The paper presents the results of theoretical and experimental studies of new mesogenic molecular complexes based on 4-alkylsulfonic acids and 4-pyridyl-4'-n-alkyloxybenzoates. Using quantum chemistry methods (DFT), the structural units of the systems under study, which are hydrogen-bonded complexes, were modeled. The relationship between molecular parameters, electronic effects of substituents, gas-phase acidity and characteristics of the formed H-complexes is shown. Electron-donating alkyl substituents in the para-position of benzenesulfonic acid reduce gas-phase acidity compared to the unsubstituted molecule, enhancing the electron-withdrawing properties of the sulfo group. The type and potential barrier of the calculated potential functions of proton transfer from the sulfo group to the pyridine fragment in the molecular complexes under study allowed us to conclude that gas-phase acidity directly determines the characteristics of this process. It was found that para-alkyl-substituted benzenesulfonic acids form stronger hydrogen bonds in proton transfer complexes compared to unsubstituted benzenesulfonic acid. The synthesis of three samples of molecular complexes of 1:1 composition was performed (4-methylbenzenesulfonic acid : 4-pyridyl-4'-n-dodecyloxybenzoate, 4-ethylbenzenesulfonic acid : 4-pyridyl-4'-n-heptyloxybenzoate, 4-ethylbenzenesulfonic acid : 4-pyridyl-4'-n-dodecyloxybenzoate). IR spectra recorded at room temperature showed that the systems under study are H-complexes with proton transfer from the sulfo group to the pyridine fragment with an intermolecular hydrogen bond of the N -H center dot center dot center dot O type. It was determined that all H-complexes have enantiotropic mesophorism, as evidenced by DSC and polarization thermomicroscopy data. The recorded mosaic textures in a polarizing microscope suggested that the samples under study had a smectic type of mesophase. It has been shown that the temperatures of phase transitions from the mesophase to the isotropic liquid phase depend on the length of the alkyl substituents in the components of the complexes, which may be a manifestation of the odd-even effect.

An ethylene glycol (EG)–acetone (AC) system is studied via differential scanning calorimetry in the −140 to +40°С range of temperatures. A phase diagram is plotted over the range of concentrations. It is found that the mixtures in the system are supercooled by more than 30°C. Low-temperature melting is recorded in the region around −98°C, which corresponds to the eutectic point temperature. The devitrification of rapidly cooled samples is observed in the range of concentrations up to ~21 mol % AC, and the temperature of devitrification is determined ( T g ~ −120°C). The plotted phase diagram of the EG–AC system is compared to a water–acetone phase diagram.

Changes in the composition and physicochemical properties of porous monolithic 3D nanostructures of aluminum oxyhydroxides (porous monolithic aluminum oxides, PMAO) chemically modified in methyltrimethoxysilane vapors have been studied by thermal-analysis methods. The conditions of formation and compositions of organosilicon compounds on the PMAO surface have been determined, a high degree of hydrolysis (91

Thermally stimulated processes in mixtures of boric acid (BA) with aluminum after plastic deformation under a pressure of 0.5–4.0 GPa were studied by differential scanning calorimetry (DSC) and thermogravimetry. In the original BC, in the range of 20–200°C, splitting of water occurs, accompanied by an endothermic effect. In deformed mixtures BC–Al = 50–50, the endoprocess was recorded on DSC thermograms in the range of 20–200°С, an exoprocess in the range of 200–550°С, an aluminum-oxidation exoprocess at 620°С, and an aluminum melting endoprocess at 656°С. The baric dependences of the parameters of thermal processes in deformed mixtures exhibited extrema at pressures of 1.0 and 2.5 GPa, which were associated with changes in the electronic structure of aluminum caused by high pressure. Such changes can be retained in deformed mixtures after completion of pressure treatment and manifest themselves upon heating due to the formation of electrical double layers in mixture samples.

