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 wer e synthesized. The good solubility of these compounds allowed a comprehensi ve spectroscopic characterization in solution. Both 3a and 4 form liquid cr ystalline phases, while only in the case of 4 could a highly ordered column ar structure with a hexagonal superstructure be observed. Photophysical stu dies in solution revealed a strong intramolecular interaction of the aromat ic cores of 3a, in contrast to 4, where only weak intramolecular interactio ns could be observed. Compound 3a forms monomolecular adsorbate layers on g raphite which were characterized by scanning tunneling microscopy.