An aperiodic chiral tiling by topological molecular self-assembly
Studying the self-assembly of chiral molecules in two dimensions offers insights into the fundamentals of crystallization. Using scanning tunneling microscopy, we examine an uncommon aggregation of polyaromatic chiral molecules on a silver surface. Dense packing is achieved through a chiral triangular tiling of triads, with N and N ± 1 molecules at the edges. The triangles feature a random distribution of mirror-isomers, with a significant excess of one isomer. Chirality at the domain boundaries causes a lateral shift, producing three distinct topological defects where six triangles converge. These defects partially contribute to the formation of supramolecular spirals. The observation of different equal-density arrangements suggests that entropy maximization must play a crucial role. Despite the potential for regular patterns, all observed tiling is aperiodic. Differences from previously reported aperiodic molecular assemblies, such as Penrose tiling, are discussed. Our findings demonstrate that two-dimensional molecular self-assembly can be governed by topological constraints, leading to aperiodic tiling induced by intermolecular forces.
2-s2.0-85213861034
École Polytechnique Fédérale de Lausanne
2025-12-01
16
1
83
REVIEWED
EPFL
| Funder | Funding(s) | Grant Number | Grant URL |
Swiss National Science Foundation | Advanced Molecular Chiral Surface Systems | 212167 | |
Swiss National Science Foundation | Advanced Molecular Chiral Surface Systems | 182082 | |
Swiss National Science Foundation | Opto-electronic and spintronic quantum transport in metal-organic nanowires and nanosheets | 202775 | |
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