V‐Shaped Linkers Modulate Covalent Organic Frameworks' Interlayer Spacing for Efficient Iodine Capture

ABSTRACT Significantly enlarging and precisely regulating the interlayer spacing of two‐dimensional covalent organic frameworks (2D COFs) is both meaningful and challenging. Capitalizing on the weak conjugation effects inherent in flexible monomer assembly, this study proposes an interlayer regulation strategy for constructing 2D flexible COFs using dual‐flexible monomers. By introducing nonlinear V‐shaped linkers, we elucidated the core structure‐property relationship of “angle‐packing‐spacing” and established a novel assembly method for synthesizing highly crystalline 2D nonlinear COFs (NLCOFs). Crucially, the V‐shaped topology effectively suppresses interlayer π‐π stacking interactions, thereby enabling controllable expansion and precise tuning of COF interlayer spacing within the range of 4.2 Å to 4.5 Å. Moreover, fine‐tuning the included angle of linkers allows NLCOFs' structural optimization, allowing control over the adsorption and transport properties toward guest molecules such as iodine vapor and iodomethane. This work provides fundamental insights into the rational design of flexible crystalline COFs and establishes a potentially generalizable strategy for interlayer engineering.