Олимпиадные задачи по химии
ИОХ РАН, 2017.
Svitanko I., Кисин В. В., Чуранов С. С.
Leading author: Svitanko I.
Editor-in-chief: Svitanko I.
Development of surface-sulfonated graft anion-exchange membranes with monovalent ion selectivity and antifouling properties for electromembrane processes
, , Journal of Membrane Science 2020 Vol. 612 P. 118408
This communication describes the development of anion-exchange membrane (AEM) with a modified surface possessing monovalent ion selectivity and antifouling properties. Modified AEMs series was obtained by the formation of an oppositely-charged thin layer utilizing the surface sulfonation of the grafted AEMs. The creation of the interface layer leads to a significant increase in the Cl/SO4 ...
Added: August 30, 2020
, , et al., The European Physical Journal E - Soft Matter 2022 Vol. 45 Article 24
A model is developed for describing the transport of charged colloidal particles in an evaporating sessile droplet on the electrified metal substrate in the presence of a solvent flow. The model takes into account the electric charge of colloidal particles and small ions produced by electrolytic dissociation of the active groups on the colloidal particles ...
Added: March 15, 2022
A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones
, , et al., Angewandte Chemie - International Edition 2018 Vol. 57 No. 26 P. 7714-7718
The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective ...
Added: September 29, 2020
, , et al., Organic Letters 2020 Vol. 22 No. 7 P. 2740-2745
Spiro[imidazol-5-one-4,1′-cyclopropanes] behave as donor–acceptor (D–A) cyclopropanes in a formal cycloaddition reaction with aldehydes. The activation of such type of cyclopropanes is achieved with an equivalent of Brønsted acid. The reaction proceeds in high yields of 51–92% and demonstrates moderate diastereoselectivity at the quaternary stereocenter, which is determined by the electron-donating nature of the aldehyde partner. ...
Added: September 29, 2020
, , et al., ChemistrySelect 2017 Vol. 2 No. 25 P. 7508-7513
New β‐diazopyrrole and β‐triazenylpyrrole derivatives were synthesized from isoxazoles and pyridinium salts in two and three steps, respectively. The apoptotic/necrotic difference for these compounds was estimated on THP‐1 cell line. The most effective of the panel is methyl 3‐diazo‐2‐(2,4‐dimethylphenyl)‐4‐phenyl‐3H‐pyrrole‐5‐carboxylate which demonstrated cytotoxic activity from the lowest concentration of 3.3 μM with a steep rise of the ...
Added: June 25, 2019
, , et al., Journal of Physical Chemistry C 2018 Vol. 122 No. 50 P. 28862-28867
Coadsorption of chlorine and oxygen on the Ag(111) surface has been studied with low-temperature scanning tunneling microscopy in combination with density functional theory calculations. Room-temperature adsorption of chlorine onto the Ag(111)-p(4 X 4)-O surface leads to the appearance of new bright objects located between protrusions of the 4 X 4 reconstruction. As chlorine adsorbs, objects form "rosettes" around corner holes. This configuration coincides with the configuration of the chlorine atoms in the Ag(111)-(3 X 3) Cl reconstruction structure. We conclude that the adsorption of chlorine on the Ag(111)-p(4 x 4)-O surface ...
Added: October 25, 2021
Synthesis of Diazanorcaradienes and 1,2-Diazepines via the Tandem [4+2]-Cycloaddition/Retro-[4+2]-Cycloaddition Reaction between Methoxycarbonylcyclopropenes and Dimethoxycarbonyltetrazine
, , et al., European Journal of Organic Chemistry 2019 Vol. 2019 No. 26 P. 4133-4138
The reaction of di(methoxycarbonyl)tetrazine with substituted cycloprop-2-ene-1-carboxylates gives a series of 3,4-diazanorcaradienes and 1,2-diazepines. The influence of the nature of cyclopropenes and the reaction conditions on its selectivity was investigated. The addition of nucleophiles to norcaradienes was studied and a rare example of the “walk” rearrangement in this class of compounds was revealed. ...
Added: October 12, 2019
, , Polymer Science - Series C 2018 Vol. 60 No. Supplement 1 P. 148-159
Theoretical models of the conformational behavior of flexible polymer chains in mixed solvents enunciated in the world literature during the last decade are critically reviewed. Models describing different mechanisms of coil-to-globule transitions in a good solvent induced by cosolvent addition are highlighted. Special attention is given to the analysis of theoretical approaches to describing the ...
