20 марта 2023
Ученые ФИЦ «Институт катализа СО РАН» создают материалы для суперконденсаторов из скорлупы кедрового ореха
2 марта 2023
Ученые Института катализа СО РАН использовали СИ для исследования поведения биметаллических катализаторов
The scientific cooperation of the Boreskov Institute of Catalysis with the catalytic communities from various countries is effected in accordance with various forms of cooperation: conducting joint seminars on catalysis, exchanging the information and appropriate materials, exchanging research fellows, visiting scientific centers, and participating in congresses and symposia on theoretical and applied catalysis.
According to research programs, projects and grants, the fundamentals of catalysis are studied jointly with researchers from various universities, institutions, research laboratories and companies. BIC collaborates fruitfully on a commercial basis with the leading companies from more than 20 countries, sells licenses, know-how and performs research projects according to client requests.
Academician Valentin N. Parmon is the Russian representative in the European Federation of Catalytic Societies (EFCATS), Member of the International Association of the Catalysis Societies (IACS).
Austria | 2 | Germany | 26 | South Korea | 3 |
Belarus | 3 | Greece | 11 | Saudi Arabia | 6 |
Belgium | 2 | Ireland | 1 | Spain | 5 |
Bulgaria | 1 | Israel | 5 | Switzerland | 2 |
Brazil | 2 | Italy | 15 | Tunisia | 1 |
China | 9 | Japan | 6 | Turkey | 2 |
Cyprus | 1 | Kazakhstan | 1 | Ukraine | 5 |
Czechia | 1 | Netherlands | 13 | United Kingdom | 7 |
Finland | 22 | Poland | 2 | USA | 13 |
France | 16 | Portugal | 2 |
Visits of foreign specialists to the Boreskov Institute of Catalysis in 2007
Bulgaria | 1 | Italy | 5 | South Korea | 8 |
Finland | 1 | Japan | 8 | United Kingdom | 1 |
France | 4 | Kazakhstan | 4 | USA | 29 |
Germany | 1 | Netherlands | 10 |
ITALY
The cooperation in the frame of the agreement between Russian Academy of Sciences (RAS) and National Council on the Scientific Research of Italy:
FRANCE According to the agreement between RAS and CNRS BIC collaborates with:
INDIA
In the frame of Indo-Russian Integrated Long Term Programme of cooperation in science and technology (ILTP) BIC collaborates with:
• Indian Institute of Chemical Technology, Hyderabad, on the Project “Study and Development of Heterogeneous Photocatalytic Removal of Hazardous Compounds
from Air and Water”. Coordinators: Dr. A. Vorontsov (BIC) and Dr. M. Sabramaniam (Indian Institute of Chemical Technology).
• National Chemical Laboratory, Pune on the Project “Design of Bifunctional Supported Non-Iron Catalysts for Low Temperature Ammonia Synthesis”.
Coordinators: Dr. B. Moroz (BIC) and Dr. A.V. Ramaswamy (National Chemical Laboratory).
Coordinators on the Program “Catalysis” are Acad. V. Parmon and Dr. S. Sivaram.
POLAND
In the frame of RAS-PAS agreement BIC cooperates with:
GERMANY
The cooperation in the frame of the agreement between RAS and German Scientific Research Society (GSRS) with
The cooperation with J. Heyrovského Ústav Fyzikální Chemie AV ČR (J. Heyrovsky Institute of Physical Chemistry ASCR) on the Projects
CHINA
The cooperation in the frame of Associated Research Laboratory which was established by an agreement signed December 4, 2004 by the Boreskov Institute of Catalysis and Heilundzyan University, Harbin. Chief Executive officers of Laboratory are:
Prof. V. Bukhtiyarov (BIC) and Fu Hong-Gang (Heilundzyan University) on the Project
“Synthesis and Modification of ZSM-12 Zeolites. Zeolite ZSM-12 in Reaction of Naphthalene Alkylation with Methanol”. Coordinators: Prof. G.J. Sheng (Heilundzyan University), Prof. G. Echevsky (BIC).
SPAIN
The cooperation with Instituto de Catalisis y Petroleoquimica (Institute of Catalysis and Petroleochemistry), Madrid on the Project “Fundamental and Technical Aspects of in situ Spectroscopic Studies of Oxide Catalysts”. Coordinators: Prof. O. Lapina (BIC) and M.A. Bañares (Instituto de Catalisis y Petroleoquimica).
