Hydration-Accelerated Crown Ether Diffusion within Single Three-Dimensional Covalent Organic Frameworks.
Xiaojuan Li1, Qianxi Wang2, Jian Tang2
1School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
Nano Letters
|July 24, 2024
Summary
We visualized 12-crown-4 diffusion in covalent organic framework-300 (COF-300) using microscopy. Hydration unexpectedly accelerated diffusion, revealing new insights into COF-crown ether interactions.
Area of Science:
- Materials Science
- Supramolecular Chemistry
- Chemical Engineering
Background:
- Covalent organic frameworks (COFs) are crystalline porous polymers with tunable structures.
- Understanding guest molecule diffusion within COFs is crucial for their applications.
- Crown ethers (CEs) are cyclic molecules known for their selective binding properties.
Purpose of the Study:
- To visualize and quantify the diffusion behavior of 12-crown-4 within COF-300 single crystals.
- To investigate the factors influencing 12-crown-4 diffusion, including hydration effects.
- To elucidate the noncovalent interactions between COFs and CEs.
Main Methods:
- Operando dark-field optical microscopy was employed to track 12-crown-4 diffusion in real-time.
- Diffusion coefficients (D) were quantified by analyzing the diffusion area and front.
- Heterogeneity in diffusion was assessed across intraparticle and interparticle scales.
Main Results:
- Direct visualization of 12-crown-4 diffusion within COF-300 single crystals was achieved.
- Intraparticle and interparticle heterogeneity in diffusion was observed.
- An unexpected hydration-accelerated diffusion of 12-crown-4 was discovered, with aqueous solutions diffusing faster than pure liquid.
- Pure 12-crown-4 liquid was unable to access the COF-300 framework.
Conclusions:
- Hydrogen-bonding interactions between surface water and COF imine groups drive the accelerated diffusion.
- The study expands the mechanistic understanding of COF-CE interactions.
- Findings will aid in designing advanced CE-based COFs with enhanced performance.
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