Highly fluorescent Cucurbit[7]uril covalent organic frameworks for fluorescence sensor array

Developing highly fluorescent COFs represents a challenging task due to their aggregation-caused quenching effect. In this research, highly fluorescent COFs were successfully constructed by introducing Q[7] as a macrocyclic framework unit into their backbone via a mechanical interlocking strategy. These Q[7]-based polycyclic COFs exhibited fluorescence quantum yields that were 10 times higher than those of their Q[7]-free counterparts, owing to the weakened interlayer aggregation and the cavity confinement effect of Q[7]. The recognition sites from Q[7] and also endowed these Q[7]-based polycyclic COFs with a prominent fluorescence response to various targets. These prominent properties enable COFs as a sensor array for highly sensitive identification and detection of 13 sulfonamide antibiotics (SAs) with detection limits down to the nanomolar range, with recovery rates of 90.3%–104.7% in real samples. The supramolecular isolation strategy and cavity confinement effect caused by Q[7] will drive increased interest in fabricating COFs using macrocyclic molecules.