COOPERATION IN THE FRAME OF PROJECTS FINANCED BY INTERNATIONAL FOUNDATIONS
INTAS SUPPORTED PROJECTSI. Novel Catalytic Process for Industrial Waste Water Treatment < /p>
Project Coordinator:
Dr. P. Gallezot, Institut de Recherches sur la Catalyse, Villeurbanne, France Participants:
Participants:
Acad. V. Parmon, The Boreskov Institute of Catalysis, Novosibirsk, Russia
Prof. B. Laskin, Research Scientific Center for Applied Chemistry, St. Petersburg, Russia.
II. Competitive Hydrogen from Agro-Forestry Residues
Project Coordinator:
Prof. G. Grassi, European Biomass Industry Association (EUBIA), Brussels, Belgium
Participants:
Prof. V. Kirillov, The Boreskov Institute of Catalysis, Novosibirsk, Russia.
III. Sustainable Route to the Generation of Synfuels via Syngas Derived from Biomass
Project Coordinator:
Prof. J. Ross, University of Limerick, Limerick, Ireland
Participants:
Dr. K. Seshan, Universiteit Twente, Enschede, The Netherlands
Dr. O. Hazewinkel, Techno Invent Ingenieursbureau voor Milieutechniek b.v., Zoetermeer, the Netherlands
Prof. V. Sadykov, The Boreskov Institute of Catalysis, Novosibirsk, Russia
Prof. A. Rozovskii, Topchiev Institute of Petrochemical Synthesis, Moscow, Russia.
INTAS - SB RAS Supported Project
Electromagnetic Response Properties of Carbon Onions and Carbon Onion-Based Composites
Project Coordinator:Participants:
Belarus State University, Minsk, Belarus; University of Joensuu, Finland; Institute for Technical Physics and Materials Science, Budapest, Hungary; The Boreskov Institute of Catalysis, Novosibirsk, Russia (Dr. V. Kuznetsov), Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia.
EUROPEAN COMMUNITY SIXTH FRAMEWORK PROGRAM
I. International Partnership for a Hydrogen Economy for Generation of New Ionomer Membranes
Coordinator:
Dr. R. Mallant, Energy Research Centre of The Netherlands, Petten, The Netherlands
Partners:
Daimler Chrysler; FuMA-Tech GmbH; CNRS Montpellier; Dohgyue Chenzhou New Materials Company; Shanghai Jiao Tong University, Shanghai, China; The Boreskov Institute of Catalysis, Novosibirsk, Russia (Prof. V. Bukhtiyarov).
II. Co-Processing of Upgraded Bio-Liquids in Standard Refinery Units
Coordinator:
Dr. Y. Solantausta, VTT Processes, Espoo, Finland
Partners:
Rijksuniversiteit Groningen, The Netherlands; The Boreskov Institute of Catalysis, Novosibirsk, Russia (Prof. V. Kirillov); Uhde Hochdrucktechnik GmbH, Germany; BTG Biomass Technology Group BV, The Netherlands; University of Twente, The Netherlands; STFI-PACKFORSK AG, Sweden; Institute of Wood Chemistry, Hamburg, Germany; Slovenian Institute of Chemistry, Slovenia; Arkema SA, France; Helsinki University of Technology, Finland; ALMA Consulting Group SAS, France; Centre National de la Recherche Scientifique, France; Chimar Hellas SA, Greece; Albermarle Catalysts Company BV, The Netherlands; Metabolic Explorer, France; Shell Global Solutions International, The Netherlands.
III. Non-Noble Catalysts for Proton Exchange Membrane Fuel Cell Anodes
Coordinator:
Dr. G. Tsotridis, Institute for Energy, Joint Research Centre, Petten, The Netherlands
Partners:
Technical University of Denmark, Lyngby, Denmark; The Boreskov Institute of Catalysis, Novosibirsk, Russia (Acad. V. Parmon); Southampton University, United Kingdom; Technical University of Munich, Germany; Bavarian Center for Applied Energy Research; Umicore, AG & Co KG, Germany.
