RAS Semenov Institute of Chemical Physics

Moscow, Russia

RAS Semenov Institute of Chemical Physics

Moscow, Russia

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Kirillov A.M.,University of Lisbon | Shul'pin G.B.,RAS Semenov Institute of Chemical Physics
Coordination Chemistry Reviews | Year: 2013

The development of new metal complex catalysts and efficient protocols for the mild and selective oxidation of alkanes, arenes, olefins, alcohols, and other organic substrates is a challenging topic in areas of homogeneous catalysis, coordination, and organic chemistry. In these oxidation reactions, the activity of many metal complex catalysts is dramatically improved upon addition of certain co-catalysts or promoters, which can also act as ligands in simple catalytic systems generated in situ. Given the fact that 2-pyrazinecarboxylic acid (Hpca) and analogous heteroaromatic acids such as 2,3-pyrazinedicarboxylic (H2pdca), picolinic (Hpic), and dipicolinic (H2dipic) acids are remarkably efficient and versatile co-catalysts in a high diversity of oxidation systems, the present review summarizes the state-of-the-art knowledge in this field. In particular, this contribution focuses on the use of Hpca as the most active co-catalyst and describes its coordination chemistry with regard to the oxidative transformations of various organic substrates, providing an overview of isolated vanadium, iron, and some other transition metal complexes derived from Hpca. The review also summarizes the applications of Hpca-assisted and related systems in the oxidation of various organic substrates by different oxidants, and highlights the main selectivity, kinetic, and mechanistic features of these oxidative transformations. The paper covers the application of catalytic systems wherein Hpca, H2pdca, Hpic, and H2dipic are used either as co-catalysts (additives) or as ligands within a metal complex catalyst. A special emphasis has been made on the oxidation of alkanes as very inert substrates, and the use of simple and highly efficient [VO3]-/Hpca/H2O2 system. The multifaceted roles of Hpca and analogous co-catalysts have been identified and the analysis of main mechanistic pathways and possible intermediates has been performed. © 2012 Elsevier B.V.


Buchachenko A.L.,RAS Institute of Problems of Chemical Physics | Kuznetsov D.A.,RAS Semenov Institute of Chemical Physics | Breslavskaya N.N.,RAS Kurnakov Institute of General and Inorganic Chemistry
Chemical Reviews | Year: 2012

A study was conducted to demonstrate that an isotope provided significant information about chemistry of enzymatic ATP synthesis. Isotope-containing MgCl 2, CaCl 2, and ZnCl 2 samples were obtained using the treatment of magnesium, calcium, and zinc oxides with analytically pure HCl. Monomeric creatine kinase was purified from Vipera xanthia venom, phosphoglycerate kinase was purified from pig skeletal muscle, and pyruvate kinase was isolated and purified from rabbit muscles. The catalytic activities of enzymes were measured conventionally as the amounts of labeled ATP formed in the presence of [ 32P]phosphocreatine, [ 32P] phosphoglycerate, or [ 32P]phosphopyruvate in 1minute at optimal incubation conditions and corrected to 1 mg of tested pure enzyme. The original electrophoretic technique was employed for loading or substitution of magnesium, calcium, and zinc ions into the enzyme active sites.


Savin A.V.,RAS Semenov Institute of Chemical Physics | Kosevich Y.A.,École Centrale Paris
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

We provide molecular-dynamics simulation of heat transport in one-dimensional molecular chains with different interparticle pair potentials. We show that the thermal conductivity is finite in the thermodynamic limit in chains with the potentials that allow for bond dissociation. The Lennard-Jones, Morse, and Coulomb potentials are such potentials. The convergence of the thermal conductivity is provided by phonon scattering on the locally strongly stretched loose interatomic bonds at low temperature and by the many-particle scattering at high temperature. On the other hand, chains with a confining pair potential, which does not allow for bond dissociation, possess anomalous thermal conductivity, diverging with the chain length. We emphasize that chains with a symmetric or asymmetric Fermi-Pasta-Ulam potential or with combined potentials, containing a parabolic and/or a quartic confining potential, all exhibit anomalous heat transport. © 2014 American Physical Society.


