A Series of Tetrathiafulvalene-Based Lanthanide Complexes Displaying Either Single Molecule Magnet or Luminescence鈥擠irect Magnetic and Photo-Physical Correlations in the Ytterbium Analogue

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• 作者：Fabrice Pointillart ; Boris Le Guennic ; Thomas Cauchy ; St茅phane Golhen ; Olivier Cador ; Olivier Maury ; Lahc猫ne Ouahab
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：May 20, 2013
• 年：2013
• 卷：52
• 期：10
• 页码：5978-5990
• 全文大小：691K
• 年卷期：v.52,no.10(May 20, 2013)
• ISSN：1520-510X

文摘

The reaction between (4,5-bis(2-pyridyl-N-oxidemethylthio)-4鈥?5鈥?-ethylenedithiotetrathiafulvene (L¹) or -methyldithiotetrathiafulvene (L²) ligands and Ln(hfac)₃路nH₂O precursors (Ln^III = Pr, Tb, Dy, Er, and Yb) leads to the formation of seven dinuclear complexes of formula [Ln₂(hfac)₆(H₂O)_x(L^y)₂] (x = 2 and y = 1 for Ln^III = Pr (1); x = 0 and y = 1 for Ln^III = Tb (2), Dy (3), Er (4) and Yb (5); x = 0 and y = 2 for Ln^III = Tb (6) and Dy (7)). Their X-ray structures reveal that the coordination environment of each Ln^III center is filled by two N-oxide groups coming from two different ligands L^y. UV鈥搗isible absorption properties have been experimentally measured and rationalized by TD-DFT calculations. The temperature dependences of static magnetic measurements have been fitted. The ground state corresponds to the almost pure |M_J = 卤13/2 while the first excited state (卤0.77|卤11/2 卤 0.50|卤3/2 卤 0.39|卤5/2) is located at 19 cm^鈥? and 26.9 cm^鈥? respectively for 3 and 7. Upon irradiation at 77 K and at room temperature, in the range 25鈥?00鈥?0鈥?35 cm^鈥?, both compounds 4 and 5 display a metal-centered luminescence attributed to ⁴I_13/2 鈫?⁴I_15/2 (6660 cm^鈥?) and ²F_5/2 鈫?²F_7/2 (9972 cm^鈥?) transitions, respectively. Emission spectroscopy provides a direct probe of the |卤5/2 ground state multiplet splitting, which has been confronted to magnetic data. The energy separation of 225 cm^鈥? between the ground state and the first excited level (M_J = 卤3/2) fits exactly the second emission line (234 cm^鈥?). While no out-phase-signal is detected for 3, the change of ligand L¹ 鈫?L² induces a change of coordination sphere symmetry around the Dy^III increasing the energy splitting between the ground and first excited states, and 7 displays a single molecule magnet behavior.