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Magnesium–aluminum layered double hydroxides and mixed oxides based on them were obtained by high and low supersaturation methods and analyzed. It was shown that the phase composition and formation of nano-sized particles with a large surface area is significantly affected by the rate of introduction of magnesium–aluminum systems into the medium of the precipitated material. All of the obtained samples were studied by thermogravimetric analysis with mass-spectrometric detection, X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and infrared spectroscopy. [ABSTRACT FROM AUTHOR]

An investigation is performed of the effect the nature of organic anions of cobalt, nickel, and copper salts have on the results from synthesizing composite materials consisting of nanodispersed particles of these metals, distributed in a glassy carbon matrix The uniformity of the distribution of metal particles in the matrix is studied, and their sizes are estimated. The morphologies of the composites synthesized using 8‑hydroxyquinoline or benzoic, salicylic, phthalic, and N-phenylanthranilic acids are compared. [ABSTRACT FROM AUTHOR]

Ionothermal synthesis of carbon nitride paved the way to a new structural allotrope—polytriazine imide. In this work, we screen available precursors for pristine polytriazine imides and for their graphitic analogs narrowing it to the melamine—urea mixture as the most promising starting material. Photocatalytic activity of materials verified in reaction of benzyl alcohol oxidation to benzaldehyde, which is known to be highly requested chemical with thousands of tons of annual production. Therefore "green" and selective route of production is highly desired. Developed PTI-LiCl was tested for selective photooxidation of benzyl alcohol to benzaldehyde, demonstrating precious conversion and selectivity rates—96.3% and 91.6%, respectively after 5 hours of UV irradiation. Detailed physical-chemical characterization revealed that PTI materials possessed more ordered and highly condensed structure which grant them improved photocatalytic properties in comparison to graphitic carbon nitride polymorph. Graphical abstract represents two different lines of materials which are known to be various polymorphs of carbon nitride studied comparatively in the present work. One of them is convenient graphitized carbon nitride which is prepared from precursors (melamine, urea or thiourea) via the simple thermal treatment. Another line of materials are prepared via thermal treatment in the eutectic mixture of molten salts. The later line of materials is more active in selective photocatalytic oxidation of benzyl alcohol. [ABSTRACT FROM AUTHOR]

Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability. [ABSTRACT FROM AUTHOR]

The binary phase diagram of pyrene with 2,3-7,8-dibenzpyrene-1,6-quinone C24H12O2 was studied experimentally in 20–400 °C temperature interval at 0–100% of pyrene. The melting point of C24H12O2 was found to be 375 °C. The experimental data made it possible to estimate for the first time the thermal effect of melting of C24H12O2. The additive method was used to estimate the thermodynamic characteristics of C24H12O2. Obtained data allow to perform the thermodynamic modeling and calculation of the phase diagram of the C24H12O2–C16H10 system. Components form simple eutectic with coordinates of eutectic point: 94.70 mol% (91.58 mass%) of pyrene and 146.3 °C. [ABSTRACT FROM AUTHOR]

The crystal structures of two polymorphs of cis‐perinone (bisbenzimidazo[2,1‐b:1′,2′‐j]benzo[lmn][3,8]phenanthroline‐6,9‐dione, Pigment Red 194) were solved from single crystals obtained solvothermally from 1,2‐dichlorobenzene or n‐butanol at 220°C. Both crystal structures (space group P21/c) derive from stacking of flat molecules arranged due to π–π interaction. The melting points of these two polymorphs are 471°C and 468°C and their respective optical bandgaps are 1.94 eV and 1.71 eV. One of the polymorphs demonstrates drift and hopping mechanisms of electric conductivity, whereas the other one is dominated by the drift conductivity. The direct current (DC) electric conductivity of the samples are 4.77 × 10−13 S m−1 and 6.84 × 10−10 S m−1 at room temperature. The significant difference in DC conductivities can be explained by the dependence of the mobility and concentration of charge carriers on the structure of the samples. [ABSTRACT FROM AUTHOR]

Abstract: A technique for growing 2,3-7,8-dibenzpyrene-1,6-quinone single crystals is described. Its crystal structure, IR transmission spectra, reflection spectra in the visible spectral range, results of thermal analysis, and XPS spectroscopy data are reported for the first time. The crystalline structure of this compound is described within the sp. gr. P21/n; its unit cell parameters are a = 17.4346(19) Å, b = 4.8717(5) Å, c = 18.263(2) Å, and β = 105.857(2)°. The structure can be characterized as a herringbone stacking of flat molecules, between which weak О...H‒C interactions of carbonyl oxygen atoms and hydrogen atoms of aromatic rings exist. [ABSTRACT FROM AUTHOR]

The most widespread procedure for the synthesis of oxyhydrate materials by the sol-gel method is fast alkaline hydrolysis of the soluble salts of heavy metals. Oversaturation of the mother solution during fast hydrolysis provides high dispersity and hence large surface area and availability of the sorption centers of the aggregates being formed. The number and accessibility of sorption centers is also determined by the structure of gel particles. At low hydrolysis rates, there are good possibilities for the structural rearrangements of gel elements, which leads to the formation of ordered supramolecular structures with developed surfaces. The structural characteristics of zirconium gels obtained by fast (5 s), slow (5 days), and ultraslow (5 mos.) alkaline hydrolysis of zirconium oxychloride were determined by derivatography combined with mass and IR spectroscopy (of thermolysis products), X-ray diffraction, IR spectroscopy (xerogels), NMR, electron microscopy, and other methods. [ABSTRACT FROM AUTHOR]

Oxyhydrate gels have a hydrophilic surface, due to which they undergo destruction and secondary polymerization in aqueous media. Prolonged storage in aqueous solution gives rise to regions with selfsimilar helical ordering in gels. Structuring of this kind is also observed when synthesis is conducted under conditions that provide low gelation rates. Electromagnetic UV and visible radiation is another means to change the gel structure; it makes the oligomer species pass into the excited state, due to which one of the directions of structuring becomes dominant. This work summarizes the results of computer simulation of gel agglomerates. For oxyhydrate systems, helical ordering was found to be one of the local energy minima. The units of a macrohelix can lie at various angles relative to one another, and they can change, after absorption of energy, the helix pitch and the order of elements in the helix. [ABSTRACT FROM AUTHOR]

The formation of oxyhydrate gel systems occurs under conditions that are far from equilibrium. Classical methods of synthesis lead to low reproducibility of the properties of these gels, which is due to principal irreproducibility of colloid systems. When special conditions of the synthesis are used (slow precipitation and prolonged aging at room temperature), directed structure formation takes place: self-similar helical structures are formed, variations of physicochemical characteristics of air-dry samples being insignificant. The directions in structure formation of oxyhydrate gels that lead to self-similar helical structures are discussed. Oligomeric gel moieties, the ratio between which determines the properties of the sample as a whole, have been revealed. The results of computer simulation of gel agglomerates are briefly outlined. [ABSTRACT FROM AUTHOR]