The self-assembled nanostructures of rod-like molecules, such as rod-like macromolecules and liquid crystals, are commonly limited to nematic and/or layered smectic types of supramolecular structures due to the energetically preferred parallel orientation of rods. To explore a wide range of supramolecular structures of rod-like molecules, a series of dendritic rod-like oligo-fluorene (s) capped by tri(hydroxyl) group were designed and precisely synthesized. The synergistic effect of hydrogen bonding and dendritic molecular architecture successfully break the preferred parallel orientation of rods and endow the molecules with specific shape (fan-shape or cone-shape), which could be varied by changing the linking topology of rods, allowing formation of distinct motifs with curved interface (“disk” like motifs or spherical motifs). The “disk” like motifs are only able to form hexagonal packing cylinder phases; while the spherical motifs can form diverse spherical packing structures showing clear sequence from unconventional Frank-Kasper A15, to dodecagonal quasicrystalline and body centered cubic phases, governed by the competition between maximizing sphericity and uniformly filling space. These results provide a model system to achieve diverse anticipated supramolecular structures of rod-like molecules and may provide us some new insights about the formation of unconventional spherical packing structures.

Breaking parallel orientation of rods toward diverse supramolecular structures

2019 Fall National Meeting

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