Jean-Claude Bunzli - A Eu(III) Tetrakis(�-diketonate) Dimeric Complex: Photophysical Properties, Structural Elucidation by Sparkle/AM1 Calculations, and Doping into PMMA Films and Nanowires

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      Biju,Silvanose, Freire,Ricardo O., Eom,Yu Kyung,   Scopelliti,Rosario, B nzli,Jean-Claude G., Kim,Hwan Kyu   Inorganic Chemistry 2014 53  (16) 8407-8417

      Abstract: Reaction of Ln(III) with a   tetrakis(diketone) ligand H4L   [1,1?-(4,4?-(2,2-bis((4-(4,4,4-trifluoro-3-oxobutanoyl)   phenoxy)methyl)propane-1,3-diyl)bis(oxy)bis(4,1-phenylene))bis(4,4,4-trifluorob utane-1,3-dione)]   gives new podates which, according to mass spectral data and   Sparkle/AM1 calculations, can be described as dimers,   (NBu4[LnL])2 (Ln = Eu, Tb, Gd:Eu), in both solid-state and   dimethylformamide (DMF) solution. The photophysical properties of   the EuIII podate are compared with those of the mononuclear   diketonate (NBu4[Eu(BTFA)4], BTFA = benzoyltrifluoroacetonate),   the crystal structure of which is also reported. The new EuIII   dimeric complex displays bright red luminescence upon irradiation   at the ligand-centered band in the range of 250?400 nm,   irrespective of the medium. The emission quantum yields and the   luminescence lifetimes of (NBu4[EuL])2 (solid state: 51%   8% and   710   2  s; DMF: 31   5% and 717   1  s) at room temperature are   comparable to those obtained for NBu4[Eu(BTFA)4] (solid state: 60     9% and 730   5  s; DMF: 30   5% and 636   1  s). Sparkle/AM1   calculations were utilized for predicting the ground-state   geometries of the EuIII dimer. Theoretical Judd?Ofelt and   photoluminescence parameters, including quantum yields, predicted   from this model are in good agreement with the experimental   values, proving the efficiency of this theoretical approach   implemented in the LUMPAC software ( The   kinetic scheme for modeling energy transfer processes show that   the main donor state is the ligand triplet state and that energy   transfer occurs on both the 5D1 (44.2%) and 5D0 (55.8%) levels.   Furthermore, the newly obtained EuIII complex was doped into a   PMMA matrix to form highly luminescent films and one-dimensional   nanowires having emission quantum yield as high as 67%-69%   (doping concentration = 4% by weight); these materials display   bright red luminescence even under sunlight, so that interesting   photonic applications can be foreseen

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