Higher-order complexity through R-group effects in self-assembled tripeptide monolayers.

Area of Science:

• Surface science
• Supramolecular chemistry
• Origin of life studies

Background:

• Self-assembled monolayers (SAMs) are crucial for understanding molecular organization.
• Amino acid-based structures are relevant to prebiotic chemistry.
• Environmental surfaces may have played a role in early molecular evolution.

Purpose of the Study:

• To investigate the structural differences between tri-L-leucine and tri-L-valine SAMs.
• To explore how minor R-group variations affect SAMs.
• To discuss implications for prebiotic synthesis.

Main Methods:

• Scanning tunneling microscopy (STM) was used to image the monolayers.
• Highly ordered pyrolytic graphite (HOPG) served as the substrate.
• Analysis focused on structural characteristics of the self-assembled monolayers.

Main Results:

• Tri-L-leucine and tri-L-valine SAMs exhibited distinct self-assembled structures.
• A minor change in the amino acid R-group significantly altered monolayer organization.
• The balance between hydrogen bonding and van der Waals forces was identified as a key factor.

Conclusions:

• Small molecular changes can lead to significant structural diversity in SAMs.
• This finding has implications for understanding molecular evolution on surfaces.
• Environmental surfaces could have facilitated the emergence of complex molecules.