Fullerenes synthesis/purification

But a wide application of such substances is hampered by their high costs of synthesis and purification. The most popular synthesis methods are the arc-discharge and laser-ablation method which have the disadvantage of either small fullerene yield or small quantity of the fullerene containing soot. Moreover it is necessary to use vacuum technique for maintaining of low pressure of helium for these methods. For the hydrocarbon combustion method it is necessary to use the additional expenses for fullerene purification [1-3], Thus, the search for improved methods of fullerene synthesis is of considerable importance. 

Since the synthesis of macroscopic amounts of Ceo was achieved in late 1990, several strategies for each stage of fullerene synthesis and purification have been developed. 

Stevenson S, Stephen RR, Amos TM, Cadorette VR, Reid JE, Phillips JP (2005) Synthesis and purification of a metallic nitride fullerene bisadduct exploring the reactivity of Gd(NZ ,C80. J. Am. Chem. Soc. 127 12776-12777. 

Since efficient methods for the synthesis and purification of gram quantities of C60 and C70 became available in the early 1990s, fullerene chemistry has developed at a phenomenal pace. There are many reactions which can generate... 

Cyclotriveratrylene synthesis is a poorly understood process, as with many reactions between phenols and aldehydes, and yields are as variable as the methods to prepare them a review lists fifteen different conditions that give between 21 and 89% yield. Despite this the compounds are worth preparing as they have an interesting affinity for buckminsterfullerene, C6o, and are cited in papers and patents that describe methods to isolate pure C6o from a mixture of fullerenes [50], It transpires that the threefold symmetry of cyclotriveratrylene is complementary to the threefold axis of C6o and that the two form very stable complexes in toluene as shown in Fig. 1.12, which precipitate leaving other fullerenes in solution. If the precipitate is isolated and taken up in chloroform the complex dissociates leaving cyclotriveratrylene in solution and precipitates C6o- The purity of the C6o treated in this way is significantly enriched and can approach 100%. At the time of this discovery fullerene research was very much in its infancy, and the material available was of variable purity, making the purification technique an important milestone in the history of fullerene chemistry. 

Although much progress has been made in both synthesis and purification of carbon nanomaterials, commercial samples still contain nanostrucmres of different size, shape, and composition. As-produced carbon nanomaterials are frequently composed of mixtures of CNTs, fullerenes, carbon onions, amorphous carbon and graphite, which are structurally different and possess different reactivity. Since the oxidation kinetics are closely related to structural features, reaction rates and activation energies are expected to differ for the distinct carbon forms, which is an important issue for oxidation-based purification or surface functionalization. In analogy to graphite [3-6], oxidation of a carbon nanostmcture [7-9] can be described by a first-order reaction, with respect to the carbon component. 

The synthesis and purification of fullerenes were very difficult, and the prices of purified materials were high at the beginning. Later, a cheaper method was discovered, and grams of Ceo, the most important fullerene, are now available at reasonable cost [255]. 

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