Five-vertex Archimedean surface tessellation by lanthanide-directed molecular self-assembly

Area of Science:

• Surface Science and Nanotechnology
• Materials Chemistry
• Crystallography

Background:

• Tessellation of surfaces with regular polygons is a long-standing challenge in mathematics and materials science.
• Achieving specific 2D interfacial tessellations at the molecular level, particularly those with five-vertex motifs, has remained elusive.
• Molecular self-assembly offers a pathway to engineer complex surface patterns.

Purpose of the Study:

• To investigate the directed assembly of molecular linkers on a noble-metal surface.
• To explore the formation of novel five-vertex coordination motifs.
• To fabricate a surface-confined metal-organic coordination network with specific tiling patterns.

Main Methods:

• Direct scanning tunneling microscopy (STM) investigation.
• Cerium-directed self-assembly of linear polyphenyl molecular linkers with terminal carbonitrile groups.
• Controlled tuning of rare-earth metal (cerium) and ligand concentrations and stoichiometric ratios.

Main Results:

• Spontaneous formation of fivefold cerium-ligand coordination motifs was observed.
• These motifs are planar and flexible, allowing connections between trigonal and square polygons.
• Hierarchic assembly led to dodecameric units and a metal-organic coordination network forming the Archimedean snub square tiling.

Conclusions:

• The study successfully demonstrates the fabrication of a semiregular Archimedean snub square tiling via molecular self-assembly.
• Fivefold coordination motifs are key to achieving complex tessellations at the molecular level.
• This work opens new avenues for designing intricate surface structures and functional materials.