FULLERENES PROCESSING

Title Novel Water-Soluble Fullerene, Process for Producing the Same and Active Oxygen Generator Containing the Fullerene... 

Pierson, H.O., 1994. Handbook of Carbon, Graphite, Diamonds and Fullerenes Processing, Properties and Applications. William Andrew. 

Pierson, H. O. (1993). Handbook of carbon, graphite, diamonds and fullerenes Processing, properties and applications. New Jersey Noyes Publications. 

In light of oxidative processes, the high degree of resonance stabilization that arises from the maximally occupied HOMO (10 electrons), makes it an extremely difficult task to remove an electron from the HOMO level [31], Thus, [60]fullerene can be considered mostly an electronegative entity which is much more easily reduced than oxidized. 

One aspect that reflects the electronic configuration of fullerenes relates to the electrochemically induced reduction and oxidation processes in solution. In good agreement with the tlireefold degenerate LUMO, the redox chemistry of [60]fullerene, investigated primarily with cyclic voltammetry and Osteryoung square wave voltammetry, unravels six reversible, one-electron reduction steps with potentials that are equally separated from each other. The separation between any two successive reduction steps is -450 50 mV. The low reduction potential (only -0.44 V versus SCE) of the process, that corresponds to the generation of the rt-radical anion 131,109,110,111 and 1121, deserves special attention. 

In contrast to the relative ease of reduction, oxidation of fullerenes requires more severe conditions [113, 114]. Not only does the resonance stabilization raise the level of the corresponding oxidation potential (1.26 V versus Fc/Fc ), but also the reversibility of the underlying redox process is affected [115]. 

There are, indeed, many biological implications that have been triggered by the advent of fullerenes. They range from potential inhibition of HIV-1 protease, synthesis of dmgs for photodynamic therapy and free radical scavenging (antioxidants), to participation in photo-induced DNA scission processes [156, 157, 158, 159, 160, 161, 162 and 163]. These examples unequivocally demonstrate the particular importance of water-soluble fullerenes and are summarized in a few excellent reviews [141, 1751. 

Abstract—Carbon nanotubules were produced in a large amount by catalytic decomposition of acetylene in the presence of various supported transition metal catalysts. The influence of different parameters such as the nature of the support, the size of active metal particles and the reaction conditions on the formation of nanotubules was studied. The process was optimized towards the production of nanotubules having the same diameters as the fullerene tubules obtained from the arc-discharge method. The separation of tubules from the substrate, their purification and opening were also investigated. 

High-resolution transmission electron microscopy (HREM) is the technique best suited for the structural characterization of nanometer-sized graphitic particles. In-situ processing of fullerene-related structures may be performed, and it has been shown that carbonaceous materials transform themselves into quasi-spherical onion-like graphitic particles under the effect of intense electron irradiation[l 1],... 

At the end of this section, let us return briefly to the spectra shown in Fig. 3. Notice the structure in the mass spectrum of QoCa, between the completion of the first metal layer at 32 and the second at 104. This structure is identical in the fragmentation mass spectra of fullerenes covered with Ca and with Sr. It is reminiscent of the subshell structure of pure Ca clusters. The subshells could be correlated with the formation of stable islands during the growth of the individual shells[10,l 1]. The sublayer structure we observe here may also give some clue to the building process of these layers. However, the data is presently insufficient to allow stable islands to be identified with certainty. 

For multielectron-transfer (reversible) processes, the cyclic voltammogram consists of several distinct peaks if the E° values for the individual steps are successively higher and are well separated. An example of such a mechanism is the six-step reduction of the fullerenes C60 and C70 to yield the hexaanion products and C7q. Such six successive reduction peaks are observed in Figure 2-4. 

Figure 2. The new species added to our chemical models of interstellar clouds. The species range in complexity from 10-64 carbon atoms and comprise the following groups of molecules linear carbon chains, monocyclic rings, tricyclic rings, and fullerenes. The synthetic pathways are also indicated. See ref. 83. Reproduced from the International Journal of Mass Spectrometry and Ion Processes, vol. 149/150, R.P.A. Bettens, Eric Herbst "The interstellar gas phase production of highly complex hydrocarbons construction of a model", pp 321-343 (1995) with kind permission from Elsevier Science-NL, Sara Burgerhartstraat 25,1055 KV, Amsterdam, The Netherlands.

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