Bottom-up Synthesis of Novel 3D Carbon-Allotropes, Derived from 6.8² P and 6.8² D Polybenzene

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The central goal of this project is to develop the synthetic methodologies required to access molecular building blocks that can be assembled into the three-dimensional structure of both 6.8² D and 6.8² P polybenzene which can be added to the family of synthetic carbon allotropes (SCA). SCAs such as fullerenes, carbon nanotubes and graphene exhibit enormous potential for high-performance application which is why the quest for new carbon-based functional nanomaterials is a topic that currently receives tremendous attention. One of the most auspicious form is represented by the polybenzene (pbz) network. The two possible tillings, 6.8² D and 6.8² P polybenzene, are both 3D tilings of sp² hybridized carbon atoms contain just a single type of carbon atom which assemble into six- and eight-membered rings in a ratio of 2:3. Due to the different connectivity, the structure, stability, and electronic characteristic differs much. While the metallic 6.8² P polybenzene has a stability comparable to C60 fullerene and provides cavities large enough for intercalation of bigger ions (K+, Sr2+, Br–) or even small molecules (CO, N2, O2), the indirect semiconductor 6.8² D polybenzene is significantly more stable than the 6.8² P network and exhibits an intrinsic porosity suitable for the encapsulation of small ions (Li+, Na+, Mg2+). I seek to design a scalable synthesis and a detailed characterisation of the small molecular building block cycloocta-1,3,5,7-teraone featuring functional keto-groups that will allow for a controlled cross-linking reaction to the desired 3D carbon-network. The proposed reticular self-assembly of this key precursor is based on iterative Lewis or Brønsted acid catalysed enolizations followed by self-condensations. I will herein rely on the reversibility of the aldol condensation mechanism in the presence of water to facilitate the dynamic error-correction essential to the formation of a highly crystalline sample. To realise the development of the thermodynamically less stable 6.8² P polybenzene tiling, I intend to take advantage of template assisted crystallisation methods relying on no-covalent cation-π interactions. Complete structural characterisation will be performed using synchrotron X-ray diffraction, transmission electron microscopy and solid state 13C NMR techniques.