Fluorescent probe for detection of formaldehyde based on UiO-66-NH2

Formaldehyde (FA) is a harmful substance commonly found in the environment, so effective testing is essential. Consequently, we designed and synthesized a novel fluorescent probe, which is based on covalent post-synthetic modification (PSM) of UiO-66-NH2 by naphthylamide (NI). The combination of the metal-organic frameworks (MOFs) and the covalent PSM makes the probe with large amount of hydrazine group exposed on the surface, which results excellent FA sensing performance like an ultrafast response time (20 ​s) and a low detection limit of 0.167 ​μM. The presence of covalent bonds can lock the fluorophore and prevent strong π-π interactions to exhibit aggregation-induced emission (AIE). Further we confirmed that such probe can be applied to real water samples and portable test strip experiment. In addition, experimental evidence such as fluorescence lifetime decay curves suggest that the main mechanism of fluorescence quenching is Förster resonance energy transfer (FRET). On the left is a description of the quenching mechanism for the reaction of UiO-66-HN with FA, and on the right are descriptions of UiO-66-HN's exceptional qualities, including its high sensitivity and AIE features. [Display omitted] •It is the first time that FA has been detected after covalent PSM of MOFs using NI.•It is the first time that NI transition from ACQ to AIE by covalently linking it to a kind of MOF.•UiO-66-HN exhibited rapid and sensitive detection for FA.