Vol 66, No 8 (2017)
- Year: 2017
- Articles: 24
- URL: https://journals.rcsi.science/1066-5285/issue/view/14916
Reviews
From lithium-ion to sodium-ion battery
Abstract
The review discusses the problems of development of sodium-ion batteries intended to replace lithium-ion batteries used in large power plants (electric transport, smart grids). The literature data, mainly for the last five years, devoted to electrode functional materials and electrolytes used in sodium-ion batteries are presented and analyzed.
Lithium deintercalation/intercalation processes in cathode materials based on lithium iron phosphate with the olivine structure
Abstract
This review describes the current state of the studies of lithium deintercalation/intercalation processes in cathode materials based on lithium iron phosphate with olivine structure. The limiting factors of LiFePO4 charge/discharge processes, as well as the main methods for their acceleration are considered. A partial replacement of iron cations in the structure improves the electrochemical characteristics of the cathode materials, including the discharge capacity, charge/discharge rate, and, in some cases, changes the charge/discharge mechanism. The use of nanoscale phosphate LiFePO4 with the olivine structure considerably increases the charge/discharge rate of cathode materials based on it by reducing the diffusion path length. Methods for LiFePO4 surface modification are considered. Particular attention is paid to the development of composite materials with electron-conducting additives. Combining of various approaches to the modification of the material in question makes it possible to obtain materials with a discharge capacity close to the theoretical value (170 mA h g–1) at a low charge/discharge rate and to considerably increase its capacity at high charge and discharge currents.
Modern level for properties prediction of iodine-containing organic compounds: the halogen bonds formed by iodine
Abstract
The modern concepts on specific features of anisotropy of the electron density of valence shells of bound atoms and chemical bonds providing the successful description of the properties of halogen bonds formed by the iodine molecule in compounds with useful physicochemical properties are generalized in the review. The prognoses of basicity by the diiodine basicity scale for the nitrogen-containing compounds are illustrated. The regularities and peculiarities of shifting bands in Raman spectra of iodine-containing organic crystals are considered. The methodical and specific problems of modeling appeared when the electronic characteristics of the iodine compounds are estimated and briefly discussed.
Mechanism of the unusual substituent exchange in the reactions of alkylene oxides with organic compounds bearing β-hydroxyalkyl groups at heteroatoms S, Se, N, and P
Abstract
The review summarizes the data on the study of the unusual exchange reaction between alkylene oxides and organic compounds of groups 15 and 16 of the Periodic Table bearing β-hydroxyalkyl substituents at the S, Se, N, and P heteroatoms. Despite the apparent identity of one of the starting reagents and the reaction product (retention of the three-membered ring), the structures of the formed alkylene oxide and organic compound with β-hydroxyalkyl group at the heteroatom differ from the structures of the starting materials. Using β-hydroxyalkyl sulfides as a model, the plausible mechanisms of the exchange reactions were discussed taking into account the change in the reaction order in β-hydroxyalkyl sulfide with its concentration increase. Irrespectively of the mechanism, the first stage of the reaction is the formation of an intermediate H-complex due to the H-bond formation between the OH sulfide group and the alkylene oxide oxygen atom and subsequent (for the dilute solutions) monomolecular intracomplex transformation of this H-complex. The mechanism was confirmed by semi-empirical quantum chemical calculations. In the case of concentrated solutions of β-hydroxyalkyl sulfides, possibility of the formation of intermediate sulfonium salt was discussed. Each pathway proceeds via its unique intermediates and transition states but the final stage results in the same intermediate bipolar ion with an intramolecular H-bond thus leading to the same nature and compositions of the reaction products for all reaction pathways.
Hydrogen sulfide as a source of hydrogen production
Abstract
Potentialities and perspectives of using the known processes of hydrogen sulfide decomposition (thermal, plasmochemical, electrochemical, and photochemical) to produce hydrogen are examined. The results of theoretical and experimental studies of hydrogen sulfide dissociation on the surface of single crystals are presented. The data on the low-temperature decomposition of H2S on the sulfide and metal catalysts are discussed. The electronic structure of diatomic sulfur and thermodynamics of its formation in the processes of H2S decomposition are considered. The decomposition of hydrogen sulfide on the heterogeneous catalysts placed under the solvent layer is shown to be promising. The mechanism of assimilation of hydrogen sulfide by colorless sulfur bacteria is proposed.
