Giant fullerenes

The remarkable stability of onion-like particles[15] suggests that single-shell graphitic molecules (giant fullerenes) containing thousands of atoms are unstable and would collapse to form multi-layer particles in this way the system is stabilized by the energy gain from the van der Waals interaction between shells [15,26,27],... 

Carbon nanotubes (CNTs) as well as fullerenes are splendid gift brought to the Earth from the red giant carbon stars in the long-distant universe through the spectroscopy. Moreover, those belong to new carbon allotropes of the mesoscopic scale with well-defined structures. In particular, CNTs are considered to be the materials appropriate to realise intriguing characteristics related to the mesoscopic system based on their size and physicochemical properties. 

M. Terrones, G. Terrones, H. Terrones, Structure, chirality, and formation of giant icosahedral fullerenes and spherical graphitic onions, Struct. Chem., vol. 13, pp. 373-384, 2002. 

The raw product obtained by the evaporation of graphite is soot and slag. Next to soluble fullerenes the soot and slag contain other kinds of closed carbon structures, e.g. giant fullerenes [187] and nanotubes [188, 189] the rest is amorphous carbon. Fullerenes can be isolated from the soot either by sublimation or by extraction. The first isolation of fullerenes was achieved by a simple sublimation with a Bunsen... 

As a third group of fullerene-like systems whose synthetic development is identified as a major future challenge are structurally defined single-walled carbon nanotubes (SWNTs) with uniform helicity and length, including their covalent and non-covalent derivatives. SWNTs can be considered as elongated giant fullerenes. 

Interaction-induced absorption by the vibrational or rotational motion of an atom, ion, or molecule trapped within a Ceo cage, so-called endohedral buckmin-sterfullerene, has excited considerable interest, especially in astrophysics. The induced bands of such species are unusual in the sense that they are discrete, not continuous they may also be quite intense [127]. Other carbon structures, such as endohedral carbon nanotubes, giant fullerenes, etc., should have similar induced band spectra [128], but current theoretical and computational research is very much in flux while little seems to be presently known from actual spectroscopic measurements of such induced bands. 

Fullerenes and graphite may originate abundantly in stellar atmospheres rich in carbon like those of some giant stars and some progenitors of planetary nebulae (Fig. 1.5). These objects display for important mass loss rates and are therefore able to greatly enrich the interstellar medium. 

Many carbon rich stars also present an important emission at 11.3 pm associated with solid carbon and some of them present nebulosity of reflection as a consequence of the scattering of the circumstellar grains. There are indications that in the material ejected by these stars, carbon must exist, apart from CO molecules and solid grains, in some other form or species until now unknown, fullerenes are a possibility. Unfortunately, there is very little information about the presence of molecules of intermediate size (between 10 and 106 atoms) in circumstellar regions. There are bands in carbon rich planetary nebulae, for example those of 3.3,6.2,7.7, 8.6 and 11.3 pm which have not been detected in carbon stars but are observable in transition objects evolving between the giant red phase and the planetary nebula as for example, the Egg Nebula (Fig. 1.5) and the Red Rectangle. These infrared bands are normally associated with the vibration modes of materials based on carbon, possibly PAHs. But until now it has not been possible to make a conclusive identification of the carrier. 

Dreams in a charcoal fire predictions about giant fullerenes and graphite nanotubes... 

Figure 1. The diatom Aulonia hexagona is an almost perfect 100000-fold model of a giant fullerene with about 1200 carbon atoms. (From On growth and form, by W. D Arey Thompson. Courtesy of Cambridge University Press.)...

Between 1985 and 1990, the structure and bulk properties of buckminsterfullerene remained uncertain. I was able to maintain an optimistic hope that predictions 2-4 would turn out to apply even to this small and compact molecule (prediction 1, a consequence of the empty space inside a large hollow molecule, could only be true of giant fullerenes). But when C6 was produced in macroscopic quantities (Kratschmer... 

The determined theorist should make an orderly retreat in the face of the advancing facts. Giant fullerenes have not yet been made in bulk, so I am still free to maintain my original claims in respect of these as yet hypothetical substances. Predictions 2 and 3 were based essentially on my intuitions about the weakness of the expected interaction between big spherical molecules. I buttressed them with some highly over-simplified calculations, not hitherto published. They are more of a speculation than a rigorous argument. 

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