Self-Assembly of a Tripod Aromatic Rod into Stacked Planar Networks

Threefold symmetric rigid-core molecules with an internally grafted poly(ethylene oxide) (PEO) chain were synthesized, and their self-assembled structures were characterized using differential scanning calorimetry, TEM, and 1D and 2D X-ray scatterings in the solid state. The tripod compounds based on short PEO chains (n=8, 13, 17, 21), self-assemble into 2D channel-like network structures, whereas the compound with the longest PEO chain (n=34) forms a lamellar liquid crystalline phase. The interiors of the channel structures are filled with flexible PEO chains along the double-walled aromatic circumference. In these channel-like networks, three aromatic rods connected in the meta-position to each other are superimposed in parallel to other adjacent molecules to form the double-walled aromatic frameworks stacked perpendicular to the resulting channels. These are novel examples of supramolecular channel-like structures developed using amphiphilic diblock molecules based on a threefold symmetric rigid scaffold.