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

Abstract

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.

Keywords: Aldehyde-amine condensation reaction; Antenna effect; Formaldehyde; Ratiometric fluorescence.