Preparation and fluorescence properties of novel 2-quinolone derivatives and their corresponding Eu(III) complexes

A series of novel 2-quinolone ligands and their corresponding Eu(III) complexes were prepared. The effect of different solvents, different ligand concentrations and different substituents on the fluorescence intensity of ligands were investigated in detail. The fluorescence intensity of Eu(III) complexes were studied by comparing different substituents on the ligand. The results indicate that all ligands show the strongest fluorescence intensity in ethanol with the ligand concentration of 50 μM. Among these ligands, the ligand (K 6 ) containing -COOCH 3 group owns the strongest fluorescence intensity and the corresponding fluorescence quantum yield reaches 0.317. All complexes exhibit characteristic red light of Eu(III) ions with good thermal stability. The effect of diverse substituents on the fluorescence intensity is ordered: -COOCH 3 >-Cl> -Br> -OCH 3 >-CH 3 >-H, which indicates the complex [EuK 6 (NO 3 ) 3 ]·2H 2 O with the strongest electron-donating group (-COOCH 3 ) possesses the strongest fluorescence intensity. The above analysis shows that the ligand (K 6 ) and corresponding Eu(III) complex [EuK 6 (NO 3 ) 3 ]·2H 2 O own the best fluorescence property, which has an outstanding application prospect in the field of optical materials and biomedicine materials.