Showing papers on "Fullerene published in 2004"

The Differential Cytotoxicity of Water-Soluble Fullerenes

Abstract: We show that the cytotoxicity of water-soluble fullerene species is a sensitive function of surface derivatization; in two different human cell lines, the lethal dose of fullerene changed over 7 orders of magnitude with relatively minor alterations in fullerene structure. In particular, an aggregated form of C 60, the least derivatized of the four materials, was substantially more toxic than highly soluble derivatives such as C3, Na+ 2-3[C60O7-9(OH)12-15] (2-3)- , and C60(OH)24. Oxidative damage to the cell membranes was observed in all cases where fullerene exposure led to cell death. We show that under ambient conditions in water fullerenes can generate superoxide anions and postulate that these oxygen radicals are responsible for membrane damage and subsequent cell death. This work demonstrates both a strategy for enhancing the toxicity of fullerenes for certain applications such as cancer therapeutics or bactericides, as well as a remediation for the possible unwarranted biological effects of pristine fullerenes.

Nanoscale Morphology of Conjugated Polymer/Fullerene-Based Bulk- Heterojunction Solar Cells†

Abstract: The relation between the nanoscale morphology and associated device properties in conjugated polymer/fullerene bulk-heterojunction “plastic solar cells” is investigated. We perform complementary measurements on solid-state blends of poly[2-methoxy-5-(3,7-dimethyloctyloxy)]-1,4-phenylenevinylene (MDMO-PPV) and the soluble fullerene C60 derivative 1-(3-methoxycarbonyl) propyl-1-phenyl [6,6]C61 (PCBM), spin-cast from either toluene or chlorobenzene solutions. The characterization of the nanomorphology is carried out via scanning electron microscopy (SEM) and atomic force microscopy (AFM), while solar-cell devices were characterized by means of current–voltage (I–V) and spectral photocurrent measurements. In addition, the morphology is manipulated via annealing, to increase the extent of phase separation in the thin-film blends and to identify the distribution of materials. Photoluminescence measurements confirm the demixing of the materials under thermal treatment. Furthermore the photoluminescence of PCBM clusters with sizes of up to a few hundred nanometers indicates a photocurrent loss in films of the coarser phase-separated blends cast from toluene. For toluene-cast films the scale of phase separation depends strongly on the ratio of MDMO-PPV to PCBM, as well as on the total concentration of the casting solution. Finally we observe small beads of 20–30 nm diameter, attributed to MDMO-PPV, in blend films cast from both toluene and chlorobenzene.

