Positively Charged Lanthanide Complexes with Cyclen-Based Ligands: Synthesis, Solid-State and Solution Structure, and Fluoride Interaction

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• 作者：Luı ; ́ ; s M. P. Lima ; Alexandre Lecointre ; Jean-Fran莽ois Morfin ; Andr茅s de Blas ; Dimitris Visvikis ; Loı ; &#776 ; c J. Charbonni猫re ; Carlos Platas-Iglesias ; Rapha毛l Tripier
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：December 19, 2011
• 年：2011
• 卷：50
• 期：24
• 页码：12508-12521
• 全文大小：764K
• 年卷期：v.50,no.24(December 19, 2011)
• ISSN：1520-510X

文摘

The syntheses of a new cyclen-based ligand L² containing four N-[2-(2-hydroxyethoxy)ethyl]acetamide pendant arms and of its lanthanide(III) complexes [LnL²(H₂O)]Cl₃ (Ln = La, Eu, Tb, Yb, or Lu) are reported, together with a comparison with some Ln^III complexes of a previously reported analogue L¹ in which two opposite amide arms have been replaced by coordinating pyridyl units. The structure and dynamics of the La^III, Lu^III, and Yb^III complexes in solution were studied by using multinuclear NMR investigations and density functional theory calculations. Luminescence lifetime measurements in H₂O and D₂O solutions of the [Ln(L²)(H₂O)]³⁺ complexes (Ln = Eu or Tb) were used to investigate the number of H₂O molecules coordinated to the metal ion, pointing to the presence of an inner-sphere H₂O molecule in a buffered aqueous solution. Fluoride binding to the latter complexes was investigated using a combination of absorption spectroscopy and steady-state and time-resolved luminescence spectroscopy, pointing to a surprisingly weak interaction in the case of L² (log K = 1.4 卤 0.1). In contrast to the results in solution, the X-ray crystal structure of the lanthanide complex showed the ninth coordination position occupied by a chloride anion. In the case of L¹, the X-ray structure of the [(EuL¹)₂F] complex features a bridging fluoride donor with an uncommon linear Eu鈥揊鈥揈u entity connecting two almost identical [Eu(L¹)]³⁺ units. Encapsulation of the F^{鈥?/sup> anion within the two complexes is assisted by 蟺鈥撓€ stacking between the pyridyl rings of two complexes and C鈥揌路路路F hydrogen-bonding interactions involving the anion and the pyridyl units.}