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121.
Oleg V. Yazyev 《Solid State Communications》2012,152(15):1431-1436
Recent experimental investigations show that large-area samples of graphene tend to be polycrystalline. Physical properties of such samples are strongly affected by the presence of intrinsic topological defects of polycrystalline materials—dislocations and grain boundaries. This article reviews recent progress in understanding dislocations and grain boundaries in graphene. First, a systematic approach towards constructing topological defects in graphene is introduced. Then, the review discusses the formation energies of these defects, stressing the dramatic stabilization of dislocations and small-angle grain boundaries in graphene due to the two-dimensional nature of this material. Finally, the electronic transport properties of polycrystalline graphene are considered, showing that topological defects may present novel opportunities towards engineering electronic devices based on graphene. 相似文献
122.
Oleg M. Demchuk I. Justyniak B. Miroslaw R. Jasinski 《Journal of Physical Organic Chemistry》2014,27(1):66-73
Because of their unique visual optic and electronic properties, substituted quinones are commonly used as dyes and pigments; nevertheless, a theoretic background of relationship between the structures and optical properties of such compounds seems to be still undeveloped. Two crystalline forms of 2‐methoxynaphth‐1‐yl‐naphthoquinone (MNQ) have been synthesized and characterized by means X‐ray, NMR, UV–VIS, as well as, MS spectroscopy. The interpretation of intriguing optical properties of two crystalline forms of MNQ, based on detailed spectral and structural characterization, as well as, DFT and MP2 computations clearly connects the conformation of the molecules with their optical and electronic properties. Thus, flatter conformation, stabilized by crystal net force, favours the intense electron density transition from auxochrome to chromophore moiety (which corresponds excitation from HOMO to LUMO), as well as, favours the π‐stacking interaction, that eventually results in colour enhancement. At the same time, small molecules of solvents included into the crystal net allow molecules of arylnaphthoquinones to adopt less rigid conformation what has a dramatic optical outcome. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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125.
Yana I. Sakhno Svetlana V. Shishkina Oleg V. Shishkin Vladimir I. Musatov Elena V. Vashchenko Sergey M. Desenko Valentin A. Chebanov 《Molecular diversity》2010,14(3):523-531
Heterocyclization reactions of pyruvic acids, aromatic aldehydes and 5-amino-N-aryl-1H-pyrazole-4-carboxamides yielding four different types of final compounds are described. The reactions involving arylidenpyruvic
acids lead with high degree of selectivity to either 4,7-dihydropyrazolo[1,5-a]pyrimidine-5-carboxylic acids or 5-[(2-oxo-2,5-dihydrofuran-3-yl)amino]-1H-pyrazoles, depending on the catalyst type or temperature regime. The interactions based on arylpyruvic acids can take place
under kinetic or thermodynamic control producing 7-hydroxy-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine-7-carboxylic acids or 3-hydroxy-1-(1H-pyrazol-5-yl)-1,5-dihydro-2H-pyrrol-2-ones, respectively. 相似文献
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127.
Evgenyi V. Gryshkun Natalia V. Andrushko Oleg I. Kolodiazhnyi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1027-1046
Racemic chlorophosphines react stereoselectively with chiral l-phenylethylamines or amino acid esters to give diastereomerically enriched aminophosphines 3, which were isolated as diastereomerically pure crystalline borane complexes. Oxidation, thionation, the reaction with methyl iodide provide optically active derivatives of aminophosphines. (R,S)- and (S,S)-stereomers of phosphinic acid amides were separated by crystallization and a flash-chromatography. The stereochemical properties of phosphorus acid amides were investigated. The mechanism of asymmetric induction at the trivalent phosphorus atom was rationalized. 相似文献
128.
Anastasia O. Kolodiazhna Irina V. Guliaiko Oleg I. Kolodiazhnyi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2335-2346
Abstract The addition of silylphosphines to chiral aldehydes proceeds with high diastereoselectivity to give optically pure tertiary α -trimethylsiloxyalkylphosphines. The diastereomeric excesses of the addition products were achieved to 90–100%. The reaction of bis(trimethylsilyl)phenylphosphine with the acetonide of (R)-glyceraldehyde provides diastereomerically enriched tertiary bis(glyceryl)phosphines. 相似文献
129.
Oleg G. Sinyashin Elvira S. Batyeva Oleg V. Ugryumov Ilyas S. Nizamov Olga A. Varnavskaya S. I. Vasyukov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):21-23
Abstract Novel ammonium salts of O,O-dialkyl dithiophosphoric acids were obtained by one-pot synthesis from white phosphorus, elemental sulfur, industrial alcohols or phenols, and amines. Long-chain S-alkyl O,O-dialkyldithiophosphonates were prepared by the reaction of red phosphorus with elemental sulfur, alcohols, and the cheap industrial fractions of С16–С18 and С20–С26 of higher α-olefins in the presence of Lewis acid catalyst. The dithiophosphates obtained possess the high anticorrosion activities toward mild steel. 相似文献
130.
Almaz Zagidullin Yulia Ganushevich Vasili Miluykov Oleg Sinyashin Evamarie Hey-Hawkins 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):238-242
Abstract The reactivity of 1-alkyl-1,2-diphospholes in cycloaddition reactions with dienes, dienophiles or 1,3-dipoles was examined. 1-Alkyl-1,2-diphospholes (2 ) exhibit dual reactivity and act as diene toward maleic acid derivatives or as dienophiles with 2,3-dimethyl-1,3-butadiene. The 1-alkenyl-1,2-diphospholes (4 ) are readily involved in intramolecular [4 + 2] cycloaddition reactions leading to cage phosphines (5 ). Interaction of 1-alkyl-1,2-diphospholes (2) with 1,3-dipolar reagents (diphenyldiazomethane and nitrones) results in formation of the bicyclic phosphiranes (8) and dimers of 1-alkyl-1,2-diphosphole oxides (9) or bicyclic phosphine oxides (10) with a β-lactam moiety depending on temperature. 相似文献