Bilateral π-extension of an open-[60]fullerene in a helical manner

Abstract

The conventional π-elongation of open-[60]fullerenes could only give unilaterally π-extended derivatives. Herein, we report the further π-elongation at another site to achieve bilateral π-elongation via a consecutive nucleophilic addition of 4,5-dimethyl-o-phenylenediamine. The thus-formed π-extended open-[60]fullerene bears two-fold diaza[n]helicene (n = 5 and 6) motifs in its skeleton. The crystallographic analysis revealed the characteristic helicene–fullerene interactions with close contacts of 3.09 and 3.14 Å.