Breaking π–π Stacking in One‐Dimensional Covalent Organic Frameworks

Abstract

ABSTRACT Covalent organic frameworks (COFs) constructed from aromatic building blocks typically incorporate specific functional groups to achieve target properties; however, the active role of intrinsic aromatic backbones remains underexplored due to their limited accessibility usually imposed by interlayer π–π stacking. Herein, we report a steric‐hindrance‐driven breaking of interlayer π–π stacking in one‐dimensional (1D) COFs built from sterically enforced non‐coplanar monomers, thereby rendering the accessibility of aromatic domains and enabling superior adsorption performance, as exemplified by I 2 uptake. Two COFs, TFPE‐MDA, and TFPB‐MDA, are assembled via interlayer van der Waals stacking, where the aromatic moieties orient toward the pore channels exposing the backbone π electrons; electron population analysis verifies that this packing does not perturb the π‐electron distribution. Iodine‐vapor adsorption measurements show high I 2 uptake capacities of 4.80 and 5.61 g·g −1 for TFPE‐MDA and TFPB‐MDA, respectively. FTIR, Raman, and XPS characterizations combined with theoretical calculations confirm I···π interactions between I 2 and the accessible π electrons of aromatic moieties in the COF frameworks. This study provides a novel design strategy for high‐performance COF materials by utilizing sterically enforced non‐coplanar monomers for breaking the commonly observed interlayer π–π stacking, thus enabling the access and utilization of the intrinsic π electrons in COF backbones.