Four-coordinate six-membered ketiminate and diketiminate boron complexes. Synthesis, structure, reactivity, and application in the design of nitrogen heterocycles
Abstract
The data on ketiminate and diketiminate boron complexes are first reviewed. The present review is focused on the synthesis and chemical transformations of these chelates. The special attention is paid to the application of these boron chelates in the synthesis of nitrogen heterocycles including CF3-substituted derivatives.
Full Articles
Calculations of interaction energy between certain components of large multimolecular complexes
Abstract
A scheme is proposed for calculating the energies of interaction between certain components of large multimolecular systems. These energies are used to model the binding and extraction of metal ions and metal complexes in solutions. The procedure can be extended with ease to calculate the energies of interaction between any two components of an arbitrary polyatomic system. Practical application of the scheme is illustrated taking actinide binding by different sorbents in solutions as examples.
Potentiometric method for determination of kinetic characteristics of radical reactions in aqueous media
Abstract
Kinetic features of the reactions of K4[Fe(CN)6] with radicals initiated by water-soluble azo-initiator 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) at 37 °C were studied using the potentiometric method. Potassium ferrocyanide was shown to be a radical acceptor, whereas K3[Fe(CN)6] formed by the oxidation with the radicals in combination with K4[Fe(CN)6] is an electrochemical system, the study of which makes it possible to determine kinetic characteristics of radical reactions. The rate constants for the reactions of peroxide radicals RO2 · with K4[Fe(CN)6] were calculated.
Effect of parameters of pulse electrolysis on concentration changes in the loose zinc deposit and deposit properties
Abstract
The parameters of pulse current modes (durations of pulses and pauses between pulses) have a significant influence on the growth dynamics and properties of loose zinc deposits if the process takes place under unsteady-state diffusion conditions. The coefficient k defined as the ratio of the growth time of the loose deposit to the transition time in the pulse was proposed as a criterion for describing the concentration changes. By varying the parameters of pulse electrolysis, one can change the density in situ and the morphology of the electro-deposited metal from highly porous loose deposits with branched dendritic particles to compact deposits.
Synthesis and piezoelectric properties of N-phthaloylglutamic acid derivatives
Abstract
The (S,S)- and (R,R)-enantiomers of dimethyl 2,4-diphthalimidoglutarate were synthesized by nucleophilic substitution of bromine in dimethyl (2S,4RS)-4-bromo-N-phthaloyl-glutamate upon treatment with potassium phthalimide, followed by separation. The crystal structure of the obtained compounds was studied by X-ray diffraction. Crystals of enantiomerically pure dimethyl 4-hydroxy- and 4-phthalimido-N-phthaloylglutamates were found to possess a noticeable piezoelectric activity.
Fe and Ni-catalyzed electrochemical perfluoroalkylation of C—H bonds of coumarins
Abstract
A new method for the preparation of perfluoroalkylcoumarins in a single step is developed. The compounds are prepared via electrocatalytic reduction of a 1 : 1 mixture of an aromatic compound (coumarin, 6-methylcoumarin, and 7-methylcoumarin) and a fluoroalkylating reagent under mild conditions (room temperature, normal pressure) using [bipyFeII] or [bipyNiII] complexes as catalysts. The developed method makes it possible to obtain perfluoroalkylcoumarins in high yields and 100% conversion of the fluoroalkylating reagent.
