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Published on: May 15, 2017
Liquid crystalline order from ortho-phenylene ethynylene macrocycles
Sang Hyuk Seo1, Ticora V Jones, Helga Seyler
1School of Materials Science and Engineering, Hyperstructured Organic Materials Research Center, Seoul National University, Seoul 151-742, Korea.
Journal of the American Chemical Society
|July 20, 2006
Summary
Novel triangular macrocycles with ortho-phenylene ethynylene (o-PE) structures exhibit unique liquid crystalline properties. These shape-persistent molecules self-assemble into ordered columnar and nematic phases, paving the way for advanced nanotechnology applications.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Organic Chemistry
Background:
- Shape-persistent macrocycles are crucial for supramolecular materials and host-guest chemistry.
- Ortho-phenylene ethynylene (o-PE) cyclic trimers are a novel class of macrocycles.
- Discotic liquid crystals (LCs) are of significant interest for advanced materials.
Purpose of the Study:
- To synthesize and characterize novel triangular ortho-phenylene ethynylene (o-PE) cyclic trimers.
- To investigate the liquid crystalline properties of these novel macrocycles.
- To explore the self-assembly behavior of o-PE macrocycles with different side chains.
Main Methods:
- Synthesis of triangular o-PE cyclic trimers with alkoxy and triethylene glycol (TEG) side chains.
- Polarized optical microscopy (POM) to observe mesophases.
- Differential scanning calorimetry (DSC) for thermal analysis.
- X-ray diffraction (XRD) to determine structural ordering.
Main Results:
- The synthesized o-PE macrocycles exhibit novel discotic liquid crystalline properties.
- Self-assembly into thermotropic rectangular columnar (Colr), hexagonal columnar (Colh), and discotic nematic mesophases was observed.
- Alkyl side chains promoted molecular order, while hydrophilic TEG chains induced amphiphilic structures influencing organization.
- Demonstrated that electron-rich PE macrocycles can form liquid crystalline materials.
Conclusions:
- Triangular o-PE macrocycles are a new class of shape-persistent molecules with tunable liquid crystalline behavior.
- The nature of side chains significantly influences the self-assembly and resulting mesophases.
- These findings highlight the potential of electron-rich macrocycles for creating ordered, self-assembling materials in nanotechnology.
