Cyanomethylene-bis(phosphonate)-Based Lanthanide Complexes: Structural, Photophysical, and Magnetic Investigations

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• 作者：Catalin Maxim ; Diana G. Branzea ; Carmen Tiseanu ; Mathieu Rouzi猫res ; Rodolphe Cl茅rac ; Marius Andruh ; Narcis Avarvari
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：March 3, 2014
• 年：2014
• 卷：53
• 期：5
• 页码：2708-2717
• 全文大小：551K
• 年卷期：v.53,no.5(March 3, 2014)
• ISSN：1520-510X

文摘

The syntheses, structural investigations, magnetic and photophysical properties of a series of 10 lanthanide mononuclear complexes, containing the heteroditopic ligand cyanomethylene-bis(5,5-dimethyl-2-oxo-1,3,2位⁵-dioxa-phosphorinane) (L), are described. The crystallographic analyses indicate two structural types: in the first one, [Ln^III(L)₃(H₂O)₂]路H₂O (Ln = La, Pr, Nd), the metal ions are eight-coordinated within a square antiprism geometry, while the second one, [Ln^III(L)₃(H₂O)]路8H₂O (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er), contains seven-coordinated Ln^III ions within distorted monocapped trigonal prisms. Intermolecular hydrogen bonding between nitrogen atoms of the cyano groups, crystallization, and coordination water molecules leads to the formation of extended supramolecular networks. Solid-state photophysical investigations demonstrate that Eu^III and Tb^III complexes possess intense luminescence with relatively long excited-state lifetimes of 530 and 1370 渭s, respectively, while Pr^III, Dy^III, and Ho^III complexes have weak intensity luminescence characterized by short lifetimes ranging between a few nanoseconds to microseconds. The magnetic properties for Pr^III, Gd^III, Tb^III, Dy^III, and Ho^III complexes are in agreement with isolated Ln^III ions in the solid state, as suggested by the single-crystal X-ray analyses. Alternating current (ac) susceptibility measurements up to 10 kHz reveal that only the Ho^III complex shows a frequency-dependent ac response, with a relaxation mode clearly observed at 1.85 K around 4500 Hz.