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Dive into the research topics where A. S. Mendkovich is active.

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Featured researches published by A. S. Mendkovich.


Russian Chemical Bulletin | 2012

Method for the improved semiempirical description of intermolecular interactions of biomolecules and their fragments

N. A. Anikin; V. L. Bugaenko; M. B. Kuzminskii; A. S. Mendkovich

A new method was proposed for the improvement of the semiempirical (PM3, etc. levels of theory) description of intermolecular potential energy surfaces in biomolecules, primarily hydrophobic dispersion-type interactions. The intermolecular interaction energy calculated by the PM3 method is supplemented with the sum of atom-atom corrections represented in a physically meaningful functional form. The corresponding empirical parameters were selected by the least-squares procedure minimizing the root-mean-square deviation of the intermolecular interaction energies from the reference values calculated by the high-accuracy ab initio MP2 method with the quadruple zeta aug-cc-pVTZ basis set. The empirical parameters depend on the valence environment of atoms. The root-mean-square deviation for 74079 reference calculations of small-molecule dimers (with molecular fragments typical of docking complexes) is ∼1.6 kJ mol−1, being about 2.5 times lower than that obtained from conventional PM3 calculations (∼4.0 kJ mol−1). It is important to take into account weak intermolecular atom-atom pairwise interactions because there is a lot of such interacting pairs in biomolecules.


Russian Journal of Electrochemistry | 2011

Dimerization and protonation reactions of nitrosonitrobenzenes radical anions

L. V. Mikhal’chenko; Mikhail A. Syroeshkin; M. Yu. Leonova; A. S. Mendkovich; A. I. Rusakov; V. P. Gul’tyai

The electrochemical behavior of 2-, 3-, and 4-nitrosonitrobenzenes (NNB) in DMF (with Bu4NClO4 suppoting salt) in the presence and in the absence of different proton donors (water, phenol, benzoic, acetic, chloroacetic, and sulfuric acids) is studied by the methods of cyclic voltammetry, chronoamperometry and also by electrolysis at the controlled potential. The electrochemical reduction of these compounds is shown to preferentially afford either monomeric (N-nitrophenylhydroxylamines) or dimeric (azoxy compounds) products, which is determined by the interplay between reactions of protonation and dimerization of NNB radical anions. The dimerization reactions proceed fast and reversibly to afford the corresponding dimeric dianions with the basicity much higher as compared with NNB radical anions as the result of which the monomeric products are formed in the presence of “strong” proton donors and the dimeric products form in the presence of “weak” proton donors. Like the effective rate of formation of dimeric products, the basicity of radical anions increases in the row 4- < 3- < 2-NNB.


Russian Chemical Bulletin | 2014

Fast method for quantum chemical calculations of large molecules with the approximation of the DFT Hamiltonian

N. A. Anikin; V. L. Bugaenko; M. B. Kuz’minskii; A. S. Mendkovich

The fundamentally new method NESE is proposed for quantum chemical calculations of large molecules, which employs the approximation of the Hamiltonian of the commonly used DFT method and is as fast as the AM1 and PM3 semi-empirical methods or the DFTB method. The parameters for the new method were chosen by the least-squares method based on the comparison of its matrix elements with the reference DFT/PBE Hamiltonian. The initial non-iterative version NESE-0 was computer-implemented and approved on many thousands of various molecules containing H, C, N, and O atoms. The NESE-0 method moderately outperforms the DFTB approach and is an order of magnitude better than the AM1, PM3, and PM6 levels in reproducing the one-electron energies calculated in terms of the DFT/PBE.


Russian Chemical Bulletin | 1991

EXPERIMENTAL STUDY OF DIMERIZATION OF RADICAL ANIONS OF AROMATIC CARBONYL COMPOUNDS

A. S. Mendkovich; A. P. Churilina; A. I. Rusakov; V. P. Gul'tyai

The rate constants of dimerization (k1) of radical anions of acetophenone, 1-acetylnaphthalene, 9-acetylanthracene, 9-formylanthracene, and anthracene in DMF containing 0.02 M tetrabutylammonium bromide were determined by differential cyclic voltammetry. It was shown that the values of k1 of the radical anions investigated are correlated with the values of the boundary electron density on the reaction sites, which in turn increase symbatically with an increase in the size of the aryl fragment or on incorporation of electron-acceptor functional groups in the anthracene nucleus.


Russian Chemical Bulletin | 1990

Effect of the structure of the aromatic system on the rate of dimerization of radical anions of aromatic nitro compounds

A. S. Mendkovich; A. P. Churilina; Ludmila V. Mikhalchenko; V. P. Gul'tyai

The radical anions formed in the first stage of electrolytic reduction of 9-nitroanthracene, 1-nitronaphthalene, and nitrobenzene enter into a secondorder reaction in which the value of the rate constant increases as the degree of localization of the unpaired electron on the reaction site increases.


