首页> 外文期刊>Inorganic Chemistry: A Research Journal that Includes Bioinorganic, Catalytic, Organometallic, Solid-State, and Synthetic Chemistry and Reaction Dynamics >Enhanced Near-Infrared Emission from Eight-Coordinate vs Nine-Coordinate YbIII Complexes Using 2-(5-Methylpyridin-2-yl)-8-hydroxyquinoline
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Enhanced Near-Infrared Emission from Eight-Coordinate vs Nine-Coordinate YbIII Complexes Using 2-(5-Methylpyridin-2-yl)-8-hydroxyquinoline

机译:使用2-(5-甲基吡啶-2-基)-8-羟基喹啉增强八坐标与九坐标YbIII配合物的近红外发射

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Enhanced near-infrared (NIR) luminescence from two structurally related heterobinuclear Na~(I)Yb~(III) eight-cooridnate and heterobinuclear Yb~(III)Na~(I) eight-coordinate (CN = 8) complexes is reported and compared to a nine-coordinate (CN = 9) homoleptic complex. For the heteroleptic complex, Yb(MPQ_(2))(acac), the Yb~(III) cation is coordinated to two tridentate 2-(5-methylpyridin-2-yl)-8-quinolinate (MPQ) anions, with a bidentate acetylacetonate (acac) anion completing the coordination sphere. Instead, the heterobinuclear NaYb(MPQ)_(4) complex comprises a total of four anionic MPQ ligands, two of which exhibit κ~(3)-coordination to the Yb~(III) cation. The remaining two MPQ anions are unidentate toward the lanthanide and form μ_(2)-bridges via the deprotonated quinolinate oxygens to a bound Na~(I) cation which is also coordinated to the remaining nitrogen donor atoms. The structural properties of these complexes were evaluated by single-crystal X-ray diffraction (SXRD), continuous shape measure (CShM) analysis, and ~(1)H NMR spectroscopy using a diamagnetic Lu~(III) analogue. The corresponding photophysical properties were examined in CH_(2)Cl_(2) solution by using absorption and emission spectroscopy. For both the complexes, characteristic Yb~(III) emission is observed at ca. 980 nm, with recorded photoluminescence quantum yields (Φ_(obs)) and NIR luminescence lifetimes (τ_(obs)) of 2.0 and 14.0 μs vs 1.5 and 11.6 μs for the NaYb(MPQ)_(4) and Yb(MPQ)_(2)(acac) complexes, respectively. Interestingly, the eight-coordinate Yb~(III) complexes both have higher photoluminescence quantum yields when compared to the homoleptic Yb(MPQ)_(3) complex, which has a reported quantum yield of 1.0 and a NIR lifetime determined herein of 13.3 μs under identical conditions. These results have been rationalized by considering the overall efficiency of the ligand-centered sensitization process (η_(sens) = Φ_(isc) × Φ_(eet)), together with subsequent radiative (k _(r)) and nonradiative (k _(nr)) deactivation of the Yb~(III) cation. Moreover, the efficiency of the intersystem crossing (Φ_(isc)) and electronic energy transfer (Φ_(eet)) processes involved in the antennae effect have been quantified for the new complexes using a combination of nanosecond and femtosecond transient absorption techniques and have been compared to our previous results using Ln(MPQ)_(3) complexes with Ln = Yb and Lu.
机译:报道了两个结构相关的异核Na~(I)Yb~(III)八色和异核Yb~(III)Na~(I)八坐标(CN = 8)配合物的增强近红外(NIR)发光,并与九坐标(CN = 9)同质复合物进行了比较.对于异质配合物[Yb(MPQ_(2))(acac)],Yb~(III)阳离子配位为两个三齿2-(5-甲基吡啶-2-基)-8-喹啉酸(MPQ)阴离子,与二齿乙酰丙酮(acac)阴离子完成配位球。相反,异双核 [NaYb(MPQ)_(4)] 复合物总共包含四个阴离子 MPQ 配体,其中两个对 Yb~(III) 阳离子表现出 κ~(3) 配位。其余两个MPQ阴离子对镧系元素无齿,通过去质子化的奎啢酸氧形成μ_(2)-桥,形成结合的Na~(I)阳离子,该阳离子也与剩余的氮供体原子配位。采用单晶X射线衍射(SXRD)、连续形状测量(CShM)分析和~(1)H NMR波谱等方法,采用抗磁性Lu~(III)类似物对配合物的结构性质进行了评价。采用吸收和发射光谱法研究了CH_(2)Cl_(2)溶液中相应的光物理性质。对于这两种配合物,在约980 nm处观察到特征Yb~(III)发射,记录的光致发光量子产率(Φ_(obs))和NIR发光寿命(τ_(obs))分别为2.0%和14.0 μs,而1.5%和11。[NaYb(MPQ)_(4)] 和 [Yb(MPQ)_(2)(acac)] 配合物分别为 6 μs。有趣的是,与同质 [Yb(MPQ)_(3)] 配合物相比,八配位 Yb~(III) 配合物都具有更高的光致发光量子产率,据报道,同质 [Yb(MPQ)_(3)] 配合物的量子产率为 1.0%,本文确定的近红外寿命为 13.3 μs。通过考虑配体中心敏化过程的总体效率(η_(sens) = Φ_(isc) × Φ_(eet)),以及随后的辐射(k _(r))和非辐射(k _(nr))的Yb~(III)阳离子失活,这些结果得到了合理化。此外,使用纳秒和飞秒瞬态吸收技术的组合,已经量化了天线效应中涉及的系统间交叉(Φ_(isc))和电子能量转移(Φ_(eet))过程的效率,并与我们之前使用Ln = Yb和Lu的[Ln(MPQ)_(3)]配合物的结果进行了比较。

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