Fe³⁺ sensitivity fluorescence sensor from β-cyclodextrin-enhanced Eu³⁺ luminescence aggregates

In this work, novel β-cyclodextrin-enhanced Eu³⁺ luminescence aggregates (CELAs) with bright red fluorescence of Eu³⁺ are prepared. These CELAs exhibit the quick response and highly selective sensitivity at the concentration of 50 µM Fe³⁺. A series of ligands (such as TTA, phen, β-cyclodextrin) sensitizes the luminescence of Eu³⁺ (the “antenna effect”), and metal ions–ligands interactions can differentially alter the antenna effect of ligands toward Eu³⁺. Addition of EDTA to chelate Fe³⁺ restores the fluorescence, indicating that the fluorescence quenching in the presence of Fe³⁺ is reversible. This research provides that CELAs integrate these merits of superior lanthanide fluorescence and the amphiphilia property of β-cyclodextrin (β-CD). It is a unique system with enhancement Eu³⁺ luminescence in ethanol–water system and will be applied for aqueous solution detection sensor with high selectivity and reversibility for Fe³⁺. On the other hand, the on-off fluorescence property of the CELAs is convenient for environmental detection system.