Eu³⁺ doped ethylenediamine functionalized UiO-66 probe for fluorescence sensing of formaldehyde

The development of probes with selectivity and prompt detection of aldehydes molecules is of great importance for protecting human health and public security. Herein, a system based on ethylenediamine (EDA) functionalized and Eu³⁺-doped UiO-66, namely EDA-Eu³⁺@UiO-66, was designed to detect formaldehyde molecules. Based on the "antenna effect" of lanthanide elements, UiO-66 transfers the absorbed energy to Eu³⁺ ions and emits characteristic fluorescence belonging to Eu³⁺. By using the fluorescence peaks of UiO-66 and Eu³⁺ respectively, a ratiometric fluorescence sensing probe can be constructed. Formaldehyde molecules react with the -NH₂ on the surface of EDA-Eu³⁺@UiO-66 through an aldehyde-amine condensation reaction and connect to the functionalized surface of UiO-66. Due to the absorption of excitation light energy by formaldehyde molecules, the energy transfer efficiency from UiO-66 to Eu³⁺ ions is reduced, resulting in the fluorescence quenching of EDA-Eu³⁺@UiO-66, thus achieving selective detection of formaldehyde. The fabricated sensing platform successfully detected residual formaldehyde in frozen shrimp tail samples. The system was also used to respond to formaldehyde vapor, and a significant fluorescence quenching effect was observed. This strategy provides a sensitive, selective, and reliable method for the visual sensing of formaldehyde.