Covalent Quinazolinone Frameworks via Direct and Post-Synthetic Linker-Exchange Synthesis: Iodine Capture and Antibacterial Activity

We report the synthesis of new covalent quinazolinone-linked frameworks (CQFs) via two metal-free routes: direct oxidative cyclization (d-CQFs) and post-synthetic linker exchange (t-CQFs). The direct route affords amorphous polymers, whereas the linker-exchange method exploits the reversibility of imine precursors to preserve crystallinity and surface areas up to 1516 m² g^-1. Structural characterization of the CQFs confirmed the successful formation of the quinazolinone motif across both methodologies. The CQFs demonstrate high affinity for iodine, arising from strong donor-acceptor interactions with pore-confined polyiodides (I₃ ^-, I₅ ^-), leading to a capture capacity of up to 4.54 g g^-1. Furthermore, the iodine-loaded CQFs serve directly as highly effective antibacterial agents, delivering dose-dependent inhibition of E. coli and S. aureus in both contact and contactless assays. This work not only introduces a new linker chemistry but also establishes both amorphous and crystalline CQFs as a robust, dual-action platform for stable iodine capture and sustained iodine release for antibacterial action.