Construction of 2-azidacetic acid functionalized high-crystallinity fluorescent covalent organic framework: Applications in mitoxantrone and Fe3+ sensing and adsorption.

Due to the dual functions of fluorescence detection and adsorption, fluorescent covalent organic frameworks (COFs) have attracted significant attention. However, common fluorescent COFs often exhibit unsatisfactory fluorescence properties and selectivity, coupled with poor solution dispersibility, which limit their effectiveness in detection and adsorption applications. In response, a novel post-modified fluorescent COF (named AZC-COF) was synthesized by connecting a fluorescent COF (COF-TB) with 2-azidacetic acid through a copper-catalyzed aide-alkyne cycloaddition (CuAAC) reaction. AZC-COF demonstrated excellent solution dispersibility and robust green fluorescence, boasting an absolute fluorescence quantum yield (QY) of 7.58%, which was 13.5 times higher than that of COF-TB. Furthermore, leveraging the active carboxylic acid and triazole sites, AZC-COF exhibited remarkable binding abilities for mitoxantrone (MIX) and Fe³⁺, enabling sensitive detection and efficient adsorption of them. In contrast, due to the absence of these functional sites, COF-TB showed poor detection and enrichment capabilities for MIX and Fe³⁺. The impressive detection and adsorption efficiencies of MIX and Fe³⁺ in environmental water, aquatic organism (fish) and plasma samples underscore the potential of AZC-COF as a detection-adsorption platform. Additionally, AZC-COF demonstrated low toxicity and hemolytic activity, alongside promising potential for cell imaging and detection of MIX and Fe³⁺, highlighting its considerable application prospect in biological systems.