L-Tryptophan on Cu(111): engineering a molecular labyrinth driven by indole groups

Area of Science:

• Surface science
• Biomolecular chemistry
• Materials science

Background:

• L-Tryptophan is an essential amino acid vital for protein synthesis.
• It holds potential for chiral molecular electronics and biocompatible applications.

Purpose of the Study:

• Investigate L-Tryptophan adsorption and molecular orientation on Cu(111).
• Determine the influence of temperature and surface coverage on adsorption structures.

Main Methods:

• Scanning tunneling microscopy (STM)
• Scanning tunneling spectroscopy (STS)
• Experiments conducted at 55 K and room temperature.

Main Results:

• Adsorption structures of L-Tryptophan on Cu(111) depend on temperature and coverage.
• Low coverage: small clusters form.
• High coverage: ordered chains at room temperature, molecular labyrinth at 55 K.
• Superstructure dominated by hydrogen and π-bonding interactions.

Conclusions:

• Chemisorption of L-Tryptophan on Cu(111) is temperature and coverage dependent.
• Intermolecular hydrogen bonding and π-bonding interactions dictate molecular arrangement.
• Findings are relevant for designing molecular electronic and biocompatible devices.