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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
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(E)-4-Bromo-2-[(phenylimino)methyl]phenol: a new polymorph and thermochromism
Helen E Mason1, Judith A K Howard1, Hazel A Sparkes2
1Department of Chemistry, Durham University, South Road, Durham DH1 3LE, England.
Acta Crystallographica. Section C, Structural Chemistry
|November 5, 2020
Summary
A new yellow crystal form of a brominated phenol derivative was discovered. This new polymorph, alongside the previously known orange form, exhibits distinct molecular planarity and thermochromic properties, changing color with temperature.
Area of Science:
- Crystallography
- Solid-state chemistry
- Organic chemistry
Background:
- Polymorphism is crucial in determining the physical and chemical properties of organic compounds.
- Understanding molecular structure and its relation to observed properties like color and thermochromism is key.
Purpose of the Study:
- To report a new polymorph of (E)-4-bromo-2-[(phenylimino)methyl]phenol.
- To characterize the crystal structure and properties of both known and new polymorphs.
- To investigate the relationship between molecular planarity, color, and thermochromism.
Main Methods:
- Single crystal X-ray diffraction at low temperatures.
- Structural analysis, including dihedral angle measurements.
- Observation and comparison of crystal colors and thermochromic behavior.
Main Results:
- A new yellow polymorph of (E)-4-bromo-2-[(phenylimino)methyl]phenol was synthesized and characterized.
- Both polymorphs exhibit intramolecular O-H...N hydrogen bonding forming S(6) rings.
- Significant differences in molecular planarity were observed between the orange (Φ = 1.8°) and yellow (Φ = 45.6°) polymorphs.
- Both polymorphs demonstrated thermochromism, with color changes upon cooling.
Conclusions:
- The discovery of a new polymorph highlights the structural diversity of (E)-4-bromo-2-[(phenylimino)methyl]phenol.
- Molecular planarity is a key factor influencing the distinct colors of the polymorphs.
- The observed thermochromism suggests potential applications in temperature-sensitive materials.
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