摘要:
A new amide-based ligand derived from biphenyl, N-benzyl-2-{2'-[(benzyl-methyl-carbamoyl)-methoxy]-biphenyl-2-yloxy}-N-methylaceamide (L) was synthesized. Solid complexes of lanthanide picrates with this new ligand were prepared and characterized by elemental analysis, conductivity measurements, IR and electronic spectroscopies. The molecular structure of [Eu(pic)(3)L] shows that the Eu(III) ion is nine-coordinated by four oxygen atoms from the L and five from two bidentate and one unidentate picrates. All the coordinate picrates and their adjacent equivalent picrates form intermolecular pi-pi stacking. Furthermore, the [Eu(pic)3L] complex units are linked by the pi-pi stacking to form a two-dimensional (2-D) netlike supramolecule. Under excitation, the europium complex exhibited characteristic emissions. The lifetime of the D-5(0) level of the Eu(III) ion in the complex is 0.22 ms. The quantum yield phi of the europium complex was found to be 1.01 x 10(-3) with quinine sulfate as reference. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion. (C) 2007 Elsevier B.V. All right; reserved.