Die lösungsmittelunterstützte Selbstorganisation Oligomer‐substituierter formtreuer Makrocyclen führt zur Bildung von Zylinderaggregaten (siehe schematische Darstellung), die in Lösung vollständig charakterisiert wurden und sich als supramolekulare hohle Polymerbürsten bezeichnen lassen.
Shape-persistent macrocycles based on the phenyl-ethynyl-butadienyl backbone containing two extraannular hydroxyl groups were prepared by the oxidative coupling of the appropriate phenylethynyl oligomers. Carbodiimide-directed coupling with independently synthesized polystyrene carboxylic acid oligomers led to ABA coil-ring-coil block copolymers in which the central macrocycle serves as rigid and the polystyrene oligomers as flexible elements. Depending on the size of the coil blocks, these structures aggregate in cyclohexane into supramolecular hollow cylindrical brushes in which the rigid core is surrounded by the flexible matrix. However, in the solid state it is not possible to identify a morphology in which isolated channels based on aggregated macrocycles are embedded in a matrix of polystyrene. Detailed X-ray and electron diffraction studies on samples prepared from a solution in cyclohexane under equilibrium conditions show that the material adopts a lamellar morphology in the solid state in which columns of macrocycles are aggregated into layers which are separated by polystyrene.
What is the design principle of a discotic liquid crystal? Up to now, such systems have involved a more or less rigid core surrounded by flexible side groups that point outward. Herein, shape‐persistent macrocycles are introduced with flexible side chains that have intraannular positions (see picture).
Solvent‐induced self‐assembly of oligomer‐substituted shape‐persistent macrocycles leads to the formation of cylindrical aggregates (see the schematic representation), which have been fully characterized in solution. These aggregates, bound by nonspecific interactions, can be described as supramolecular hollow polymer brushes.
Alkyl‐ and Oligostyrene substituents were attached to shape‐persistent macrocycles based on a phenyl‐ethynyl backbone. In good solvents for both the rigid core and the flexible corona no aggregation occurred. Whereas, addition of a solvent that selectively solubilizes the corona induced a solvophobic aggregation. For alkyl substituted rings the experimental data were described by a monomer‐dimer equilibrium. In contrast, the oligostyrene substituted rings formed more expanded aggregates which were investigated by scattering and by imaging methods. The superstructures are consequently described as hollow supramolecular cylindrical brushes.
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