Fullerenes : chemistry and reactions

Abstract: Foreword. Preface of "The Chemistry of the Fullerenes" by Andreas Hirsch (1994). Abbreviations. 1 Parent Fullerenes. 1.1 Fullerenes: Molecular Allotropes of Carbon. 1.2 Discovery of the Fullerenes. 1.3 Fullerene Production. 1.4 Separation and Purification. 1.5 Properties. References. 2 Reduction. 2.1 Introduction. 2.2 Fulleride Anions. 2.3 Reductive Electrosynthesis. 2.4 Reduction with Metals. 2.5 Reduction with Organic Donor Molecules. References. 3 Nucleophilic Additions. 3.1 Introduction. 3.2 Addition of Carbon Nucleophiles. 3.3 Addition of Amines. 3.4 Addition of Hydroxide and Alkoxides. 3.5 Addition of Phosphorus Nucleophiles. 3.6 Addition of Silicon and Germanium Nucleophiles. 3.7 Addition of Macromolecular Nucleophiles - Fullerene Polymers. References. 4 Cycloadditions. 4.1 Introduction. 4.2 [4+2] Cycloadditions. 4.3 [3+2] Cycloadditions. 4.4 [2+2] Cycloadditions. 4.5 [2+1] Cycloadditions. References. 5 Hydrogenation. 5.1 Introduction. 5.2 Oligohydrofullerenes C60Hn and C70Hn (n = 2-12). 5.3 Polyhydrofullerenes C60Hn and C70Hn (n = 14-60). References. 6 Radical Additions. 6.1 Introduction. 6.2 ESR Investigations of Radical Additions. 6.3 Addition of Tertiary Amines. 6.4 Photochemical Reaction with Silanes. 6.5 Metalation of C60 with Metal-centered Radicals. 6.6 Addition of bis(Trifluoromethyl)nitroxide. References. 7 Transition Metal Complex Formation. 7.1 Introduction. 7.2 (eta2-C60) Transition Metal Complexes. 7.3 Multinuclear Complexes of C60. 7.4 Hydrometalation Reactions. 7.5 Organometallic Polymers of C60. References. 8 Oxidation and Reactions with Electrophiles. 8.1 Introduction. 8.2 Electrochemical Oxidation of C60 and C70. 8.3 Oxygenation. 8.4 Osmylation. 8.5 Reactions with Strong Oxidizing Reagents and Acids. 8.6 Reactions with Lewis Acids and Fullerylation of Aromatics and Chloroalkanes. References. 9 Halogenation. 9.1 Introduction. 9.2 Fluorination. 9.3 Chlorination. 9.4 Bromination. 9.5 Reaction with Iodine. References. 10 Regiochemistry of Multiple Additions. 10.1 Introduction. 10.2 Addition of Segregated Addends - The Inherent Regioselectivity. 10.3 Concepts for Regio- and Stereoselective Multiple Functionalization of C60. References. 11 Cluster Modified Fullerenes. 11.1 Introduction. 11.2 Cluster Opened Fullerene Derivatives. 11.3 Quasi-fullerenes. 11.4 Outlook. References. 12 Heterofullerenes. 12.1 Introduction. 12.2 Synthesis of Nitrogen Heterofullerenes from Exohedral Imino Adducts of C60 and C70. 12.3 Chemistry of Azafullerenes. 12.4 Outlook. References. 13 Chemistry of Higher Fullerenes. 13.1 Introduction. 13.2 Exohedral Reactivity Principles. 13.3 Adducts of C70. 13.4 Adducts of C76, C78 and C84. References. 14 Principles and Perspectives of Fullerene Chemistry. 14.1 Introduction. 14.2 Reactivity. 14.3 Regiochemistry of Addition Reactions. 14.4 Aromaticity of Fullerenes. 14.5 Seven Principles of Fullerene Chemistry: a Short Summary. 14.6 The Future of Fullerene Chemistry. 14.7 Fullerenes as Building Blocks for Molecular Engineering (Nanotechnology) and Practical Applications. References. Subject Index.

Ultra-stable nanoparticles of CdSe revealed from mass spectrometry

Abstract: Nanoparticles under a few nanometres in size have structures and material functions that differ from the bulk because of their distinct geometrical shapes and strong quantum confinement. These qualities could lead to unique device applications. Our mass spectral analysis of CdSe nanoparticles reveals that (CdSe)(33) and (CdSe)(34) are extremely stable: with a simple solution method, they grow in preference to any other chemical compositions to produce macroscopic quantities. First-principles calculations predict that these are puckered (CdSe)(28)-cages, with four- and six-membered rings based on the highly symmetric octahedral analogues of fullerenes, accommodating either (CdSe)(5) or (CdSe)(6) inside to form a three-dimensional network with essentially heteropolar sp(3)-bonding. This is in accordance with our X-ray and optical analyses. We have found similar mass spectra and atomic structures in CdS, CdTe, ZnS and ZnSe, demonstrating that mass-specified and macroscopically produced nanoparticles, which have been practically limited so far to elemental carbon, can now be extended to a vast variety of compound systems.

Velocity Effects on Fullerene and Oxide Nanoparticle Deposition in Porous Media

Abstract: Products of nanochemistry have been proposed in a number of applications ranging from soil stabilization and cosmetics to groundwater remediation. A fundamental understanding of the transport properties of these materials is essential to assess their efficacy and environmental impact in such applications. In this work, we consider the effect of flow on nanoparticle transport and deposition in porous media. The transport of three aqueous suspensions of fullerenes in a well-characterized porous medium is compared with that of two oxide nanomaterials at two flow rates. Despite significant differences in surface chemistry and size, the fullerenes exhibited an unexpected and similar breakthrough behavior at the higher flow rate. A striking characteristic of the fullerene breakthrough curves obtained at the higher Darcy velocity was an initial enhancement in nanoparticle deposition shortly after the passage of the first pore volume of suspension, followed by an increase in passage. This velocity-sensitive "affinity transition" in the initial deposition of nanoparticles in the porous medium was observed for fullerene-based materials only at the higher velocity and was in no case observed for silica or titania nanoparticles. The removal of fullerene-based nanoparticles was observed to converge to a level that was independent of flow velocity, suggesting that under these conditions time scales for attachment or reorganization on the surface are greater than the time scale for transport to collector surfaces.

