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.