexpectedly leads to naphtho[1,2-d]oxazole derivatives with degradation of the cyclopropane ring.

It is shown that acoustic treatment of piezoelectric zinc selenide crystals by exciting strong natural elastic vibrations can specifically alter their photoelectric and other properties. Irreversible changes in the stressed-strained state of the crystals under this treatment are responsible for characteristic features in the spectral dependences of the permittivity e′(λ) and the dielectric loss coefficient e′’(λ). These dependences plotted in the form of e*(λ) diagrams on the complex plane and also the spectrum of natural elastic vibrations can be used to monitor the treatment process.

Methyl 2-cyclopropyl-2-diazoacetate was synthesized from acetylcyclopropane in few chemical steps in ∼55% total yield. Its copper or rhodium-catalyzed dediazoniation exclusively proceeds through the intramolecular isomerization of generated cyclopropyl(methoxycarbonyl)carbene to 1-methoxycarbonylcyclobutene, irrespective of the presence or the absence of unsaturated compounds. However, in the presence of acrylates or strained cycloalkenes, this diazo ester is being slowly involved into the 1,3-dipolar cycloaddition, giving cyclopropyl-substituted pyrazolinecarboxylates, which in case of 1-pyrazolines easily lose nitrogen molecule to selectively afford 1-cyclopropylcyclopropanecarboxylate derivatives.

4′,4′-Dimethyl[16α,17α]spiropentanopregn-4-ene-3,20-dione was synthesized. The addition of diazo-2,2-dimethylcyclopropane generated from N-(2,2-dimethylcyclopropyl)-N-nitrosourea to 16,17-didehydropregnenolone acetate occurs regio-and stereospecifically to give 3β-acetoxy-1′,1′-dimethyl-20-oxopregn-5-ene-[16α,17α;7′,6′]-4′, 5′-diazaspiro[2.4]-hept-4′-ene in high yield. Its thermolysis affords a spiropentane-containing steroid, which is transformed into the target diketone. The anti position of the gem-dimethyl group in the fused spiropentane fragment is evident from the X-ray diffraction study of the final product.

The reaction of phenol with cyclopropanediazonium ion generated in situ from N-cyclopropyl-N-nitrosourea by the action of K2CO3 or Cs2CO3 was studied. The main reaction pathway is diazo coupling of cyclopropanediazonium with phenol to give 4-(cyclopropyldiazenyl)phenol, and only traces of isomeric 2-(cyclopropyldiazenyl)phenol were formed. The reaction was accompanied by partial denitrogenation of the diazonium ion with formation of cyclopropyl and allyl cations which gave rise to a number of by-products. All transformation products were characterized by the 1H and 13C NMR spectra with detailed signal assignment.

N-(1,3,3-Trideuterio-2-methylidenecyclopropyl)-N-nitrosourea was synthesized and its decomposition on treatment with K2CO3 in the presence of acrylonitrile and ethyl acrylate or on treatment with MeONa in the absence of unsaturated substrates was studied. The rate of decomposition of the nitrosourea is much lower than that of the nondeuterated analog. The use of acrylates for trapping the intermediate 3,3-dideuterio-1-diazo-2-methylidenecyclopropane results in the corresponding 2"-methylidenespiro[4,5-dihydropyrazole-5,1"-cyclopropanes] containing two deuterium atoms in the cyclopropane fragment. The resulting dihydropyrazoles are isomerized almost entirely over a period of 1—3 days to give a mixture (∼1 : 1) of isopropenylpyrazoles in which both deuterium atoms occur either in the methyl or in the methylidene groups of the isopropenyl substituent. A possible mechanism of this transformation is considered.

N-(2-Methylenecyclopropyl)-N-nitrosourea (2) was synthesized for the first time (yield 70%) and its decomposition induced by bases was studied. In particular, treatment with MeONa/MeOH at-30°C in the presence of methyl methacrylate gives the corresponding I-pyrazoline stereoisomers, the products of [3+2]-cycloaddition of diazo-2-methylene-cyclopropane (1) generatedin situ. Decomposition of2 on treatment with K2CO3 at 0–5°C in the presence of acrylonitrile also proceeds as [3+2]-cycloaddition: however, the expected 2-pyrazoline easily isomerizes into 5(3)-isopropenyl-3(5)-cyanopyrazole. Buta1,2,3-triene is the main product of base-induced decomosition of2 in the absence of unsaturated substrates.

Aminoacyl-tRNA synthetases play a crucial role in the fidelity of translation of the genetic code. Recognition of tRNA by aminoacyl-tRNA synthetase is accompanied by mutual conformational changes of both partners. Fundamental properties of these enzymes can be adequately described from the standpoint of their dynamics in solution. In this work we have studied the intramolecular dynamics of mammalian tyrosyl-tRNA synthetase in solution by ultraviolet fluorescence spectroscopy. Tyrosyl-tRNA synthetase of bovine liver is a structural dimer of α2-type having molecular weight Mr 2*59 000.

An increased requirement for carbon fibers has brought about a large number of works related to studies of structural transformations during a carbon fiber heat-treatment. The present-day knowledge of the structure and mechanism of thermal transformations of carbon fibers from polyacrylonitrile is elucidated in work [1].

Pitch - based carbon fibers (CF's) brominated for 2–144 hrs have been characterized by thermogravimetric analysis (TGA) in 25–800 °C temperature range with the purpose of determination of bromine state and changes in the carbon fiber structure on molecular level in these materials upon the bromination process. Thermal stability of brominated CF's has been studied in both the flowing argon and flowing air atmospheres by dynamic TGA. The variations of kinetic parameters (activation energy E a , rate constant k) of the debromination process in air atmosphere have been evaluated based on the TGA results.

Preliminary irradiation of technical polyacrylonitrile tow with CO2 laser radiation leads to initiation of cyclization processes on subsequent heat treatment and to a decrease in oxidation time.

The activation energy of destruction U 0 and the structurally sensitive coefficient γ have been determined for polyvinylbutyrals (PVB) with varying degrees of substitution N . It was found that up to N = 60 mole% relations of γ to N are satisfactorily described by the formula γ = γ 0 + AN , where γ 0 is the structurally sensitive coefficient for PVA, A is a constant multiplier for a given series of polymers. By determining limits of applicability of the above formula for any series of copolymers one can predict the strength properties of polymers in the series in question.

The structure-sensitive coefficient of oriented fluorine-containing monofilaments rises with increase in the melt flow index.

1. An anomalous decrease in the yield point of the03Kh20N16AG6steel was observed for T < 60 °K. It is shown that the temperature of the anomaly fits into the graph representing the dependence of the temperature of anomalies on the nickel content of stainless steels with a nickel concentration of 8–25%. 2. It is also shown that the application of the external magnetic field H = 20 kOe results in a monotonic increase in the temperature dependence of the yield point in the temperature range of the anomaly observed at H = 0. 3. An anomaly of the linear thermal expansion coefficient of the03Kh20N16AG6steel was observed at low temperatures.

The paper presents the results of the study on the influence of a high substrate bias voltage from 300 up to 1300 V on the titanium nitride coating deposition under nitrogen pressure of 2 Pa. The deposition rate, phase and chemical composition, adhesion and mechanical properties of coatings, macroparticle number and size distribution were investigated.

The IR spectra of films of PVA subjected to acetalation with furfural and to coupling with maleic anhydride by the diene synthesis have been obtained, and an assignment of absorption bands is given. The alkali treatment of the adduct of poly(vinyl furfural acetal) with maleic anhydride is apparently accompanied by the epimerization of one carboxyl group.