Thermal Contraction of Carbon Fullerenes and Nanotubes

Abstract: We perform molecular dynamics simulations to study shape changes of carbon fullerenes and nanotubes with increasing temperature. At moderate temperatures, these systems gain structural and vibrational entropy by exploring the configurational space at little energy cost. We find that the soft phonon modes, which couple most strongly to the shape, maintain the surface area of these hollow nanostructures. In nanotubes, the gain in entropy translates into a longitudinal contraction, which reaches a maximum at T approximately 800 K. Only at much higher temperatures do the anharmonicities in the vibration modes cause an overall expansion.

Room-Temperature Scanning Tunneling Microscopy Manipulation of Single C60 Molecules at the Liquid−Solid Interface: Playing Nanosoccer

Abstract: This scanning tunneling microscopy (STM) study uses a supramolecular two-dimensional architecture of trimesic acid molecules adsorbed on a graphite substrate as a host for the incorporation of C60 as a molecular guest. By choosing a proper solvent, it was possible to verify that self-assembly of the host−guest structure can be accomplished at the liquid solid interface. Because of the ideal steric match with the molecular bearing of the host structure, C60 buckminster fullerenes are feasible guests. It was possible to coadsorb C60 within cavities of the open TMA structure from the liquid phase, and lateral manipulation of the molecular guest by the STM tip was demonstrated at room temperature. Because of the increased tip−sample interaction as a result of lower tunneling resistance, a transfer of a C60 molecule from one cavity of the host structure to an adjacent one was achieved.

Raman spectroscopy of fullerenes and fullerene-nanotube composites.

Abstract: The discovery of fullerenes in 1985 opened a completely new field of materials research. Together with the singlewall carbon nanotubes (SWCNTs) discovered later, these curved carbon networks are a ...

Selective extraction of higher fullerenes using cyclic dimers of zinc porphyrins.

Abstract: Higher fullerenes (≥C76) were selectively extracted from a fullerene mixture obtained from a combustion-based industrial production source by cyclic dimers of β-unsubstituted porphyrin zinc complexes 2C5−2C7 with C5−C7 alkylene spacers as host molecules. Results of single extraction of the fullerene mixture with 2C5−2C7 together with a β-substituted analogue of 2C6 (1C6) and spectroscopic titration of 2C6 and 1C6 with C60, C70, and C96 indicated that the host selectivity toward higher fullerenes is much dependent on the structure of the porphyrin units and the size of the host cavity. Sequential three-stage extraction of the fullerene mixture with the best-behaved 2C6 resulted in considerable enrichment in very rare fullerenes C102−C110 (<0.1 abs %) up to 82 abs % (C76−C114, 99 abs %) (356 nm) of total fullerenes.

Magnetic properties of carbon structures

Abstract: Magnetic properties of the main allotropic modifications of carbon (diamond, graphite, nanographite, nanotubes, and fullerenes) are described. Properties of nanocarbon are considered from the standpoint of the interrelation between structural imperfection and magnetic ordering. Experimental data on high-temperature ferromagnetism in carbon structures and some theoretical models of magnetic carbon are reported.

Intelligent Macromolecules for Smart Devices: From Materials Synthesis to Device Applications

