Effect of Ligand Polarization on Asymmetric Structural Formation for Strongly Luminescent Lanthanide Complexes
Effect of Ligand Polarization on Asymmetric Structural Formation for Strongly Luminescent Lanthanide Complexes
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DOI：
10.1002/ejic.201301102
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发表时间：
2013-12-02
影响因子：
2.3
通讯作者：
Fushimi, Koji
中科院分区：
文献类型：
--
作者：
Hasegawa, Yasuchika;Ohkubo, Tomoki;Fushimi, Koji
首次报道了配体极化对具有不对称结构的强发光镧系配合物形成的影响。镧系元素配合物由Eu-III离子、三个六氟乙酰丙酮（hfa）配体和两个单齿氧化膦配体组成，即三苯基氧化膦（TPPO）、对甲苯基二苯基氧化膦（TPPO-Me）、三对甲苯基氧化膦（TPPO-3 Me）或邻苯氧基苯基二苯基氧化膦（TPPO-OPh）。Eu-III配合物的发光性质的特征在于它们的发射量子产率、发射寿命以及它们的辐射速率常数（k（r））和非辐射速率常数（k（nr））。Eu-III配合物与TPPO-OPh配体提供了一个显着高的发射量子产率（72%，在[D-6]丙酮，85%，在固态），由于增强的电偶极跃迁和抑制的振动弛豫，这是直接相关的k（r）和k（nr）。的Eu-III配合物的配位几何形状进行分类的形状测量计算。Eu-III配合物表现出特征的正方形反棱柱或三角形十二面体结构，这取决于配体极化。强发光的Eu（hfa）（3）（TPPO-OPh）（2）具有不对称的十二面体结构。扭曲的十二面体结构的形成与低振动频率的发光增强阐明在Eu-III配合物中的单齿氧化膦配体的配体极化。
The effect of ligand polarization on the formation of strongly luminescent lanthanide complexes with asymmetric structures is described for the first time. The lanthanide complexes are composed of Eu-III ions, three hexafluoroacetylacetonate (hfa) ligands, and two monodentate phosphine oxide ligands, namely, triphenylphosphine oxide (TPPO), p-tolyldiphenylphosphine oxide (TPPO-Me), tri-p-tolylphosphine oxide (TPPO-3Me) or o-phenoxyphenyldiphenylphosphine oxide (TPPO-OPh). The luminescence properties of the Eu-III complexes are characterized by their emission quantum yields, emission lifetimes, and their radiative (k(r)) and nonradiative (k(nr)) rate constants. The Eu-III complex with TPPO-OPh ligands offers a markedly high emission quantum yield (72% in [D-6]acetone, 85% in the solid state) owing to enhancement of the electric dipole transition and suppression of vibrational relaxation, which are directly related to k(r) and k(nr). The coordination geometries of the Eu-III complexes are categorized by shape-measure calculations. The Eu-III complexes exhibit characteristic square-antiprismatic or trigonal-dodecahedral structures, depending on the ligand polarization. Strongly luminescent Eu(hfa)(3)(TPPO-OPh)(2) has an asymmetric dodecahedron structure. The formation of distorted dodecahedral structures with low vibrational frequencies for the enhancement of luminescence is elucidated in terms of the ligand polarization of the monodentate phosphine oxide ligands in the Eu-III complexes.