Structure-activity relationships in linear oligoester ion-channels

Area of Science:

• Supramolecular Chemistry
• Membrane Biophysics
• Materials Science

Background:

• Understanding ion transport across lipid bilayers is crucial for biological processes and synthetic membrane applications.
• Oligoesters represent a class of synthetic molecules with potential ion-channeling capabilities.
• Structure-activity relationships for oligoester ion transport remain largely unexplored.

Purpose of the Study:

• To quantitatively assess the ion transport activity of a series of linear oligoesters.
• To identify structural features of oligoesters that correlate with significant ion transport.
• To investigate the role of molecular aggregation in the ion transport mechanism.

Main Methods:

• Quantitative fluorescence assay utilizing a pH gradient collapse across vesicle bilayer membranes.
• Pyrene fluorescence probe employed to detect compound aggregation in aqueous solutions.
• Sequential vesicle experiments to determine rate-limiting steps in ion transport.

Main Results:

• Significant ion transport activity was observed for oligoesters with lengths comparable to membrane thickness.
• Hydrophilicity emerged as a critical factor, with more hydrophilic oligoesters exhibiting higher activity.
• Distinct differences in activity were noted between constitutional isomers, highlighting stereochemical influences.
• Oligoester aggregation in solution was detected and identified as a rate-limiting step in the transport process.

Conclusions:

• Oligoester length and hydrophilicity are key determinants of ion transport efficiency across lipid bilayers.
• Molecular aggregation plays a significant role in modulating the ion transport mechanism.
• These findings provide insights into the design of synthetic ionophores based on oligoester structures.