Heptagonal Molecular Tiling via Self-Assembly of Heptagonal Phenylene-Ethynylene Macrocycle at the Liquid-Solid...

Area of Science:

• Surface Science
• Supramolecular Chemistry
• Materials Science

Background:

• On-surface tiling at the molecular level is a key area of scientific interest.
• Designing molecular building blocks is crucial for controlling self-assembly and creating ordered structures.

Purpose of the Study:

• To demonstrate molecular-level heptagonal tiling using a specific macrocyclic building block.
• To investigate the influence of solvent choice on the self-assembly patterns of heptagonal macrocycles.
• To advance the field of two-dimensional crystal engineering.

Main Methods:

• Utilized scanning tunneling microscopy (STM) to observe molecular self-assembly at the liquid-graphite interface.
• Employed a heptagonal meta-phenylene-ethynylene macrocycle with 14 alkoxy substituents.
• Investigated self-assembly in two different solvent environments: 1-phenyloctane and 1,2,4-trichlorobenzene.

Main Results:

• Achieved antiparallel molecular tiling at the 1-phenyloctane-graphite interface driven by van der Waals interactions of alkoxy chains.
• Observed an oblique pattern with four molecular orientations at the 1,2,4-trichlorobenzene-graphite interface.
• Demonstrated that solvent coadsorption can induce core distortion and alter tiling patterns.

Conclusions:

• The choice of the heptagonal molecular building block is critical for achieving heptagonal tiling.
• Solvent engineering provides a method to control the self-assembly and resulting patterns of macrocycles.
• This study contributes to the understanding of two-dimensional crystal engineering and molecular design.