[COF Morphology Control] Functional COF Microspheres via Self-limited Dynamic Linker Exchange for Stationary Phases
Abstract:
1) A novel approach termed "self-limited dynamic linker exchange" has been introduced for the synthesis of uniform functional covalent organic framework (COF) microspheres, which are crucial for their application as stationary phases in liquid chromatography.
2) The strategy has been successfully applied to create six different types of COF microspheres, showcasing its versatility and superiority over existing methods.
3) The unique feature of this strategy is its ability to balance reaction thermodynamics and molecular diffusion, leading to a controlled functionalization process that maintains the microspheric morphology.
Background:
1) Industry Problem: Traditional COFs used in chromatography suffer from irregular shapes and small sizes, leading to inefficiencies and high back-pressure.
2) Previous Solutions: Limited work has focused on the direct synthesis of homogeneous COF microspheres due to challenges in controlling the morphology during functionalization.
3) Innovation by Authors: The authors propose a dynamic linker exchange method that not only functionalizes COFs while preserving their microspheric shape but also offers a universal strategy applicable to various functional building blocks.
Experimental Details:
1) Synthesis of Uniform COF Microspheres: The authors synthesized PCOF microspheres with high crystallinity and a specific surface area of 211 m² g⁻¹, using a room-temperature approach.
2) Functionalization via Linker Exchange: By introducing functional building blocks into PCOF suspensions at elevated temperatures, the authors achieved in-situ functionalization while maintaining the spherical morphology.
3) Optimization of Reaction Conditions: The effect of temperature and monomer quantity on the exchange degree was systematically studied, identifying 90 °C as the optimal temperature for the reaction.
4) Characterization of Functionalized COFs: Employing techniques like FT-IR, PXRD, HR-TEM, and BET, the authors confirmed the successful functionalization and preservation of crystallinity.
Test & Analysis Summary:
1) FT-IR Analysis: New peaks corresponding to the functional groups confirmed the successful linker exchange.
Acidolyis Experiment: The degree of exchange was quantified using 1H NMR, with the highest exchange degree achieved at 90 °C.
2) Morphology and Size Distribution: SEM and TEM showed that the functionalized COFs maintained their spherical shape and narrow size distribution.
3) Thermal Stability (TGA): Both PCOF and ECOF-1 exhibited high thermal stability, indicating the robustness of the functionalized materials.
4) Solvent Stability Test: The materials demonstrated excellent stability in various solvents, preserving their structure and crystallinity.
Conclusion:
1) The authors successfully synthesized functionalized COF microspheres with uniform morphology and high crystallinity using a novel strategy.
2) The "self-limited dynamic linker exchange" method was proven to be a universal approach for the surface functionalization of COFs, applicable to a variety of building blocks.
3) The functionalized COFs were demonstrated to be effective as chiral stationary phases for chromatography, showcasing their potential in enantioselective separations.
4) to explore additional applications of the functionalized COFs beyond chromatography and to investigate the mechanism of the linker exchange process in more depth.
Functional Covalent Organic Frameworks Microspheres Synthesized by Self-limited Dynamic Linker Exchange for Stationary Phases
Jiabi Xu, Guangyuan Feng, Dana Ao, Xiaojuan Li, Mengqian Li, Shengbin Lei, Yong Wang
DOI:10.1002/adma.202406256
Link:https://onlinelibrary.wiley.com/doi/10.1002/adma.202406256