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An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation
Published on: February 27, 2019
Chromonic liquid crystal formation by Edicol Sunset Yellow
D J Edwards1, J W Jones, O Lozman
1School of Chemical Engineering & Analytical Science, University of Manchester, PO Box 88, Manchester, M60 1QD, UK.
The Journal of Physical Chemistry. B
|August 30, 2008
Summary
Edicol Sunset Yellow (ESY) in water forms hydrazone structures in solution and liquid crystalline phases. These phases exhibit nematic and hexagonal structures with single-molecule stacks, suggesting head-to-tail packing.
Area of Science:
- Physical Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Edicol Sunset Yellow (ESY) is an azo dye used in various applications.
- Understanding the solution behavior and phase formation of dyes is crucial for their application and stability.
Purpose of the Study:
- To investigate the solution and liquid crystalline phases of Edicol Sunset Yellow (ESY) in water.
- To determine the tautomeric form of ESY in these phases.
- To characterize the structure and properties of the observed mesophases.
Main Methods:
- Optical microscopy
- Multinuclear Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 2H, 13C, 23Na)
- X-ray diffraction
Main Results:
- The hydrazone tautomeric form (NH) is prevalent in all studied phases, not the expected azo form (OH).
- Two distinct chromonic mesophases were identified: a nematic (N) phase (30-40 wt %) and a hexagonal (M) phase (40-45 wt %).
- X-ray diffraction revealed single-molecule stacks with ~3.5 Å spacing and unusual diffuse reflections at ~6.8 Å, indicative of head-to-tail molecular packing.
Conclusions:
- ESY exists predominantly in its hydrazone tautomeric form in aqueous solutions and liquid crystalline phases.
- The observed nematic and hexagonal mesophases are characteristic of chromonic systems with single-molecule aggregates.
- The diffuse X-ray reflections suggest a specific head-to-tail arrangement of ESY molecules within the stacks, influencing phase behavior.
