Showing papers in "Russian Chemical Reviews in 1997"
TL;DR: In this paper, the synthesis, properties and applications of polypyrrole (PPy), a representative of conducting polymers, are reviewed, in particular, synthesis of PPy from pyrrole derivatives with the appropriate electroactive groups and introduction of electroactive dopant anions.
Abstract: The synthesis, properties and applications of polypyrrole (PPy), a representative of conducting polymers, are reviewed. Chemical and electrochemical methods for the preparation of PPy and PPy films and the effect of the reaction conditions on the properties of the polymer produced are discussed. The mechanisms of electrochemical polymerisation of pyrrole are compared. The physicomechanical properties of the polymer, its morphology and structure are discussed. The mechanism of charge transfer in PPy is considered within the framework of the model of quasi-equilibrium concentrations of polarons and bipolarons. The methods for modification of the electrochemical performance of PPy are reviewed, in particular, synthesis of PPy from pyrrole derivatives with the appropriate electroactive groups and introduction in the PPy of electroactive dopant anions and the effect of those on the electrochemical performance of PPy films are considered. Examples of the use of PPy are given and the prospects for its application in various areas are discussed. The bibliography includes 254 references.
506 citations
TL;DR: Methods of preparation of phosphorus ylides substituted at the carbon atom of the P=C group with atoms of various elements and their application in organic synthesis are systematised and generalised as discussed by the authors.
Abstract: Methods of preparation of phosphorus ylides substituted at the carbon atom of the P=C group with atoms of various elements and their application in organic synthesis are systematised and generalised The bibliography includes 508 references
166 citations
TL;DR: In this paper, the authors examined the role of hydrogen spillover in various adsorption and catalytic processes, particularly in reactions involving hydrogen on multiphase catalysts. But they focused on the detection of the spillover.
Abstract: The phenomenon of hydrogen spillover (interphase diffusion of adsorbed hydrogen), the methods for its detection, and the factors influencing it are examined. The common occurrence of the spillover and its role in various adsorption and catalytic processes, particularly in reactions involving hydrogen on multiphase catalysts, are demonstrated. The possible mechanisms of the spillover are analysed. The bibliography includes 189 references.
132 citations
TL;DR: In this article, the activation energies for a wide variety of radical abstraction reactions are analyzed. But the activation energy for such reactions depend on their enthalpies, on the force constants of the reacting bonds, the strength, length, and polarity of the X-Y bond in the X• +HY reaction, and also the presence in the reactants of one or several polar groups, π-bonds, and bulky groups adjoining the reaction centre.
Abstract: Two physical models of radical abstraction reactions are described: the model of intersecting parabolas and the model of intersecting Morse curves. A systematic account is given of the results of the analysis of a large set of experimental data (rate constants and activation energies) for a wide variety of radical reactions. It is shown that the activation energies for such reactions depend on their enthalpies, on the force constants of the reacting bonds, the strength, length, and polarity of the X–Y bond in the X• +HY reaction, and also the presence in the reactants of one or several polar groups, π-bonds, and bulky groups adjoining the reaction centre. Solvation plays an important role in processes involving polar reactants. Both methods are compared as instruments for the calculation of the activation energy and bond strengths. The limits of applicability of the methods are examined. The bibliography includes 93 references.
105 citations
TL;DR: The literature data, mainly of the last ten years, on the synthesis, reactions, and practical utilisation of selenium-containing heterocycles are analysed, treated systematically, and surveyed as discussed by the authors.
Abstract: The literature data, mainly of the last ten years, on the synthesis, reactions, and practical utilisation of selenium-containing heterocycles are analysed, treated systematically, and surveyed. The bibliography includes 516 references.
76 citations
TL;DR: In this article, the relationship between electronic transitions and molecular topology of linear conjugated systems, viz. polymethine dyes and α,ω-disubstituted polyenes, is considered.
