Jinghang Wu, Qianfeng Gu, Qi Zhang
Achieving precise control over molecular structures is a central goal in modern chemistry. Most organic polymers are built using irreversible covalent bonds, which often lead to amorphous powders due to kinetic trapping during synthesis. The lack of crystallinity limits the use of single-crystal X-ray diffraction, making it difficult to understand structure-property relationships. To address this issue, dative boron-nitrogen (B ← N) bonds have emerged as a promising solution. These bonds combine high directionality with dynamic reversibility, enabling error correction during molecular assembly and promoting the formation of high-quality single crystals. This review summarizes recent advances in B ← N-based crystalline polymers. We discuss the evolution of their structural topologies, from one-dimensional to three-dimensional structures. We also highlight emerging applications in separation, photocatalysis, and batteries. The atomically precise structures of these materials offer valuable insights into charge transport and host-guest interactions. Finally, we outline current challenges and future research directions. This review aims to provide useful guidance for designing functional crystalline covalent organic polymers/frameworks (COPs/COFs).