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首页> 外文期刊>Chemistry: A European journal >High-spin iron(II) as a semitransparent partner for tuning Europium(III) luminescence in heterodimetallic d-f complexes
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High-spin iron(II) as a semitransparent partner for tuning Europium(III) luminescence in heterodimetallic d-f complexes

机译：高自旋铁（II）作为半透明配体，用于调节异双金属d-f配合物中的Euro（III）发光

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摘要

The segmental ligand 2-{6-N,N-diethyrcarbamoyl)pyridin-2-yl}-1,1 dimethyl-5,5'-methylene-2'-(6-methylpyridine-2-yl)bis[1H-benzimidazole] (L-3) reacts with a stoichiometric mixture of Ln(III) (Ln = La, Eu, Gd) and M-II (M = Zn, Fe) in acetonitrile to produce selectively the heterodimetallic triple-stranded helicates (HHH)-[LnM(L-3)(3)](5+). In these complexes, M-II is pseudooctahedrally coordinated by the three wrapped bidentate binding units, thus forming a noncovalent tripod which organizes the three unsymmetrical tridentate segments to give ninefold coordination to Ln(III). The introduction of a methyl group at the 6 position of the terminal pyridine in L-3 sterically reduces the complexing ability of the bidentate segment for M-II. Spectroscopic (ESI-MS. UV/Vis/NIR, NMR), magnetic and electrochemical measurements show that 1) the head-to-head-to-head triple helical complexes (HHH)-[LnM(L-3)(3)](5+) are quantitatively formed in solution only for ligand concentrations larger than 0.01M, 2)Fe-II adopts a pure high-spin electronic configuration in (HHH)-[LnFe(L-3)(3)](5+), and 3) the (FeFeIII)-Fe-II/ oxidation process is prevented by steric constraints. Detailed photophysical studies of (HHH)-[Eu-Zn(L-3)(3)](5+) confirm that the pseudotricapped trigonal-prismatic lanthanide coordination site is not affected by the methyl groups bound to the terminal pyridine, thus leading to significant Eu-centered emission upon UV irradiation. In (HHH)-[EuFe(L-3)(3)](5+), a resonant intramolecular Eu --> Fe-hs(II) energy transfer partially quenches the Eu-centered luminescence; however, the residual red emission demonstrates that high-spin iron(Ii) is compatible with the sensitization of Eu-III heterodimetallic d-f complexes. The influence of the electronic configuration of Fe-II on the efficiency of Eu-III--> Fe-II energy-transfer processes is discussed together with its consequence for the design of optically active spin-crossover supramolecular devices. [References: 99]
机译：段配体2- {6-N，N-二乙氨基甲酰基）吡啶-2-基} -1,1二甲基-5,5'-亚甲基-2'-（6-甲基吡啶-2-基）双[1H-苯并咪唑]（L-3）与Ln（III）（Ln = La，Eu，Gd）和M-II（M = Zn，Fe）的化学计量混合物在乙腈中反应，以选择性地产生异双金属三链螺旋体（HHH） -[LnM（L-3）（3）]（5+）。在这些复合物中，M-II由三个包裹的二齿结合单元伪八面体配位，从而形成一个非共价三脚架，该三脚架组织了三个不对称的三齿链段，使Ln（III）具有九倍的配位。在L-3的末端吡啶的6位上引入甲基在空间上降低了双齿链段对M-II的络合能力。光谱法（ESI-MS.UV / Vis / NIR，NMR），磁和电化学测量表明1）头对头三螺旋复合物（HHH）-[LnM（L-3）（3） ]（5+）仅在配体浓度大于0.01M时在溶液中定量形成; 2）Fe-II在（HHH）-[LnFe（L-3）（3）]（5中采用纯高自旋电子构型+）和3）由于空间限制而阻止了（FeFeIII）-Fe-II /氧化过程。 （HHH）-[Eu-Zn（L-3）（3）]（5+）的详细光物理研究证实，假三键三角棱晶镧系元素配位位点不受与末端吡啶结合的甲基的影响，因此导致在紫外线照射下达到明显的以Eu为中心的发射。在（HHH）-[EuFe（L-3）（3）]（5+）中，共振分子内Eu-> Fe-hs（II）能量转移部分淬灭了以Eu为中心的发光。然而，残留的红色发射表明高自旋铁（Ii）与Eu-III异双金属d-f配合物的敏化相容。讨论了Fe-II的电子构型对Eu-III-> Fe-II能量转移过程效率的影响及其对光学活性自旋交联超分子器件设计的影响。 [参考：99]

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