Fragmentation of fullerenes

L. T. Scott, Fragments of Fullerenes Novel Syntheses, Structures and Reactions , Pure Appl. Chem 1996, 68, 291-300. 

Hathiramani D, Aichele K, Arnold W, Huber K, Salzborn E, Scheier P (2000) Electron-impact induced fragmentation of fullerene ions. Phys Rev Lett 85 3604-3607... 

Keywords radiation defects optical transitions electron structure fragmentation of fullerenes... 

TTie mass spectrum of (obtained by the FAB method using m-nitrotenzyi alcohol as the matrix) exhibits the parent ion at miz = 720 with complete absence of a peak at iniz = 840, showing the sample to be free from C70, confirming the NMR result. The mass spectrum of C70, similarly obtained, shows the main peak at mh — 840, but also a small peak at mh. = 720 which we attribute to fragmentation of C70 to Ceo-Analogous fragmentation of fullerenes has been indicated by earlier work. ... 

R142 D. Eisenberg, R. Shenhar and M. Rabinovitz, Anions in Buckybowls , in Fragments of Fullerenes and Carbon Nanotubes Designed Synthesis, Unusual Reactions, and Coordination Chemistry, eds. M. A. Petrukhina and L. T. Scott, John Wiley Sons, Inc., Hoboken, N. J., 2012, p. 63. 

Abstract This chapter summarizes the synthesis, physical properties, structure, and crystal packing of buckybowls. Buckybowls exemplify an intermediate class of polynuclear aromatic compounds between the closed-shell fullerenes and the flat extended arrays of graphene. These warped sheets can be seen as fragments of fullerenes or the end cap of single-waUed carlxMi nanotubes and, their curvature endows them with physical properties distinct from flat polynuclear hydrocarbons, which opens up unique possibilities for molecular bowls in various organic materials applications. 

Scott, L. T. Petrukhina M. Fragments of Fullerenes and Garbon Nanotubes Designed Synthesis, Unusual Reactions, and Goordination Ghemistry John Wiley Sons, Inc. Hoboken, NJ, 2011. 

The new carbon allotropes, fullerenes [14] and nanotubes [15], can accept a large number of electrons to their -system however, the neutral compounds are hardly soluble, especially in THF. Because of the low solubility of fullerenes, their complete reduction to hexaanions with Li is possible only under extreme conditions, such as the use of an ultrasound bath [16], When the reduction of fullerenes is performed in the presence of a small amount of 2, moderate conditions are required, e.g., low temperature and without sonication [17]. Corannulene, which is a fragment of fullerenes, is highly soluble in THF and is easily reduced. The resulting corannulene anion serves as an efficient electron shuttle, which assists in complete reduction of the practically insoluble fullerenes. In a similar way, single walled nanotubes were reduced by charge transfer by the use of small aromatic compounds, such as naphthalene, fluorenone and anthraquinone [18]. 

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. 

Supramolecular chemistry of fullerenes linked or fused with heterocylic fragments 99CSR263. 

Electrochemistry of fullerene derivatives with heterocyclic fragments 98ACR593. 

Regioselective and stereoselective template synthesis in chemistry of fullerenes annelated with heterocycles or linked with heterocyclic fragments 99ACR537. 

Dipolar cycloaddition in the synthesis of fullerene Ceo derivatives containing heterocyclic fragments 98KGS291. 

As with conventional Cl, this is a very mild form of ionization leading to molecular species with little or no fragmentation, i.e. (M + H)+ and (M — H) . This is not, however, always the case. The use of chromatographic modifiers may change the composition of the Cl plasma to such a state that, as in Cl and thermospray, other ions may be formed, e.g. the presence of ammonium acetate may lead to (M - - NH4)+ and (M - - CHsCOO)" ions in the positive- and negative-ion modes, respectively. The chemistry of the analyte may also have an effect, as has been discussed for ESI, with, for example, the spectra of fullerenes extracted from soot particles yielding an M+ molecular species [16],... 

Fig. 6.4 DNA fragmentation (% from control) in thymocytes (a), L1210 (b), and EAC cells (c) incubated for 5 and 20 h in the presence of photoexcited samples of fullerenes (1 - fullerene C 2 - C -composite-1 3 - C -composite-2). P < 0.05 compared to the control...

As seen, fullerenes behave as unsaturated ligands. Hence it is expected that coordination to metal fragments might saturate (at least partially) their electron-affinity. Hence it is expected that the electron-withdrawing ability of fullerenes is lowered after complexation with respect to that in their free state. 

Beck, R.D. Weis, P. Hirsch, A. Lam-parth, I. Laser Desorption-MS of Fullerene Derivatives Laser-Induced Fragmentation and Coalescence Reactions. J. Phys. Chem. 1994, 98, 9683-9687. 

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