Charge‐Directed Ionic Frameworks Based on Pillar[6]arene for Iodine Capture: Synergistic Confinement and Polyiodide Stabilization

Abstract This study pioneers the design of ionic crystalline frameworks using charged pillar[n]arenes. A tetrapyridinium‐functionalized pillar[6]arene ( P6TMe ) is synthesized as a multivalent cationic building block and is electrostatically assembled with polyaromatic sulfonates (1,5‐naphthalenedisulfonate ( NDS ) and 1,3,6,8‐pyrenetetrasulfonate ( PTS )) to form two novel pillararene ionic frameworks ( PIF‐1 and PIF‐2 , respectively). Single‐crystal X‐ray analysis reveals that PIF‐1 adopted an S‐shaped layered structure stabilized by synergistic π – π and cation‐ π interactions, while PIF‐2 possesses a staggered 2D architecture with embedded PTS linkers. Both frameworks exhibit exceptional iodine vapor uptake capacities (4.51 g g −1 for PIF‐1 ; 3.3 g g −1 for PIF‐2 ), which are attributed to their electron‐rich nanochannels and charge‐transfer‐driven polyiodide (I 2 /I 3 − /I 5 − ) formation. Spectroscopic studies (X‐ray photoelectron spectroscopy/Raman) confirm critical host–guest interactions involving pyridinium cations and sulfonate groups. The materials demonstrate iodine retention of >97% over 14 d, showcasing high stability for environmental applications).