A Rigid Molecular Triangle as an Ultrafast and Highly Selective Transmembrane Li⁺ Channel

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Achieving high ion transport efficiency and selectivity simultaneously is a key challenge in artificial ion channel engineering.
• Existing artificial ion channels often face trade-offs between transport speed and selectivity.
• Developing precise molecular architectures is crucial for controlling ion transport.

Purpose of the Study:

• To design and synthesize a unimolecular artificial ion channel for efficient and selective lithium ion (Li+) transport.
• To investigate the transport properties and selectivity of the novel Li+ channel.
• To establish a molecular platform for Li+-selective applications.

Main Methods:

• Fabrication of a C3-symmetric pyromellitic diimide molecular triangle with a defined pore structure.
• Single-channel electrical measurements to assess ion transport.
• Determination of ion selectivity ratios for Li+ over other ions (Na+, K+).

Main Results:

• The unimolecular Li+ channel exhibits ultrafast Li+ transport with a conductance of 57.4 pS.
• Achieved record-high selectivity ratios: 50.1 for Li+/Na+ and 171.4 for Li+/K+.
• The channel's structure includes a 2.2 nm wall height and a 4.1 Å pore lined with carbonyl oxygens.

Conclusions:

• The developed molecular triangle represents one of the most efficient and selective artificial Li+ channels to date.
• This system demonstrates a versatile platform for creating Li+-selective membranes.
• Potential applications include targeted therapeutics and advanced separation technologies.