Halogen‐Bonded Organic Frameworks (XOFs) Based on N⋅⋅⋅Br⁺⋅⋅⋅N Bonds: Robust Organic Networks Constructed by Fragile Bonds

Abstract

Organic frameworks face a trade‐off between the framework stability and the bonds dynamics, which necessitates the development of innovative linkages that enable stable frameworks without hindering efficient synthesis. While iodine(I)‐based halogen‐bonded organic frameworks (XOFs) have been developed, constructing XOFs based on bromine(I) is desirable yet challenging due to the high sensitivity of bromine(I) species. Here, we present the inaugural construction of stable bromine(I)‐bridged two‐dimensional (2D) halogen‐bonded organic frameworks, XOF(Br)‐TPy‐BF4/OTf, based on sensitive [N…Br…N]+ halogen bonds. The formation of XOF(Br)‐TPy‐BF4/OTf was monitored by 1H NMR, XPS, IR, SEM, TEM, HR‐TEM, SEAD. Their framework structures were established by the results from PXRD, theoretical simulations and SAXS. More importantly, XOF(Br) exhibited stable two‐dimensional framework structures in various organic solvents and aqueous media, even over a wide pH range (pH 3‐12), while the corresponding modelcompounds BrPy2BF4/OTf decomposed quickly even in the presence of minimal water. Furthermore, the influence of the counterions were investigated by replacing BF4 with OTf, which obviously improved the stability of XOF(Br). This characteristic enabled XOF(Br) to serve as efficient oxidizing reagents in aqueous environments, contrasting with the sensitivity of BrPy2BF4/OTf, which performed well only in organic media. This study opens new avenues for the development and application of multifunctional XOFs.