A water-soluble m-phenylene ethynylene foldamer.

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Organic Chemistry

Background:

• m-Phenylene ethynylene (mPE) foldamers are known for their unique structural and electronic properties.
• Developing water-soluble foldamers is crucial for applications in biological and environmental systems.
• Controlling foldamer conformation and host-guest interactions in aqueous media remains a challenge.

Purpose of the Study:

• To synthesize a water-soluble mPE foldamer by incorporating hexaethylene glycol side chains.
• To investigate the conformational behavior of the foldamer in aqueous solutions.
• To evaluate the host-guest binding properties with (-)-alpha-pinene as a function of water composition.

Main Methods:

• Synthesis of a water-soluble mPE foldamer with hexaethylene glycol side chains.
• UV-Vis spectroscopy to analyze conformational changes in aqueous solutions.
• Binding studies to determine association constants and kinetics with (-)-alpha-pinene in varying water/acetonitrile mixtures.

Main Results:

• The synthesized mPE foldamer demonstrated water solubility and adopted a helical conformation in aqueous solutions, confirmed by UV spectra.
• A dramatic increase in the association constant between the foldamer and (-)-alpha-pinene was observed with increasing water content, reaching a maximum at 90% water in acetonitrile.
• The rate of host-guest complexation significantly decreased as the water content increased, indicating slower equilibration.

Conclusions:

• The incorporation of hexaethylene glycol chains successfully rendered the mPE foldamer water-soluble and induced a helical structure.
• The foldamer exhibits tunable host-guest binding properties, with enhanced affinity for (-)-alpha-pinene in highly aqueous environments.
• The findings suggest potential applications for these foldamers in water-based separation or sensing technologies.