Chiral stacks of a curved nanographene

Abstract

Despite enormous advances in the edge extension chemistry of nanographenes, examples of peri-annulations and the knowledge of their effect on molecular properties remain scarce. Here, we show the synthesis of a curved C60S5 nanographene comprising quintuple [5]thiahelicenes arranged in a C5-symmetric fashion on the zigzag edge (L-region) of a bowl-shaped corannulene core. The synthesis is achieved with the help of Stille coupling, alkynyl thiolation, sulfide/aryne cyclization, and direct arylation reactions. The prepared bowl-helix chiral structure absorbs and emits in the visible and near-IR regions. It assembles into persistent molecular bilayer graphene stacks in solution, solid state, and gas phase. The concave cavities of the supramolecular dimers can recognize the convex surfaces of fullerene C60 through shape complementarity and π-π stacking interactions in the solid state. A properties comparison with ortho-annulated analogs and archetypical nanographenes indicates the superiority of peri-annulations in the design of molecular graphenes.