Influence of Symmetry on the Luminescence and Radiative Lifetime of Nine-Coordinate Europium Complexes
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- 作者：Nail M. Shavaleev ; Svetlana V. Eliseeva ; Rosario Scopelliti ; Jean-Claude G. B眉nzli
- 刊名：Inorganic Chemistry
- 出版年：2015
- 出版时间：September 21, 2015
- 年：2015
- 卷：54
- 期：18
- 页码：9166-9173
- 全文大小：449K
- ISSN：1520-510X
文摘
Homoleptic mononuclear nine-coordinate lanthanum(III) and europium(III) tris-complexes [Ln(N鈭?/sup>N鈭?/sup>O)3]路nH2O with two tridentate N-benzylbenzimidazole pyridine-2-carboxylates exhibit a rare C3-symmetry of the lanthanide coordination polyhedron in the solid state, as confirmed by luminescence spectroscopy and by X-ray crystallography (the three N鈭?/sup>N鈭?/sup>O ligands are arranged 鈥渦p鈥搖p鈭抲p鈥?around the lanthanide ion). The symmetry, however, is changed to the more common C1 upon dissolution of the complexes in dichloromethane, as revealed by luminescence spectroscopy (the three ligands are likely to be arranged 鈥渦p鈥搖p鈥揹own鈥?. The new europium complexes emit efficient ligand-sensitized metal-centered luminescence with excited-state lifetimes of 1.56鈥?.18 ms and quantum yields of 25鈥?1% in the solid and in solution. The change of the symmetry from (a higher) C3 to (a lower) C1 alters the luminescence spectrum, shortens the radiative lifetime, and increases the luminescence efficiency of the europium complexes.