We investigate the dynamical properties (translation and rotation) of the glass-forming liquid meta-cresol by molecular dynamics simulations. This system is investigated at 9 temperatures between 230 K and 400 K, encompassing the liquid and glassy states of meta-cresol. In order to get insight into the coupling between the translational and rotational motions, the centre of mass velocity autocorrelation function is calculated along the principal axes of meta-cresol. We show that the time behaviour of the velocity and angular velocity is connected to the change in the local structure occurring upon the glass transition. Indeed, the long-time negative region in the velocity autocorrelations is associated with a caging effect while the occurrence of a short time negative region in these functions is considered as a signature of hydrogen bonding interactions. By studying, the centre of mass velocity of meta-cresol in the molecular frame, the translation and rotation coupling was directly evidenced. The time evolution of the translational-rotational coupling is evaluated from the difference Delta RTC alpha (t) between the velocity autocorrelation function calculated with respect to the molecular frame (where alpha stands for the three axes of the local cartesian frame fixed to the individual molecule, x, y, and z) of the meta-cresol molecule and that of the same function calculated in the frame of the hypothesis that there is no statistical correlation between the translational and rotational motions. The positive regions of Delta RTC alpha (t) indicate an occurrence of a cooperative effect, which means that the each of the two motions is realized in the favour of the other. Conversely, negative regions indicate that the rotation and translation motions are anti-cooperative. Our results show that a strong coupling between translation and rotation occurs along the x axis that is perpendicular to the ring of meta-cresol molecule, and also along which the hydrogen bond is established.

This study examines the influence of mefenamic acid on the physical and chemical properties of silica aerogels, as well as its effect on the sorption characteristics of the composite material. Solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and high-pressure 13C NMR kinetic studies were conducted to identify the presence of mefenamic acid and measure the kinetic rates of CO2 sorption. Additionally, a high-pressure T1–T2 relaxation-relaxation correlation spectroscopy (RRCOSY) study was conducted to estimate the relative amount of mefenamic acid in the aerogel’s pores, and a high-pressure nuclear Overhauser effect spectoscopy (NOESY) study was conducted to investigate the conformational preference of mefenamic acid released from the aerogel. The results indicate that mefenamic acid is affected by the chemical environment of the aerogel, altering the ratio of mefenamic acid conformers from 75% to 25% in its absence to 22% to 78% in the presence of aerogel.

Mixtures of polypropylene (10 wt %) with anthracene, phthalocyanine, indigo, adamantane, congo red, spiropyran, safranin, methyl orange, bromocresol purple, phenolphthalein, fluorescein, phenol red, thymol blue, aspartic acid, cyanuric acid, thymolphthalein, and rhodamine were subjected to plastic deformation at a pressure of 1 GPa on an anvil-type high-pressure apparatus. It was found by DSC that the thermograms of heating of the deformed mixtures in the temperature range below T m of the polymer contain endothermic peaks of melting of small polymer crystallites with enthalpies reaching 220–240 J/g in some samples, as well as exothermic peaks of cold crystallization with enthalpies reaching 430–470 J/g. The melting was described by bi- and trimodal peaks, whose total enthalpy reached 2200–2400 J/g in some mixtures. The polymer crystallization in the deformed mixtures was described by single exothermic peaks, whose enthalpies differed little from the crystallization enthalpy of the starting polypropylene. An increase in the enthalpies of thermal processes in the deformed mixtures was attributed to the appearance of double electric layers at interfaces between the mixed phases.

The thermomechanical properties of high-density polyethylene samples (Тmlt = 142°С) subjected to plastic deformation under a pressure of 0.5–1.0–2.0 GPa at room temperature have been investigated on an anvil-type high-pressure apparatus. The decrease in the thickness of deformed samples upon heating depends on the processing pressure and the state of the compressive anvils, namely, grounded or insulated. UV irradiation and storage of the samples at room temperature reduced the effect caused by deformation. The established effects have been associated with a significant influence of charges trapped by structural defects formed during plastic deformation of the polymer on the thermomechanical properties of deformed samples.

Al + 50 wt % Al(OH) 3 mixture was subjected to plastic deformation under a pressure of 1–4 GPa on an anvil-type high-pressure apparatus. The samples were characterized by the methods of differential scanning calorimetry and X-ray diffraction. The baric dependences of the enthalpy of aluminum oxidation and melting and the baric dependence of sizes of coherent scattering regions displayed the extremum points at the pressures of 1.5 and 2.5 GPa. The reasons for these features are the variations in the electron structure of aluminum and/or the mechanism of aluminum deformations at the specified pressures.

