Related Experiment Video
Updated: Jan 1, 2026
10:33
An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation
Published on: February 27, 2019
8.8K
Helicoids in chiral liquid crystals under external fields
G De Matteis1,2, L Martina1,3, C Naya3
1Dipartimento di Matematica e Fisica, Università del Salento, Via Arnesano, 73100 Lecce, Italy.
Physical Review. E
|December 25, 2019
Summary
Cholesteric liquid crystals transition to helicoidal phases under magnetic fields. Researchers mapped these transitions using molecular chirality and magnetic field strength.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Cholesteric liquid crystals exhibit unique optical and structural properties.
- External stimuli, such as magnetic fields, can induce phase transitions in liquid crystals.
- Homeotropic anchoring conditions influence the alignment and behavior of liquid crystals at interfaces.
Purpose of the Study:
- To investigate the phase transitions of cholesteric liquid crystals under magnetic fields.
- To characterize the resulting helicoidal configurations and disclinations.
- To establish a phase diagram based on molecular chirality and magnetic field strength.
Main Methods:
- Analytical studies to understand the theoretical framework of the transitions.
- Numerical simulations to model and visualize the helicoidal phases.
- Experimental confinement between parallel planar surfaces with homeotropic anchoring.
Main Results:
- Observed transitions from the nematic state to various helicoidal configurations.
- Identified the formation of disclinations within these helicoidal phases.
- Developed a phase diagram illustrating the relationship between molecular chirality, magnetic field strength, and phase behavior.
Conclusions:
- Magnetic fields effectively control the phase transitions of cholesteric liquid crystals.
- The molecular chirality and magnetic field strength are critical parameters determining the observed helicoidal structures.
- The phase diagram provides a valuable tool for predicting and utilizing these liquid crystal phases.
Related Concept Videos
02:25Chirality
28.8K
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
28.8K
02:30Chirality in Nature
16.4K
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid.
16.4K
02:25Molecules with Multiple Chiral Centers
14.7K
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
14.7K
02:24Properties of Enantiomers and Optical Activity
20.9K
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,...
20.9K
02:33Stereoisomerism of Cyclic Compounds
10.8K
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
10.8K
02:05Prochirality
4.8K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
4.8K