Related Experiment Video
Updated: Sep 19, 2025
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
6.5K
Orthogonal Photoswitching in Nematic Liquid Crystals
Hoàn Quân Trân1, Bart Jan Ravoo1
1Organisch-Chemisches Institut and Center for Soft Nanoscience, Universität Münster, Busso-Peus-Strasse 10, Münster, 48149, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 10, 2025
Summary
This study presents a dual light-responsive liquid crystal system using peri-anthracenethioindigo (PAT) and arylazopyrazole (AAP) switches. These photoresponsive materials enable orthogonal and path-independent switching for advanced adaptive materials.
Area of Science:
- Materials Science
- Supramolecular Chemistry
- Photochemistry
Background:
- Photoresponsive materials are key for adaptive technologies.
- Orthogonal and path-independent switching enables precise control over material properties.
- Liquid crystalline systems offer unique optical properties modulated by external stimuli.
Purpose of the Study:
- To develop a dual light-responsive nematic liquid crystalline system.
- To achieve orthogonal and path-independent photoisomerization of two distinct photoswitches.
- To demonstrate reversible phase transitions between nematic and isotropic states using light.
Main Methods:
- Doping peri-anthracenethioindigo (PAT) and arylazopyrazole (AAP) photoswitches into 4-cyano-4'-pentylbiphenyl (5CB) liquid crystal.
- Utilizing polarized optical microscopy to observe phase transitions.
- Irradiating the system with different wavelengths of light (UV to near-IR) to induce photoisomerization.
Main Results:
- The co-assembled supramolecular material exhibited reversible nematic-isotropic phase transitions upon light irradiation.
- Independent and efficient photoisomerization of both PAT and AAP photoswitches was achieved, demonstrating orthogonality and path independence.
- Distinct optical properties (birefringent vs. dark states) were observed via microscopy corresponding to the phase states.
Conclusions:
- This dual light-responsive system provides a proof-of-concept for multifunctional materials.
- Orthogonal switching capability allows precise, reversible modulation of material properties.
- Light serves as an effective noninvasive stimulus for controlling material states.
Related Concept Videos
02:24Properties of Enantiomers and Optical Activity
18.0K
It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
18.0K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.9K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
1.9K
02:52Stereoisomerism
12.5K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
12.5K
01:31Dielectric Polarization in a Capacitor
5.1K
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
5.1K
01:34The Fluid Mosaic Model
155.3K
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.
155.3K
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
3.3K
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
3.3K