Aromatic Beta-diamide and beta-monoketo-monoamide as promising ligands for Eu(III) and Tb(III) complexes with high luminescence

Europium and terbium complexes with beta-diketones coordination are well-known for their luminescent properties, however there is almost none description of these complexes with amides. The present work describes the synthesis, characterization and luminescent studies with six complexes formed between the ligands 1A and 1B with europium, terbium and gadolinium. Ligands and complexes have been synthesized with reasonable yields and characterized by usual techniques. Eu(III) and Tb(III) complexes were luminescent, red and green, respectively. From the obtained spectroscopic data for Gd(III) complex the triplet energy of the ligand 1A in 23980 cm-1 could be achieved. Eu1B complex that had greater structural rigidity, showed higher thermal stability and quantum yield (Eu1B: 28.31%, Eu1A 8.03%) and these data corroborated the great importance from the structural rigidity for the highest luminescence. Complexes rate of decay measured values (Eu1A-0.685 ms;Eu1B-0.684 ms;Tb1A-0.487 ms;Tb1B-0.656 ms;Gd1A-1.501 ms,Gd1B-1.670 ms). These diamides are really promising ligands for the development of luminescent complexes with high efficiency and stability.