Assembling Surface Molecular Sierpiński Triangle Fractals via K⁺-Invoked Electrostatic Interaction

Area of Science:

• Supramolecular chemistry
• Surface science
• Nanotechnology

Background:

• Molecular Sierpiński triangles (STs) are well-known fractals constructible on surfaces with atomic precision.
• Previous methods utilized hydrogen bonds, halogen bonds, coordination, and covalent bonds for molecular ST construction on metal surfaces.

Purpose of the Study:

• To investigate the use of electrostatic attraction for fabricating defect-free molecular Sierpiński triangles.
• To explore the construction of molecular fractals on Cu(111) and Ag(111) surfaces.

Main Methods:

• Fabrication of molecular STs using 4,4″-dichloro-1,1':3',1″-terphenyl (DCTP) molecules and potassium cations on Cu(111) and Ag(111) surfaces.
• Experimental confirmation using scanning tunneling microscopy (STM).
• Theoretical validation using density functional theory (DFT) calculations.

Main Results:

• Successfully fabricated defect-free molecular STs through electrostatic attraction.
• Demonstrated that electrostatic interaction between potassium cations and polarized chlorine atoms in DCTP drives fractal formation.
• Confirmed the electrostatic interaction mechanism via both STM and DFT.

Conclusions:

• Electrostatic interaction is an effective driving force for constructing molecular fractals.
• This finding expands the available methods for bottom-up fabrication of complex supramolecular nanostructures.
• Enables new possibilities for designing functional nanomaterials.