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An aperiodic chiral tiling by topological molecular self-assembly
Jan Voigt1, Miloš Baljozović1, Kévin Martin2
1Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
Nature Communications
|January 3, 2025
Summary
Chiral molecules self-assemble into aperiodic triangular tilings on silver surfaces. Topological constraints and intermolecular forces drive this unique two-dimensional molecular aggregation, forming distinct defects and supramolecular spirals.
Area of Science:
- Surface science
- Crystallization fundamentals
- Supramolecular chemistry
Background:
- Two-dimensional self-assembly of chiral molecules is key to understanding crystallization.
- Polyaromatic chiral molecules exhibit unique aggregation behaviors on surfaces.
Purpose of the Study:
- To investigate the uncommon aggregation of polyaromatic chiral molecules on a silver surface.
- To understand the role of topological constraints and intermolecular forces in driving aperiodic tiling.
Main Methods:
- Scanning tunneling microscopy (STM) was employed to examine molecular aggregation.
- Analysis of molecular packing, tiling patterns, and defect formation.
Main Results:
- Chiral molecules formed dense, chiral triangular tilings of triads on a silver surface.
- A random distribution of mirror-isomers was observed within triangles, with an excess of one isomer.
- Topological defects at domain boundaries, driven by chirality, led to supramolecular spirals.
- Observed tiling was aperiodic, differing from known patterns like Penrose tiling.
Conclusions:
- Two-dimensional molecular self-assembly can be dictated by topological constraints.
- Intermolecular forces play a crucial role in inducing aperiodic tiling.
- Entropy maximization influences the arrangement of chiral molecules.
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