Properties of C 60 polymerized under high pressure and temperature

Rao, Apparao M.; Eklund, P. C.; Venkateswaran, U. D.; Tucker, J.; Duncan, M. A.; Bendele, G. M.; Stephens, Peter W.; Hodeau, Jean Louis; Marques, L.; Núñez-Regueiro, M.; Bashkin, I. O.; Ponyatovsky, E.G.; Morovsky, A.P.

doi:10.1007/s003390050472

Cited by 103 publications

(61 citation statements)

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“…These peaks are well explained in terms of those reported for an HPHT dimerized C60 crystal ͑filled triangles͒ 27 or those reported for a photodimerized C60 film ͑open triangles͒. 28 After annealing at 523 K, the A g ͑2͒ peak revived and the C60 dimer-related peaks disappeared. These observations indicate C60 dimer formation in the in situ irrad.…”

Section: Uniformly Dimerized C60 Film Prepared By Deposition Under Insupporting

confidence: 77%

“…In ͑a͒, the filled and open triangles indicate the peak positions reported for a dimerized HTHP C60 specimen 27 and a photopolymerized C60 film, 28 respectively. The spectrum obtained for a pristine C60 film ͑165 nm thick͒ deposited without photoirradiation is shown in ͑c͒, where the peak at 521 cm −1 was due to the Si substrate and the vertical bars indicate the peak positions reported for the pristine fcc C60 material.…”

Section: Figmentioning

confidence: 99%

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Uniformly dimerized C60 film prepared by deposition under in situ photoirradiation

Tanimoto

Yamada

Mizubayashi

et al. 2008

Applied Physics Letters

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C60 films with thicknesses of 100–480 nm were deposited on Si reed substrates under in situ photoirradiation. In anelasticity measurements, no internal friction peaks associated with rotational motions of the C60 molecules were observed, and Young’s modulus was 1.5 times larger than that of a pristine C60 material. X-ray diffraction patterns suggested that the face-centered cubic lattice was contracted by about 3% and locally distorted from the pristine C60 material. Raman spectra very similar to those reported for dimerized C60 were also obtained. These characteristics recovered to those of the pristine C60 materials after annealing the C60 films at 523 K. These results indicate uniform dimerization in C60 films deposited under in situ photoirradiation.

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Section: Uniformly Dimerized C60 Film Prepared By Deposition Under Insupporting

confidence: 77%

Section: Figmentioning

confidence: 99%

Uniformly dimerized C60 film prepared by deposition under in situ photoirradiation

Tanimoto

Yamada

Mizubayashi

et al. 2008

Applied Physics Letters

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“…It is well established that polymerization 22 and subsequent fusion [23][24][25] of fullerenes starts by the ͑2+2͒ cycloaddition reaction. This reaction, depicted as the 0 → 1 transition in Fig.…”

mentioning

confidence: 99%

Microscopic mechanism of fullerene fusion

et al. 2004

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Combining total energy calculations with a search of phase space, we investigate the microscopic fusion mechanism of C 60 fullerenes. We find that the ͑2+2͒ cycloaddition reaction, a necessary precursor for fullerene fusion, may be accelerated inside a nanotube. Fusion occurs along the minimum energy path as a finite sequence of Stone-Wales transformations, determined by a graphical search program. Search of the phase space using the "string method" indicates that Stone-Wales transformations are multistep processes, and provides detailed information about the transition states and activation barriers associated with fusion. The discovery of fullerenes 1 and nanotubes 2 has ignited strong interest in these and related carbon nanostructures. Due to the unusual stability of the graphitic sp 2 bond, largescale structural changes in bulk fullerene crystals occur only under extremely high pressures and temperatures.3,4 On the other hand, fullerenes in nanotube peapods 5 have been observed to fuse 6,7 at relatively low temperatures near 1100°C, significantly below the decomposition temperature of fullerenes 8 or graphite 9 near 4000°C. No information is available about the detailed fusion process except the obvious conclusion that strong sp 2 bonds should not be broken during structural rearrangements leading to fusion. In view of the fact that even minor structural changes in carbon nanostructures may modify significantly their physical properties, including magnetism, 10,11 there is additional interest in understanding fusion as a way to control large-scale structural transformations.Here we study the microscopic fusion mechanism of fullerenes. We show that large-scale structural changes, including fusion, can be achieved by a finite sequence of generalized Stone-Wales transformations, which involve only bond rotations and avoid bond breaking. Using a graphical search program, 12 we determine the optimum reaction pathway for thermal fusion of fullerenes. Search of the phase space by the "string method" provides detailed information about the optimum pathway, including the identification of activation barriers and transition-state geometries. We find the fusion process to be exothermic. The fusion dynamics is fast in spite of the formidable total activation barrier close to 5 eV, associated with each Stone-Wales transformation. These bond rotations turn out to be multistep processes with lower individual activation barriers.We calculate the total energy of the fullerene system using an electronic Hamiltonian that had been applied successfully to describe the formation of peapods, 13 multiwall nanotubes, 14 the dynamics of the "bucky shuttle," 15 and the melting of fullerenes. 8 Our numerical results are compared to those of ab initio density functional calculations, which use a numerical basis to represent localized atomic orbitals, 16 and which have been applied successfully to nanotubes and fullerenes. 17 Structural optimization is performed using the conjugate gradient technique. Our total energy formalism describe...

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“…The electrochemical retro-Bingel reaction of the (alkoxycarbonyl)methanofullerenes of C 60 , C 70 , C 76 , and ent-C 76 at the second reduction potential by controlled potential electrolysis (CPE) has been reported by Echegoyen, Diederich and co-workers [55]. The retro-cyclopropanation by CPE is selective for the methano-addend, which must have at least one strong electron-withdrawing group.…”

Section: Retro-cyclopropanation Reactionmentioning

confidence: 97%

Buckyballs

Delgado

Filippone

Giacalone

et al. 2013

Topics in Current Chemistry

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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 review on buckyballs we have mainly focused on the most recent and novel covalent chemistry of fullerenes involving metal catalysis and asymmetric synthesis, as well as on some of the most significant advances in supramolecular chemistry, namely H-bonded fullerene assemblies and the search for efficient concave receptors for the convex surface of fullerenes. Furthermore, we have also described the recent advances in the macromolecular chemistry of fullerenes, that is, those polymer molecules endowed with fullerenes which have been classified according to their chemical structures. This review is completed with the study of endohedral fullerenes, a new family of fullerenes in which the carbon cage of the fullerene contains a metal, molecule, or metal complex in the inner cavity. The presence of these species affords new fullerenes with completely different properties and chemical reactivity, thus opening a new avenue in which a more precise control of the photophysical and redox properties of fullerenes is possible. The use of fullerenes for organic electronics, namely in photovoltaic applications and molecular wires, complements the study and highlights the interest in these carbon allotropes for realistic practical applications. We have pointed out the so-called non-IPR fullerenes - those that do not follow the isolated pentagon rule - as the most intriguing class of fullerenes which, up to now, have only shown the tip of the huge iceberg behind the examples reported in the literature. The number of possible non-IPR carbon cages is almost infinite and the near future will show us whether they will become a reality.

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Properties of C 60 polymerized under high pressure and temperature

Cited by 103 publications

References 1 publication

Uniformly dimerized C60 film prepared by deposition under in situ photoirradiation

Uniformly dimerized C60 film prepared by deposition under in situ photoirradiation

Microscopic mechanism of fullerene fusion

Buckyballs

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