Endohedral Fullerenes, Nanotubes and Graphene

Crystalline nanorings, literally closed circular nanoparticles with a hollow centre, were first prepared from zinc oxide in 2004 by a spontaneous self-coiling process from polar nanobelts. Semiconductor nanorings and indeed interestingly shaped nanoobjects in general, promise much in the way of applications as tools to probe fundamental physical phenomena and as nanoscale sensors, transducers, and resonators. 

Another interesting development is the imparting of valency to nanoparticles to make them behave like single atoms. Work by Francesco Stellacci (MIT, USA) has allowed the selective functionalisation of the axial polar positions of a gold nanoparticles with carboxylate-terminated thiols. This turns the nanoparticle into effectively a divalent superatom . Condensation of the carboxylic acid groups with 

6-diaminocyclohexane gives ID polymeric strands of nanoparticles up to 20 nm long.  

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Figure 34.1 Representative examples of [60]fullerene, endohedral fullerene, graphene and a single-walled carbon nanotube.

Metal-free reactions represent a direct way to study the confinement effects induced by the nanotube itself. Few such reactions have been carried out within CNTs, but notable examples include the formation of linear structures, such as fuUerene [151] and fullerene epoxide oligomers [174], formation of DWCNTs from endohedral fiiUerenes encapsulated in SWCNTs [71,155,156], or from encapsulated ferrocene [165], graphene nanoribbons (GNR) [186,187], the transformation of [Fe(C6oMc5)Cp] into encapsulated C70 [157], or the transformation of adamantane [188] and functionalized diamantine [189] in carbon chains. 

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