Coumarin-embedded MOF UiO-66 as a selective and sensitive fluorescent sensor for the recognition and detection of Fe3+ ions

A fluorescent composite, HCAA@UiO-66, was prepared by encapsulating fluorescent 7-hydroxycoumarin-4-acetic acid (HCAA) molecules in the pores of a metal-organic framework (MOF, UiO-66). The encapsulation of HCAA in the pores of UiO-66 does not affect its crystalline and porous structure. HCAA@UiO-66 in ethanol displays a strong fluorescence emission and a highly selective fluorescence response towards Fe3+ ions. The fluorescence intensity of HCAA@UiO-66 at 451 nm shows a satisfactory linear relationship with the concentration of Fe3+ ions in a wide range of 0-400 mu mol L-1 with a low detection limit (LOD) of 4.87 x 10(-6) mol L-1. The fluorescence quenching is attributed to the interaction of Fe3+ ions with HCAA@UiO-66 and the absorption competition quenching (ACQ). HCAA@UiO-66 proved that the encapsulation of fluorescent dyes in the MOF is an efficient approach to fabricate fluorescent chemosensors for the determination of metal ions.

Automated summary

HCAA@UiO-66 is a fluorescent composite with a strong fluorescence emission and highly selective fluorescence response towards Fe3+ ions in ethanol. The fluorescence intensity at 451 nm shows a satisfactory linear relationship with the concentration of Fe3+ ions in a wide range, with a low detection limit. This encapsulation approach in MOFs proves to be an efficient method for fabricating fluorescent chemosensors for metal ion determination.