Synthesis, Characterization and Properties of Novel Coumarin Derivatives and Their Europium Complexes.

Seven novel coumarin derivatives derived from salicylaldehyde and phenol were synthesized and characterized by (1)H NMR and (13)C NMR spectra, mass spectra, infrared spectra and elemental analysis. Their corresponding Eu(III) complexes having general formula EuL(1-7)(NO3)3[Symbol: see text]2H2O were successfully prepared and characterized by elemental analysis, EDTA titrimetric, molar conductivity, UV-Vis, FT-IR and thermal performance studies. The luminescence properties, fluorescence quantum yields and the electrochemical properties of the title complexes were investigated. The results showed that the title complexes exhibited characteristic emissions of europium ions and possessed relatively good fluorescence quantum yields. The luminescence intensity of the complex with bromine-substituted group is the strongest among all the title complexes. The introduction of electron-withdrawing groups can increase the luminescence properties and fluorescence quantum yields, decrease the HOMO and LUMO energy levels of the title europium complexes, but electron-withdrawing group conversely. And these title complexes may possibly be useful for studying in luminescent materials field. Graphical Abstract Synthesis route of the ligands L (1-7).