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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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How Do Intermolecular Interactions Evolve at the Nematic to Twist-Bent Phase Transition?
Katarzyna Merkel1, Barbara Loska1, Yuki Arakawa2
1Institute of Materials Engineering, Faculty of Science and Technology, University of Silesia, ul. 75 Pułku Piechoty, 41-500 Chorzów, Poland.
International Journal of Molecular Sciences
|October 14, 2022
Summary
Polarized infrared spectroscopy revealed molecular reorientation in thioether dimers transitioning to the twist-bend phase. Density functional theory calculations confirmed these changes, highlighting intermolecular pairing and axial shifts.
Area of Science:
- Materials Science
- Physical Chemistry
- Spectroscopy
Background:
- Polarized infrared (IR) spectroscopy is crucial for analyzing molecular orientation in liquid crystal phases.
- Understanding intermolecular interactions is key to elucidating the formation of the twist-bend (NTB) phase.
Purpose of the Study:
- To investigate the molecular structure and interactions in the nematic (N) and twist-bend (NTB) phases of thioether dimers.
- To correlate changes in IR absorbance with molecular reorientation and intermolecular forces.
Main Methods:
- Infrared absorbance measurements using polarized light.
- Quantum chemistry calculations employing density functional theory (DFT).
Main Results:
- Significant changes in mean IR absorbance were observed in the NTB phase.
- A decrease in absorbance for longitudinal dipoles and an increase for transverse dipoles upon cooling indicated molecular ordering.
- DFT calculations showed changes in transition dipoles and revealed molecular pairing and axial shifts.
Conclusions:
- The study successfully linked IR spectral changes to molecular reorientation and intermolecular interactions in thioether dimers.
- Molecular pairing and axial shifts are significant factors driving the formation of the twist-bend phase.
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