Abstract: The current state of investigations of the relationship between electronic transitions and molecular topology of linear conjugated systems, viz. polymethine dyes and α,ω-disubstituted polyenes, is considered. The effect of parity of methine groups in a polymethine chain, of filling of the electronic shell, molecular symmetry, and the topology of terminal groups on the electronic structure of polymethines and polyenes are described. Spectral effects arising upon changes in the structures of chromophores, and the nature of the first and higher transitions in linear conjugated compounds containing several chromophores are discussed. The localisation of transitions in molecular fragments and the conditions for the inversion of the polymethine and local electronic transitions in polyenes and polymethines are considered. The bibliography includes 242 references.
74 citations
TL;DR: The results of the studies of the structure and properties of non-crystalline (liquid and amorphous) oxide systems obtained using computer simulation methods are summarised in this paper.
Abstract: The results of the studies of the structure and properties of non-crystalline (liquid and amorphous) oxide systems obtained using computer simulation methods are summarised. The models of simple oxides, homologous series of non-crystalline oxides and of binary and multi-component oxide systems are considered. The results of the simulation of the ion transfer are discussed. The ionic theory of oxides allows one to predict adequately the structural and thermodynamic properties of oxide systems except for the phosphate oxides and some other systems. The bibliography includes 222 references.
63 citations
TL;DR: In this paper, the competitive binding of metals in complexes of bi-and poly-dentate ligand systems was surveyed and treated systematically, focusing on nontraditional ways in which typical ligand system are coordinated and on regioselective synthesis as a method for the specific synthesis of metal complexes with a specified location of the coordinate bond.
Abstract: Data on the problem of competitive coordination, obtained mainly during the last 10 years, are surveyed and treated systematically. The competitive binding of metals in complexes of bi- and poly-dentate ligand systems — simple diatomic and triatomic compounds (N2, O2, CO, CO2, CS2, etc.), ambident anions (CN-, NCX-, NO2-, SO32-, etc.), and neutral aliphatic, aromatic, and heterocyclic compounds, including chelating organic ligands — is examined. Attention is specially concentrated on nontraditional ways in which typical ligand systems are coordinated and on regioselective synthesis as a method for the specific synthesis of metal complexes with a specified location of the coordinate bond. The bibliography includes 575 references.
51 citations
TL;DR: In this article, a review of the self-assembly of lecithin in non-aqueous media is presented, focusing on the dependence of selfassembly at the macroscopic level on interactions at the molecular level, shape of molecules, and their solvation and packing at the interface.
Abstract: Modern concepts of the self-assembly of amphiphiles are considered on the example of self-organising structures of the natural lecithin. Binary, ternary and multicomponent systems are discussed. A considerable part of the review is devoted to the peculiarities of self-organisation of this phospholipid in non-aqueous media and to the role of polar inorganic solvents. Virtually all of the structures formed by lecithin are examined: micelles, swollen micelles, microemulsions, emulsions, organogels, vesicles (liposomes), and lyotropic liquid crystals. In each specific case, attention is drawn to the dependence of self-assembly at the macroscopic level on interactions at the molecular level, shape of molecules, and their solvation and packing at the interface. The self-organising lecithin structures formed in the interfacial area of immiscible liquids in the course of unrestricted adsorption from the bulk of non-aqueous solution are considered. The bibliography includes 282 references.
48 citations
TL;DR: In this paper, the principal features of the thermodynamics and kinetics of ion exchange processes in inorganic ion exchangers are discussed and the literature data on the ion exchange properties of oxide systems, globular hydrates, and salts of polyvalent cations are surveyed.
Abstract: The principal features of the thermodynamics and kinetics of ion-exchange processes in inorganic ion exchangers are discussed. The literature data on the ion-exchange properties of oxide systems, globular hydrates, and salts of polyvalent cations are surveyed. The methods for carrying out ion-exchange processes and the characteristic features of their occurrence on typical inorganic ion-exchange materials are examined. The bibliography includes 306 references.
46 citations
TL;DR: In this article, the authors studied the physicochemical properties of polymer-immobilized nanoparticles in polymeric matrices for both macroligands and the matrices formed in situ, focusing on the controlled chemical passivation of extremely active particles of colloidal size using high-molecular-weight compounds.
