Theoretical and Experimental Chemistry最新文献

New catalytic methods for the hydrodehalogenation of haloarenes with hydrogen and hydrogen-containing reagents (metal and non-metal hydrids, organic hydrogen-containing compounds, etc.), which are essential for fine organic synthesis and neutralization of toxic production waste and persistent organic pollutants. The paper focuses on such catalysts as complexes of stable heterocyclic carbenes, transition metals, and nanosized metal particles and their composites, as the most promising for industrial chemistry. Catalysts with particularly high efficiency have been highlighted.

It is shown that the derivatives of 4,5-diazafluorenone-9-hydrazone containing thiophene and aldehyde anchor groups, as well as mixed-ligand Ru(II) complexes with these dyes and bipyridine, have the properties of sensibilizers of TiO₂-based photovoltaic cells. The power conversion efficiency (η) in such photovoltaic elements under simulated 100 mW/cm² solar radiation is in the range of 0.25-0.48%. The value of η in the case of compounds, bearing thiophene-2,5-dicarbaldehyde fragment as an anchor, is almost two times higher compared to the analogues, containing non-substituted thiophene fragment.

The influence of carbon dioxide concentration in biogas on the composition of its reforming products has been studied to achieve optimal methanol synthesis conditions. A model of the biogas reforming stage is proposed. An optimal concentration of carbon dioxide in biogas essential for maximizing methanol production has been found. The effect of geometric characteristics of the mixing device on the homogeneity of the reacting flow, which is a critical for the process performance, has been established.

A method of montmorillonite modification with polar oligourethane containing reactive amino groups has been developed. It is shown that functionalized montmorillonite is capable of adding aromatic and aliphatic diisocyanates, as well as sequential addition of aromatic diisocyanates and glycerol, which is essential for montmorillonite application as filler for polymer materials. According to wide-angle X-ray scattering, interlayer distance d₀₀₁ of montmorillonite in the obtained samples varies depending on nature of oligomer macromolecules in the interlayer space that is explained with different conformation and orientation of aromatic and aliphatic oligourethane fragments.

The effect of the zeolite framework composition on the selectivity and thermodynamic parameters of ion exchange is studied for the exchange reaction of Ca²⁺ cations on Na-forms of clinoptilolites from nine deposits of Central and Southeast Europe, Northeast Asia, and North America. An increase in the thermodynamic affinity of Na-forms towards Ca²⁺ cations is shown with a decrease in the Si/Al ratio in their zeolite framework.

The photocatalytic conversion of lignin, obtained from camelina (Camelina sativa), over titania and iron titanate films has been studied with analysis of the products using laser desorptiopn/ionization and high-performance liquid chromatography. The photocatalytic reaction over titania films leads to the formation of the mixture of compounds, such as phenol, vanillic acid, resorcinol, and p-coumaryl alcohol. In the presence of iron titanate films, the predominant reaction products are vanillic acid and p-coumaryl. The highest antioxidant activity has been revealed in the case of lignin conversion products obtained over nitrogen-containing iron titanate films under visible light exposure.

Nitrogen-doped carbon, which is characterized by a large surface area and the presence of micro- and mesopores, has been obtained by pyrolysis of polyaniline (emeraldine base) in a reducing atmosphere. It is found that the surface layer of such material contains nitrogen in pyridinic, pyrrolic, and quaternary configurations, as well as hydroxyl and carbonyl groups. It is shown that carbonized polyaniline reveals catalytic properties in the processes of gas-phase and liquid-phase hydrogenation with molecular hydrogen of organic substrates containing C=C double bond and nitro group (ethylene, α-methylstyrene, p-nitrotoluene) are revealed.

It is shown that deposition of Rh-CD (CDs are carbon dots)onto SiO₂, Al₂O₃, and ZrO₂ oxide supports contributes to the appearance of the catalytic activity in the process of glycerol conversion. It is established that acrolein and acetaldehyde are oxygen-containing products in this reaction system. It is found that the yield of reaction products increases when using a support with a smaller specific surface area, which is caused by an increase in the surface concentration of acid sites.

The current state of research on non-conventional luminescence of unconjugated polymers, which is caused by the occurrence of through-space conjugation due to the overlapping of electronic orbitals of atoms in aggregates formed at high concentrations of substances in solutions or the solid state, is considered. The luminescent properties of different types of polymers containing oxygen, nitrogen, sulfur, silicon, boron, phosphorus is analyzed. The possibilities of the practical applications of polymer cluster luminophores in the fields such as ecosystem monitoring, medicine, biology, encryption, forensics, and optoelectronics are shown.