Supramolecular Approach to Schwarzite Carbon Materials

forthcoming

Considerable progress has been made over the past thirty years in the synthesis and preparation of 0D, 1D, and 2D sp2-hybridized carbon materials, as well as for their smaller discrete nanosized polycyclic aromatic hydrocarbon (PAH) counterparts. However, 3D sp2-hybridized carbon networks, called schwarzite carbons or Mackay-Terrones crystals – first proposed in the early 1990s – remain elusive, despite exciting electronic properties and important applications being predicted for these porous crystalline all-carbon solids by theoreticians. Little activity has been devoted to this new class of carbon materials due to the enormous challenges foreseen for their synthesis. Even research towards 7- and 8-membered rings, whose saddle-shaped structures are the prerequisite for schwarzite-type molecular carbon materials, has only recently become a research focus for a still small number of chemists. Based on an efficient synthetic method for heptagon-containing PAHs recently developed by our laboratory and the subsequent demonstration of the perfect schwarzite-like organization of four of such molecules around a C60-fullerene template, we herein propose rational strategies for both schwarzite-inspired saddle-shaped nanostructures as well as 3D schwarzite-like porous pi-conjugated solid-state materials. Thus, in this project, novel saddle-shaped PAHs bearing schwarzite-inspired sequences of hexagons and heptagons will be synthesized and self-assembled around fullerenes and other spherical template molecules, and characterized by supramolecular binding studies and single-crystal X-ray diffraction. Various synthetic approaches will be pursued for the post-functionalization of these complexes to afford pi-conjugated cage molecules and schwarzite-type pi-conjugated 3D materials. The functional properties of these novel materials will be explored with a broad repertoire of available techniques in our laboratory.