IV. Novel Materials for Silicate-Based Fuel Cells
Coordinator:
Dr. Ch. Arguirusis, Technische Universität Clausthal, Clausthal, Germany
Partners:
University of Aveiro, Aveiro, Portugal; Foundation of Research and Technology Hellas, Greece; Katholieke University of Leuven, Belgium; Max-Plank Institute of Colloids and Interfaces, Munchen, Germany; The Boreskov Institute of Catalysis, Novosibirsk, Russia (Prof. V. Sadykov); Ceramics and Refractories Technological Development Company, Greece; Ceramiques Techniques et Industrielles, France.
NATO PROGRAMME: SCIENCE FOR PEACE
I. Solid Oxide Fuel Cells for Energy Security
NATO Country Project Director:
Prof. N. Orlovskaya, Drexel University, Philadelphia, United States
Partner Country Project Director:
Prof. O. Vasiliev, Frantcevych Institute for Problems of Material Science, Kiev, Ukraine
Project Co-Directors:
Prof. V. Sadykov, The Boreskov Institute of Catalysis, Novosibirsk, Russia
Prof. J. Irvine, University of St. Andrews, St. Andrews, United Kingdom
Prof. N. Sammes, University of Connecticut, Storrs, United States
Prof. R. Hasanov, Azerbaijan State Oil Academy, Baku, Azerbaijan
Dr. A. Schokin, State Committee for Energy Saving of Ukraine, Kiev, Ukraine
Prof. John Kilner, Imperial College, London, United Kingdom.
II. Mixed Conducting Membranes for Partial Oxidation of Natural Gas to Synthesis Gas
NATO Country Project Director:
Prof. J. Frade, Departamento de Engenharia Cerâmica e do Vidro, Universidade de Aveiro, Aveiro, Portugal
Partner Country Project Director:
Dr. V. Kharton, Institute of Physicochemical Problems, Belarus State University, Minsk, Belarus
Project Co-Directors:
Dr. J. Irvine, School of Chemistry, University of St. Andreas, Scotland, United Kingdom Dr. T. Norby, SMN, Universitetet i Oslo, Oslo, Norway Dr. J. Jurado, Instituto de Cerámica y Vidrio, CSIC, Madrid, Spain Prof. V. Sobyanin, The Boreskov Institute of Catalysis, Novosibirsk, Russia Prof. V. Kozhevnikov, Institute of Solid State Chemistry, Ekaterinburg, Russia Dr. L. Boginsky, Institute for Personal Development and Staff Retraining in New Areas of Techniques, Technologies and Economics of the Belarus Ministry of Education, Minsk, Belarus.
NATO PROGRAMME: SCIENCE FOR PEACE AND SECURITY
Capture and Decontamination of Chemical & Biological Agents by Novel Catalysts and Millisecond Jet Reactors
Project Coordinator from a NATO Country:
Prof. P. Smirniotis, University of Cincinnaty, Cincinnaty, United States Project Coordinator from a Partner Country: Dr. A. Vorontsov, The Boreskov Institute of Catalysis, Novosibirsk, Russia.
Project Coordinator from a NATO Country:
Dr. M. Banares, Instituto de Catalisis y Petroleoquimica, Madrid, Spain Dr. M. Ziolek, Adam Mickieiwcz University, Poznan, Poland Project Coordinator from a Partner Country: Prof. O. Lapina, The Boreskov Institute of Catalysis, Novosibirsk, Russia.
INTERNATIONAL SCIENCE AND TECHNOLOGY CENTER (ISTC)
I. Development of Catalysts and Reactors for Syn-Gas Production from Diesel Fuel and for Selective NOx Reduction with Syn-Gas in Diesel Exhausts Project Manager from BIC Prof. V. Kirillov.
II. Development of High-Performance Oxygen-Containing Membranes and Compact Syn-Gas Generators on Their Base
Project Manager from BIC Prof. V. Sadykov.
III. Synthesis and Investigation of the Metal Oxide Catalysts for Photocatalytic Degradation of Harmful Gases Resulted from Terrorist Acts and Man-Caused Catastrophes
Project Manager from BIC Dr. A. Vorontsov.
IV. Catalytic Production of SO3 for Conditioning of Electrostatic Precipitators Using in Russia and the Newly Independent States (NIS)
Project Manager from BIC Prof. A. Zagoruiko.
