Supramolecular Self-Assembly of Discotic Liquid Crystalline LEGOs

Discotic liquid crystals with well-defined columnar self-assemblies are promising for technological applications in organic electronics such as organic solar cells and field-effect transistors. In this entry, we review the self-assembly behavior of discotic supermolecules comprised of various discotic and cubic building blocks, including porphyrin, phthalocyanine, triphenylene, and polyhedral oligomeric silsesquioxane (POSS). With the help of amide hydrogen bonding, triphenylenes and porphyrins stack into the ordered “lamello-columnar” phase. Without hydrogen bonding interaction, the π-π stacking interaction leads to a hexagonal columnar phase with mixed phthalocyanine and triphenylene columns. For a POSS molecule covalently attached to eight triphenylenes, the triphenylenes and the POSS core can form a super-column when the space length is short. Self-assembly of these supercolumns can lead to a hexagonal superlattice. From this study, the spacer length, molecular geometry/size, and intermolecular interactions play an important role in the self-assembly of the discotic liquid crystalline LEGOs.