Related Experiment Video
Updated: Apr 23, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
5.7K
Dynamic mirror-symmetry breaking in bicontinuous cubic phases.
Christian Dressel1, Feng Liu, Marko Prehm
1Institute of Chemistry, Organic Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle (Germany).
Angewandte Chemie (International Ed. in English)
|September 27, 2014
Summary
Achiral molecules spontaneously form chiral cubic liquid crystal phases. This symmetry breaking arises from helical twists propagating through network junctions, explaining previously unrecognized chirality in specific crystalline superstructures.
Area of Science:
- Materials Science
- Crystallography
- Supramolecular Chemistry
Background:
- Chiral segregation during self-assembly has long fascinated chemists.
- Understanding the formation of chiral superstructures from achiral molecules is a key challenge.
Purpose of the Study:
- To investigate spontaneous mirror-symmetry breaking in cubic phases of achiral molecules.
- To explain the origin of chirality in specific crystalline superstructures.
Main Methods:
- Studied self-assembly of achiral multichain-terminated diphenyl-2,2'-bithiophenes.
- Analyzed bicontinuous cubic liquid crystal phases (Im3̄m and Ia3̄d).
- Investigated helix matching at network junctions.
Main Results:
- Observed spontaneous mirror-symmetry breaking in cubic phases of achiral compounds.
- Found the Im3̄m cubic phase to be consistently chiral, while the Ia3̄d phase is achiral.
- Demonstrated that helical twist propagation explains the observed chirality and phase transitions.
Conclusions:
- Symmetry breaking is a general phenomenon in cubic liquid crystal phases of achiral rod-like compounds.
- The Im3̄m phase's chirality originates from its three-network structure and high twist.
- The Ia3̄d phase's achirality results from the cancellation of opposing chiralities in its two networks.
Keywords:
chiral isotropic liquidconglomeratederacemizationpolycatenar liquid crystalspontaneous chiral inductionMore Related Videos
Related Concept Videos
01:29Crystallographic Point Groups
120
Crystallographic point groups represent the various symmetry operations that can occur within crystals. They are unique in that at least one point will always remain unchanged during these actions. For instance, consider the triclinic system. This system, devoid of any axis or plane of symmetry, aligns with the C1 and Ci point groups.where Cᵢ is characterized solely by a center of inversion.Contrastingly, the monoclinic system introduces an element of symmetry. This system with one plane...
120
02:22Structures of Solids
17.6K
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
17.6K
02:25Chirality
23.1K
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...
23.1K
01:27Gauss's Law: Planar Symmetry
7.5K
A planar symmetry of charge density is obtained when charges are uniformly spread over a large flat surface. In planar symmetry, all points in a plane parallel to the plane of charge are identical with respect to the charges. Suppose the plane of the charge distribution is the xy-plane, and the electric field at a space point P with coordinates (x, y, z) is to be determined. Since the charge density is the same at all (x, y) - coordinates in the z = 0 plane, by symmetry, the electric field at P...
7.5K
01:24The Seven Crystal Systems: Overview
269
Crystals with various point group symmetries belong to different crystal classes, which are synonymous terms. Despite being in the same class, crystals may have distinct shapes, like cubes and octahedra. There are 32 three-dimensional point groups, all of which are systematically divided into seven crystal systems.The basic cubic crystal system, exemplified by NaCl, features orthogonal vectors (α = β = �� = 90°) of equal lengths (a = b = c). When specific...
269
01:25Imperfections in Crystal Structure: Point, Line and Plane Defects
142
A perfect crystal, in theory, has a uniform structure with the same unit cell and lattice points throughout. However, any deviation from this periodic arrangement is known as an imperfection or defect. These defects can be categorized into three types: point, line, and plane defects.Point defects occur when there is a deviation from the ideal due to missing atoms, displaced atoms, or additional atoms. These imperfections might occur due to imperfect packing during crystallization or because of...
142