An experimental and theoretical study of the structure and mesomorphic proper-ties of supermolecules (H-complexes) formed by 4-n-propyloxycinnamic acid (A) with 4,4'-azopyridine and 4,4'-dithiopyridine (B) has been carried out. The relationship between mesomorphic properties and structural features of H -com-plexes was shown. Using quantum chemistry (DFT) and FTIR spectroscopy methods, it was shown that as a result of self-organization in systems with a molar ratio of components 2:1 (acid : pyridine derivative), H-complexes of the compo-sition A center dot center dot center dot B center dot center dot center dot A are formed. The geometric shape of the H-complexes is deter-mined by the shape of the central molecules - 4,4'-azopyridine and 4,4'-dithio-pyridine. Molecular complexes with 4,4'-azopyridine have a rod-like structure, replacing the central azo group of the non-mesogenic H-complex component with a dithio group leads to a change in the H-complex geometric shape to an angular (V-shaped) one. The energies of H-complex formation and the characteristics of the formed intermolecular hydrogen bonds have been calculated. The geometric anisotropy of the H-complexes is estimated. With the help of experimental meth-ods (differential scanning calorimetry and polarizing optical microscopy), the presence of mesomorphic properties of the H-complex based on 4,4'-azopyridine and their absence in the H-complex based on 4,4'-dithiopyridine was shown. Using experimental and theoretical methods, it has been shown that the strength of the formed N center dot center dot center dot O-H hydrogen bonds in both complexes is comparable. Thus, the replacement of the -N=N- bridging group by -S-S- of the non-mesogenic component of the H-complex affects not only its geometry, but also the liquid -crystal properties.

С помощью методов ДСК и поляризационной термомикроскопии определены температуры фазовых переходов и получены данные о мезоморфных свойствах трех анизотропных производных 1,2,5-тиадиазола: 4,7-бис(додецилсульфанил) [2,3,1]бензотиадиазол BTDA, 4,7-бис(додецилсульфанил)[1,2,5]тиадиазоло [3,4-c]пиридин PyTDA, 4,7-бис(додецилсульфанил)[1,2,5]тиадиазоло[3,4-c]пиридазин PrdTDA. Показано, что среди исследуемых соединений мезогенным является PrdTDA, для которого наблюдается индуцирование мезофазы в темепературном интервале 95.63 – 91.62 ºС в режиме охлаждения из изотропножидкой фазы. С помощью методов квантовой химии: DFT (B3LYP, B97D) с базисными наборами cc-pVTZ и 6-311++G** изучено строение и определены конформационные свойства свободной молекулы PrdTDA, а также смоделированы возможные межмолекулярные взаимодействия, наблюдаемые в кристаллической фазе. Анализ потенциальных функций внутреннего вращения алкилсульфанильных заместителей относительно циклического ядра показал, что молекула PrdTDA имеет 3 конформера. На основании структуры наиболее энергетически выгодного конформера молекулы выполнена геометрическая оптимизация димерного фрагмента цепочечного ассоциата PrdTDA∙∙∙PrdTDA, характерного для кристаллической фазы. Анализ распределения электронной плотности (NBO) показал, что межмолекулярное взаимодействие возможно за счет неподеленных пар LP(S), LP(N) и разрыхляющих NBO σ-типа σ*(С–N), σ*(S–N). Показана прямая связь между строением молекул и возможностью индуцировать мезофазу за счет нековалентных межмолекулярных взаимодействий – халькогенной связи.

By differential scanning calorimetry and polarized light thermal microscopy the phase transition temperatures are determined and the data on the mesomorphic properties are obtained for three anisotropic 1,2,5-thiadiazole derivatives: 4,7-bis(dodecylsulfanyl)[2,3,1]benzothiadiazole BTDA, 4,7-bis (dodecylsulfanyl)[1,2,5]thiadiazolo[3,4-c]pyridine PyTDA, 4,7-bis(dodecylsulfanyl)[1,2,5]thiadiazolo[3,4-c]pyridazine PrdTDA. It is shown that among the studied compounds only PrdTDA is mesogenic. The induction of the PrdTDA mesophase is observed in a temperature range of 95.63-91.62 °C on cooling from the isotropic liquid phase. Using the quantum chemistry method DFT (B3LYP, B97D) with the cc-pVTZ and 6-311++G** basis sets, the structure of a free PrdTDA molecule is studied, its conformational properties are determined, and possible intermolecular interactions occurring in the crystalline phase are simulated. The analysis of potential functions of internal rotation of alkylsulfanyl substituents relative to the cyclic core shows that the PrdTDA molecule has three conformers. Based on the structure of the most energetically favorable conformer of the molecule, the geometry of the dimeric moiety of PrdTDA···PrdTDA chain associate characteristic of the crystalline phase is optimized. The analysis of electron density distribution (NBO) suggests that intermolecular interaction is possible due to LP(S), LP(N) lone pairs and σ-type anti-bonding NBOs σ*(C–N), σ*(S–N). A direct relationship between the molecular structure and the possibility of inducing mesophase due to non-covalent intermolecular interactions–chalcogen bond–is shown.