V. Development of an Integrated Separator for Direct Reforming of Hydrocarbons in High-Temperature Fuel Cells
Project Manager from BIC Prof. Z. Ismagilov.
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A COMPUTATIONAL STUDY OF H2 DISSOCIATION ON SILVER SURFACES: THE EFFECT OF OXYGEN IN THE ADDED ROW STRUCTURE OF Ag(110)
A.B. Mohammad*, K.H. Lim*, I.V. Yudanov, K.M. Neyman*, N. Rösch* (*Technische Universität München, Garching, Germany)
Phys. Chem. Chem. Phys. 9(10) (2007) pp. 1247-1254.
The activation of H2 on clean planar (111), (110) and stepped (221) as well as oxygen pre-covered silver surfaces using a density functional slab model approach was studied computationally. In line with previous data clean silver was determined to be inert towards H2 dissociation, both thermodynamically and kinetically. The reaction is endothermic by approximately 40 kJ mol-1 and exhibits high activation energies of approximately 125 kJ mol-1T>. However, oxygen on the surface, modeled by the reconstructed surface p(2x1)O/Ag(110) that exhibits -O-Ag-O-added rows, renders H2 dissociation clearly exothermic and kinetically feasible. The reaction was calculated to proceed in two steps: first the H-H bond is broken at an Ag-O pair with an activation barrier Ea approximately 70 kJ mol-1, then the H atom bound at an Ag center migrates to a neighboring O center with Ea approximately 12 kJ mol-1.
MECHANISM OF OLEFIN EPOXIDATION WITH TRANSITION METAL PEROXO COMPLEXES: DFT STUDY
I.V. Yudanov
J. Struct. Chem., supply_48 (2007) pp. S111-S124.
Using density functional calculations over the last decade led to considerable progress in understanding the mechanism of olefin epoxidation with Ti, V, Mo, W, and Re peroxo complexes. According to calculations, the reaction occurs by direct electrophilic transfer of one of the atoms of the peroxo group to the olefin. The alternative stepwise mechanism, which has been discussed for a long time and suggested the formation of a metallocyclic intermediate, is characterized by higher activation barriers than direct transfer. The electrophilic character of the direct transfer of oxygen was interpreted at the level of molecular orbital analysis as interaction between the HOMO of the olefin π(C-C) and the LUMO of the peroxo group σ*(O-O). The factors determining the activity of various metal complexes in epoxidation were examined in relation to the ligand environment and the structure of the peroxo group.
ELECTRONIC STRUCTURE AND BONDING OF {Fe(PhNO2)}6 COMPLEXES: A DENSITY FUNCTIONAL THEORY STUDY
O. Isayev*, L. Gorb*, I.L. Zilberberg, J. Leszczynski* (*Jackson State University, Jackson, USA)
J. Phys. Chem. A, 111(18) (2007) pp. 3571-3576.
Reduction of nitro-aromatic compounds (NACs) proceeds through intermediates with a partial electron transfer into the nitro group from a reducing agent. To estimate the extent of such a transfer and, therefore, the activity of various model ferrous-containing reductants toward NAC degradation, the unrestricted density functional theory (DFT) in the basis of paired Lowdin-Amos-Hall orbitals has been applied to complexes of nitrobenzene (NB) and model Fe(II) hydroxides including cationic [FeOH]+, then neutral Fe(OH)2, and finally anionic [Fe(OH)3]-. Electron transfer is considered to be a process of unpairing electrons (without the change of total spin projection Sz) that reveals itself in a substantial spin contamination of the unrestricted solution. The unrestricted orbitals are transformed into localized paired orbitals to determine the orbital channels for a particular electron-transfer state and the weights of idealized charge-transfer and covalent electron structures. This approach allows insight into the electronic structure and bonding of the {Fe(PhNO2)}6 unit (according to Enemark and Feltham notation) to be gained using model nitrobenzene complexes. The electronic structure of this unit can be expressed in terms of π-type covalent bonding [Fe+2(d6, S = 2) - PhNO2(S = 0)] or charge-transfer configuration [Fe+3(d5, S = 5/2) - {PhNO2}-((π*)1, S = 1/2)].