Abstract: The essential data on the immobilisation of nanoscale and cluster metal particles in polymeric matrices are considered and systematised for both macroligands and the matrices formed in situ. Special attention is paid to the controlled chemical passivation (stabilisation) of extremely active particles of colloidal size using high-molecular-weight compounds. The routes of formation of polymer-immobilised nanoparticles directly in the polymer medium are analysed. This allows the preparation of compositions characterised not only by the most regular distribution of these particles over the bulk of polymer but also by a strong chemical interaction between the components. Studies in the field of polymer-analogous transformations, which offer a promising approach to the binding of mono- and heterometallic clusters as a new direction in the physicochemistry of nanoparticles, are discussed in detail. The peculiarities of the immobilisation of clusters, polynuclear structures, and nanoparticles by synthetic polymers, on the one hand, and by biopolymers, on the other hand, are considered. The basic fields of the application of the products obtained and the prospects of the development of this direction are outlined. The bibliography includes 394 references.
TL;DR: In this article, the structures of allenes and their reactions with electrophiles were surveyed for the first time and it was shown that the influence of intramolecular interactions on the reactivity of the unsaturated centres is reflected in the selectivity of reactions of PA with electophores.
Abstract: Data on the structures of phosphorylated allenes (PA) and their reactions with electrophiles are surveyed for the first time. It is shown that the influence of intramolecular interactions on the reactivity of the unsaturated centres is reflected in the selectivity of the reactions of PA with electrophiles. Depending on the nature of the reactants and the structure of the PA, various reaction mechanisms may operate. The bibliography includes 163 references.
TL;DR: The use of analytical reagents immobilised on the surface of sorbents in sorption-spectroscopic methods of analysis is surveyed in this article, which includes 131 references.
Abstract: The use of analytical reagents immobilised on the surface of sorbents in sorption-spectroscopic methods of analysis is surveyed. The bibliography includes 131 references.
TL;DR: The main methods of the synthesis of nitrobutadienes and their halogen derivatives, which are multipurpose electrophiles, are surveyed in this article, where the literature data on their chemical transformations are generalised, the possibilities for the preparation of new polyfunctional derivatives of different classes on the basis of the nitro- and halo-nitrobutadiene that have been inaccessible earlier are demonstrated.
Abstract: The main methods of the synthesis of nitrobutadienes and their halogen derivatives, which are multipurpose electrophiles, are surveyed. The literature data on their chemical transformations are generalised, the possibilities for the preparation of new polyfunctional derivatives of different classes on the basis of nitro- and halo-nitrobutadienes that have been inaccessible earlier are demonstrated. The bibliography includes 112 references.
TL;DR: The results of studies on the methods of synthesis of exohedral fullerene hydrides, including the reduction of fullerenes by hydrocarbons, the catalytic hydrogenation of the same, etc., are surveyed in this article.
Abstract: The results of studies on the methods of synthesis of exohedral fullerene hydrides, including the reduction of fullerenes by hydrocarbons, the catalytic hydrogenation of fullerenes, etc., are surveyed. Much attention is devoted to the state of hydrogen in solid fullerene hydrides, the structure of fullerene hydrides, and their reactivity. The bibliography includes 148 references.
TL;DR: In this paper, the methods of synthesis of interstitial phase films (transition metal carbide, nitride, boride, and hydride films) are described and different versions of their chemical and physical deposition from the gas phase are compared.
Abstract: The methods of synthesis of interstitial phase films (transition metal carbide, nitride, boride, and hydride films) are described. Different versions of their chemical and physical deposition from the gas phase are compared and discussed. The available information about the structures, electronic structures, and physicochemical properties of the films (including alloyed and multilayer films) is surveyed and analysed. The bibliography includes 225 references.
TL;DR: In this article, the results of studies on the kinetics of fast reactions of these ions with primary products of water radiolysis (hydrated electron e-aq, H, OH, and O- radicals and H2O2), many inorganic (Cl2-, NO3, SO4-, CO3-, O3- etc.) and organic free radicals are analyzed.
Abstract: The data on radiolytic transformations of ions of uranium, neptunium, plutonium, americium, curium and transcurium elements in aqueous solutions are generalised. The results of studies on the kinetics of fast reactions of these ions with primary products of water radiolysis (hydrated electron e-aq, H, OH, and O- radicals and H2O2), many inorganic (Cl2-, NO3, SO4-, CO3-, O3- etc.) and organic free radicals are analysed. The mechanism of γ- and α-radiolysis of solutions of actinide ions is discussed. The bibliography includes 183 references.
