Oxidative cage opening in the C70 fullerene facilitated by preceding trifluoromethylation.

Two novel derivatives of the C70 fullerene with 9- and 10-membered cage openings were obtained by means of oxidation and decarbonylation of C70(CF3)8. The major product, C70(O)(CF3)8O2, features a cleaved C-C bond transformed into two carbonyl functions plus an ether bridge. The second product, C69O(CF3)8O, has one of the carbonyls replaced with another ether bridge. We provide a DFT analysis of the possible formation pathways to give the oxidized compounds under the action of pyridine N-oxide.

Reversibly switchable methanofullerene by photoexcitation and reduction.

A cyclopropanated derivative of the trifluoromethylated fullerene Cs-C70(CF3)8 demonstrates reversible switching behavior triggered by excited state electron transfer or by negative charging. The switching between the state with connected 62-electron π-system and the state with disjoint 28- and 32-electron conjugated caps is effected by opening/closure of the cyclopropanated bond. A pronounced alteration of the electronic properties upon seemingly minor changes in a large fullerene molecule is an attractive feature for the organic electronic devices where similar fullerene compounds are commonly utilized as electron acceptor materials.