Description
Research areas
Development of methods for calculating the electronic structure and technology of high-performance computing for solving problems of chemistry.
Conducting non-empirical calculations of high-level molecular systems and mechanisms of chemical reactions.
Calculations of the kinetics and modeling of near-electrode reactions
Development of information technology and professional communications for chemical research.
Main results
New methods for calculating the electronic structure of super-large biomolecules and nano-objects
To improve the quantum-chemical description of intermolecular dispersion interactions that play an important role in giant biomolecules, a method has been developed to improve the accuracy of a semi-empirical description of potential energy surfaces, taking into account the valence environment of atoms interacting when molecules approach each other. Based on more than 70,000 reference high-precision non-empirical MP2 / aug-cc-pVTZ calculations for 514 different types of dimers, a significant 2-2.5 times increase was achieved in the accuracy of semi-empirical calculations of intermolecular interactions: from 4.03 kJ / mol in the standard PM3 method to 1.56 kJ / the mole of the proposed method.
A fundamentally new method is currently being developed that combines the speed of semi-empirical methods with accuracy approaching the level of the most widely used modern DFT methods. The current non-iterative version of this method, created so far, reproduces the DFT Fokian an order of magnitude more accurate than the semi-empiric, and 2-3 times more accurate than the DFTB (modeling DFT) method.
Investigation of the structure of radical anions and dianions
Non-empirical multi-configuration methods CASSCF produced a comparative study in the gas and condensed phases of the radical anion and dianion of 1,3-dinitrobenzene. In the ground state, the radical anion exists in the form of two structures, the more stable of which has an asymmetrical structure with an unpaired electron localized on one of the NO2 groups. In contrast to the radical anion, the dianion has a symmetric structure both in the main triplet and in the lowest excited singlet states, the wave function of which is essentially biradical.
Study of the reactivity of radical anions and dianions
Protonation and dimerization reactions
The theoretical (quantum chemistry, numerical simulation) and electroanalytical methods (together with lab. 9) established the mechanism for the electroreduction of dinitrobenzenes in proton-donating media and determined the rate constants of its key stages. It is shown that the selectivity of this process is due to the localization of the electron boundary density in the radical anions of intermediate products — nitronitrosobenzenes — on the nitroso group and the orbital control of the protonation of the latter. This also explains the existence of a dimerization reaction of these particles competing with protonation. A theoretical model describing the influence of various factors on the competition of the mentioned reactions is proposed.
Reactions of breaking the bond
Comprehensive, theoretical and experimental, showed that the factor determining the selectivity of the electroreduction of arylhydroxylamines is the previously unknown reaction of the elimination of hydroxide anions from the radical anions nitrophenylhydroxylamines, which initiates the competing processes of formation of hydrazo and azo derivatives, the output ratio of which changes radically from electroanalytical methods to electrolysis at a controlled potential. Numerical simulation showed that, violation of the principle of scalability, uncharacteristic for other electrochemical processes, in this case is due to the effect on the speed of the cyclic response of mass transfer to the electrode surface: diffusion in electroanalytical methods and forced convection in electrolysis.
It is established that in the anion radical of the product of the reaction of Henri, 1-phenyl-2-nitroethanol, the C – C bond breaks, with the formation of the free radical of benzyl alcohol and the nitromethane anion. The reaction of proton transfer between these particles leads to nitromethane and the radical anion of benzaldehyde, which initiates a cyclic reaction by transferring an electron to the molecule of the original nitro alcohol. The possibility of this reaction should be taken into account both in the implementation of the Henri reaction and in the reduction of β-nitroalcohol to the corresponding amino alcohols.
Theory of the reactivity of radical anions and dianions
The theory of the reactivity of radical anions and dianions, which was developed earlier in the laboratory, was supplemented with theoretical models of the effect of solvation on the chemical behavior of these particles. The results of the study of reactions of anion radicals are summarized in monographs.
