Photoluminescent and Magnetic Properties of a Series of Lanthanide Coordination Polymers with 1H-Tetrazolate-5-formic Acid

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• 作者：Mei-Feng Wu ; Ming-Sheng Wang ; Sheng-Ping Guo ; Fa-Kun Zheng ; Hui-Fen Chen ; Xiao-Ming Jiang ; Guang-Ning Liu ; Guo-Cong Guo ; Jin-Shun Huang
• 刊名：Crystal Growth & Design
• 出版年：2011
• 出版时间：February 2, 2011
• 年：2011
• 卷：11
• 期：2
• 页码：372-381
• 全文大小：1154K
• 年卷期：v.11,no.2(February 2, 2011)
• ISSN：1528-7505

文摘

Reaction of lanthanide oxides and 1H-tetrazolate-5-ethyl formate in water at 50 掳C in the presence of pyridine afforded a series of lanthanide coordination polymers, {(Hpy)₂[Pr₄(tzf)₇(H₂O)₁₁]路10H₂O}_n (1) and {[Ln₂(tzf)₃(H₂O)₆]路4H₂O}_n, where Ln = Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Hpy = protonated pyridine, and H₂tzf = 1H-tetrazolate-5-formate acid. Polymer 1 features a three-dimensional (3-D) anion framework built up by cross-linkage of tetrameric [Pr₄(tzf)₄]⁴⁺ units and tzf^{2鈭?/sup> ligands, showing a six-connected primitive cubic (pcu) topology (412路63). Isomorphous polymers 2鈭?b>6 present a two-dimensional (2-D) neutral structure with a four-connected (4,4) topology. Four new coordination modes of the tzf2鈭?/sup> ligand are first observed in tetrazolate-5-carboxylate complexes. The lanthanide contraction effect and coordination flexibility of tzf2鈭?/sup> ligand play a key role in governing the formation of coordination polymers with different polymeric architectures. The photoluminescent analyses for 2, 3, 5, and 6 suggest that ligand-to-Ln(III) energy transfer is efficient, especially for Eu(III) and Tb(III) ions, and the tzf2鈭?/sup> ligand may act as a good 鈥渁ntenna molecule鈥?to sensitize Ln(III) emission. The variable-temperature magnetic study shows that magnetic interactions between the Ln(III) ions in 1鈭?b>6 are mainly ascribed to the antiferromagnetic coupling as well as the depopulation of the Stark levels. The spin鈭抩rbit coupling parameters (位) for Sm(III) in 2 and Eu(III) in 3 are 259(2) and 344(1) cm鈭?, respectively, based on the free-ion approximation.}