Supramolecular Chiral Halogen‐Bonded Organic Frameworks Enhance Efficient Chirality‐Induced Spin Selectivity

ABSTRACT Chirality‐induced spin selectivity (CISS) has attracted extensive interest for its various potential applications. However, the development of high‐spin‐polarization CISS materials still represents a significant challenge. We report the design and preparation of two novel 2D chiral halogen‐bonded organic frameworks (XOFs), XOF‐TPH and XOF‐TPO , constructed from chiral binaphthyl crown ether‐based ligands. By modulating the crown ether size, we controlled the molecular flexibility and consequently the crystallinity of the XOFs. The formation of XOF‐TPH/TPO was characterized by 1 H NMR, XPS, IR, XAFS, PXRD, SAXS, HR‐TEM, and SEAD. The frameworks exhibited pronounced Cotton effects and magnetic circular dichroism (CD), confirming their chiral nature. XOF‐TPH/TPO exhibited superior charge‐transport capability over the ligands. More importantly, both XOFs demonstrated significantly enhanced CISS effects compared to the monomeric ligands. This enhancement was attributed to the well‐ordered framework structures and the heavy‐atom effect of iodine, which amplifies spin‐orbit coupling. Notably, XOF‐TPH , with higher crystallinity, exhibited remarkable CISS performance with a spin polarization up to 94%, implying the crucial role of structural order. This work showed the tremendous potential of chiral XOFs for high spin selectivity and offered valuable insights into the structure–property relationship within CISS, which is crucial for the development of high‐performance CISS materials.