DENSITY FUNCTIONAL THEORY STUDIES OF NITROUS OXIDE ADSORPTION AND DECOMPOSITION ON Ga-ZSM-5
V.N. Solkan*, G.M. Zhidomirov, V.B. Kazansky*
(*Zelinsky Institute of Organic Chemistry, Moscow, Russia)
Int. J. Quantum Chem., 107(13) (2007) pp. 2417-2425.
In this study, density functional theory (DFT/B3LYP) was used to assess a possible reaction pathway for the catalytic dissociation of N2O. The active centers were taken to be mononuclear [Ga]+ and [Ga=O]+, and the surrounding portion of the zeolite was represented by a 3T cluster, namely (AlSi2O4H8). The first step of N2O decomposition involves the formation of [GaO]+ and the release of N2. The metaloxo species produced in this step then react with N2O again, to release N2 and form GaO2. The calculated activation energies for N2O dissociation in Ga-ZSM-5 and GaO-ZSM-5 at B3LYP/6-31+G* level are 22.2 and 24.9 kcal/mol, respectively. The calculated energy of the molecular oxygen elimination from 3T-(GaO2) cluster is ΔH (298 K) = +46.5 kcal/mol and ΔG (298 K) = 35.9 kcal/mol.
SWIFT HOPPING GALLIUM [AlO4]-TETRAHEDRA IN Ga/ZSM - A DFT STUDY
I.V. Kusmin*, G.M. Zhidomirov, V.N. Solkan*
(*Zelinsky Institute of Organic Chemistry, Moscow, Russia)
Int. J. Quantum Chem., 107(13) (2007) pp. 2434-2441.
Density functional theory calculations were carried out to investigate gallium species (Ga+, [GaH2]+, and [GaO]+) stabilization in Ga-exchanged HZSM-5, using cluster modeling approach. Three isomeric gallium positions over [AlO4]- zeolite fragment at T12 position were found. These isomers are turning into each over with low activation energy barrier and gallium fragment revolves around [AlO4]tetrahedron by hopping between cationic positions. Activation energies of gallium fragment hopping were computed and compared for different gallium containing cations. Those barriers were found to be times less than the activation energies of catalytic processes on gallium-exchanged zeolite.
MODELS OF ACTIVE SITES IN SUPPORTED Cu METAL CATALYSTS IN 1,2-DICHLOROETHANE DECHLORINATION. DFT ANALYSIS
V.I. Avdeev, V.I. Kovalchuk*, G.M. Zhidomirov, J.L. d’Itri* (*University of Pittsburgh, Pittsburgh, USA)
J. Struct. Chem., supply_48 (2007) pp. S160-S170.
It is suggested that a set of discrete Cu nanoclusters satisfying the conditions of structural and electron stability should be used as models of active sites on supported metal catalysts. The close-packed Cu20 tetrahedral nanocluster that satisfies these two conditions was taken as a base model of active sites on supported copper catalysts. Theoretical analysis of two possible mechanisms of C-Cl bond dissociation of 1,2-dichloroethane on copper catalysts was performed by the density functional theory method. The first mechanism involves sequential splitting of C-Cl bonds in the molecule in three stages with further stabilization of chloroalkyl intermediates (stepwise mechanism). All these stages are activated. The limiting stage is the one that corresponds to dissociation of the first C-Cl bond with an activation energy of E# =34.3 kcal/mol. The second mechanism corresponds to the simultaneous elimination of two chlorine atoms from 1,2-dichloroethane with liberation of ethylene in the gas phase; this is a one-stage process with an activation energy of E#=26.1 kcal/mol (direct mechanism). A comparison of the two reaction routes shows that the direct mechanism is most probable on copper catalysts.
