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Updated: May 2, 2026
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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
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Orientational changes of supported chiral 2,2'-dihydroxy-1,1'binaphthyl molecules
Philipp Heister1, Tobias Lünskens, Martin Thämer
1Lehrstuhl für physikalische Chemie & Catalysis Research Center, Chemistry Department, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany. ulrich.heiz@mytum.de.
Physical Chemistry Chemical Physics : PCCP
|March 13, 2014
Summary
This study investigated chiral binaphthol (binol) molecular films on glass using SHG-ORD spectroscopy. Binol molecules achieve a stable orientation at a surface coverage of 5 × 10(16) molecules/cm², revealing coverage-dependent chiral properties.
Area of Science:
- Molecular and Surface Science
- Chirality Studies
- Thin Film Characterization
Background:
- Understanding molecular orientation is crucial for thin film applications.
- Chiral molecules exhibit unique optical properties dependent on their spatial arrangement.
- 2,2'-dihydroxy-1,1'binaphthyl (binol) is a well-studied chiral molecule with potential in various fields.
Purpose of the Study:
- To investigate the orientation evolution of binol molecular films on glass substrates.
- To determine the coverage-dependent chiral properties of binol enantiomers.
- To analyze the ratio of chiral and achiral susceptibility components in binol films.
Main Methods:
- Thin films of binol molecules were prepared on BK7 glass substrates under ultra-high-vacuum (UHV) conditions.
- Second-Harmonic-Generation Optical-Rotatory-Dispersion (SHG-ORD) measurements were performed.
- Surface coverage was precisely monitored during SHG-ORD experiments at 674 nm.
Main Results:
- Binol molecules reached a stable orientation at a surface coverage of 5 × 10(16) molecules/cm².
- Rotation angles up to 38 degrees were measured for the SH-signal of binol enantiomers.
- The ratio of chiral and achiral susceptibility components was calculated and found to vary with surface coverage.
Conclusions:
- The study successfully characterized the coverage-dependent orientation of chiral binol films.
- SHG-ORD is an effective technique for studying molecular chirality in thin films.
- The observed changes in susceptibility ratios highlight the influence of molecular coverage on chiral properties.
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