Supramolecular Approach to Schwarzite Carbon Materials

Projektbeschreibung

Aufbau dreidimensionaler Kohlenstoffnetzwerke inspiriert von Schwarziten

In den letzten drei Jahrzehnten wurden erhebliche Fortschritte bei der Entwicklung von null-, ein- und zweidimensionalen sp²-hybridisierten Kohlenstoffmaterialien erzielt. Ihre dreidimensionalen Gegenstücke, bekannt als Schwarzit-Kohlenstoffe oder Mackay-Terrones-Kristalle, wurden jedoch trotz ihres vorhergesagten elektronischen Potenzials bisher nicht realisiert. Vor diesem Hintergrund zielt das vom Europäischen Forschungsrat finanzierte Projekt SCHWARZITE darauf ab, praktische Synthesewege für diese porösen, kristallinen Kohlenstoffstrukturen zu entwickeln. Aufbauend auf einer neuen Methode zur Herstellung von heptagonhaltigen polyzyklischen aromatischen Kohlenwasserstoffen (PAKs) wird das Team sattelförmige Nanostrukturen entwerfen, die sich selbst um Fullerenvorlagen herum zusammenlagern. Mithilfe supramolekularer Bindungsstudien und Röntgenbeugung werden die Forschenden π-konjugierte Gerüste herstellen und charakterisieren. Dies soll den Weg für eine neue Klasse von porösen, leitfähigen Kohlenstoff-Werkstoffen ebnen.

Ziel

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.