DFT ANALYSIS OF THE MECHANISM OF 1,2-DICHLOROETHANE DECHLORINATION ON SUPPORTED Cu-Pt BIMETALLIC CATALYSTS
V.I. Avdeev, V.I. Kovalchuk*, G.M. Zhidomirov, J.L. d’Itri * (*University of Pittsburgh, Pittsburgh, USA)
J. Struct. Chem., supply_48 (2007) pp. S171-S183.
The reaction routes of 1,2-dichloroethane dechlorination to ethylene on discrete nanoclusters that served as models of the active sites of supported Cu-Pt catalysts were calculated. Two reaction pathways were predicted. The first route corresponds to sequential elimination of the chlorine atoms from 1,2-dichloroethane; this is a three-stage reaction that occurs via two stable intermediates (stepwise mechanism). The limiting stage is the stage that corresponds to the dissociation of the first C-Cl bond. The second channel corresponds to a simultaneous one-stage elimination of two chlorine atoms (direct mechanism). Both reaction routes are thermodynamically possible, but the stepwise process is more probable, in contrast to the process on monometallic Cu catalysts. For the stepwise process, the vibrational spectra of stable intermediates were calculated for identification of the latter. A set of spectral data characteristic for the stepwise mechanism were determined. The three-step molecular mechanism suggested for 1,2-dichloroethane dechlorination to ethylene is compared with several kinetic schemes known from the literature. Possible modifications of the reaction route that forms ethane and monochloroethane are analyzed.
DENSITY FUNCTIONAL THEORY MOLECULAR CLUSTER STUDY OF COPPER INTERACTION WITH NITRIC OXIDE DIMER IN Cu-ZSM-5 CATALYSTS
I.I. Zakharov,Z.R. Ismagilov, S.Ph. Ruzankin, V.F. Anufrienko, S.A. Yashnik, O.I. Zakharova*
(*East Ukrainian National University, Severodonetsk, Ukraine)
J. Phys. Chem. C, 111(7) (2007) pp. 3080-3089.
The various quantum chemical models of catalytic active site in Cu-ZSM-5 zeolites are analyzed. The density functional theory (DFT) is used to calculate the electronic structure of molecular cluster (HO)3Al-O-Cu-O-Cu modeling the catalytic active site in Cu-ZSM-5 zeolites and study the interaction and decomposition of NO. It is assumed that the rate-determining stage of the low-temperature selective catalytic reduction of NO is the formation of the π-radical (N2O2)-on electron donor sites of Cu-ZSM-5 catalysts. This is in good agreement with the high electron affinity of the molecular dimer ONNO (Ea = -1.5 eV) and is confirmed by the experimental data on the formation of surface anion π-radical (N2O2)- on electron donor sites of supported organo-zirconium surface complex. The DFT calculated electronic structure and excitation energy spectra for the model system (HO)3Al-O-Cu-O-Cu show that it is a satisfactory model for description of experimental UV-vis spectra of Cu-ZSM-5, containing (-O-Cu-O-Cu-) chain structures in the zeolite channels. The calculated reaction energy profile of ONNO adsorption and decomposition on the model catalytic active site shows the possibility of the low-temperature decomposition of dimer (NO)2 with low activation energy and the important role of copper oxide chains (-O-Cu-O-Cu-) in the channels of Cu-ZSM-5 zeolite during selective reduction of NO.
DFT QUANTUM-CHEMICAL CALCULATIONS OF NITROGEN OXIDE CHEMISORPTION AND REACTIVITY ON THE Cu(100) SURFACE
I.I. Zakharov, A.V. Suvorin*, A.I. Kolbasin*, O.I. Zakharova* (*East Ukrainian National University, Severodonetsk, Ukraine)
J. Struct. Chem., supply_48 (2007) pp. S147-S159.
A DFT quantum-chemical study of NO adsorption and reactivity on the Cu20 and Cu16 metal clusters showed that only the molecular form of NO is stabilized on the copper surface. The heat of monomolecular adsorption was calculated to be ΔHm = −49.9 kJ/mol, while dissociative adsorption of NO is energetically unfavorable, ΔHd = +15.7 kJ/mol, and dissociation demands a very high activation energy, Ea = +125.4 kJ/mol. Because of the absence of NO dissociation on the copper surface, the formation mechanism of the reduction products, N2 and N2O, is debatable since the surface reaction ultimately leads to N-O bond cleavage. As the reaction occurs with a very low activation energy, Ea = 7.3 kJ/mol, interpretation of the NO direct reduction mechanism is both an important and intriguing problem because the binding energy in the NO molecule is high (630 kJ/mol) and the experimental studies revealed only physically adsorbed forms on the copper surface. It was found that the formation mechanism of the N2 and N2O reduction products involves formation (on the copper surface) of the (OadN-NOad) dimer intermediate that is chemisorbed via the oxygen atoms and characterized by a stable N-N bond (rN-N ~1.3 Å). The N-N binding between the adsorbed NO molecules occurs through electron-accepting interaction between the oxygen atoms in NO and the metal atoms on the “defective” copper surface. The electronic structure of the (OadN-NOad) surface dimer is characterized by excess electron density (ON-NO)δ− and high reactivity in N-Oad bond dissociation. The calculated activation energy of the destruction of the chemisorbed intermediate (Oad N-NOad) is very low (Ea = 5–10 kJ/mol), which shows that it is kinetically unstable against the instantaneous release of the N2 and N2O reduction products into the gas phase and cannot be identified by modern experimental methods of metal surface studies. At the same time, on the MgO surface and in the individual (Ph3P)2Pt(O2N2) complex, a stable (OadN-NOad) dimer was revealed experimentally.
