Synthesis and luminescence properties of 1,3,4-oxadiazole acetamide derivatives and their rare earth complexes

• A series of 1,3,4-oxadiazole acetamide derivatives and corresponding complexes with Eu(III) and Tb(III) have been prepared.
• All the target rare earth complexes emit characteristic fluorescence of center ions.
• The relationship between the structure of ligands and the fluorescence intensities of target complexes have been discussed.
• The HOMO and LUMO energy levels of the rare earth complexes have been estimated.

A series of 1,3,4-oxadiazole acetamide derivatives have been designed and synthesized, and their complexes with Eu(III) and Tb(III) were also prepared. The luminescence properties of the target complexes were investigated, and the results indicated that all target complexes showed the characteristic luminescence of the central ions. The relative fluorescence intensities of the complexes with Eu(III) are higher than that of the complexes with Tb(III). The fluorescence quantum yields of the target complexes were calculated by the reference method, and the results showed that the complexes substituted by electron-donating group possess higher fluorescence quantum yields, compared with that of the complex without substituent, while the complexes substituted by electron-withdrawing group possess lower fluorescence quantum yields. The electrochemical properties of the target complexes were investigated by cyclic voltammetry, the HOMO energy levels of the target complexes substituted by electron-donating group are higher than that of the target complexes substituted by electron-withdrawing group.