Search results for "FULLERENE"
showing 10 items of 197 documents
Effect of the nanotube aspect ratio and surface functionalization on the morphology and properties of multiwalled carbon nanotube polyamide-based fib…
2013
In this study, the effect of the carbon nanotube (CNT) aspect ratio and surface functionalization on the mechanical behavior and morphological changes of polyamide (PA)-based fibers was investigated. Composites were prepared by the melt blending of CNTs with PA, and at a later time, the fibers were prepared by melt spinning and cold drawing. A reinforcement effect was noticed for all of the CNTs samples, and the increase in the mechanical properties and dimensional stability was more pronounced for highly oriented filaments. When the elongational flow was increased, the orientation of CNTs along the fiber direction was observed, but the nanotube alignment was much more difficult for CNTs wi…
Fullerene as a Platform for Recyclable TEMPO Organocatalysts for the Oxidation of Alcohols
2014
[60]Fullerene has been employed successfully as a molecular platform to anchor 12 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties. Such an octahedrally substituted C60-derivative has been employed as an organocatalyst for the oxidation of primary and secondary alcohols using the Anelli protocol. The reaction showed a general applicability to various alcohols, and the catalyst was recovered easily and could be recycled for at least seven cycles with no loss in catalytic activity. EPR spectroscopy studies revealed that the amount of radicals decreases during the catalytic cycles, even if the recovered material still displays unchanged catalytic activity. This new approach paves the way …
Nanostructures Cluster Models in Solution
2014
The existence of Single-Wall C-Nanocones (SWNCs), especially nanohorns (SWNHs), and BC2N/Boron Nitride (BN) analogues in cluster form is discussed in solution in this chapter. Theories are developed based on models bundlet and droplet describing size-distribution function. The phenomena present unified explanation in bundlet in which free energy of (BC2N/BN-)SWNCs involved in cluster is combined from two parts: volume one proportional to the number of molecules n in cluster and surface one, to n1/2. Bundlet enables describing distribution function of (BC2N/BN-)SWNC clusters by size. From geometrical differences bundlet [(BC2N/BN-)SWNCs] and droplet (C60/B15C30N15/B30N30) predict dissimilar …
Fullerite crystal thermodynamic characteristics and the law of corresponding states.
2010
The existence of single-wall carbon nanotubes in organic solvents in the form of clusters is discussed. A theory is developed based on a bundlet model, which enables describing the cluster-size distribution function. Comparison of calculated solubilities with experiments would permit obtaining energetic parameters, characterizing the interaction of a nanotube with its surrounding. Fullerenes and nanotubes are objects whose behaviour in many physical situations is characterized by peculiarities, which show up in that these systems represent the only soluble forms of carbon, what is related to their molecular structures. The fullerene molecule is a virtually uniform closed spherical-spheroida…
Synthesis of Fullerene- and Nanotube-Like SnS2 Nanoparticles and Sn/S/Carbon Nanocomposites
2009
SnS2 nested fullerene-type (IF) nanoparticles, nanotubes, and SnS2/C hybrid nanostructures were obtained by vapor transport starting from elemental tin and CS2. The reaction was carried out in a single-step process by heating elemental tin metal powder in a horizontal tube furnace at 800−1000 °C. TEM analysis allowed proposing a plausible mechanism for the formation of fullerene-like particles of SnS2 as well as tubes and scrolls from nanosheets of SnS2. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX…
Modified Nanocarbons for Catalysis
2018
Nanocarbons represent useful scaffolds in the preparation of last generation nanostructured catalysts, and their chemical functionalization through covalent or non-covalent modification is becoming an important tool for introducing well-distributed anchoring points and, in the meantime, could be the first step toward the assembling of hybrid nanostructured materials with a hierarchical order. In this Review are reported synthesis and catalytic applications of chemically modified nanocarbons such as fullerene, carbon nanotubes, graphene, nanohorns and nanodiamonds in organocatalytic and metal-based (metal nanoparticles, organometallic complexes) reactions, covering major chemical reactions e…
Buckyballs
2013
Buckyballs represent a new and fascinating molecular allotropic form of carbon that has received a lot of attention by the chemical community during the last two decades. The unabating interest on this singular family of highly strained carbon spheres has allowed the establishing of the fundamental chemical reactivity of these carbon cages and, therefore, a huge variety of fullerene derivatives involving [60] and [70]fullerenes, higher fullerenes, and endohedral fullerenes have been prepared. Much less is known, however, of the chemistry of the uncommon non-IPR fullerenes which currently represent a scientific curiosity and which could pave the way to a range of new fullerenes. In this revi…
High-precision measurement of the electron spin g factor of trapped atomic nitrogen in the endohedral fullerene N@C60
2018
Abstract The electronic g factor carries highly useful information about the electronic structure of a paramagnetic species, such as spin-orbit coupling and dia- or paramagnetic (de-)shielding due to local fields of surrounding electron pairs. However, in many cases, a near “spin-only” case is observed, in particular for light elements, necessitating accurate and precise measurement of the g factors. Such measurement is typically impeded by a “chicken and egg situation”: internal or external reference standards are used for relative comparison of electron paramagnetic resonance (EPR) Larmor frequencies. However, the g factor of the standard itself usually is subject to a significant uncerta…
Insertion of Be Atoms inC60Fullerene Cages:Be@C60
1996
Radioactive endohedral {sup 7}Be@C{sub 60} can be detected using radiochemical and radiochromatographic techniques in the final solvent. Such a {sup 7}Be atom can penetrate into the C{sub 60} cage to produce {sup 7}Be@C{sub 60} by a recoil process of the nuclear reactions. An {ital ab} {ital initio} molecular dynamics simulation was carried out to demonstrate that a direct insertion process is really possible. Both the experimental and the theoretical results were consistent with each other. {copyright} {ital 1996 The American Physical Society.}
Solid film versus solution-phase charge-recombination dynamics of exTTF-bridge-C60 dyads.
2005
The charge-recombination dynamics of two exTTF-C 6 0 dyads (exTTF=9,10-bis(l,3-dithiol-2-ylidene)-9,10-dihydroanthracene), observed after photoinduced charge separation, are compared in solution and in the solid state. The dyads differ only in the degree of conjugation of the bridge between the donor (exTTF) and the acceptor (C 6 0 ) moieties. In solution, photoexcitation of the nonconjugated dyad C 6 0 -BN-exTTF (1) (BN=1,1'-binaphthyl) shows slower charge-recombination dynamics compared with the conjugated dyad C 6 0 -TVB-exTTF (2) (TVB = bisthienylvinylenebenzene) (lifetimes of 24 and 0.6 μs, respectively), consistent with the expected stronger electronic coupling in the conjugated dyad.…