Layered magnesium silicate was modified by water-insoluble chlorin e6 derivatives with two and three ethanolamine fragments on the periphery of the macrocycle by introducing chlorin e6 derivatives into the reaction medium as solutions in hydrochloric acid without the use of organic solvents. The modified layered silicates obtained are characterized by intense fluorescence along with photostability and exhibit photochemical activity in reactions of photosensitized oxidation of model pollutants like xanthene (rhodamine 6G) and azo dyes (methyl orange).

In this review, we generalize the research results obtained by Russian scientists in the last 10-15 years for porphyrins, related compounds, and their metal complexes with a pronounced application potential. The main attention is paid to the analysis of relationships between the spectral, catalytic, and sensor properties of tetrapyrrole compounds and the structure of peripheral substituents and axial ligands and the nature of the coordinating metal atom.

В данном обзоре обобщены результаты исследований в области порфиринов, родственных соединений и их металлокомплексов с явно выраженным прикладным потенциалом, выполненных российскими учеными в последние 10-15 лет. Основное внимание сосредоточено на анализе взаимосвязи спектральных, каталитических и сенсорных свойств тетрапиррольных соединений со строением экваториального порфиринового и аксиальных лигандов и природой координирующего атома металла.

Synthetic samples of layered magnesium silicate modified with mono-, di-, and tricationic chlorin е6 derivatives have exhibited comparable photochemical activity towards a series of reductants: 1,3-diphenylisobenzofuran selectively oxidizable with singlet oxygen and 1,2-phenylenediamine readily oxidizable with hydrogen peroxide. The optimal photochemical activity of the modified magnesium silicates has been achieved at the ratio of 4–8 μmol of chlorin e6 derivative per 1 g of magnesium silicate.

We show that the colloidal particles formed by chlorin e6 cationic derivatives have a positive charge and their stability decreases with decreasing chlorin concentration. The concentration at which colloid formation begins was found to be determined by the number of cationic groups in the molecule; moreover, as it should be expected, the more cationic groups, the higher this concentration. The formation of stable colloidal particles is facilitated by the presence of a cationic group distant from the macrocycle.

The charge for the iron-potassium oxide system containing powdered cellulose was prepared by the sol-gel procedure and coprecipitation of salts. The influence of the charge preparation procedure, introduction of powdered cellulose, and its amount on the phase formation in the system [Fe 2 O 3 : K 2 O: MoO 3 : CeO 2 : CaO: TiO 2 : MgO: SiO 2 ]: powdered cellulose = (100 − x ) [56.71: 20.88: 11.55: 6.38: 3.68: 0.58: 0.11: 0.11]: x , where x = 0–3 wt %, on the phase formation in the system in the temperature interval 25–1200°C was studied by differential calorimetry and by thermal and X-ray diffraction analysis. The influence of the sintering conditions, introduction of powdered cellulose, and its amount on the textural characteristics of the iron-potassium oxide material was examined. The activation energies of the transformation of maghemite to hematite in the samples were calculated. The contribution of the energy released in thermal degradation of powdered cellulose to the total amount of energy was estimated. Samples of the iron-potassium oxide material with the preset phase composition and textural characteristics required for further studies of the catalytic activity were prepared.

Hectorite type layered magnesium silicate have been synthesized by heat treatment of reaction mixture freshly prepared magnesium hydroxide suspension, silica sol, lithium fluoride solution. The starting Mg(OH)2 : SiO2 : LiF molar ratio was 1 : 1.51 : 0.25. Hybrid systems have been synthesized by heat treatment of synthetic layered magnesium silicate in water-ethanol solution of chlorin е6 13 (1), 17(3)-N,N'-(2-hydroxyethyl) diamide 15(2)-methyl ester. The systems contain of 0.85∙10-6 and 1.4∙10-6mol of the organic component per 1 g of layered magnesium silicate. The introduction of the chlorin e6 derivative into hectorite type layered magnesium silicate sol promotes the aggregation processes and growth particles of the hybrid samples (250±5 nm), as compared with the particles of magnesium silicate (133±1 nm). X-ray phase analysis, UV-Vis spectroscopy and laser Doppler electrophoresis studies have been allowed to establish that non-aggregated molecules of the chlorin e6 derivative are located on the surface of magnesium silicate particles.UV-Vis spectroscopy study showed protonation of nitrogen atoms of the chlorine macrocycle of the chlorin e6 derivative molecules (Soret band 405-406 nm; Q-band 642-643 nm) by hydroxyl groups of the layered magnesium silicate. Chlorin е6 13 (1), 17(3)-N,N'-(2-hydroxyethyl) diamide 15(2)-methyl ester sorption on the surface of magnesium silicate particles occurs due to electrostatic interaction between protonated chlorine e6 derivative molecules and ionized hydroxyl groups of the magnesium silicate.

