Superspreading‐Confined Assembly of Oriented 2D MOF Membranes for Biomimetic Cation‐Regulated Ion Transport

• Published in: Advanced functional materials 2024-07, Vol.34 (28), p.n/a
• Main Authors: Qiu, Ming, Zhu, Zhongpeng, Wang, Dianyu, Xu, Zhe, Xia, Fan, Jiang, Lei, Tian, Ye
• Format: Article
• Language: English
• Subjects: Assembly; Benzene; Binding sites; Channels; Confined spaces; Diffusion layers; Divalent cations; Fluidics; Ion transport; Membranes; Metal-organic frameworks; nanofluidics; Nanofluids; oriented membranes; space‐confined assembly; superspreading surfaces; Thickness; Transport phenomena
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202316040

Inspired by biological channels, metal‐organic framework (MOF) membranes with sub‐nanometer sized channels offer an ideal platform to construct high‐performance artificial nanofluidic system. However, fabricating long‐range ordered MOF membranes is still a significant challenge. Herein, a superspreading‐confined assembly method is developed to prepare large‐scale oriented 2D MOF (Zn‐TCPP (TCPP = meso‐tetra(4‐carboxyphenyl) porphine)) membranes. The superspreading of reactant liquid under oil phase to form liquid layer plays a critical role in membrane formation, which provides a dynamic confined space for layered assembly of Zn‐TCPP nanosheets. Accompanied with solvent diffusion, such liquid layer is completely converted into ‐oriented MOF membrane with controlled thickness. The prepared membrane exhibits distinct divalent cation (Mx2+)‐regulated ion transport behavior as that demonstrated in biological channels: K+ flux can be precisely adjusted by anchoring diverse Mx2+ ions to binding sites, which is appealing in designing high‐performance nanofluidic iontronics. Moreover, similar strategies can be employed to fabricate other MOF membranes (such as Hf‐BTB (BTB = 1,3,5‐tris(4‐carboxyphenyl)benzene) and Ni‐TCPE (TCPE = tetrakis(4‐carboxyphenyl)ethylene)), indicating the broad applicability of this method in 2D membrane fabrication. A general superspreading‐confined assembly method is developed, by which metal‐organic framework (MOF) nanosheets generate and in situ assembly into oriented 2D membranes under the confinement of spreading liquid layer. The prepared porphyrin‐based MOF membranes exhibit biomimetic cation‐regulated ion transport behavior. Multi‐state ion‐transport is achieved by anchoring divalent cations with different affinities to the membrane binding sites.