3 Catalysts based on Ag/γ-Al 2 O 3 are perspective systems for practical implementation of catalytic 4 NO reduction. Nevertheless, mechanism and regularities of this process are still not fully 5 investigated. Herein, we present the results of quantum-chemical research of Ag/γ-Al 2 O 3 catalyst 6 surface and some aspects of NO reduction mechanism on it. Proposed calculation methods using 7 DFT and cluster models of the catalyst surface are compared and verified. The possibility of 8 existence of small adsorbed neutral and cationic silver clusters on the surface of the catalyst is 9 shown. It is demonstrated that NO adsorption on these clusters is energetically favorable, both in 10 the form of monomer and dimer. Scheme of NO selective catalytic reduction (SCR) that explains 11 increasing of N 2 O side-product amount on catalysts with silver fraction more than 2 wt% is 12 proposed. The feasibility of this scheme is justified with calculated data. Some recommendations 13 that allow decreasing amount of N 2 O are developed.
Boron‐dipyrromethene dyes (BODIPY) are of great interest nowadays mostly due to their valuable optical properties. Nevertheless, no systematic research of the optical property dependence on the structure of dyes has been performed yet. In this work, analysis of the available quantum‐chemical methods for BODIPY optical property calculations has been carried out. The accuracy of eight DFT functionals has been studied. The solvation effects upon excitation have been considered within two schemes. The methods that predict the absorption and emission spectra of BODIPY derivatives with high accuracy have been proposed. Using the suggested methods, the influence of nature of substituents and their position in the BODIPY core on the optical spectra of the dyes has been studied. A complex pattern of red‐ and blue‐shifts in optical spectra in dependence of nature and position of substituents has been revealed. The results of this work provide the way for efficient design of BODIPY derivatives with desired optical properties.
Brønsted
superbases have wide applications in organic chemistry
due to their ability to activate C–H bonds. The strongest neutral
bases to date are substituted aminophosphazenes developed in the late
1980s by Reinhard Schwesinger. Since then, much effort has been expended
to create even stronger neutral bases. In this article, the reasons
for the instability of very basic compounds are investigated by means
of high-level quantum-chemical calculations. Theoretical basicity
limits are suggested for solutions as well as for the gas phase. A
record-breaking superbase most likely to be synthesizable and stable
at ambient conditions is proposed. Hexamethylphosphoramide is considered
a reliable ionizing solvent for superbases.
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