Self-assembly of diphenylalanine with preclick components as capping groups

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Peptide Self-Assembly

Background:

• Diphenylalanine (FF) derivatives are explored for self-assembly.
• Click chemistry moieties (alkyne and azide) are utilized as capping groups.
• Weak intermolecular interactions, including dipole-π and π-π stacking, are investigated.

Purpose of the Study:

• To investigate the self-assembly of two engineered FF derivatives with distinct alkyne and azide capping group positions.
• To understand the influence of peptide concentration, medium polarity, and substrate on self-assembly.
• To elucidate the role of weak interactions in stabilizing supramolecular structures.

Main Methods:

• Synthesis of two diphenylalanine derivatives: Poc-FF-N3 and N3-FF-OPrp.
• Extensive study of self-assembly in the "pre-click" state under varying conditions.
• Characterization of resulting supramolecular structures and morphologies.
• Theoretical calculations on model complexes to understand molecular interactions.

Main Results:

• Poc-FF-N3 self-assembles into microfibers that form hierarchical, stable, birefringent dendritic-like microstructures.
• These dendritic structures arise from ordered microfiber agglomeration and are uncommon for short FF sequences.
• N3-FF-OPrp shows poor organization into well-defined structures, forming amorphous agglomerates.
• Molecular-level organization of Poc-FF-N3 involves antiparallel β-sheets stabilized by hydrogen bonds and reinforced by azide-alkyne interactions.

Conclusions:

• The positioning of alkyne and azide capping groups significantly impacts FF peptide self-assembly.
• Weak interactions involving capping groups play a crucial role in stabilizing peptide-peptide hydrogen bonds and π-stacking.
• Engineered FF peptides with specific capping groups can form complex and stable supramolecular architectures.