Fluorescence Detection of Doxycycline by UiO-66(DPA)@4-MU/Eu3+ Material

Zirconium-based metal–organic framework (MOF) UiO-66 is a commonly used host framework material in the research field of fluorescent probes. However, the pure UiO-66 material lacks functional sites for targeted recognition and thus cannot achieve specific fluorescence detection. In view of this, terephthalic acid (TPA) and 2,6-pyridinedicarboxylic acid (DPA) were used as mixed ligands to coordinate with Zr 4+ for constructing a MOF in this paper. Subsequently, 4-methyl-7-hydroxycoumarin (4-Mu) and Eu 3+ were introduced for functional modification, and UiO-66(DPA)@4-Mu/Eu 3+ fluorescent material with dual emission centers was finally synthesized. It was investigated that UiO-66(DPA)@4-Mu/Eu 3+ can serve as a dual-emission ratiometric fluorescent probe for the efficient detection of doxycycline (DOX) content in aqueous solution. Under the excitation wavelength of 365 nm, the fluorescence color of the probe system gradually changed from blue to red with the increase of DOX concentration. Further analysis revealed that the fluorescence intensity ratio I 618 /I 430 of the system was positively correlated with DOX concentration, enabling highly sensitive detection of DOX with a limit of detection as low as 2.64 µM. Graphical Zr 4+ coordinates with terephthalic acid and 2,6-pyridinedicarboxylic acid as mixed ligands. 4-Methyl-7-hydroxycoumarin is introduced together with Eu 3+ to realize functionalization. The obtained UiO-66(DPA)@4-Mu/Eu 3+ material exhibits dual-emission property and can efficiently detect doxycycline in aqueous solution, which provides a new strategy for the functional design of metal–organic frameworks (MOFs).