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Frontispiece: Novel Peptide Chemistry in Terrestrial Animals: Natural Luciferin Analogues from the Bioluminescent Earthworm Fridericia heliota 下载免费PDF全文
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A quasichemical method that combines ab initio treatment of explicit solvent with dielectric continuum models has been used to study the origin of a strong effect of methanol on the extent of iron(III) [tetrakis(pentafluorophenyl)]porphyrin chloride dissociation in acetonitrile-methanol solutions. It is shown that the dissociation is energetically more favorable in methanol than in acetonitrile primarily because of the strong specific interactions between the chloride anion and the solvent methanol molecules in its first solvation shell. These interactions are weaker in acetonitrile. The final estimate for the difference in the dissociation free energies in methanol and acetonitrile is -23 kJ/mol, in a good agreement with the experimental value of -21 kJ/mol. Energy decomposition analysis of chloride-solvent interactions suggests that stronger chloride-methanol binding is a result of the contribution of charge delocalization effects to the chloride-methanol interactions. 相似文献
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Prof. Dr. Alexey A. Goryunkov Dr. Nail L. Asfandiarov Rustam G. Rakhmeev Angelina V. Markova Dr. Stanislav A. Pshenichnyuk Alexey V. Rybalchenko Dr. Natalia S. Lukonina Prof. Dr. Ilya N. Ioffe 《Chemphyschem》2022,23(10):e202200038
Gas phase molecules of hexachlorobenzene (C6Cl6) were investigated by means of dissociative electron attachment spectroscopy (DEAS). Three channels of molecular negative ions decay have been identified: abstraction of Cl− and Cl2− as well as electron detachment (τa∼250 μs at 343 K). All three channels exhibit temperature dependence. The adiabatic electron affinity estimated using a simple but typically accurate Arrhenius model (EAa=1.6–1.9 eV) turns out to be much higher than the quantum-chemical predictions (EAa=0.9–1.0 eV). We discuss the possible reasons behind the observed discrepancy. 相似文献
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Vladimir A. D’yakonov Rustam K. Timerkhanov Tatiana V. Tumkina Natal’ya R. Popod’ko Askhat G. Ibragimov Usein M. Dzhemilev 《Tetrahedron letters》2009,50(12):1270-1272
Catalytic intermolecular cycloalumination of cyclo-1,2-dienes and olefins assisted by EtAlCl2 in the presence of Cp2ZrCl2 as catalyst gave rise to unsaturated di- and polycyclic aluminacarbocycles. 相似文献
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AbstractThe grain refinement and mechanical properties of a Cu–0.1Cr–0.06Zr alloy subjected to equal channel angular pressing (ECAP) at a temperature of 673 K were examined. The microstructure evolution was characterised by the development of a large number of low-angle subboundaries at small strains. An increase in the true strain resulted in gradual transformation of low-angle subboundaries into high-angle grain boundaries that was assisted by the deformation micro-banding. The development of new ultra-fine grains was considered as a kind of continuous dynamic recrystallization, the kinetics of which was characterised by a sigmoid-type dependence on strain and could be expressed by a modified Johnson–Mehl–Avrami–Kolmogorov equation. ECAP led to significant strengthening of the alloy. The yield strength increased from 105 MPa in the initial state to 390 MPa after 8 ECAP passes. A modified Hall–Petch relationship was applied to analyse the contributions of grain refinement and dislocation density to the overall strengthening. In spite of significant strengthening, the electro-conductivity remained at a level of 80% IACS. 相似文献
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Altu? Mert Sevim Rustam Hojiyev Ahmet Gül Mehmet Sabri ?elik 《Monatshefte für Chemie / Chemical Monthly》2012,102(1):385-400
Abstract
Adsorption of an octacationic tetrapyrrole, octakis(2-trimethylammoniumethylsulfanyl)porphyrazinatocobalt octaiodide (QCoPz), from aqueous solutions on to negatively charged bentonite was investigated. Effects of temperature, dye concentration, solid concentration, and contact time on adsorption were determined. Zeta potential and ion-release measurements were also used as supporting experiments. Experimental data were analyzed using four adsorption kinetic models; a pseudo second-order kinetic model resulted in better correlation with experimental results than the others. Experimental equilibrium data were analyzed by non-linear regression using five adsorption isotherm models with two, three, or four terms. Free energies, enthalpies, and entropies for the adsorption process were determined. The results indicated that adsorption of QCoPz on bentonite was exothermic and spontaneous in nature. FT-IR spectroscopy of the composite and its desorptive behavior were also investigated to identify the mechanism of adsorption. The novel QCoPz–bentonite composites obtained are likely to be used in “green chemistry” and in a wide range of optical and/or catalytic applications, especially those crucially important in the petroleum and pulp/paper industries for waste water cleaning (destruction of mercaptans, sulfides, phenol, and halogenated aromatics, etc.) and removal of bad odor. 相似文献50.
Alexey Suknev Vladimir Goncharov Alexey Korchagin Vladislav Cherepkov Rustam Salimov Nikolay Kuksanov Vladimir Zaikovskii Irina Kraevskaya Sergey Bogdanov Bair Balzhinimaev 《Reaction Kinetics and Catalysis Letters》2005,86(1):179-185
Summary Structural properties of ultra-dispersed silver powders synthesized via high-temperature electron-beam evaporation of silver in different gases (Ar, N2, He) were studied with XRD, TEM, EDX and XRF. The formation of specific oxide-like species on the particle surface of an Ag(Ar) powder was found. It was shown that these particles can contain argon atoms. 相似文献