Структура молекулы 2-нитро-2’-гидрокси-5’-метилазобензола: Теоретическое и спектральное исследование

Objectives. 2-Hydroxy-nitroazobenzenes comprise reagents for the synthesis of heteroaromatic compounds, in the molecules of which the benzene and azole cycles are annulated. These reagents are widely used in the production of chemical products for various industries. In particular, 2-2’-hydroxy-5’-methylphenylbenzotriazole is used as an effective photo stabilizer for polystyrene and polyethylene. A promising method for its preparation is the liquid-phase catalytic hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene (2NAB). The aim of the present study was to establish the structure of 2NAB in solutions of different composition.Methods. Theoretical calculations were carried out within the framework of the density functional theory at a temperature of 298.15 K for the gas phase at B3LYP/6-311++G(d, p) and M06-2X/6-311++G(d, p) levels; for hexane, 2-propanol, toluene at B3LYP/6-311++G(d, p) level using the conductor-like polarizable continuum model. An experimental study to determine the probable isomeric structure of 2NAB in various solvents, including sodium hydroxide (NaOH) and acetic acid (CH3COOH) additives, was carried out using infrared (IR) and ultraviolet (UV) spectroscopy.Results. The most probable structure of 2NAB isomers for the gas phase and a number of solvents was determined. Experimental and theoretical IR and UV spectra were obtained. The thermodynamic characteristics of the reaction of intramolecular proton transfer from –OH to –N=N– group in the gas phase were calculated.Conclusions. A comparison of the experimental and calculated results supports the conclusion that the cis-isomer should be considered most probable for the gas phase. For the studied solutions, a trans-isomer of 2NAB with hydrogen bonds formed between the hydroxyl group hydrogen and the β-nitrogen atom of the azo group of dye molecule should be considered as the most likely structure. In the studied individual and binary solvents, prototropic equilibrium is shifted towards the azo form of the dye, while intramolecular proton transfer is possible only in aqueous diethylamine and dimethylformamide solutions with additions of NaOH. Цели. 2-Гидроксинитроазобензолы – реагенты синтеза гетероароматических соединений, в молекулах которых аннелированы бензольный и азольный циклы, широко использующиеся при производстве химических продуктов для различных областей промышленности. В частности, 2-2’-гидрокси-5’-метилфенилбензотриазол используется в качестве эффективного фотостабилизатора полистирола и полиэтилена. Перспективным методом его получения является жидкофазная каталитическая гидрогенизация 2-нитро-2’-гидрокси-5’-метилазобензола (2НАБ). Целью нашей работы стало установление структуры 2НАБ в растворах различного состава.Методы. Теоретические расчеты проводились в рамках теории функционала плотности при температуре 298.15 К для газовой фазы на уровнях B3LYP/6-311++G(d, p) и M06-2X/6-311++G(d, p), для гексана, 2-пропанола, толуола на уровне B3LYP/6-311++G(d, p) с использованием континуальной модели сольватации. Экспериментальное изучение предполагаемого изомерного строения 2НАБ в различных растворителях, в том числе с добавками гидроксида натрия (NaOH) и уксусной кислоты (CH3COOH), проведено с помощью инфракрасной (ИК) и ультрафиолетовой (УФ) спектроскопии.Результаты. Определена наиболее вероятная структура изомеров 2НАБ для газовой фазы и ряда растворителей. Получены экспериментальные и теоретические ИК-, УФ-спектры исследуемых веществ. Рассчитаны термодинамические характеристики реакции внутримолекулярного переноса протона от –ОН к –N=N– группе в газовой фазе.Выводы. Сравнение экспериментальных и расчетных результатов позволило сделать заключение, что наиболее вероятным для газовой фазы следует считать цис-изомер, а для изученных растворов транс-изомер 2НАБ с водородными связями, образующимися между водородом гидроксигруппы и β-атомом азота азогруппы. В изученных индивидуальных и бинарных растворителях прототропное равновесие смещено в сторону азоформы красителя, а внутримолекулярный перенос протона возможен только в водных растворах диэтиламина и диметилформамила с добавками NaОН.