Added: November 30, 2018
Adsorption of molecular oxygen on the Ag(111) surface: A combined temperature-programmed desorption and scanning tunneling microscopy study
, , et al., Journal of Chemical Physics 2018 Vol. 148 No. 24 Article 244702
The adsorption of O-2 on Ag(111) between 300 and 500 K has been studied with temperature-programmed desorption (TPD) and scanning tunneling microscopy (STM). At the first stage of adsorption, the disordered local oxide phase (commonly looking in STM as an array of black spots) is formed on the surface irrespective of the substrate temperature. The maximum concentration of black spots was found to be approximate to 0.11 ML, which corresponds to an oxygen coverage of approximate to 0.66 ML. Taking into account that the nucleation of the Ag(111)-p(4 x 4)-O phase starts after the saturation of the disordered phase, one ...
Added: October 25, 2021
Computation of drug solvation free energy in supercritical CO2: alternatives to all-atom computer simulations
, , et al., Fluid Phase Equilibria 2021 Vol. 544-545 Article 113096
Despite the modern level of development of computational chemistry methods and technological progress, fast and accurate determination of solvation free energy remains a huge problem for physical chemists. In this paper, we describe two computational schemes that can potentially solve this problem. We consider systems of poorly soluble drug compounds in supercritical carbon dioxide. Considering that the biggest contribution ...
Added: June 1, 2021
Electron deficient cyclopentadienolate in the synthesis of chromophores with mono-and poly-cyclic hydrazonocyclopentadiene acceptor moieties
, , et al., Dyes and Pigments 2021 Vol. 187 Article 109132
The use of stabilized exocyclic cyclopentadienone enolate, containing three ester groups and a dicyanomethylene fragment, allowed the replacement of unstable cyclopentadienones in the synthesis of arylhydrazonopentadiene chromophores. The presence of reaction centers in the resulting chromophores allowed three additional series of compounds to be obtained. Two series of compounds lost coplanarity in conjugated systems and ...
Added: September 28, 2021
, , et al., RSC advances 2021 Vol. 11 P. 30195-30205
The synthesis and crystal structure of the first molecular yttrium lactate complex, Y(Lac)3(H2O)2, is reported, where the coordination sphere of yttrium is saturated with lactate ligands and water molecules, resulting in a neutral moiety. In Y(Lac)3(H2O)2, hydrogen bonding between a-hydroxy groups and water molecules allows for the formation of 2D layers. A subtle variation in ...
Added: September 23, 2021
Radiation-induced chemistry in the C2H2–H2O system at cryogenic temperatures: a matrix isolation study
, , et al., Monthly Notices of the Royal Astronomical Society 2020 Vol. 491 No. 4 P. 5140-5150
Investigations of the low-temperature radiation-induced transformations in the C2H2–H2O system are relevant to the chemistry occurring in interstellar and cometary ices. In this work, we applied a matrix isolation technique to study the radiation-driven evolution of this system at molecular level in order to get new mechanistic insight. The 1:1 C2H2⋅ ⋅ ⋅H2O complexes were prepared in ...
Added: January 21, 2021
Novel anion exchange membrane with low ionic resistance based on chloromethylated/quaternized‐grafted polystyrene for energy efficient electromembrane processes
, , , Journal of Applied Polymer Science 2020 Vol. 137 No. 19 P. 48656
A novel anion-exchange membrane has been manufactured by chloromethylation and subsequent quaternization of polystyrene within a graft copolymer films based on UV-oxidized polymethylpentene. Particular attention is given to the kinetics of chloromethylation and the influence of the reaction conditions on the properties of the anion-exchange membranes. By means of variation of the polystyrene content and ...
Added: February 27, 2020
Rotating ring-disk electrode as a quantitative tool for the investigation of the oxygen evolution reaction
, , et al., Electrochimica Acta 2018 Vol. 286 P. 304-312
In this work we analyze the applicability limits of the rotating ring-disk electrode (RRDE) technique for quantifying the amount of oxygen produced during the oxygen evolution reaction (OER). We utilize a state-of-the art IrO2 oxide as a carbon-free OER catalyst and La1xSrxMn0.5Co0.5O3d, x . 0.25 and 0.5 perovskites, which are studied in the presence of carbon. RRDE experiments ...