Chromatographic isolation of vanadyl porphyrins from heavy oil resins
Abstract
A broad fraction of petroleum vanadyl porphyrins of high spectral purity was isolated from heavy oil resins with high vanadium content using a two-step chromatographic method. At the first step, the primary concentrate of vanadyl porphyrins was separated from the resins on the silica gel column. At the second step, it was further purified by the gradient elution through the column packed with sulfo-cationite. According to UV—VIS spectroscopy, this technique allows one to isolate up to 70% of vanadyl porphyrins with the spectral purity corresponding to the best results of other purification methods providing only narrow fractions of vanadyl porphyrins of comparable purity. Deoxophylloerythroetioporphyrin (DPEP) and etioporphyrin (Etio) series of vanadyl porphyrins with the carbon number range of C28—C42 and DPEP/ Etio ratio equal to 1.18 were identified by MALDI-TOF mass-spectrometry.
Synthesis of porphyrin-diazacrown ether and porphyrin-cryptand conjugates for fluorescence detection of copper(II) ions
Abstract
Palladium-catalyzed amination was used for the synthesis of the macrocycles containing trioxadiamine linker and the fragments of either 3,3′-disubstituted biphenyl or 2,7-disubstituted naphthalene. Catalytic macrocyclization gives diazacrown ether-based cryptand with trioxadiamine linker. The synthesized compounds were involved in Pd-catalyzed arylation of zinc meso-(bromophenyl)porphyrin to obtain polymacrocyclic conjugates bearing one or two porphyrin units. The synthesized conjugates were studied as fluorescence sensing material and molecular probes for 18 metal ions. It was found that two of them are very promising fluorescent chemosensors for copper(II) cations.
Sorption of boric acid by polymers containing dihydroxypropylamine fragments
Abstract
Products of polymer-analogous transformations of chitosan, aminopolystyrene, and polyallylamine containing dihydroxypropylamine fragments were used as sorbents of boric acid. A dependence of their sorption properties on the structure of the main polymeric chain and its functionalization degree was found.
Structure-forming role of heterocyclic compounds in the synthesis of metal-organic frameworks based on cadmium(II)
Abstract
The influence of heterocyclic compounds on the formation of coordination polymers in the system of cadmium(II) nitrate tetrahydrate and biphenyl-4,4′-dicarboxylic acid is demonstrated. Two new coordination polymers [Cd(H2O)(bpdc)(im)2] (1, bpdc2– is biphenyl-4,4′-dicarboxylate, im is imidazole) and [(CH3)2NH2]4[Cd6(dmf)(bpdc)8]·10DMF (2) were obtained under solvothermal conditions in the presence of imidazole or benzimidazole, respectively. Product 1 has a chain structure, while compound 2 possesses a three-dimensional structure with the hex topology. The obtained compounds were characterized by IR spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction.
Structural features of polymeric silicon glycerolate hydrogels
Abstract
Structural features of polymeric silicon glycerolate hydrogels based on tetrafunctional silicon glycerolates were investigated using model process, namely, hydrolytic transformation of difunctional silicon glycerolates, by IR and 1H NMR spectroscopy, elemental analysis, atomic emission spectrometry. The possibility of forming a polymer network containing Si—O—Si and Si—OCH2CH(OH)CH2O—Si fragments was demonstrated. The molecular weight of the sub-chains in the network was calculated using Flory—Rehner approach based on the mechanical properties of the swollen network of flexible polymeric chains.
Synthesis of novel non-natural spiro[2.3]hexane amino acids, the conformationally restricted analogs of γ-aminobutyric acid
Abstract
3-Methylenecyclobutanecarboxylic acid and its methyl ester were used as the starting compounds for the synthesis of new spiro[2.3]hexane amino acids, the conformationally rigid analogs of γ-aminobutyric acid, namely, 5-aminospiro[2.3]hexanecarboxylic and 5-amino-spiro[2.3]hexanephosphonic acids, promising modulators of GABAergic cascades in the human central nervous system. The methods developed for the synthesis of the target amino acids are based on the reactions of catalytic [1+2] cycloaddition of diazoacetic and diazophosphonic esters to 3-substituted methylenecyclobutanes, as well as on a modified Curtius reaction for the transformation of a carboxy group to the amine one.
