Ligand Exchanges Among [N-I⁺-N] Halogen Bonds: A Robust Strategy for the Construction of Functional Halogen-Bonded Organic Frameworks (XOFs)

The development of diverse linking methods in organic framework materials is crucial for advancing materials science and engineering. The [N-X + -N] halogen bonds are a powerful tool for constructing supramolecular aggregates, including halogen-bonded organic frameworks (XOFs), which have emerged as a new class of organic frameworks. However, the existing production of XOFs often yields insoluble AgI byproducts, impeding XOF crystallinity, performance, and functionality. Hence, alternative methods for XOF preparation are required. Here, we present a novel approach to constructing 2D XOFs via reversible ligand exchange reactions, avoiding unwanted AgI byproducts and enhancing crystallinity. Notably, this approach successfully yields highly crystalline XOF-TPT E, which was unattainable with the previous method. XOF-TPT E exhibits exceptional catalytic activity and recyclability upon Pd(II) loading, showing remarkable selective performance in Heck coupling reactions and indicating its potential for diverse applications. This method broadens XOF construction horizons and expands their preparation and applications.