Oleg A. Levitskiy

Copper-Assisted Amination of Boronic Acids for Synthesis of Bulky Diarylamines: Experimental and DFT Study

Comparative investigation of copper-assisted oxidative and reductive amination showed that the latter was preferable for the synthesis of bulky diarylamines. DFT estimation of the mechanism of copper(I)-assisted reductive amination of boronic acids with aryl nitroso compounds was performed and possible active species were identified. DFT estimation of the steric penalty revealed that the barrier for the transmetalation step for the hindered nitroso compound was almost the same as that for the unsubstituted one, whereas a bulky group in the boronic acid increased the activation energy. A DFT study of the influence of the electronic properties of the substituents in both reactants on the activation energy revealed that the optimal combination for the synthesis of unsymmetrical diarylamines to provide better yields was an electron-rich aryl boronic acid and an electron-deficient nitroso compound. By using these helpful guidelines, a series of new bulky diarylamines were obtained and fully characterized.

Cerium bis(tetradiazepinoporphyrazinate): synthesis and peculiarities of spectral and electrochemical behavior

Bis{tetrakis(5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazinato} cerium has been prepared for the first time via two alternative synthetic pathways: template macrocyclization of 5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepine-2,3-dicarbonitrile and direct complexation employing its cyclic tetramer, a free-base porphyrazine ligand. A combination of HRMS, UV-Vis, FT-IR and NMR spectroscopic methods allowed the identification of the tetravalent oxidation state of cerium ion in the double-decker obtained. Unlike Pc2CeIV (Pc2− = phthalocyaninate anion), the compound revealed a complicated UV-Vis spectrum that demonstrated a strong solvent dependence. A comparative electrochemical study of the cerium complex and the corresponding free-base ligand was carried out. Ligand-centered processes are diffusion controlled, whereas Ce4+/3+ transformation is characterized by slow electron transfer kinetics. This is as a result of poor accessibility of the metal center to an electrode surface due to the presence of bulky ligands, as well as a considerable structural rearrangement of the sandwich molecule.

Individual (f,tA)- and (f,tC)-Fullerene-Based Nickel(II) Glycinates: Protected Chiral Amino Acids Directly Linked to a Chiral π-Electron System

Stereoselective electrosynthesis of the first individual (f,t A)- and (f,t C)-1,4-fullerene derivatives with a non-inherently chiral functionalization pattern is described, as well as the first example of an optically pure protected primary amino acid directly linked to the fullerene through only the chiral α-amino-acid carbon atom. An application of an auxiliary chiral nickel-Schiff base moiety as derivatizing agent allowed separation of (f,t A)- and (f,t C)-1,4-fullerene derivatives using an achiral stationary phase, a separation which has never been done before.

Correction to: Sol-gel-modified membranes for all-organic battery based on bis-(tert-butylphenyl)nitroxide

The author would like to add photos and biographies as the paper is a Special Issue dedicated to Prof. Vladimir Sergeyev. The original article has been corrected.

Sol-gel-modified membranes for all-organic battery based on bis-(tert-butylphenyl)nitroxide

It has been shown that sol-gel modification of Nafion membrane with amino-containing silica nanoparticles followed by neutralization converting the membrane in the salt form prevents decomposition of the model redox-active compound, bis(tert-butylphenyl)nitroxide, and suppresses its crossover yet maintaining sufficient permeability of a supporting electrolyte in acetonitrile solution. Bis(tert-butylphenyl)nitroxide is stable under the operation conditions of the redox flow battery assembled with Celgard membrane.