Ratiometric Fluorescence Detection of Sodium Dehydroacetate in Bread Using a Dual-Emission Tb-MOF Constructed from Dual Ligands

Sodium dehydroacetate (SDHA) is an efficient antifungal preservative widely used in food. However, excessive intake may cause potential damage to human health. Hence, developing rapid and sensitive detection methods for SDHA is of great significance. Herein, a novel Tb-MOF, {[Tb(Pim)(1,5-NDS) 0.5 (H 2 O)] 2 ·3H 2 O} n, was successfully constructed using pimelic acid (Pim) and 1,5-naphthalene disulfonic acid (1,5-NDS) as dual ligands. The Tb-MOF presents a three-dimensional (3D) structure, which displays a (3,8)-connected tfz-d network and exhibits dual emission from ligand-centered emission and the characteristic Tb(III)-centered emission. Based on the distinct fluorescence response of the two emission signals toward SDHA, a sensitive ratiometric sensing platform based on the Tb-MOF was established with a limit of detection (LOD) of 7.8 nM. The sensing mechanism was verified to be dominated by the sensitization effect of SDHA on Tb(III) and the photoinduced electron transfer (PET) process. Notably, smartphone-assisted visual detection of SDHA was explored based on the distinguishable fluorescence color change from blue to green. The proposed sensing method was also employed to monitor SDHA in bread with good recoveries. This research presents a rarely documented ratiometric fluorescence sensor for SDHA, which extends the application of Ln-MOFs in food safety.