Rare-Earth Complexes of Ferrocene-Containing Ligands: Visible-Light Excitable Luminescent Materials

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline (Fc2phen) and ferrocenoyltrifluoroacetone (Hfta)
have been used to synthesize ferrocene-containing rare-earth β-diketonate complexes. The complexes [Ln(tta)3(Fc2phen)] and [Ln(fta)3(phen)] (where Ln = La, Nd, Eu, Yb) show structural similarities to the tris(2-thenoyltrifluoroacetonate)(1,10-phenanthroline)lanthanide(III) complexes, [Ln(tta)3(phen)]. The coordination number
of the lanthanide ion is 8, and the coordination sphere can be described as a distorted dodecahedron. However,
the presence of the ferrocene moieties shifts the ligand absorption bands of the rare-earth complexes to longer
wavelengths so that the complexes can be excited not only by ultraviolet radiation but also by visible light of
wavelengths up to 420 nm. Red photoluminescence is observed for the europium(III) complexes and near-infrared
photoluminescence for the neodymium(III) and ytterbium(III) complexes. The presence of the ferrocene groups
makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents.

本研究以二茂铁衍生物双(二茂铁基乙炔基)-1,10-菲咯啉（bis(ferrocenyl-ethynyl)-1,10-phenanthroline，Fc2phen）和二茂铁甲酰三氟丙酮（ferrocenoyltrifluoroacetone，Hfta）为配体，合成了含二茂铁基团的稀土β-二酮配合物。所得到的配合物[Ln(tta)3(Fc2phen)]与[Ln(fta)3(phen)]（其中Ln代表La、Nd、Eu、Yb），其结构与三(2-噻吩甲酰三氟丙酮根)(1,10-菲咯啉)镧(III)配合物[Ln(tta)3(phen)]具有相似性。该类稀土离子的配位数为8，配位球可被描述为畸变十二面体构型。然而，二茂铁基团的存在使稀土配合物的配体吸收带发生红移，使得该类配合物不仅可通过紫外线辐射激发，还可被波长高达420 nm的可见光激发。铕(III)配合物表现出红色光致发光，钕(III)与镱(III)配合物则展现出近红外光致发光。二茂铁基团的引入使该类稀土配合物具有疏水性，可良好溶解于非极性有机溶剂中。