TL;DR: The available data on the problem of hypothetical crystalline carbon nitride are considered in this article, which involve the crystal structure, the nature of chemical bonding, and physical properties of carbon Nitride of which the most interesting is its predicted high hardness comparable with that of diamond.
Abstract: The available data on the problem of hypothetical crystalline carbon nitride are considered. These involve the crystal structure, the nature of chemical bonding, and physical properties of carbon nitride of which the most interesting is its predicted high hardness comparable with that of diamond. The experiments aimed at synthesising carbon nitride are described, and properties of the materials obtained are characterised. The results of thermodynamic calculations pertinent to carbon nitride and processes of its synthesis are discussed. The bibliography includes 144 references.
TL;DR: In this article, the properties of short-lived metal atoms and ions in unusual oxidation states in aqueous solutions, characterised by the presence of one electron in the outer s or p orbitals (the d10s1 and D10s2p1 configurations respectively), are discussed.
Abstract: The properties of short-lived metal atoms and ions in unusual oxidation states in aqueous solutions, characterised by the presence of one electron in the outer s or p orbitals (the d10s1 and d10s2p1 configurations respectively), are discussed. The results of studies on such ions by pulse radiolysis with rapid optical detection and by the matrix isolation method in frozen aqueous solutions are presented. The nature of the dependences of fundamental characteristics of metal atoms and ions (optical transition energies, the electronic structures of various complexes, the oxidation–reduction potentials, etc.) on their positions in the Periodic System are analysed. The bibliography includes 93 references.
TL;DR: The published data on the biological role of nitric oxide formed in vivo by enzymatic oxidation of L-arginine are generalised and the bibliography includes 161 references.
Abstract: The published data on the biological role of nitric oxide formed in vivo by enzymatic oxidation of L-arginine are generalised. Special attention is given to exogenous nitric oxide donors, which can release NO in vitro and in vivo in oxidation, reduction, or hydrolytic cleavage. Also considered are the data on the chemical nature of inhibitors of NO-synthase responsible for nitric oxide formation from L-arginine. The bibliography includes 161 references.
TL;DR: In this article, the synthesis of polyconjugated polyarylenevinylenes and polyeryleneethynylenes based on polycondensation catalysed by palladium complexes is reviewed.
Abstract: Methods for the synthesis of polyconjugated polyarylenevinylenes and polyaryleneethynylenes based on polycondensation catalysed by palladium complexes are reviewed. The bibliography includes 134 references.
TL;DR: Theoretical and experimental data on the electronic structure, chemical bonding, and charge distributions in condensed boron and solid-phase BORON compounds with a number of sp-elements are reviewed in this paper.
Abstract: Theoretical and experimental data on the electronic structure, chemical bonding, and charge distributions in condensed boron and solid-phase boron compounds with a number of sp-elements are reviewed. The applicability of quantum chemistry methods to a description of the physicochemical properties of boron and borides of nonmetals, as well as prospects of using computational methods in the theoretical materials science of borides, are discussed. The bibliography includes 452 references.
TL;DR: In this paper, the processes of electrochemical reduction and oxidation of organosilicon compounds of various classes as well as on the interaction of these compounds with electrically generated reagents are generalised and surveyed systematically.
Abstract: Data on the processes of electrochemical reduction and oxidation of organosilicon compounds of various classes as well as on the interaction of these compounds with electrically generated reagents are generalised and surveyed systematically. The electrochemical reactivity of organic derivatives of silicon is considered taking into account their structures and reaction conditions. The bibliography includes 245 references.
TL;DR: In this paper, published data on the methods for synthesis, reactions and natural occurrence of imidazo[1,2-a]pyrazines are surveyed and some other properties and applications of these compounds are also considered.
Abstract: Published data on the methods for synthesis, reactions and natural occurrence of imidazo[1,2-a]pyrazines are surveyed. Some other properties and applications of these compounds are also considered. The bibliography includes 273 references.
TL;DR: In this paper, the synthesis, chemical properties and practical use of carborane-containing organophosphorus compounds are surveyed and compared with those of similar organophorus derivatives without carboranyl groups.
