نتایج جستجو برای: boron nitride crown ethers
تعداد نتایج: 53535 فیلتر نتایج به سال:
The structures and stability of 531 novel boron nitride substituted isomers of 12-crown-4 etherverified theoretically. For a collection of 23 selected BN isomers, structural geometry, vibrationalstability, energy gaps, natural bond population analysis, and nonlinear optical responses investigatedtheoretically. The changes of standard enthalpies for ionization reactions and electron affinityreac...
The aim of the present review is to highlight the state of the art in high-pressure design of new advanced materials based on boron nitride. Recent experimental achievements on the governing phase transformation, nanostructuring and chemical synthesis in the systems containing boron nitride at high pressures and high temperatures are presented. All these developments allowed discovering new mat...
Devices made from graphene encapsulated in hexagonal boron-nitride exhibit pronounced negative bend resistance and an anomalous Hall effect, which are a direct consequence of room-temperature ballistic transport at a micrometer scale for a wide range of carrier concentrations. The encapsulation makes graphene practically insusceptible to the ambient atmosphere and, simultaneously, allows the us...
We have synthesized boron nitride nanotubes (BNNTs) in an arc in presence of boron and nitrogen species only, without transition metals. We find that BNNTs are often attached to pure boron nanoparticles, suggesting that root-growth is a likely mechanism for their formation. To gain further insight into this process we have studied key mechanisms for root growth of BNNTs on the surface of a liqu...
Boron nitride nanotubes have been proposed as a suitable reinforcement for metal matrix composites. In order to be effective, the interaction between the metal and the nanotube needs to be strong while retaining the nanotube structure. Computational quantum chemistry was used to study interactions of aluminium and titanium metal clusters with boron nitride nanotubes. The effect of varying the r...
Anionic B complexes have been known and extensively studied as intermediates of nucleophilic aromatic substitution since the beginning of the century.l In a paper that still makes fascinating reading, Meisenheimer describes the formation and isolation of anionic B complexes by reaction of picryl ethers with potassium alkoxides. Structural proof is derived from the fact'that identical u complexe...
A series of adamantane functionalized diaza-lariat ethers 1–6 have been prepared and alkali metal picrate extraction profiles determined. The ability of aza-crown ethers 1–6 to extract the alkali metal picrates was compared with that of diaza-18-crown-6 (7) and N,N '-dibenzodiaza-18-crown-6 (8). Na and K transport across bulk liquid membrane was also measured. The results of alkali metal cation...
we study the coherent spin-polarized transport through a zigzag-edge graphene flake (zgf), using hubbard model in the nearest neighbor approximation within the framework of the green function’s technique and landauer formalism. the system considered consists of electrode/ (zgf)/electrode, in which the electrodes are chosen to be armchair nanoribbons. the study was performed for two types of ele...
sp(2)-Bonded boron nitride aerogels are synthesized from graphene aerogels via carbothermal reduction of boron oxide and simultaneous nitridation. The color and chemical composition of the original gel change dramatically, while structural features down to the nanometer scale are maintained, suggesting a direct conversion of the carbon lattice to boron nitride. Scanning and transmission electro...
We study hydrogen chemisorption at full coverage and low concentrations on hexagonal boron nitride (h-BN). Chemisorption trends reveal the complex nature of hydrogenation. Barriers for diffusion are found to be significantly altered by the presence of additional H atoms. Moreover, the presence of a Stone-Wales defect may dramatically enhance the bond strength of H to the h-BN surface. These fin...
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