Magnesium silicates modified with 15(2)-methyl ester of 13(1),17(3)-diamino- N,N ′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e 6 have been synthesized by heat treatment in water containing small fraction of ethanol. X-ray phase analysis, differential scanning calorimetry, thermogravimetry, and UV-Vis spectroscopy studies have shown that the synthesized samples contain individual molecules of 15(2)-methyl ester of 13(1),17(3)-diamino- N,N ′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e 6 held on the inorganic substrate surface by electrostatic interaction and hydrogen bonding.

A ceramic composite [78ZrO2–21CeO2–Y2O3]/La0.85Y0.15Al11O18/Al2O3 (zirconium dioxide submicroparticles stabilized by cerium and yttrium oxides), which consists of a matrix filled with layered submicroparticles of lanthanum hexaaluminate modified by yttrium oxide and reinforced by Al2O3 nanofibers, was obtained. Components of the composite were synthesized by the sol-gel method, except for Al2O3 nanofibers obtained by the electric explosion method. The microstructure and properties of the composite depend on the composition and methods of its formation and sintering. The composite is intended to be used as a construction material.

A ceramic composite [78ZrO(2)-21CeO(2)-Y2O3]/La0.85Y0.15Al11O18/Al2O3 (zirconium dioxide submicroparticles stabilized by cerium and yttrium oxides), which consists of a matrix filled with layered submicroparticles of lanthanum hexaaluminate modified by yttrium oxide and reinforced by Al2O3 nanofibers, was obtained. Components of the composite were synthesized by the sol-gel method, except for Al2O3 nanofibers obtained by the electric explosion method. The microstructure and properties of the composite depend on the composition and methods of its formation and sintering. The composite is intended to be used as a construction material.

Magnesium silicates modified with 13(1)-N-methylamide-17-methyl-15-diethylene glycol ester of chlorin е 6 have been prepared for the first time via heat treatment. The studies by means of X-ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis have revealed that variation of the synthesis conditions affords products differing in the size, particles morphology, and chlorin concentration.

Ceramic fibers of zirconium oxide partially stabilized by ceric oxide were obtained by the template synthesis using sols of initial metals oxides. The formation of the microstructure of ceramic fibers has been studied by the methods of thermal analysis, differential scanning calorimetry, X-ray analysis, scanning electron microscopy, and X-ray spectral analysis. Features of formation of a microstructure of fibers depending on conditions of their preparation were revealed.

Thermal effects accompanying heat treatment of cotton fibers impregnated with mixed sols of zirconium and ceric oxides have been studied by thermogravimetric analysis and differential scanning calorimetry. Increase of ceric oxide fraction changes the temperature of zirconium oxide transition into the high-temperature tetragonal modification.

Organically modified layered magnesium silicate was for the first time synthesized by thermal treatment of a sol of silicon dioxide, magnesium hydroxide, and hexadecyl trimethylammonium bromide, with reflux of the liquid phase. The material obtained can be used as an ultradispersed component in polymer-inorganic composites.

Results of the extraction of aluminum oxide from the product obtained at combined mechanochemical activation of kaolinite and aluminum sulfate crystal hydrate are given. The possibility of increasing the efficiency of aluminum extraction from the activation product with the use of sulfuric acid solutions was determined.

Physicochemical processes that occur in mechanical activation of kaolinite in centrifugal-planetary mills in the presence of concentrated sulfuric acid were studied. A scheme of formation of aluminum sulfate in the course of acid activation was analyzed.

The p K spectra of kaolinite of the Puzlinsk deposit (Komi Republic) mechanically activated in centrifugal planetary mills are obtained. It is shown that even a short mechanical activation of kaolinite is accompanied by significant changes in its structure as demonstrated by variations in the p K spectra of kaolinite and by an increase in its exchange capacity.