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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Seven-coordinate lanthanide complexes with a tripodal redox active ligand: structural, electrochemical and spectroscopic investigations
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Seven-coordinate lanthanide complexes with a tripodal redox active ligand: structural, electrochemical and spectroscopic investigations

机译：七坐标镧系元素与三码头氧化还原活性配体：结构，电化学和光谱研究

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The tripodal ligand TREN-(3,5-di-tert-butylsalicylidene)(3) (H3L) was synthesized and its tris(phenolato) lanthanide complexes L-Ln (Ln = Nd-III, Eu-III, Tb-III, Gd-III, Er-III, Yb-III and Lu-III) were prepared. The X-Ray crystal structures confirm that each metal ion resides in a similar monocapped octahedral geometry, excluding water molecules from the coordination sphere. The coordination bond distances are in agreement with the lanthanide contraction, with Ln-O bond lengths in the range 2.139-2.216 angstrom. The complexes show three reversible monoelectronic oxidation waves, which are assigned to the successive oxidation of the phenolate moieties to phenoxyl radicals. The L-Nd complex is the easiest to oxidize, with E11/2 = 0.11, E21/2 = 0.21 and E31/2 = 0.34 V vs. Fc(+)/Fc, due to the larger size of the lanthanide ion. The E-1/2 value (E-1/2 = E21/2 - E11/2) is correlated to the lanthanide radius, with values of 0.10 V for L-Nd and 0.22 V for L-Lu. The monoradical species were persistent in solution, allowing for their characterisation. All exhibit a distinct absorption band at around 445 nm due to the phenoxyl -* transitions. The EPR spectrum of L-Lu+ consists of a single resonance at g(iso) = 1.999, confirming the radical nature of the oxidized product. Most of the other complexes (L-Gd, L-Er, L-Yb) show a quenching of the Ln(III)-based resonances upon oxidation, indicative of magnetic interactions between the metal and the radical spins. The L-Ln (L = Nd, Er, Yb) complexes exhibit a metal-based luminescence upon excitation of the ligand. A significant quenching of the luminescence was observed upon radical formation: 92%, 83% and 79% respectively for L-Nd+, L-Er+ and L-Yb+.
机译：三码头配体Tren-（3,5-二叔丁基丙烯三苯基）（3）（3）（H3L）合成，其Tris（苯酚）镧系元络合物L-Ln（LN = Nd-III，Eu-III，TB-III，制备GD-III，ER-III，YB-III和LU-III）。 X射线晶体结构确认每个金属离子驻留在类似的单次八面体几何形状中，不包括来自协调球体的水分子。协调键距离与镧系元素收缩一致，LN-O键长在2.139-2.216埃范围内。复合物展示了三个可逆单电子氧化波，其被分配到酚醛部分的连续氧化成苯氧基自由基。 L-Nd复合物是最容易氧化，E11 / 2 = 0.11，E21 / 2 = 0.21和E31 / 2 = 0.34V Vs.FC（+）/ Fc，由于镧系元素的尺寸较大。 E-1/2值（E-1/2 = E21 / 2 -E11 / 2 - E11 / 2）与镧系元素相关，对于L-Lu的L-Nd和0.22V的值为0.10V。单传理物种在溶液中持续存在，允许其表征。由于苯氧基 - *过渡，所有这些都具有约445nm的不同吸收带。 L-LU +的EPR光谱由G（ISO）= 1.999的单一共振组成，确认氧化产物的自由基性质。大多数其他复合物（L-Gd，L-ER，L-YB）显示氧化时LN（III）基的共振的猝灭，指示金属和自由基旋转之间的磁相互作用。 L-LN（L = Nd，ER，Yb）复合物在激发配体时表现出基于金属的发光。在自由基形成时观察到发光的显着猝灭：L-Nd +，L-ER +和L-YB +分别为92％，83％和79％。

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