A EuIII Tetrakis(尾-diketonate) Dimeric Complex: Photophysical Properties, Structural Elucidation by Sparkle/AM1 Calculations, and Doping into PMMA Films and Nanowires

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• 作者：Silvanose Biju ; Ricardo O. Freire ; Yu Kyung Eom ; Rosario Scopelliti ; Jean-Claude G. B眉nzli ; Hwan Kyu Kim
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：August 18, 2014
• 年：2014
• 卷：53
• 期：16
• 页码：8407-8417
• 全文大小：596K
• ISSN：1520-510X

文摘

Reaction of Ln^III with a tetrakis(diketone) ligand H₄L [1,1鈥?(4,4鈥?(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-trifluorobutane-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 Eu^III 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 Eu^III dimeric complex displays bright red luminescence upon irradiation at the ligand-centered band in the range of 250鈥?00 nm, irrespective of the medium. The emission quantum yields and the luminescence lifetimes of (NBu₄[EuL])₂ (solid state: 51% 卤 8% and 710 卤 2 渭s; DMF: 31% 卤 5% and 717 卤 1 渭s) at room temperature are comparable to those obtained for NBu₄[Eu(BTFA)₄] (solid state: 60 卤 9% and 730 卤 5 渭s; DMF: 30 卤 5% and 636 卤 1 渭s). Sparkle/AM1 calculations were utilized for predicting the ground-state geometries of the Eu^III dimer. Theoretical Judd鈥揙felt 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 (http://lumpac.pro.br). 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 Eu^III complex was doped into a PMMA matrix to form highly luminescent films and one-dimensional nanowires having emission quantum yield as high as 67%鈥?9% (doping concentration = 4% by weight); these materials display bright red luminescence even under sunlight, so that interesting photonic applications can be foreseen.