Abstract: Published data on the synthesis, chemical properties and practical use of carborane-containing organophosphorus compounds are surveyed. Their properties are compared with those of similar organophosphorus derivatives devoid of carboranyl groups. The bibliography includes 89 references.
TL;DR: In this article, the use of alkyl 2-cyanoacrylates in organic synthesis, in polymers and in the chemistry of adhesives is described.
Abstract: Methods for the synthesis, properties and applications of alkyl 2-cyanoacrylates are surveyed. The reactions of alkyl 2-cyanoacrylates with various nucleophiles (thiols, alcohols, diols, hydrogen sulfide, phosphines, etc.) including a new reaction involving insertion of isocyanates and isothiocyanates into the C=C bonds in the adducts of alkyl 2-cyanoacrylates with trialkylphosphines are considered. The prospects for the use of alkyl 2-cyanoacrylates in organic synthesis, in the chemistry of polymers and in the chemistry of adhesives are described. The bibliography includes 117 references.
TL;DR: In this paper, the physical properties of polymers are analyzed on the basis of the physical network model and the possibility of representing the system of intermolecular interactions by an infinite network of physical links is considered.
Abstract: The current views on the nature of the intermolecular interaction and the interchain organisation of polymers in the rubber-elastic state are described. The possibility of representing the system of intermolecular interactions by an infinite network of physical links (the physical network model) is considered. Polymeric physical networks are compared with associated species formed in low-molecular-mass organic compounds containing localised intermolecular interaction centres. The principal physical properties of polymers are analysed on the basis of the physical network model. The bibliography includes 280 references.
TL;DR: In this paper, a systematic account is given of the known data on polytypism in nonmetallic substances with various structures, and the existing hypotheses concerning the nature of poly typism are discussed.
Abstract: A systematic account is given of the known data on polytypism in nonmetallic substances with various structures. The existing hypotheses concerning the nature of polytypism are discussed. It is shown that polytype formation in nonmetallic crystals is a solid-state relaxation rearrangement accompanied by the formation of planar defects of various types, inducing the breakdown in the periodicity of the packing of atomic layers. Such defects and hence structural elements of polytypes may be structural (growths, deformation) and chemical packing defects, microtwins, antiphase boundaries, layers of vacancies, as well as layers of other phases coupled coherently with the basic structure. For diamond-like phases (SiC, AlN, BN), intragranular polytype transformations, induced by the migration of boundaries, occur together with intragranular polytype transformations. The bibliography includes 294 references.
TL;DR: In this article, the main reactions of azafluorenes are analyzed, their reactivity is determined by the presence and mutual influence of two different conjugated fused rings (benzene and pyridine) and the mode of fusion of the indene and Pyridine fragments.
Abstract: Data on the chemistry of azafluorenes (indenopyridines) for the last two decades are summarised. Methods of synthesis of all isomeric (as regards the position of the nitrogen atom) azafluorenes are considered. The main reactions of azafluorenes are analysed, their reactivity is determined by the presence and mutual influence of two different conjugated fused rings (benzene and pyridine) and the mode of fusion of the indene and pyridine fragments. The principal conversions of substituents at different positions of the azafluorene system are considered. Evidence is presented on the natural occurrence of azafluorenes, the biological activity of their synthetic derivatives, and on the structure and physicochemical properties of azafluorenes and their derivatives. The bibliography includes 204 references.
TL;DR: The application of low-frequency vibrational spectroscopy to studies of amides and urethanes including polyamides, polypeptides, and proteins is critically analysed in this paper.
Abstract: The application of the methods of low-frequency vibrational spectroscopy to studies of amides and urethanes including polyamides, polypeptides, and proteins is critically analysed. Special attention is concentrated on the spectroscopic studies of intermolecular interactions and in particular on spectral features of the intrinsic vibrations of hydrogen bonds. The methods are considered that allow one to identify experimentally the bands in the region of 90–130 cm-1 associated with the vibrations of the hydrogen bridge. The potential and limitations of the methods of low-frequency spectroscopy for the investigation of these classes of compounds are discussed. The bibliography includes 131 references.