Abstract: 1 The Concepts of Intelligent Macromolecules and Smart Devices 1.1 Introduction 1.2 The Concept of Intelligent Macromolecules 1.2.1 Synthetic Macromolecules 1.2.1.1 Chain Structure and Classification 1.2.1.2 Synthesis 1.2.1.3 Chain Conformation 1.2.1.4 Macromolecular Structure in Solution 1.2.1.5 Primary, Secondary, Tertiary and Quaternary Structure 1.2.2 Biological Macromolecules 1.2.2.1 Structure of DNA 1.2.2.2 Structure of Proteins 1.2.2.3 Structure of Polysaccharides 1.2.3 Carbon Nanomaterials 1.2.4 Intelligent Macromolecules 1.3 The Concept of Smart Devices 1.3.1 Self-assembling and Micro-/Nano-fabrication 1.3.2 Functional Structures and Smart Devices 1.4 References Part I. Intelligent Macromolecules 2 Conducting Polymers 2.1 Introduction 2.2 Conjugated Conducting Polymers 2.2.1 Structure and Properties 2.2.1.1 - * Conjugation 2.2.1.2 Doping 2.2.2 Synthesis 2.2.2.1 Syntheses of Soluble Conjugated Polymers 2.2.2.2 Syntheses of Conjugated Polymer Films 2.3 Charge Transfer Polymers 2.3.1 Organic Charge Transfer Complexes 2.3.2 Polymeric Charge Transfer Complexes 2.3.3 Charge Transfer Between Fullerene C60 and Polymers 2.4 Ionically Conducting Polymers 2.4.1 Structural Features of Polymer Electrolytes 2.4.2 Transport Properties and Chain Dynamics 2.5 Conductively Filled Polymers 2.5.1 Polymers Filled with Conductive Solids 2.5.2 Polymers Filled with Conjugated Conducting Polymers 2.6 References 3 Stimuli-responsive Polymers 3.1 Introduction 3.2 Solvent-responsive Polymers 3.3 Temperature-responsive Polymers 3.3.1 Temperature-responsive Polymers in Solution 3.3.2 Temperature-responsive Polymers on Surface 3.4 pH-responsive Polymers 3.5 Ionically Responsive Polymers 3.6 Electrically Responsive Polymers 3.7 Photoelectrochromism 3.8 PhotoresponsivePolymers 3.9 Biochromism 3.10 Photomodulation of Enzyme Activity 3.11 References 4 Dendrimers and Fullerenes 4.1 Introduction 4.2 Dendrimers 4.2.1 Synthesis 4.2.1.1 Divergent Approach 4.2.1.2 Convergent-growth Approach 4.2.1.3 Other Miscellaneous Approaches 4.2.2 Structure 4.2.2.1 Dendrimers with a Metal Core 4.2.2.2 Dendrimers with a Hollow Core 4.2.2.3 Dendrimers with a Hydrophobic Interior and Hydrophilic Exterior Layer 4.2.2.4 Dendrimers with Guest Molecules Trapped in their Cavities 4.2.2.5 Dendrimers with Different Terminal Groups 4.3 Fullerene C60 4.3.1 Chemistry of C60 4.3.1.1 Addition Reactions 4.3.1.2 Dimerization and Polymerization 4.3.2 Polymeric Derivatives of C60 4.3.2.1 Fullerene Charm Bracelets 4.3.2.2 Fullerene Pearl Necklaces 4.3.2.3 Flagellenes 4.4 References 5 Carbon Nanotubes 5.1 Introduction 5.2 Structure 5.3 Property 5.4 Synthesis 5.4.1 Multi-wall Carbon Nanotubes (MWNTs) 5.4.2 Single-wall Carbon Nanotubes (SWNTs) 5.5 Purification 5.6 Microfabrication 5.6.1 Opening, Filling and Closing 5.6.2 Filling 5.6.3 Tip-closing 5.7 Chemical Modification 5.7.1 End-functionalization 5.7.1.1 Oxidation of Carbon Nanotubes 5.7.1.2 Covalent-Coupling via the Oxidized Nanotube Ends 5.7.2 Modification of Nanotube Outerwall 5.7.2.1 Sidewall Fluorination of Carbon Nanotubes 5.7.2.2 The Attachment of Dichlorocarbene to the Sidewall 5.7.2.3 Modification via 1,3-Dipolar Cycloaddition of Azomethine Ylides 5.7.2.4 The Reaction Between Aniline and Carbon Nanotubes 5.7.3 Functionalization of Carbon Nanotube Innerwall 5.7.4 Other Physical Chemistries of Carbon Nanotubes 5.7.4.1 Modification of Carbon Nanotubes via Mechanochemical Reactions 5.7.4.2 Modification of Carbon Nanotubes via Electrochemical Reactions 5.7.4.3 Modification of Carbon Nanotubes via Photochemical Reactions 5.8 Non-covalen

Properties of fullerene[50] and D5h decachlorofullerene[50]: a computational study.

