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EDA-Mediated Aqueous Synthesis of COFs for Water Extraction
Summary:
The authors from Southeast University & Nanjing Tech University developed an EDA-COF (TpPa) with record-high crystallinity and 1 813 m² g⁻¹ BET, achieving 0.65 g g⁻¹ water harvest at 30 % RH.
Background:
1. To avoid toxic organic solvents, previous aqueous COF synthesis gave low crystallinity/porosity; co-solvents, surfactants or ionic liquids only partly solved the problem.
2. This work proposes an electron-donor–acceptor (EDA) strategy: electron-rich DMAP forms water-soluble charge-transfer complex with electron-deficient aldehyde monomers, enabling fully aqueous, reversible and scalable COF synthesis.
Research Content:
1. Synthesis: 1,3,5-triformylphloroglucinol (Tp) + 12 eq DMAP in water → orange EDA complex; add p-phenylenediamine (Pa), 120 °C 3 d, 91 % yield TpPa; similarly prepared HaPa, TpAzo, TbDt, TfTm, TfTMP-I and gram-scale 3.8 g batch.
2. Characterizations
1) BET: TpPa 1 813 m² g⁻¹ (theory 1 849), pore 1.8 nm, vol 1.33 cm³ g⁻¹; TpAzo up to 2 887 m² g⁻¹.
2) SEM/TEM: 200–500 nm nanosheets with clear (100) lattice fringes.
3) PXRD: sharp (100) peak 2θ = 4.6°, FWHM 0.40°; AA stacking confirmed; framework intact after 20 water-swing cycles, boiling water, acid/base 24 h.
3. Application: 25 °C, 30 % RH equilibrium uptake 0.65 g g⁻¹; 45 °C complete release; 20 cycles no loss; outdoor device 0.60 L kg⁻¹ day⁻¹ potable water (WHO standard).
4. Mechanism: DFT shows DMAP-Tp EDA lowers activation energy from 57.9 to 38.6 kcal mol⁻¹; water stabilizes ion-pair intermediates, enhances reversibility and self-repair of linkages, yielding highly ordered β-ketoenamine networks.
Outlook:
The EDA-mediated aqueous route breaks the crystallinity-scalability dilemma of COFs, offering a green platform for high-performance porous materials toward water harvesting, catalysis and separation.
Electron Donor–Acceptor Interactions Enabling Aqueous Synthesis of Covalent Organic Frameworks with Unprecedented Crystallinity and Porosity for Water Extraction from Arid Air
Authors: Jinglin Gao, Congcong Yin, Meng Chen, Mingjie Wei, Chuansheng Tang, Ya Du, Xin Zhao, Yuping Wu, Yong Wang
DOI: 10.1002/anie.202515651
Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202515651
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