The first hybrid organic–inorganic frameworks based on lanthanide(III) sulfate chains, in situ generated oxalate and organic pillars of 1,4-piperazinediacetic acid

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• 作者：Juan Yang ; Ning Lu ; Gong Zhang ; Lin Cheng ; Shao-Hua Gou
• 关键词：Hybrid organic– ; inorganic framework ; Magnetic properties ; Thermogravimetric properties
• 刊名：Polyhedron
• 出版年：2008
• 出版时间：26 June 2008
• 年：2008
• 卷：27
• 期：9-10
• 页码：2119-2126
• 全文大小：627 K

文摘

Two series of new three-dimensional (3D) hybrid organic–inorganic frameworks [Ln₂(H₂pda)(C₂O₄)(SO₄)₂(H₂O)₂]_n [I, Ln = Nd (1), Y (2)] and {[Ln₂(H₂pda)(C₂O₄)(SO₄)₂(H₂O)₂] · 2H₂O}_n [II, Ln = Pr (3), Ce (4) and Eu (5)] (where H₂dpa = 1,4-piperazinediacetic acid) have been synthesized by the reactions of H₂pda, lanthanide oxides and H₂SO₄ under similar hydrothermal conditions. All compounds are constructed by two-dimensional hybrid organic–inorganic layers, which originate from different lanthanide(III) sulfate chains and in situ generated μ₄-oxalates, and organic H₂dpa pillars. The coordination modes of sulfate in I and II are, respectively, η⁴,μ₃-pentadentate and η³,μ₃-tridentate, resulting in the different inorganic [Ln(SO₄)(H₂O)]∞ chains that have not been documented so far. In I, each organic H₂dpa pillar is connected with two Ln(III) ions in a bis-monodentate fashion, while it is linked to four Ln(III) ions in a bis-bidentate syn–anti mode in II. Meanwhile, each Ln(III) ion in I and II is linked by one and two H2pda ligands, respectively. The observations hint that application of lanthanide(III) sulfate chains and flexible spacer pillars can self-assemble into interesting hybrid organic–inorganic framework solids. Compounds 1 and 3 are air stable and both the three-dimensional frameworks can be retained below 180 °C. The variable-temperature magnetic studies show that the χ_M values of 1 and 3 increase on the falling temperature, which may be attributed to the depopulation of Stark levels and/or intramolecular antiferromagnetic coupling between the metal centers.