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.