Relationship between core size, side chain length, and the supramolecular organization of polycyclic aromatic hydrocarbons

The effects of the core size, the side chain length, and the number of substituents on the supramolecular organization of polycyclic aromatic hydrocarbons have been investigated by 2D wide-angle X-ray scattering experiments performed on oriented filaments prepared by extrusion. The aromatic core size of the compounds varied between the hexa-peri-hexabenzocoronene core consisting of 42 carbon atoms and the enlarged aromatic core of 132 carbon atoms, whereas the length of the side chains extended up to 20 carbon atoms per chain. It has been observed that the lateral packing characterized by the lattice constant of the 2D intercolumnar hexagonal arrangement increases with the molecular masses of the core, forming the columnar stacks, and of the side chains which fill the core periphery. A model describing the relationship between the morphological and molecular parameters for the columnar hexagonal arrangements of the discotics is suggested and indeed proven by comparison with the experimental results.