Biomimetic KcsA channels enabled by 1D MOF-in-2D COF

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Biomimetic membranes mimic biological ion channels for selective ion sieving.
• Achieving high selectivity for monovalent cations like K+/Na+ is challenging due to small ion size differences.
• Existing membranes struggle with precise ion discrimination at the sub-nanometer scale.

Purpose of the Study:

• To design and develop a single-species selective membrane for enhanced K+/Na+ separation.
• To create heterogeneous ion transport channels by integrating 1D metal-organic frameworks (MOFs) into 2D covalent organic frameworks (COFs).
• To improve K+/Na+ separation performance by narrowing pore size and tuning channel interactions.

Main Methods:

• Proposed a 1D MOF-in-2D COF concept utilizing materials rich in -COOH groups.
• Constructed composite membranes through interlocking and in situ immobilized growth of MOF ligands and metal ions within a COF.
• Leveraged coordination interactions between -NH groups in COFs and Cu centers in MOFs for hetero-framework hybridization.

Main Results:

• The composite membrane exhibited rapid K+ diffusion within confined heterogeneous channels.
• Achieved unprecedented cation sieving performance with K+/Na+ selectivity approaching 10^2.
• Demonstrated K+/Mg2+ selectivity exceeding 10^3, indicating highly specific ion recognition.

Conclusions:

• The 1D MOF-in-2D COF design offers a viable strategy for creating single-species selective biomimetic membranes.
• This approach enables ultrahigh separation performance for challenging ion mixtures.
• The findings pave the way for advanced applications in ion sieving and separation technologies.