Bishexa-peri-hexabenzocoronenyl:: A "superbiphenyl''

The alkyl-substituted bishexa-peri-hexabenzocoronenyls 3a and 3b as well as the related alkyl substituted dihexa-pevi-hexabenzocoronenyldodecane 4 were synthesized. The good solubility of these compounds allowed a comprehensive spectroscopic characterization in solution. Both 3a and 4 form liquid crystalline phases, while only in the case of 4 could a highly ordered columnar structure with a hexagonal superstructure be observed. Photophysical studies in solution revealed a strong intramolecular interaction of the aromatic cores of 3a, in contrast to 4, where only weak intramolecular interactions could be observed. Compound 3a forms monomolecular adsorbate layers on graphite which were characterized by scanning tunneling microscopy.