Russian Chemical Bulletin | 2018

A new approach for the acceleration of large-scale serial quantum chemical calculations of docking complexes

N. A. Anikin; A. M. Andreev; M. B. Kuz’minskii; A. S. Mendkovich

A new approach to radical accelerate large-scale quantum chemical calculations of docking complexes, which require large computational times, is proposed. It takes into account the local nature of protein interaction with ligands and is based on a formation of special groups of atoms, which include the compactly located ligands and the protein atoms surrounding them. The procedure based on this approach allowed more than twice to reduce the time of a very resource-consuming calculation with respect to our previous high-speed semi-empirical method without a noticeable decrease in accuracy and provided a level of the time consumption appropriate for the large-scale serial calculations of such complexes.


Russian Chemical Bulletin | 2017

Influence of the nature of solvent and substituents on the oxidation potential of 2,2,6,6-tetramethylpiperidine 1-oxyl derivatives

A. S. Mendkovich; V. B. Luzhkov; Mikhail A. Syroeshkin; V. D. Sen; D. I. Khartsii; A. I. Rusakov

The influence of solvent (DMF, MeCN, and water) and R1, R2 substituent nature on the formal oxidation potential (E°´) of 4-R1,R2-2,2,6,6-tetramethylpiperidine 1-oxyls (1a—f) on a glass carbon electrode was studied by cyclic voltammetry. It was shown that for all the solvents the observed dependence had the form E°´ = ρ″σ″ + b, where σ″ is the substituent constant. The b values decreased with an increase of the solvent solvating ability, while the values ρ″ are similar for all the solvents, surpassing the corresponding values for nitroxyls of the imidazoline series with substituents at position 3, which can be interpreted as an abnormally strong influence of the substituent remote from the reaction center in 1a—f. The experimental values E°´ were linearly correlated with the reaction free energy values (ΔG) calculated by DFT B3LYP and MP2 for the gas phase contribution and by HF/PCM for the contribution of solvation effects. When applying the B3LYP and the HF/PCM approaches in combination, the dependence of E°´ on ΔG for all the considered solvents was described by a linear correlation equation with a slope close to unity and a constant term which was close to the theoretical value of the absolute potential of the reference electrode used.


Russian Chemical Bulletin | 2017

Electroreduction mechanism of N-phenylhydroxylamines in aprotic solvents: formation of hydrogen bonds between N-(3-nitrophenyl)hydroxylamine and its radical anion

A. S. Mendkovich; Mikhail A. Syroeshkin; V. P. Gul'tyai; A. I. Rusakov

The electroreduction of N-(3-nitrophenyl)hydroxylamine in DMF was studied using cyclic voltammetry, chronoamperometry, and numerical simulation. It is shown that the stability of formed radical anion is significantly higher than that of the radical anion of the 4-nitrophenyl derivative. In the range of low concentrations and high potential scan rates, the electroreduction of N-(3-nitrophenyl)hydroxylamine is complicated only by the formation of complexes between the depolarizer molecules, most likely, due to hydrogen bonds, as well as between the depolarizer and its radical anion. The thermodynamic and kinetic parameters of these processes were evaluated.


Russian Chemical Bulletin | 1991

Electrochemically initiated fragmentation reaction of 9,9′-dinitro-9,9′,10,10′-tetrahydro-10,10′-bianthryl

A. S. Mendkovich; Ludmila V. Mikhalchenko; V. P. Gul'tyai

A mechanism for the electroreduction of 9,9′-dinitro-9,9′,10,10′tetrahydro-10,10′-bianthryl in DMF, which results in the formation of anthracene and 9-nitroanthracene has been proposed on the basis of data from polarography, cyclic voltammetry, and electrolysis at a controlled potential.


Russian Chemical Bulletin | 1987

Feasibility of a quantitative description of halide anion abstraction from aromatic radical-anions using quantum chemical reactivity indices

A. I. Rusakov; A. S. Mendkovich; V. N. Leibzon; G. S. Mironov; V. P. Gul'tyai

ConclusionsA quantum chemical reactivity has been proposed which permits the prediction of the rate constant of the halide anion from aromatic halide radical-anions in a rather broad range.

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A. I. Rusakov

Yaroslavl State University

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M. N. Mikhailov

Russian Academy of Sciences

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V. P. Gul'tyai

Russian Academy of Sciences

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N. A. Anikin

Russian Academy of Sciences

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Vadim P. Gultyai

Russian Academy of Sciences

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A. M. Andreev

Russian Academy of Sciences

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