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A new ligand, N,N 0 -bis(6-methyl-2-pyridinecarboxylamide-Noxide)-1,2-ethane (L), and its six lanthanide(III) complexes (RE 5 La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicate that the composition of the binary complexes was determined as [REL(H 2 O) 2 (NO 3 ) 2 ] NO 3 . nH 2 O (n 5 0 -2), that the six complexes are 1 : 1 electrolytes in DMF, and that the Eu 31 complex has bright red fluorescence in a solid state. At the same time, we synthesized three complexes of Eu 31 , Tb 31 , and Gd 31 with 6-methylpicolinic acid N-oxide (L , ). The intensity of sensitized luminescence for Eu 31 increases in the following order: L > L 0 . The energies of an excited triplet state for the ligands are 20704 cm 21 (L) and 20408 cm 21 (L 0 ), respectively. The fact that the ligands strongly sensitized Eu 31 and the order of the emission intensity for the Eu 31 complexes were explained by the relative energy gap between the lowest triplet energy level of the ligands (T) and 5 D of Eu 31 or Tb 31 . This means that the triplet energy level of the ligand is the chief factor, which dominates RE 31 luminescence.

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