Abstract: Stimulated by the recent preparation and characterization of the first [50]fullerene derivative, decachlorofullerene[50] (Science 2004, 304, 699), we have performed a systematic density functional study on the electronic and spectroscopic properties of C50, its anions and derivatives such as C50Cl10 and C50Cl12. The ground state of C50 has D3 symmetry with a spheroid shape, and is highly aromatic; the best D5h C50 singlet is nonaromatic. Both D3 and D5h isomers of C50 have high electron affinities and can be reduced easily. Due to the unstable fused pentagon structural features, C50 is chemically labile and subject to addition reactions such as chlorination, dimerization and polymerization. The equatorial pentagon−pentagon fusions of D5h C50 are active sites for chemical reactions; hence, D5h C50 may behave as a multivalent group. The computed IR, Raman, 13C NMR and UV−vis spectra of the D5h C50Cl10 molecule agree well with the experimental data. Finally, D5h C50Cl10 is predicted to have a high electron a...

Employing Raman spectroscopy to qualitatively evaluate the purity of carbon single-wall nanotube materials.

Abstract: Carbon single-wall nanotubes (SWNTs) have highly unique electronic, mechanical and adsorption properties, making them interesting for a variety of applications. Raman spectroscopy has been demonstrated to be one of the most important methods for characterizing SWNTs. For example, Raman spectroscopy may be employed to differentiate between metallic and semi-conducting nanotubes, and may also be employed to determine SWNT diameters and even the nanotube chirality. Single-wall carbon nanotubes are generated in a variety of ways, including arc-discharge, laser vaporization and various chemical vapor deposition (CVD) techniques. In all of these methods, a metal catalyst must be employed to observe SWNT formation. Also, all of the current synthesis techniques generate various non-nanotube carbon impurities, including amorphous carbon, fullerenes, multi-wall nanotubes (MWNTs) and nano-crystalline graphite, as well as larger micro-sized particles of graphite. For any of the potential nanotube applications to be realized, it is, therefore, necessary that purification techniques resulting in the recovery of predominantly SWNTs at high-yields be developed. It is, of course, equally important that a method for determining nanotube wt.% purity levels be developed and standardized. Moreover, a rapid method for qualitatively measuring nanotube purity could facilitate many laboratory research efforts. This review article discusses the application of Raman spectroscopy to rapidly determine if large quantities of carbon impurities are present in nanotube materials. Raman spectra of crude SWNT materials reveal tangential bands between 1500-1600 cm(-1), as well as a broad band at approximately 1350 cm(-1), attributed to a convolution of the disorder-induced band (D-band) of carbon impurities and the D-band of the SWNTs themselves. Since the full-width-at-half-maximum (FWHM) intensity of the various carbon impurity D-bands is generally much broader than that of the nanotube D-band, an indication of the SWNT purity level may be obtained by simply examining the line-width of the D-band. We also briefly discuss the effect of nanotube bundling on SWNT Raman spectra. Finally, sections on employing Raman spectroscopy, and Raman spectroscopy coupled with additional techniques, to identify the separation and possible isolation of a specific nanotube within purified SWNT materials is provided. Every SWNT can be considered to be a unique molecule, with different physical properties, depending on its (n, m) indices. The production of phase-pure (n, m) SWNTs may be essential for some nanotube applications.

Endohedral Silicon Fullerenes SiN (27 ≤ N ≤ 39)

Abstract: We have performed an unbiased search for the lowest-energy geometric structures of medium-sized silicon clusters SiN (27 ≤ N ≤ 39) using a genetic algorithm and nonorthogonal-tight-binding method, followed by a refining and biased search using basin-hopping method coupled with density-functional theory. We show that the carbon fullerene cages are most likely generic cage motifs (“magic cages”) to form low-lying stuffed-cage silicon clusters (beyond the size N > 27). An empirical rule that provides optimal “stuffing/cage” combinations for constructing low-energy endohedral silicon fullerenes is suggested, with a hope that it can provide guidance to future synthesis of “bucky” silicon.

Structural features of molecular-colloidal solutions of C60 fullerenes in water by small-angle neutron scattering

Abstract: Highly stable and reproducible molecular-colloidal water solutions of C60 fullerenes (FWS) obtained by transferring fullerenes from an organic solution into an aqueous phase with the help of ultrasonic treatment are investigated by means of small-angle neutron scattering (SANS). A polydispersity in the size of detected particles up to 84 nm is revealed. These particles are slightly anisotropic and have a characteristic size of approximately 70 nm. Along with it, there are some indications that a significant part of fullerenes composes particles with the size of the order of 1 nm. The contrast variation based on mixtures of light and heavy water shows that the mean scattering length density of the particles is close to that of the packed fullerene associates as well as that the characteristic size of possible fluctuations of the scattering length density within the particles does not exceed 2 nm. A smooth surface resulting in the Porod law for the scattering is detected. A number of models discussed in the literature are considered with respect to the SANS data.

