The STM bias voltage-dependent polymorphism of a binary supramolecular network

Area of Science:

• Supramolecular chemistry
• Surface science
• Nanotechnology

Background:

• Binary supramolecular networks offer tunable properties.
• Controlling polymorphism at interfaces is crucial for advanced materials.
• External stimuli-responsive molecular systems are of significant interest.

Purpose of the Study:

• To investigate the use of Scanning Tunneling Microscopy (STM) for inducing reversible polymorphic transitions in binary supramolecular networks.
• To explore the role of electrical bias in actuating these transitions at the liquid/solid interface.
• To demonstrate the preparation and control of diverse binary porous structures by mixing bias-sensitive and non-sensitive molecules.

Main Methods:

• Utilizing a Scanning Tunneling Microscope (STM) to probe and manipulate molecular assemblies at a liquid/solid interface.
• Applying controlled positive and negative sample bias potentials to induce polymorphic transitions.
• Systematically varying the relative concentrations of bias-sensitive and non-sensitive molecules in the binary network.

Main Results:

• Demonstrated a reversible transition between different polymorphs in a binary supramolecular network.
• Confirmed that the transition is externally driven by switching the polarity of the sample bias.
• Showcased the ability to access a variety of binary porous structures by mixing molecules with different bias sensitivities.
• Established reliable actuation of these structures for each relative concentration.

Conclusions:

• STM-induced electrical bias is an effective method for controlling polymorphism in binary supramolecular networks.
• The strategy of mixing bias-sensitive and non-sensitive molecules allows for the rational design and fabrication of tunable porous materials.
• This work provides a pathway for creating switchable and reconfigurable nanomaterials with potential applications in molecular sensing and storage.