Nanographenic bowls based on contorted hexabenzocoronene: Synthesis, structure, and supramolecular assembly with fullerene C₆₀.

Abstract

Buckybowls, the curved fragments of fullerenes, are attractive synthetic targets for exploring carbon nanomaterials, but constructing atomically well-defined, large multilayered architectures remains a formidable challenge. Here we report the synthesis of a class of coronene-bottomed nanographenic bowls, namely, tricarbon-annulated trifluorenocoronenes (TCTFCs), based on a contorted hexa-<i>cata</i>-hexabenzocoronene (<i>c</i>-HBC) skeleton. Two TCTFC derivatives bearing <i>gem</i>-diaryl or <i>gem</i>-dialkyl appendages were prepared via a "branching arms cyclization" (BAC) strategy. X-ray crystallography unambiguously confirms their C₃-symmetric bowl-shaped geometry with bowl depths up to 2.3 angstrom and diameters exceeding 1 nanometer. These bowls exhibit red-shifted absorption/emission profiles, enhanced electron affinity, and reduced aromaticity relative to the <i>c</i>-HBC derivative. Notably, both compounds form 1:1 complexes with C₆₀ in solution, while their cocrystals adopt columnar or honeycomb packing motifs. This work establishes a synthetic paradigm in constructing fully edge-closed <i>c</i>-HBC-based buckybowls, further delivering fundamental insights into their substituent-dependent host-guest binding and supramolecular assembly.