Novel intramolecular charge transfer effect‐based ligands and aggregation‐induced emission‐active europium complexes: synthesis, characterization, and fluorescence properties.

Two novel coumarin derivatives and the corresponding europium complexes were prepared using a simple procedure. The pH response of the ligand and the aggregation‐induced emission (AIE) properties of the target europium complex were studied. The ligand had an intramolecular charge transfer (ICT) effect and was linearly and sharply responsive under acidic conditions. The goal europium complexes exhibited excellent AIE performance when subjected to increasing concentrations of target europium complex or proportion of poor solvent. The effect of substituents on fluorescence strength or thermogravimetric and electrochemical properties was further investigated. The target complexes displayed the typical fluorescence of europium. The fluorescence amplitude of the target europium complexes was enhanced by the addition of electron‐donating groups to ligands. Thermogravimetric research findings indicated that the target complexes possessed extreme thermal stability. Electrochemistry discovery findings indicated that the highest occupied molecular orbit energy level of EuL1 was greater than EuL2, but the lowest unoccupied molecular orbit energy level was smaller than that of EuL2. These complexes could be applied in medicinal chemistry, substance chemistry, and fluorescence labelling areas. [ABSTRACT FROM AUTHOR]