α-Helicomimetic foldamers as electron transfer mediators

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Biophysics

Background:

• Alpha-helical peptides are effective electron transfer mediators but require significant length (7-10 residues).
• Shorter molecular structures are desirable for efficient electron transfer mediation.
• Oligoureas offer a robust 2.5-helical conformation with potential for shorter, stable structures.

Purpose of the Study:

• To synthesize and characterize α-helicomimetic foldamers based on oligourea backbones.
• To investigate the electron transfer mediation capabilities of these oligoureas.
• To compare the stability of oligourea helices with those of peptides.

Main Methods:

• Synthesis of oligoureas with varying chain lengths (2, 4, 6 residues) functionalized with thiol groups.
• Formation of self-assembled monolayers on gold surfaces.
• Characterization of helicity in solution and solid-state.
• Electron transfer studies using current sensing atomic force microscopy (CS-AFM).

Main Results:

• Oligoureas were successfully synthesized and formed stable self-assembled monolayers.
• Electron transfer mediation by oligoureas was confirmed via CS-AFM.
• Oligourea helices demonstrated superior stability compared to peptide helices under AFM tip force.

Conclusions:

• Oligourea foldamers are viable, shorter alternatives to peptides for electron transfer mediation.
• The robust helical structure of oligoureas contributes to their stability and function.
• This study opens avenues for designing novel molecular wires and electron transfer systems.