Related Experiment Video
Updated: May 1, 2026
06:35
Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
7.5K
Beyond the Solid Solution: Ordered Enantiomerically Unbalanced Packing in Surface-Confined Tetrahelicene Monolayers
Aleksandra Cebrat1, Kevin Martin2, Pingo Mutombo3,4
1Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
Chirality
|April 29, 2026
Summary
Chiral polycyclic aromatic hydrocarbons self-assemble into homochiral domains on surfaces. This study reveals how racemic tetrahelicene forms ordered, enantiomerically unbalanced phases on silver, enabling surface-confined symmetry breaking.
Area of Science:
- Surface science
- Supramolecular chemistry
- Materials science
Background:
- Chiral molecules on surfaces enable symmetry breaking.
- Polycyclic aromatic hydrocarbons offer unique electronic and structural properties.
- Controlling molecular self-assembly is key to designing nanostructures.
Purpose of the Study:
- Investigate the self-assembly of racemic 2,3-dicarbonitrile tetrahelicene on Ag(111).
- Resolve the evolution of molecular organization with changing surface coverage.
- Understand the formation of chiral nanostructures and symmetry breaking.
Main Methods:
- Low-temperature scanning tunneling microscopy (LT-STM).
- Density functional theory (DFT) calculations.
- On-surface self-assembly studies.
Main Results:
- Racemic tetrahelicene forms extended homochiral Kagomé domains at submonolayer coverage.
- A porous network of hexameric dimer motifs is observed.
- Higher coverage leads to denser packing and compositionally biased, ordered mixed phases.
Conclusions:
- Achieved surface-confined symmetry breaking via spontaneous resolution of racemic tetrahelicene.
- Demonstrated 2D conglomerate crystallization and formation of novel nanostructures.
- Identified distinct phases dependent on molecular coverage, moving beyond simple racemic mixtures.
Related Concept Videos
02:33Stereoisomerism of Cyclic Compounds
9.2K
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,...
9.2K
02:05Prochirality
4.0K
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...
4.0K
02:21Naming Enantiomers
18.9K
The naming of enantiomers employs the Cahn–Ingold–Prelog rules that involve assigning priorities to different substituent groups at a chiral center. Each enantiomer, being a distinct molecule, is assigned a unique name by the Cahn–Ingold–Prelog (CIP) rules, also called the R–S system. The prefix R- or S- attached to the chiral centers in an enantiomer is dependent on the spatial arrangement of the four substituents on the chiral center. The R–S system...
18.9K
02:02Chair Conformation of Cyclohexane
16.2K
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
16.2K
02:11Conformations of Cyclohexane
12.2K
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
12.2K
04:01VSEPR Theory and the Effect of Lone Pairs
40.2K
Effect of Lone Pairs of Electrons on Molecule Geometry
40.2K