The unusual molecular organization of 2,3-bis(n-hexyloxy)anthracene in the crystal. A hint to the origin of the gelifying properties of 2,3-bis(n-alkyloxy)anthracenes?

Unlike most anthracene derivatives and other oblong shaped aromatics, 2,3-bis(n-hexyloxy)anthracene (DHOA) crystallizes in the space group R(−3) with unit cell parameters a = b = 14.639, c = 54.435 Å. The molecular packing is composed of arrays of molecular triads. By computing the interaction potential of all the molecules with one another in space group R(−3), the lowest energy structure is found to be a triad and the lowest energy layer a coplanar head-to-tail packing of these triads; most of the crystal energy is associated with the layer formation and the binding energy of the various structures is calculated to depend essentially on the non-bonded van der Waals interactions. They might prefigure the arrangement of the anthracene nuclei in the gel network nodes formed by 2,3-di-n-alkoxyanthracenes whose alkyl chains possess six or more carbon atoms.