Fullerene formation mechanism

In this paper, we analyze the methods of synthesizing multi-shell fullerene structures and try to gather some information about their formation mechanism. We also discuss some particularities of the energetics of onion-like graphitic particles. The understanding of the parameters involved would allow the development of efficient production procedures. 

Dipolar cycloadditions of fullerene C6o to nitrones have been studied. Their mechanism, regiochemistry, and nature of addition have been investigated. All of the reactions lead to the formation of fullerene fused heterocycles. Theoretically, these reactions can lead to four types of additions, such as closed [6,6], open [5,6], closed [5,6], and open [6,6] additions (Scheme 2.317). Energetics and thermodynamic analyses of these reactions show that closed [5,6] and open [6,6]... 

The formation mechanism of EMFs remains unclear. Informative results concerning the interactions between the encaged metals and the fullerene cage in isolated EMFs have been obtained, but many mysteries remain in the early stage of the arc-discharge process. Disclosure of these mysteries is helpful to increase the production yield and broaden the applications of EMFs. 

Non-Carbon and Layered Fullerenes. Fullerene-Like Clusters Fullerene Formation Mechanism FuUerene Molecules with Defects Solid Fullerene - Fullerite... 

PREVIOUS THEORETICAL INVESTIGATIONS TOWARD FULLERENE FORMATION MECHANISMS... 

FIGURE 1.11 Zipper variant of the coagulation mechanism of formation of fullerenes from two aromatic fragments. 

M. P. Johnson, R. W. Locke, J. B. Donnet, T. K. Wang, C. Wang, P. Bertrand, Paper No. 179, Carbon Black and Fullerenes New Discoveries in Early Formation Mechanisms and Nucleation , 156th ACS Rubber Division Meeting, Orlando, FL. September 1999... 

Laser evaporation has been a very valuable method not only for discovering the fullerenes but also, as it will be treated with some more detail in a following section, for studying its formation mechanism. However, the method does not... 

Mechanism of the Self-Assembly of Fullerenes, The spontaneous formation of fullerenes under the extreme high energetic conditions imposed by the carbon vapor plasma implies a considerable entropy loss which should be considered in... 

Some of the special features appearing in the species distribution observed in the experiments on laser evaporation of graphite mentioned above (see for instance Figs. 4.18 and 4.22) can be understood by the mechanism of formation of fullerene already discussed. In the mass spectrum region corresponding to clusters with more than 30 atoms, only ions with an even number of carbon atoms are observed. This feature can be interpreted as a result of the relatively high kinetic stability of cluster structures as the fullerenes are. However the distribution of such species is rather peculiar. Some of them, especially buckmin-sterfullerene, appear to be considerably more stable than the others. The fullerene-70 follows C o in such distributions. 

Since the discovery that fullerenes form in supersonic molecular beams (7), many techniques (2-9) have been used to produce fullerenes. Out of these many techniques, carbon-arc and combustion methods have been used for commercial production of fullerenes. In the carbon-arc method, yields of 5% to 8% are common, and yields as high as 40% have been reported (10). It has been a puzzle for some time how a molecule as complex as fiillerene can be formed so readily. Various formation mechanisms have been proposed (11-14). In particular the isolated pentagon rule (IPR) appears to explain many of the experimental observations. 

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