Shul'Pin G.B.,RAS Semenov Institute of Chemical Physics
Dalton Transactions | Year: 2013

This brief essay consists of a few "exciting stories" devoted to relations within a metal-complex catalyst between a metal ion and a coordinated ligand. When, as in the case of a human couple, the rapport of the partners is cordial and a love cements these relations, a chemist finds an ideal married couple, in other words he obtains a catalyst of choice which allows him to functionalize C-H bonds very efficiently and selectively. Examples of such lucky marriages in the catalytic world of ions and ligands are discussed here. Activity of the catalyst is characterized by turnover number (TON) or turnover frequency (TOF) as well as by yield of a target product. Introducing a chelating N,N- or N,O-ligand to the catalyst molecule (this can be an iron or manganese derivative) sharply enhances its activity. However, the activity of vanadium derivatives (with additionally added to the solution pyrazinecarboxylic acid, PCA) as well as of various osmium complexes does not dramatically depend on the nature of ligands surrounding metal ions. Complexes of these metals are very efficient catalysts in oxidations with H2O2. Osmium derivatives are record-holders exhibiting extremely high TONs whereas vanadium complexes are on the second position. Finally, elegant examples of alkane functionalization on the ions of non-transition metals (aluminium, gallium etc.) are described when one ligand within the metal complex (namely, hydroperoxyl ligand HOO-) helps other ligand of this complex (H2O 2 molecule coordinated to the metal) to disintegrate into two species, generating very reactive hydroxyl radical. Hydrogen peroxide molecule, even ligated to the metal ion, is perfectly stable without the assistance of the neighboring HOO- ligand. This ligand can be easily oxidized donating an electron to its partner ligand (H2O2). In an analogous case, when the central ion in the catalyst is a transition metal, this ion changing its oxidation state can donate an electron to the coordinated H 2O2 fragment. This provokes the O-O bond rupture in the hydrogen peroxide molecule as is assumed for the role of Fe2+ ions in the Fenton system. This journal is © 2013 The Royal Society of Chemistry.


Buchachenko A.L.,RAS Semenov Institute of Chemical Physics
Journal of Physical Chemistry B | Year: 2013

Three fundamental properties of atomic nuclei - mass, spin (and related magnetic moment), and volume - are the source of isotope effects. The mostly deserved and popular, with almost hundred-year history, is the mass-dependent isotope effect. The first mass-independent isotope effect which chemically discriminates isotopes by their nuclear spins and nuclear magnetic moments rather than by their masses was detected in 1976. It was named as the magnetic isotope effect because it is controlled by magnetic interaction, i.e., electron-nuclear hyperfine coupling in the paramagnetic species, the reaction intermediates. The effect follows from the universal physical property of chemical reactions to conserve angular momentum (spin) of electrons and nuclei. It is now detected for oxygen, silicon, sulfur, germanium, tin, mercury, magnesium, calcium, zinc, and uranium in a great variety of chemical and biochemical reactions including those of medical and ecological importance. Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. On the physical basis, it is in fact a mass-dependent effect, but it surprisingly results in isotope fractionation which is incompatible with that predicted by traditional mass-dependent effects. It is supposed to be a function of dynamic parameters of reaction and energy relaxation in excited states of products. The third, nuclear volume mass-independent isotope effect is detected in the high-resolution atomic and molecular spectra and in the extraction processes, but there are no unambiguous indications of its importance as an isotope fractionation factor in chemical reactions. © 2013 American Chemical Society.


