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Abstract
This thesis present the synthesis and self-assembly of a kind of discotic liquid crystalline graphite molecules and their potential applications as materials in molecular electronics. In detail,
1) A new synthetic concept was developed. Several insoluble hexa-peri-hexabenzocoronene (HBC) building blocks were synthesized and the subsequent functionalizations by transition-metal catalyzed coupling reactions lead to a versatile synthesis of HBC materials with multifunctionalities. For example, a series of soluble, highly ordered liquid crystalline materials were synthesized and well-characterized by X-ray scattering, polarized optical microscopy and atomic force microscopy. Electro-active moieties such as hole transporting triarylamines were attached to the HBC cores to give a new “coaxial” hole transport materials with high charge carrier mobilities. Intramolecular charge transfer and intermolecular association of the mixed valence HBCs substituted by arylamine were observed by UV-vis-NIR and ESR techniques.
2) The controlled self-assembly of HBC in solution were studied. A series of alkyl- or polyphenylene dendrons substituted HBCs was synthesized and their self-association behavior in solution was studied by NMR techniques and quantum chemical calculations. An interesting monomer-dimer equilibrium was found in one of the polyphenylene dendrons-substituted HBCs.
3) The synthesis, photophysical properties and self-assembly behavior of the oligomers of HBC with different length and connection modes was presented. Electronic decoupling was observed in the oligomers. The self-assembly behavior in the bulk-state was studied by X-ray diffraction techniques.
4) One-dimensional graphite ribbons were synthesized from the branched polyphenylenes by oxidative cyclodehydrogenation. The insoluble materials were characterized by UV-vis, Raman spectroscopy and transmission electronic microscopy.
