Mercuration of α- and γ-methylpyrylium salts with mercuric acetate and trifluoroacetate

Mercury-containing methylpyrylium perchlorates were synthesized by mercuration of - and -methylpyrylium perchlorates with mercuric acetate and trifluoroacetate. A mechanism is proposed for the mercuration reaction. The salts obtained undergo decomposition upon reaction with mineral acids to give the starting methylpyrylium salts, while bromomethylpyrylium perchlorates are formed upon reaction with bromine as a result of cleavage of the C-Hg bond.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 881–886, July, 1981.     

Properties of α-Ferrocenylcarbenium and Ferricinium Salts by Nonaqueous Potentiometric Titration

Potentiometric titration of -ferrocenylcarbenium and ferricinium salts in anhydrous acetonitrile with sodium ethylate involves redox reaction between the titrate and titrant, which, once equimolar amount of the latter has been added, produces a potential jump of 300-400 mV (platinum indicator electrode). The oxida- tion potentials of the -ferrocenylcarbenium and ferricinium salts in anhydrous acetonitrile were estimated at 410-500 mV. The experimental data gave evidence for intramolecular redox processes (redox tautomerism) in the compounds studied.     

α-Ferrocenylalkylation of the benzotriazole anion

Conclusions The N--ferrocenylalkylation of the benzotriazolide ion by -hydroxyferrocenyl derivatives was carried out in a two-phase system consisting of CH₂Cl₂ and 45% aqueous HBF₄ to give high yields of N-ferrocenylalkylbenzotriazoles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1397–1400, June, 1985.Deceased.     

Synthesis and Characterization of a Sol–Gel Derived Ureasilicate Hybrid Organic-Inorganic Matrix Containing CdS Colloidal Particles

The electrical properties of sol–gel-derived films can be tailored by embedding conductive particles of ruthenium dioxide or carbon black in an insulating amorphous SiO₂ silica matrix. The preparation process included an acid hydrolysis of tetraethoxysilane and methyltrimethoxysilane. Then alcohol solutions of ruthenium chloride or carbon black were added. Films of filler concentration up to 60 vol.% were prepared by dip coating and then dried and heat-treated at various temperatures up to 600_°C. The D.C. resistance of the films can be varied within the range of 10⁹ to 10^–2 cm. A non-linear dependence on filler composition in the films was observed for both systems, which is explained by a modified percolation theory. A percolation threshold of 5.5 vol.% for SiO₂-RuO₂ or 50 vol.% for SiO₂-C films, whereby the resistance drastically decreases, was determined. Moreover the temperature dependency of resistance and the current-voltage characteristics of the films can also be explained by this geometric model.     

Mercuration of Salts of 2- and 4-Methyl-substituted Heterocyclic Cations: A Quantum-Chemical Study

The deprotonation energies (H _r) of salts of 2- and 4-methyl-substituted pyridinium, pyrylium, quinolinium, and indolinium salts were evaluated by AM1 calculations. These data allow prediction of the mercuration pathway in reactions of these compounds with mercury salts. The structural factors affecting H _r and the main trends in variation of the geometric and electronic structures of the compounds upon their deprotonation in the course of mercuration were analyzed.     

Coulomb Drag of Dipole Excitons in a Hybrid Exciton–Electron System

The effect of Coulomb drag on a gas of dipole excitons in spatially separated two-dimensional quantum wells containing electron and exciton gases is studied theoretically. The Coulomb drag of excitons can be used to control exciton transport in transistor structures whose active element is a two-dimensional gas of dipole excitons. Expressions for the exciton cross conductivity as a function of temperature are obtained for the diffusion and ballistic transport regimes. For each regime, the limiting cases in terms of the ratio of the Coulomb interaction screening length to the distance between the gases are analyzed. It is shown that, at temperatures exceeding considerably the exciton-gas degeneracy temperature, the cross conductivity is independent of the temperature, while in the opposite case it vanishes exponentially.     

Domain Structure and Magnetization Reversal in Multilayer Structures Consisting of Thin Permalloy Films Separated with Nonmagnetic Interlayers

Russian Physics Journal - Using numerical micromagnetic modeling, we have investigated the development of domain structure and magnetization reversal in multilayer thin-film structures. The...     

Neuroprotective and Antioxidant Enhancing Properties of Selective Equisetum Extracts

The sterile stems belonging to the Equisetum species are often used in traditional medicine of various nations, including Romanians. They are highly efficient in treating urinary tract infections, cardiovascular diseases, respiratory tract infections, and medical skin conditions due to their content of polyphenolic derivatives that have been isolated. In this regard, this study aimed to provide the chemical composition of the extracts obtained from the Equisetum species (E. pratense, E. sylvaticum, E. telmateia) and to investigate the biological action in vitro and in vivo. For the chemical characterization of the analyzed Equisetum species extracts, studies were performed by using ultra-high-performance liquid chromatography (UHPLC-DAD). In vitro evaluation of the antioxidant activity of the plant extracts obtained from these species of Equisetum genus was determined. The neuroprotective activity of these three ethanolic extracts from the Equisetum species using zebrafish tests was determined in vivo. All obtained results were statistically significant. The results indicate that E. sylvaticum extract has a significant antioxidant activity; whereas, E. pratense extract had anxiolytic and antidepressant effects significantly higher than the other two extracts used. All these determinations indicate promising results for the antioxidant in vitro tests and neuroprotective activity of in vivo tests, particularly mediated by their active principles.