In this work, we report the achievement of a homeotropically (or face-on) oriented bilayer formed by a pair of discotic materials designed with specific properties: selective solubility, adjusted transition temperatures, and room temperature hexagonal columnar liquid-crystalline phase. The homeotropic orientation of the bilayer which is only a few hundred nanometers thick is performed by solution-processed deposition followed by thermal annealing in the geometry of open supported films and is evidenced by X-ray scattering. This represents the first proof of principle of an organic heterojunction based on two oriented columnar liquid crystal layers.
The reaction of PTCDA (perylene‐3,4,9,10‐tetracarboxylic dianhydride) with an alcohol, a bromoalkane, and an alkylamine in the presence of DBU in DMF yields imido‐diester‐substituted perylenes. The reaction is limited to polar alcohols such as propanol, but longer alkyl chains are efficiently introduced in a second step by alkyl group exchange by using selective acidic ester hydrolysis that leaves the imide group intact. This amine‐efficient approach to imido‐diesters is used to obtain acceptor‐type self‐assembling dyes that form a hexagonal columnar liquid crystalline phase at room temperature.
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