Large Systems with Corannulene Fragments

HDFT calculations for the three possible conformers 48a-c disclosed a slightly different picture than in the case of the conformers of 47. For this case the endo-exo conformer 48b was predicted to have the lowest energy with di-exo 48a and di-endo 48c being less stable by 0.9 and 4.9 kcal mol respectively [39]. While we were not successful in growing X-ray quality crystals, we strongly believe that 48b 

The different conformational preferences of the isomeric molecules 47 and 48 clearly show that we can design the shape of the whole molecular assembly by changing the size and/or shape of the central subunit to which the corannulene moieties are attached. This is of premium importance for the potential synthesis of molecular clips, tweezers, bowls and other nanosized molecular assemblies with interesting supramolecular properties. 

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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]. 

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