Lanthanide complexes dibenzoylmethane

A broad range of metal centers have been used for the complexation of functional ligands, including beryllium [37], zinc, transition metals such as iridium [38], and the lanthanide metals introduced by Kido [39], especially europium and terbium. Common ligands are phenanthroline (phen), bathophenanthrolin (bath), 2-phenylpyridine (ppy), acetylacetonate (acac), dibenzoylmethanate (dbm), and 11 thenoyltrifluoroacetonate (TTFA). A frequently used complex is the volatile Eu(TTFA)3(phen), 66 [40]. 

Pyrazoylborates Tetradentate (86) andhexadentate (87) pyrazoylborates (seefig. 74) form a range of 1 1 and 1 2 complexes with Lnm ions, as well as ternary 1 1 1 adducts with dibenzoylmethanate, which have coordination number between 8 and 12. In the case of visible-emitting lanthanide ions, large quantum yields have been recorded, up to 50% for Tbm for instance (Armaroli et al., 1997). With Ndm and Ybm, four types of complexes... 

Using hexadentate tris[3-(2-pyridyl)pyrazol-l-yl]hydroborate (34) or tetradentate bis[3-(2-pyridyl)pyrazol-l-yl]dihydroborate (35) as a ligand, Ward and coworkers reported the preparation, characterization, and photophysical properties of a series of binary or ternary complexes of lanthanide(III) complexes with dibenzoylmethane anions (dbm) or nitrate anion as a co-ligand [58-60]. Sizeable NIR emission was detected for these pyrazolylborate-derived complexes of Nd(III), Pr(III), Er(III), and Yb(III) ions. They gave longer lifetimes of lanthanide luminescence than those of aminocarboxylate complexes due to the lack of C-H oscillators in close proximity to the lanthanide(III) ions in the pyrazolylborate complexes compared with that in the aminocarboxylate species. 

Van Deun et al. were the first to observe near-infrared luminescence from lanthanide-doped liquid crystal mixtures They studied the spectroscopic properties of the lanthanide(III) / -diketonate complexes [L (dbm)3(phen)], where Ln = neodymium, erbium, ytterbium, and dbm is dibenzoylmethane, in the liquid crystal MBBA. By incorporation of an erbium(III)-doped nematic liquid crystal (ErCls dissolved in E7) in the pores of microporous silicon, narrowing of the erbium(III) emission band in the near-infrared was observedJ Luminescent optically active liquid crystals were obtained by doping [Eu(tta)3-3H20] into a mixture of cho-lesteryl nonanoate, cholesteryl tetradecanoate and the ternary liquid crystal mixture ZLI1083 from MerckJ ... 

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