Direct Solvent-Free Amination of Closed-Cap Carbon Nanotubes: A Link to Fullerene Chemistry

Abstract: We attempted the direct solvent-free amination of closed caps of multiwalled carbon nanotubes (MWNTs) with octadecylamine (ODA), which is essentially similar to the amination of spherical fullerenes. Thermogravimetric analysis revealed a relatively high content of organics in the product of derivatization (ODA-MWNTs), suggesting that a large ODA fraction is distributed over MWNT sidewalls through chemical attachment. This was confirmed by high-resolution transmission electron microscopy observations. Quantum chemical calculations showed that the presence of pyracylene units in the closed caps is not crucial for the amine addition, although the site specificity of the reaction does depend on the mutual position of five-membered rings. If the caps contain pyracylene units, then the addition preferentially takes place on their 6,6 bonds; if they do not, then the preferential reaction sites are C−C bonds of the pentagons. Whereas ideal nanotube sidewalls composed of solely benzene rings were found to be inert...

Enhanced thermoelectric figure of merit of CoSb3 via large-defect scattering

Abstract: We have measured the structural, chemical, and transport properties of a series of CoSb3 skutterudite samples modified by fullerene additions of 0, 0.52, 3.28, 3.90, 4.77, and 6.54 mass%. Fullerene is a 60-atom carbon molecule that forms microsize clusters between the grain boundaries of CoSb3. We observed that the dominant scattering mechanism in the electrical transport changes from impurity scattering to grain-boundary scattering near a C60 content of ∼5–6 mass%, and that thermal conductivity decreases with increasing C60 content. A significant increase in the thermoelectric figure of merit is achieved for 6.54 mass% C60 compared to the pure CoSb3.

MALDI Matrices for Biomolecular Analysis Based on Functionalized Carbon Nanomaterials

Abstract: When used in small molar ratios of matrix to analyte, derivatized fullerenes and single wall nanotubes are shown to be efficient matrices for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The mixing of an acidic functionalized fullerene with a solution of bioanalyte, depositing a dried droplet, and irradiating with a pulsed nitrogen laser yields protonated or cationized molecular ions. Derivatized fullerenes could offer several advantages over conventional MALDI matrices: a high analyte ionization efficiency, a small molar ratios (less than 1) of matrix/analyte, and a broader optical absorption spectrum, which should obviate specific wavelength lasers for MALDI acquisitions. The major disadvantage to the use of fullerenes is the isobaric interference between matrix and analyte ions; however, it is overcome by using MALDI-ion mobility time-of-flight (IM-oTOF) mass spectrometry to preseparate carbon cluster ions from bioanalyte ions prior to TOF mass analysis. However, an alternati...

Fullerene-Based Carbon Nanostructures for Methanol Oxidation

Abstract: Films of C60 clusters were electrophoretically deposited on optically transparent electrode surfaces. These C60 films constitute a new class of carbon electrodes with properties that differ from graphite and diamond electrodes. The electrophoretically deposited C60 cluster film is highly porous and is quite stable to oxidative potentials. Hence C60 film provides an electrochemical window to carry out oxidation processes. Upon electrodeposition of platinum particles, these nanostructured carbon films show remarkable activity toward methanol oxidation. The dependence of methanol oxidation on the amount of platinum and C60 in a half-cell reaction demonstrates the role of fullerene nanoclusters as new form of carbon support.

On the Breaking of Carbon Nanotubes under Tension

Abstract: Molecular dynamics simulations and high resolution TEM experiments are performed to assess the fracture of nanotubes under high stretching conditions. Brittle or plastic response is controlled by the rate of applied strain to the tube as well as by the number of defects (in particular vacancies). Simulations predict that under high temperatures and presence of defects (as induced under the high-energy electron beam of the TEM) the tubes exhibit mainly plastic deformation, with the appearance of medium size carbon chains as the latest stage before fracture. These results are in agreement with in-situ TEM observation. Carbon exhibits a very rich dynamics of bond-breaking and bond-reconstruction that allows transformations from fullerenes to tubes to chains.