2D conglomerate crystallization of heptahelicene

Area of Science:

• Surface science
• Supramolecular chemistry
• Organic chemistry

Background:

• Heptahelicene is a helical aromatic hydrocarbon with unique chiral properties.
• Controlling molecular self-assembly on surfaces is crucial for advanced materials.
• Previous studies showed racemic crystallization of heptahelicene on Cu(111).

Purpose of the Study:

• To investigate the two-dimensional (2D) nucleation and crystallization of heptahelicene on a single crystalline copper(100) surface.
• To compare the self-assembly behavior of heptahelicene on Cu(100) with that on Cu(111).

Main Methods:

• Scanning tunnelling microscopy (STM) was employed to visualize and analyze the molecular arrangement.
• The study focused on the self-assembly of heptahelicene molecules on the Cu(100) surface.

Main Results:

• Heptahelicene forms distinct homochiral domains on the Cu(100) surface.
• This observation differs from the racemic 2D crystals previously reported on the Cu(111) surface.
• The specific surface crystallography of Cu(100) influences the chiral separation during crystallization.

Conclusions:

• The Cu(100) surface promotes enantioselective self-assembly of heptahelicene.
• Surface crystallography plays a critical role in dictating the chirality of 2D molecular crystals.
• This finding opens possibilities for creating surfaces with controlled chirality.