Precise construction of antiparallel-stacked 2D imine covalent organic frameworks for atmospheric water harvesting.

Abstract

Interlayer stacking modes dictated by noncovalent interactions play a pivotal role in influencing pore structures and emergent properties of 2D covalent organic frameworks (2D COFs), yet precise control over stacking modes remains challenging. Herein, we report a supramolecular strategy based on dipole-dipole interactions originated from 4,7-bis(phenylethynyl)benzo[c][1,2,5]thiadiazole (BT) units, enabling precise construction of antiparallel-stacked 2D imine-linked COFs. Single-crystal X-ray diffraction and density functional theory calculations reveal that BT incorporation directs antiparallel stacking through cooperative hydrogen bonding and multiple π-π interactions between adjacent layers. The resulting COF-BB-R (R = H, 2Me and 4Me) exhibits higher crystallinity and stability than the corresponding eclipsed-stacked COF-PB-R. Notably, COF-BB-H achieves a total water uptake of 0.70 g g-1 at 298 K, 2.2-fold higher than COF-PB-H (0.32 g g-1) and surpassing that of most imine-based COF adsorbents. This work provides an effective approach for precisely fabricating antiparallel-stacked 2D COFs for next-generation functional porous materials.

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