Al–Cu mixtures of various compositions underwent the plastic deformation under pressures from 0.5 to 4.0 GPa at room temperature on a Bridgman-anvil-type high-pressure apparatus. The influence of treatment pressure on calorimetric properties of Al and Cu powder mixtures of various compositions is studied. The thermal processes in the samples after deformation under pressure were studied with DSC and TGA within 20–800°C, whereas the structure and composition of the samples and its changes during heating were analyzed with the electron-microscopy method coupled with an energy-dispersive X-ray probe. A positron-annihilation method was used to study the atomic-electronic structure of deformed mixtures. The deformed mixtures were tested electrochemically at room temperature in a 6 M KOH solution. The results obtained indicate that the changes in the electronic subsystem of the mixtures can make a significant contribution to the heat release of the samples that underwent plastic deformation under high pressure.

Using experimental and theoretical methods, it has been shown that hydrogen-bonded mo-lecular complexes in two-component systems based on 4-pyridyl-4'-n-alkyloxybenzoates (n = 7, 12) with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol (composition of 1:1) are formed. Quan-tum chemistry methods (DFT (B3LYP)/cc-pVTZ) were used to determine the conformational prop-erties of 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol molecules. It has been shown that the introduction of 4-carboxy and 4-hydroxy groups into the azobenzene molecule has practically no effect on the energy characteristics of the trans-cis isomerization process. The energy, geometric, and electronic characteristics of intermolecular hydrogen bonds in the H-complexes have been estimated. The calculations showed that the H-complexes of 4-pyridyl-4-n-propyloxybenzoate with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol differ significantly from each other in geomet-ric structure: the complex with 4-(phenylazo)benzoic acid - rod-shaped, complex with 4-(phe-nylazo)phenol - angular. A comparison of the energy characteristics of H-complexes, as well as the characteristics of hydrogen bonds, showed that a stronger hydrogen bond is formed in the com-plex with 4-(phenylazo)benzoic acid than in the complex with 4-(phenylazo)phenol. The results of modeling dimers of molecules of 4-(phenylazo)benzoic acid, 4-(phenylazo)phenol, reproducing in-termolecular interactions in crystals, and their hydrogen-bonded complexes allow to conclude that in the process of self-organization of systems with a composition of 1:1, associates of 4-(phe-nylazo)benzoic acid molecules, associates of 4-(phenylazo)phenol molecules will be broken and H -complexes with 4-pyridyl-4'-alkyloxybenzoates will be formed instead. Changes in the experimental IR spectra recorded for the initial components and for systems with a composition of 1:1 confirm the formation of molecular complexes. The structural units of the studied systems based on 4-pyridyl-4'-alkyloxybenzoates with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol with a com-position of 1:1 can be considered supramolecules, formed by hydrogen bonding. The structure of supermolecules and the presence of their geometric anisotropy indicate their potential mesogenic-ity. The sample of H-complexes of 4-(phenylazo)phenol and 4-pyridyl-4'-n-dodecyloxybenzoate (composition of 1:1) was studied for the manifestation of mesomorphic properties using the method of polarization thermomicroscopy. The textures registered in a polarizing microscope allow to con-clude that the H-complex has a smectic mesophase in the temperature range of 101.4-109.4 degrees C.

В интервале температур 310–600 К исследована температурная зависимость термостимулированных токов (ТСТ) нанокристаллического стехиометрического гидроксиапатита кальция Са(РО)(ОН) (ГА) (НКГА) – аналога неорганической компоненты костной ткани, перспективного материала для устройств биоэлектроники, синтезированного в биомиметических условиях. Продукты синтеза идентифицированы методами физико-химического анализа (РФА, ИКС, ДТГ, ДСК, ЭСХА, СЭМ, ПЭМ), и проанализировано влияние степени дисперсности НКГА и условий синтеза на ТСТ.

Синтезированы органоминеральные композиционные материалы (ОМК) на основе биосовместимого гидроксиапатита кальция Ca(PO)(OH) (ГА) и природного биополимера фиброина шелка (ФШ) в ходе осаждения из водных растворов в системе Ca(NO)–(NH)HPO–NH–HO–ФШ. ОМК ГА/ФШ на основе нанокристаллического ГА (НКГА) и ФШ с содержанием 2; 5 и 10 масс.% ФШ идентифицированы методами рентгенофазового (РФА) и термогравиметрического (ТГА, ДТА) анализа, инфракрасной спектроскопии (ИКС), сканирующей электронной микроскопии (СЭМ) и электронной спектроскопии для химического анализа (ЭСХА). Определено влияние состава и условий получения ОМК ГА/ФШ на морфологию НКГА в составе ОМК ГА/ФШ и эксплуатационные характеристики ОМК. Проведена оценка возможности использования таких материалов в качестве элементов биоэлектронных устройств (БЭУ).