Synthesis and structure of (het)arylglutamic acids and pyroglutamic acid hydrazides
Abstract
Hydrochlorides of (2R*,3R*)-3-(het)arylglutamic acid diesters were synthesized by esterification of the corresponding glutamic acids (Glu). Diesters reacted with hydrazine hydrate to give (4R*,5R*)-2-pyrrolidone-5-carboxylic acid hydrazides. Hydrochlorides of glutamic acids diesters were found to exhibit cardioprotective properties against acute and chronic stress myocardial damage.
Synthesis and search for compounds with hemostatic activity in the series of 4-(het)aryl-4-oxobut-2-enoic acid derivatives
Abstract
New 4-aryl-2-(4-arylamino)-1-(piperazin-1-yl)but-2-ene-1,4-diones and 2-{[2-(3-R-adamantan-1-yl)-2-oxoethylidene]hydrazinyl}-4-(het)aryl-4-oxobut-2-enoic acids were synthesized and used to obtain water-soluble compounds. Their influence on the blood coagulation system was studied, which revealed compounds with a high hemostatic activity and a low acute toxicity. A relationship between structure and pharmacological effect of the synthesized compounds was established.
Adamantane acid esters with alkoxyaryl alcohols: Synthesis, antiproliferative activity, and influence on microtubule network of tumor cells
Abstract
Adamantaneacetic and adamantanecarboxylic acid esters containing 3-hydroxy-4-methoxybenzyl, 3,4,5-trimethoxybenzyl, or 5-(hydroxymethyl)-2-methoxyphenyl groups were synthesized as unusual analogs of natural antitumor and anti-tubulin agents combretastatin A-4 and 2-methoxyestradiol. The compounds were found to possess noticeable cytotoxicity to epithelial human carcinoma cell line A549 (EC50 = 4.3—81 μmol L–1). An ability to cause complete depolymerization of microtubule network of A549 cells was demonstrated for 5-(hydroxymethyl)-2-methoxyphenyl adamantan-1-ylacetate (6a) at a concentration of 100 μmol L–1. Ester 6a belongs to a new structural type, which is unusual for the ligands of the tubulin colchicine domain, and is an interesting lead compound for further structural optimization.
NO-donating and hemolytic activity of tetranitrosyl iron complexes with ligands of the 2-mercaptopyridine series
Abstract
The NO-donating and hemolytic activity of the binuclear tetranitrosyl iron complexes (TNIC) with thiolate ligands of the composition [Fe2(SR)2(NO)4], where R is pyridin-2-yl and 5-nitropyridin-2-yl, was studied. The NO-donating and hemolytic activities of the com- plex with the nitrosubstituted ligand are approximately two and three times higher than the corresponding characteristics of the complex with unsubstituted 2-mercaptopyridine, respectively. Symbate changes in these parameters confirm the conclusion made earlier on the peroxynitrite-dependent mechanism of erythrocyte hemolysis under the action of TNIC. The NO-donating activity of TNIC with ligands of the 2-mercaptopyridine series, unlike the previously studied complexes containing thioderivatives of other nitrogenous heterocycles as S-ligands, did not decrease with an increase in the concentration of erythrocytes. This allows one to consider them as promising NO-donating substances for the preparation of pharma- cological remedies.
Polyfunctional branched nitrogen-containing p-tert-butylthiacalix[4]arene derivatives as efficient agents for packaging calf thymus DNA
Abstract
Polyfunctional p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim with nitrogen-containing fragments in the cone, partial cone, and 1,3-alternate conformations were investigated in the processes of calf thymus DNA packaging. The influence of the macrocycle structure and composition on their ability to pack DNA into nano-sized particles was considered. UV spectroscopy and dynamic light scattering results showed that the synthesized p-tert-butylthiacalix[4]arenes functionalized at the lower rim with polyamine fragments in the cone and 1,3-alternate conformations can compact calf thymus DNA into nanosized particles (<100 nm). A new type of synthetic receptors based on the 1,3-alternate stereoisomer of p-tert-butylthiacalix[4]arene with ester, hydroxy, and tertiary amino groups was suggested for packaging DNA to nanoparticles of 51—85 nm in size.