Mastering Fluorescence through a Rare-Earth Ion Functional Switch in Isostructural Bimetallic MOFs

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Traditionally, organic ligands primarily influence metal-organic framework (MOF) fluorescence.
• The role of metal nodes, particularly rare-earth elements in isostructural MOFs, remains underexplored.

Purpose of the Study:

• Investigate the impact of distinct rare-earth centers on the fluorescence properties of isostructural bimetallic MOFs.
• Explore the potential of rare-earth modulated MOFs for selective sensing applications.

Main Methods:

• Synthesized two isostructural bimetallic MOFs using identical organic ligands but different rare-earth ions (La³⁺ and Eu³⁺).
• Conducted comprehensive photophysical analyses to characterize fluorescence behaviors.
• Evaluated the sensing capabilities of the MOFs for norfloxacin detection.

Main Results:

• The choice of rare-earth ion significantly altered fluorescence characteristics, including quenching mechanisms and emission intensities.
• Complex 1 (La³⁺) showed a fluorescence turn-on response to norfloxacin.
• Complex 2 (Eu³⁺) exhibited a fluorescence turn-off quenching response to norfloxacin.

Conclusions:

• Rare-earth centers act as crucial "functional switches" to tune MOF fluorescence.
• Demonstrated a targeted strategy for designing advanced fluorescent materials with selective sensing capabilities based on rare-earth ion choice.