Shushin A.I.,RAS Semenov Institute of Chemical Physics
Journal of Chemical Physics | Year: 2010

The effect of state-selective reactive decay on the relaxation kinetics of quantum multistate systems is studied in detail in the Bloch-Redfield approach (BRA). The results are applied to the analysis of this effect in radical pair recombination kinetics. The BRA is shown to be able to describe quantitatively most important specific features of the recombination kinetics including those predicted by phenomenological treatment and by recently proposed approaches based on quantum measurement theories. © 2010 American Institute of Physics.


Buchachenko A.L.,RAS Semenov Institute of Chemical Physics
Physics-Uspekhi | Year: 2014

The reasons for elastic energy accumulation in a lithospheric macroreactor - a seismic focus - are discussed. The nonlinear kinetics of the phenomena of an earthquake, a chain chemical explosion, and a nuclear explosion are analyzed. The transition from a stationary regime to an explosion in these three processes occurs as a critical phenomenon with critical parameters representing the concentrations of dislocations, active chemical centers, and neutrons, respectively. It is pro- posed to stimulate the slow relaxation of the elastic energy of the deformation stress of the seismic focus by low-frequency microwaves, which provide the accelerated motion of disloca- tions, reduce the yield limit, and increase plasticity. This phe- nomenon, known as magnetoplasticity in solid-state physics, can be used to keep the seismic focus far from a critical cata- strophic regime by artificially stimulating its slow relaxation. The observed features of the influence of magnetic storms on earthquake dynamics are, in principle, consistent with the con- cept of the stimulated magnetoplasticity of the seismic focus as a means to avoid a catastrophe. © 2014 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences.


Slinko M.M.,RAS Semenov Institute of Chemical Physics
Catalysis Today | Year: 2010

This paper demonstrates through a few selected examples including CO oxidation and methane oxidation over metallic catalysts the knowledge that may be obtained from the study of the oscillatory behaviour over supported and massive catalysts under atmospheric pressure conditions. The information about reaction mechanisms that can be obtained from the waveforms of reaction rate oscillations, from the phase shifts between oscillations of different products concentrations, and from visual observations of surface spatiotemporal behaviour is discussed. © 2010 Elsevier B.V. All rights reserved.


Shul'Pin G.B.,RAS Semenov Institute of Chemical Physics
Organic and Biomolecular Chemistry | Year: 2010

The selectivity is an extremely important characteristic of a chemical reaction. This review deals mainly with supramolecular and nano-chemical approaches to the problem of selectivity enhancement in various functionalizations of C-H compounds. Enzyme mimics is a very fruitful method to achieve the predominant formation of desirable products and isomers. By obstructing the approach of certain C-H bonds of a substrate to the active catalytic centre we simultaneously increase the relative reactivity of other fragments. This can be done by creating steric hindrance around the active centre. Spatial restrictions can be made if we place the catalyst into a nano-cavity. We can achieve discrimination in reactivity of different C-H bonds if we allow certain fragments to approach closely the active centre. In order to do this chemists use coordination of the catalyst to some groups of the substrate with the participation of relatively strong binding (chelate control) or relatively weak forces (molecular recognition). © 2010 The Royal Society of Chemistry.


Shushin A.I.,RAS Semenov Institute of Chemical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Characteristic properties of magnetic field effects (MFEs) on a spin-selective geminate and a bulk electron-hole polaron pair (PP) recombination are analyzed in detail within the approach based on the stochastic Liouville equation. Simple expressions for the magnetic field (B) dependence of recombination yield Y(B) and rate K(B) are derived within two models of relative PP motion: free diffusion and diffusion in the presence of a potential well (cage). The spin evolution of PPs is described, taking in account the relaxation, induced by hyperfine interaction, the anisotropic part of the Zeeman interaction induced, as well as the Δg mechanism. A large variety of B dependences of Y(B) and K(B) is obtained with the change of relative weights of the above-mentioned mechanisms. The proposed general method and derived particular formulas are shown to be quite useful for the analysis of recent experimental results. © 2011 American Physical Society.

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