Added: May 29, 2019
, Теоретическая и математическая физика 2019 Т. 201 № 1 С. 65-83
We study the process of a nucleon separating from an atomic nucleus from the mathematical standpoint using experimental values of the binding energy for the nucleus of the given substance. A nucleon becomes a boson at the instant of separating from a fermionic nucleus. We study the further transformations of boson and fermion states of separation in a ...
Added: November 1, 2019
Push-pull molecules bearing a hydrazonocyclopentadiene acceptor moiety: from the synthesis to organic photovoltaic applications
, , et al., Mendeleev Communications 2019 Vol. 29 No. 3 P. 304-306
First representatives of a novel class of compounds containing an electron-accepting hydrazonocyclopentadiene moiety, π-conjugated phenylene spacer, and electron-donating triphenylamine moiety have been synthesized. Investigation of their optical, electrochemical and photovoltaic properties revealed a high potential of the hydrazonocyclopentadiene acceptor moiety in the design of donor-acceptor compounds for organic photovoltaics. ...
Added: October 14, 2020
, , et al., Polymers 2021 Vol. 13 No. 15 P. 2513
Low chemical durability of proton exchange membranes is one the main factors limiting their lifetime in fuel cells. Ceria nanoparticles are the most common free radical scavengers. In this work, hybrid membranes based on Nafion-117 membrane and sulfonic or phosphoric acid functionalized ceria synthesized from various precursors were prepared by the in situ method for ...
Added: February 3, 2022
Диффузионные свойства гетерогенных мембран, допированных оксидом циркония с функционализированной поверхностью
, , , Журнал неорганической химии 2015 Т. 60 № 11 С. 1551-1553
The properties of hybrid materials based on the MK-40 heterogeneous membrane, the MF-4SK homogeneous membrane, and zirconium oxide with a functionalized surface are studied. The ionic conductivity and diffusion parameters of these materials were studied. The presence of the asymmetry effect of diffusion permeability and mutual diffusion of HCl and NaCl solutions through the studied ...
Added: November 13, 2019
, , et al., Synthesis 2021 Vol. 53 No. 24 P. 4689-4699
Directly accessible 8-substituted tetrahydroquinolines undergo 1,5-hydride shift-triggered cyclization to provide hardly accessible julolidine derivatives in 20-98% yield under scandium (III) triflate catalysis. The scope of the reaction, several follow-up transformations and a remarkable side-process discovered during the conditions optimization are highlighted. ...
Added: July 29, 2021
Effects of Support Structure and Composition on the Activity of Cu–Ni Catalysts for Methanol Steam Reforming
, , et al., Inorganic Materials 2019 Vol. 55 No. 12 P. 1230-1236
We have studied the catalytic activity of Cu–Ni bimetallic catalysts on yttrium-, tin-, zinc-, and niobium-doped zirconia and ceria supports for methanol steam reforming (MSR), a process for hydrogen production, and examined the effect of the nature of the dopants and annealing temperature on the structure and particle size of the oxide supports and the ...
Added: November 18, 2019
Reply to Comment on ‘Nonlocal statistical field theory of dipolar particles in electrolyte solutions’
, Journal of Physics: Condensed Matter 2019 Vol. 31 P. 078002-078003
We reply to the comment on our paper by Budkov (2018 J. Phys.: Condens. Matter 30 344001). ...
Added: January 4, 2019
Computational identification of disulfiram and neratinib as putative SARS-CoV-2 main protease inhibitors
, , Mendeleev Communications 2020 Vol. 30 No. 4 P. 419-420
Identification of disulfiram and neratinib as putative covalent inhibitors of SARS-CoV-2 virus main protease Mpro by a combination of 'on-top docking' procedure, expert evaluation of potential hits and molecular dynamics is reported herein. This finding shows the importance of further development of virtual screening add-ons. ...
Added: August 31, 2020
Polylactide nanoparticle impregnation with carbamazepine in supercritical media and its subsequent release in liquid solvents: insights from molecular simulation
, , , Journal of Molecular Liquids 2022 Vol. 352 Article 118758
A full-atomic classical molecular dynamics simulation of polylactide nanoparticle impregnation with carbamazepine in supercritical carbon dioxide was performed. The effect of temperature (333 K, 373 K), pressure (20 MPa, 40 MPa) and ethanol addition (1.7 mol.%) on the impregnation process was studied. Based on the solvent accessible surface area values it was concluded that a pressure increase and cosolvent addition ...
Added: February 19, 2022