Trimethylammonium-Substituted Amphiphilic Pillar[n]arene Channels for Selective Water Permeation

Area of Science:

• Supramolecular chemistry
• Biomimetic materials science

Background:

• Artificial water channels (AWCs) are synthetic systems designed to mimic the function of natural aquaporins (AQPs).
• These AWCs selectively transport water while preventing the passage of ions.
• Amphiphilic rim-differentiated pillararenes are key building blocks for constructing these channels.

Purpose of the Study:

• To investigate the structure-activity relationships of AWCs within lipid bilayers.
• To evaluate the impact of different alkyl chain lengths on membrane partitioning and water transport.
• To identify AWCs with high water permeation and ion rejection capabilities.

Main Methods:

• Synthesis of amphiphilic rim-differentiated pillar[5]arenes and pillar[6]arenes with varying alkyl chains (butyl-C4 and decatyl-C10).
• Assembly of these molecules into two-dimensional artificial water channels.
• Investigation of channel properties, including pore size, channel length, membrane partitioning, and water/ion transport within a lipid bilayer model.

Main Results:

• The AP-P6A-C10 artificial water channel exhibited the highest water permeation rate (approximately 1 × 10⁸ water molecules per channel per second).
• This enhanced performance was attributed to a synergistic effect between a large pore size and favorable lipophilicity.
• The AP-P6A-C10 channels demonstrated effective ion rejection, maintaining low ion and proton transport activity.

Conclusions:

• Artificial water channels (AWCs) based on pillararene derivatives can achieve biomimetic water transport with high selectivity.
• The AP-P6A-C10 structure represents a promising design for efficient artificial water channels.
• These findings contribute to the development of advanced materials for water purification and separation technologies.