| 초록 |
An efficient conversion of unstable linkages into stable linkages is an important objective in the chemistry of covalent organic frameworks (COFs), because it not only improves chemical and thermal stability but also preserves crystallinity. Here, unstable imine-linked COF (I-COF) was converted into stable aromatic benzoxazole-linked COF (BO-COF) via post-oxidative cyclization, based on chemistry used to form fused-aromatic polymers. The structure of the I-COF and BO-COF were confirmed by transmission electron microscopy, infrared and solid-state nuclear magnetic resonance spectroscopies, powder X-ray diffraction patterns and nitrogen adsorption-desorption isotherms. The post-modification of reversible imine linkage into irreversible benzoxazole linkage allows significantly improved thermal and chemical stabilities as well as high crystallinity. This strategy can be universally applied for the synthesis of stable fused-aromatic COFs, expanding their practical applications. |
