Synthesis endohedral fullerenes

Chaur MN, Athans AJ, Echegoyen L (2008) Metallic nitride endohedral fullerenes synthesis and electrochemical properties. Tetrahedron 64 11387-11393... 

Another striking development with endohedral fullerenes was the synthesis of N C5q, the first example of encapsulation of a reactive nonmetal atom [128-132]. 

Fullerene generation by vaporization of graphite or by combustion of hydrocarbons is very effective and certainly unbeatable what facile production in large quantities is concerned. However, total synthesis approaches are attractive because (a) specific fullerenes could be made selectively and exclusively, (b) new endohedral fullerenes could be formed, (c) heterofullerenes and (d) other cluster modified fullerenes could be generated using related synthesis protocols. 

Wang T, Chen N, Xiang J et al (2009) Russian-doll-type metal carbide endofullerene synthesis, isolation, and characterization of Sc4C2 Cgo. J Am Chem Soc 131 16646-16647 Chen N, Chaur MN, Moore C et al (2010) Synthesis of a new endohedral fullerene family, Sc2S C2n (n = 40-50) by the introduction of SO2. Chem Commun 46 4818 820... 

Fullerenes—or cage compounds built exclusively from carbon atoms—and their metal-containing derivatives, metaUofuUerenes, were first observed in the gas phase by Kroto et al. [1,2] less than 20 years ago and prepared in crystalline form by Kratschmer et al. [3] less than 15 years ago. StiU, an enormous amount of observed and computed data has been obtained during this time (see, e.g. recent surveys on fullerenes [4-8] and endohedral metallofullerenes [9,10]). In addition to spheroidal fullerene cages, fullerene science also deals with other objects like elongated cylindrical bodies known as nanotubes, prepared by lijima [11] soon after mastering the fullerene synthesis, nanocones [12] or peapods [13]. AU the species exhibit a substantial application potential, especially for molecular electronics [14]. 

One example for a challenging yet unrealized synthesis goal is the introduction of a window into the fullerene framework large enough to allow atoms, ions or small molecules to enter the cage followed by a cluster closure reaction. Such a reaction sequence would provide an elegant access to endohedral fullerenes. 

The prototype of all fullerenes is Buckminsterfullerene ,. Since it is the most abundant fiillerene obtained from macroscopic preparation procedures such as the classical Kratschmer-Huffman method, its chemical and physical properties were developed in very quick sucession soon after it became available in 1990. The icosahedral football shaped Buckminsterfrdlerene 60 is now the most intensively studied molecule of all. Many principles of the chemistry of C , are known. These allowone to tailor design new fuUerene derivates with specific properties useful for biological applications or as new materials. The main types of fullerene derivative are exohedral addition products, endohedral fullerenes, heterofullerenes and cluster opened systems. Whereas many examples of the first two groups are already known, sophisticated methods for the synthesis of the latter two groups have started to emerge only recently. 

Cso peapods, C50 encapsulated inside a CNT, were first produced and observed during CNT synthesis by pulsed laser vaporization [150]. Nowadays the synthesis of encapsulated fullerenes [151], endohedral fullerenes [71,151-156] and volatile organometallic complexes of fullerenes [157] within the CNTs is mainly achieved by vapor phase filling technique, consisting in heating at the... 

Another challenging and yet uncultivated subject in fullerene chemistry is that related to the organic synthesis of endohedral fullerenes. The development of the study on this class of compounds has been much retarded compared with the wealth of studies on the transformation of fullerenes on their outer surface. These particular fullerenes seem to be waiting for the approach of organic chemists. 

If the orifice of an open-cage fullerene encapsulating a guest species can be completely closed while retaining the guest inside, the molecular surgery approach toward the synthesis of endohedral fullerenes is actualized. In 2005, Komatsu and co-workers reported such closure of the orifice of H2 56 by a four-step sequence of... 

Y2 Cg2 denotes two Y atoms inside a Cg2 fullerene [19], Thus far, only small quantities of endohedrally-doped fullerenes have been prepared and only limited investigations of endohedrally-doped crystalline materials have been reported but steady progress is being made both in synthesis and in properties measurements [20]. 

Zhang S, Sun D, Li X, Pei F, Liu S (1997) Synthesis and solvent enhanced relaxation property of water-soluble endohedral metallofullerenes. Fullerene Sci. Tech. 5 1635-1643. 

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