QUANTUM CHEMICAL EXAMINATION OF INTERACTION OF CYTOSTATIC FLUOROURACIL WITH DEOXYRIBONUCLEIC ACIDS
G. Yuldasheva*, G.M. Zhidomirov (*Biochemistry, National Centre of Examination of Medical Products, Almaty, Kazakhstan)
Int. J. Quantum Chem., 107(13) (2007) pp. 2384-2388.
Within the framework of semiempirical method of quantum chemical PM3, the possibility of formation of paired stack structures under interaction of fluorouracil with pyrimidine and purine nitrogenous bases of nucleotides has been examined. Possible mechanism of transformation of 2-deoxyuridine-5-monophosphate into metabolite-5fluorin-2-deoxyuridine-5-monophosphate has been given. The calculations that were made allow to suppose that biotransformation of 5-FU in 5-fluorin-2deoxyuridine-5-monophosphate, most likely, is carried out not in free nucleotides, but in the structure of DNA in two nucleotide triplets UUC and UGU, including the case when directly two nucleotides of deoxyuridine monophosphate, are transformed into 5-fluorin-2-deoxyuridine-5-monophosphate.
Cytostatic ability of 5-FU is increased by its capacity to be selectively embedded into nucleotide triplets creating new chemical compounds that violate matrix RNA formation and accordingly violate protein synthesis.
CHEMICAL BONDING AND ELECTRONIC STRUCTURE OF LaMnO3 AND La0.75MnO3 ORTHORHOMBIC CRYSTALS
V.M. Tapilin
J. Struct. Chem., 48(2) (2007) pp. 212-218.
The electronic structure of the LaMnO3 orthorhombic crystal of a stoichiometric composition and of La0.75MnO3
crystals with a La vacancy in the unit cell is calculated in the LSDA+U approximation of density functional theory.
The calculations showed that LaMnO3 is an insulator with a forbidden gap of
0.5 eV and with antiferromagnetic ordering of magnetic moments. The magnetic moment on the manganese ions is 3.78 BM. The La atom has ionic bonds
in the lattice, while the bond between oxygen and manganese is covalent. After lanthanum has been removed, geometry optimization of the unit
cell leads to La0.75MnO3 stable structures.
In one of the structures, which is lower in energy, the states of manganese may be
attributed to Mn4+ ions. In both structures with removed lanthanum, the oxygen ions have reduced effective charge, so that one can speak
about O
THEORETICAL AND EXPERIMENTAL DAPS STUDY OF CLEAN, OXYGEN, AND HYDROGEN COVERED Pt(100) SINGLE CRYSTAL SURFACE
A.R. Cholach, V.M. Tapilin
Phys. Chem.: An Indian J., 2(1) (2007) 6 pages.
Local density of states is calculated for the three-fold Pt(100) slab surface covered with various coverage of hydrogen and oxygen. The formation of new surface states region below the platinum conduction band is responsible for covalent contribution to the bond formation between adsorbed species and surface Pt atoms. Resonant states around the substrate Fermi level give an ionic constituent to the adsorbate-surface chemical bond due to considerable DOS difference between adsorbed and surface platinum atoms. Calculated and experimental extended disappearance potential spectra related to different H and O coverage are in a good agreement in spite of baffling complexity of spectral structures. Remarkable similarity between theoretical and experimental results evidences for reliability of obtained data on the LDOS structure of adsorbed system considered.
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