Сalix[4]arene chalcone amides effects on myometrium mitochondria

Mitochondria are a key player in a wide range of the most important functions of the cell. Calixarenes are supramolecular compounds that have been widely used in bioorganic chemistry and biochemistry. The aim of this work was to study the effects of calix[4]arenes with two (С-1012, С-1021), three (С-1023, С-1024) and four (С-1011) chalcone amide groups on the myometrial mitochondria membranes polarization, Ca2+ concentration in the matrix of these organelles ([Ca2+]m ) and on the average hydrodynamic diameter of mitochondria. It was shown that permeabilized myometrium cells incubation with calix[4]arenes containing two or more chalcone amide groups, was accompanied by an increased level of myometrial mitochondria membranes polarization. All studied calix[4]arenes increased [Ca2+]m values in the absence and in the presence of exogenous Ca2+. The values of [Ca2+]m in the absence of exogenous Ca2+ were higher at mitochondria incubation in Mg2+-containing, than in Mg2+,ATP-containing medium. Incubation of isolated mitochondria with the studied calix[4]arenes resulted in changes of mitochondria volume: at incubation with С-1012, С-1021, C-1023 the average hydrodynamic diameter was decreased, while with С-1011 it was increased. Thus, we have shown that a short-term (5 min) incubation of mitochondria in the presence of 10 µM calix[4]arenes, which contain from two to four chalcone amide groups, increased the level of mitochondria membranes polarization, ionized Ca concentration in the matrix and had different effects on the mitochondrial volume

Historical aspects of the Ural school of traumatologists and orthopedists

The article presents information about the Ural School of Traumatologists and Orthopedists: the history of development and formation, founders, scientific ideas, research topics, continuity and traditions of the schoolВ статье представлены сведения об Уральской школе травматологов-ортопедов: история становления и формирования, основоположники, научные идеи, тематика исследований, преемственность и традиции школ

Plants with genetically encoded autoluminescence

Autoluminescent plants engineered to express a bacterial bioluminescence gene cluster in plastids have not been widely adopted because of low light output. We engineered tobacco plants with a fungal bioluminescence system that converts caffeic acid (present in all plants) into luciferin and report self-sustained luminescence that is visible to the naked eye. Our findings could underpin development of a suite of imaging tools for plants

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

The analysis of the lithology, grain-size distribution, clay minerals, and geochemistry of Upper Pleistocene sediments from the submarine Shirshov Ridge (Bering Sea) showed that the main source area was the Yukon–Tanana terrane of Central Alaska. The sedimentary materials were transported by the Yukon River through Beringia up to the shelf break, where they were entrained by a strong northwestward-flowing sea current. The lithological data revealed several pulses of ice-rafted debris deposition, roughly synchronous with Heinrich events, and periods of weaker bottom-current intensity. Based on the geochemical results, we distinguished intervals of an increase in paleoproductivity and extension of the oxygen minimum zone. The results suggest that there were three stages of deposition driven by glacioeustatic sea-level fluctuations and glacial cycles in Alaska

Characterization of the Tetraspan Junctional Complex (4JC) superfamily

Connexins or innexins form gap junctions, while claudins and occludins form tight junctions. In this study, statistical data, derived using novel software, indicate that these four junctional protein families and eleven other families of channel and channel auxiliary proteins are related by common descent and comprise the Tetraspan (4 TMS) Junctional Complex (4JC) Superfamily. These proteins all share similar 4 transmembrane α-helical (TMS) topologies. Evidence is presented that they arose via an intragenic duplication event, whereby a 2 TMS-encoding genetic element duplicated tandemly to give 4 TMS proteins. In cases where high resolution structural data were available, the conclusion of homology was supported by conducting structural comparisons. Phylogenetic trees reveal the probable relationships of these 15 families to each other. Long homologues containing fusions to other recognizable domains as well as internally duplicated or fused domains are reported. Large “fusion” proteins containing 4JC domains proved to fall predominantly into family-specific patterns as follows: (1) the 4JC domain was N-terminal; (2) the 4JC domain was C-terminal; (3) the 4JC domain was duplicated or occasionally triplicated and (4) mixed fusion types were present. Our observations provide insight into the evolutionary origins and subfunctions of these proteins as well as guides concerning their structural and functional relationships