Viewing and inducing symmetry breaking at the single-molecule limit

Area of Science:

• Surface Science
• Chirality Studies
• Molecular Interactions

Background:

• Symmetry breaking is crucial for phenomena like homochiral life and enantioselective drug synthesis.
• Understanding the mechanisms of chirality transfer is essential in chemistry and materials science.

Purpose of the Study:

• To develop and demonstrate a method for inducing and measuring symmetry breaking at the single-molecule level.
• To investigate the relationship between scanning probe tip chirality and enantiomeric excess.
• To provide a reproducible system for quantifying chirality transfer.

Main Methods:

• Utilizing scanning tunneling microscopy (STM) for in situ, single-molecule measurements.
• Applying electrical excitation to prochiral molecules adsorbed on an achiral surface.
• Correlating enantiomeric excess with the intrinsic chirality of STM tips.

Main Results:

• Achieved significant enantiomeric excesses (up to 39%) in the chiral adsorbed state of molecules.
• Demonstrated that symmetry breaking is influenced by the chirality of the scanning probe tip.
• Observed height differences between single-molecule enantiomers, correlating with tip chirality.

Conclusions:

• Electrical excitation can induce measurable symmetry breaking and chirality transfer in prochiral molecules.
• STM tips possess intrinsic chirality that influences the degree of symmetry breaking.
• This work offers a novel, quantitative method for studying chirality transfer mechanisms.