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Copper-metallomesogen structures obtained by ionic self-assembly (ISA): molecular electromechanical switching driven
Franck Camerel1, Peter Strauch, Markus Antonietti
1Max Planck Institute of Colloids and Interfaces Research Campus Golm, 14424 Potsdam-Golm, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|August 14, 2003
Summary
Copper complexes with BPS and BCS ligands undergo a color change to brick red, indicating a shift to Cu(I) species. This transition is driven by self-assembly into nanostructured liquid crystals.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Coordination Chemistry
Background:
- Ionic self-assembly (ISA) is a versatile method for creating nanostructured materials.
- Metallomesogens combine metal ions with liquid crystal properties.
- Bathophenanthrolinedisulfonic acid (BPS) and bathocuproinedisulfonic acid (BCS) are ligands used in copper complexation.
Purpose of the Study:
- To synthesize and characterize novel nanostructured copper complexes using ISA.
- To investigate the electronic transitions and liquid crystalline behavior of these complexes.
- To explore the influence of surfactant structure on material organization.
Main Methods:
- Stepwise noncovalent multiple-interaction strategy for complexation.
- Ionic self-assembly (ISA) with ammonium surfactants.
- UV-Vis spectroscopy and Electron Paramagnetic Resonance (EPR) for electronic studies.
- Polarized light microscopy, DSC, and X-ray analyses for liquid crystal characterization.
Main Results:
- Copper(II) complexes with BPS and BCS ligands were successfully organized into nanostructured materials.
- A color change from green to brick red was observed in methyl-substituted BCS complexes, indicating a Cu(II) to Cu(I) oxidation state change.
- Metallomesogenic materials exhibiting thermotropic liquid-crystalline phases were formed with double-tail ammonium surfactants.
- Phase complexity increased with surfactant tail length, with C(18) surfactants yielding highly organized materials.
Conclusions:
- Steric interactions and mechanical packing within supramolecular structures drive electronic transitions in copper complexes.
- The tail length of double-tail ammonium surfactants significantly influences the organization and liquid crystalline behavior of the resulting metallomesogenic materials.
- ISA provides a pathway to create highly organized, functional nanostructured materials from metal complexes.