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Conjugated organometallic polymers containing Vollhardt's cyclobutadiene complex: aggregation and morphologies
W Steffen1, B Köhler, M Altmann
1Department of Chemistry and Biochemistry, The University of South Carolina, Columbia 29208, USA.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|February 24, 2001
Summary
New organometallic polymers were synthesized using acyclic diyne metathesis and Pd-catalyzed coupling. These polymers exhibit liquid crystalline phases and chiroptical properties, indicating self-assembly in solution and solid states.
Area of Science:
- Organometallic chemistry
- Polymer science
- Materials science
Background:
- Organometallic polymers offer unique electronic and optical properties.
- Controlled synthesis of polymers with specific architectures is crucial for advanced materials.
Purpose of the Study:
- To synthesize novel organometallic polymers with controlled molecular weights and side chains.
- To investigate the self-assembly behavior and liquid crystalline properties of these polymers.
Main Methods:
- Synthesis via acyclic diyne metathesis (ADIMET) and palladium-catalyzed Heck coupling.
- Monomer synthesis involving palladium-catalyzed coupling reactions.
- Characterization using microscopy (polarizing, transmission electron), circular dichroism, differential scanning calorimetry, and X-ray diffraction.
Main Results:
- Organometallic polymers with degrees of polymerization (Pn) up to 60 (Heck coupling) and 230 (ADIMET) were obtained.
- Polymers with hexyl, ethylhexyl, and (S)-3,7-dimethyloctyl side chains were synthesized.
- Nematic and lyotropic liquid crystalline phases were observed.
- Chiroptical properties indicated aggregation in poor solvents and the solid state.
- Electron microscopy revealed lamellar or honeycomb morphologies.
Conclusions:
- The synthetic methods allow for the preparation of organometallic polymers with tunable properties.
- The polymers exhibit liquid crystalline behavior and self-assembly, influenced by side chain structure.
- The observed morphologies are consistent with the liquid crystalline phases and molecular structure.