Symmetry-Related [LnIII6MnIII12] Clusters toward Single-Molecule Magnets and Cryogenic Magnetic Refrigerants

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• 作者：Jun-Liang Liu ; Wei-Quan Lin ; Yan-Cong Chen ; Ji-Dong Leng ; Fu-Sheng Guo ; Ming-Liang Tong
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：January 7, 2013
• 年：2013
• 卷：52
• 期：1
• 页码：457-463
• 全文大小：538K
• 年卷期：v.52,no.1(January 7, 2013)
• ISSN：1520-510X

文摘

A family of high-nuclearity [Ln^III₆Mn^III₁₂] (Ln = Gd, Tb) nanomagnets has been synthesized, of which two are in D₂ molecular symmetry and the other two are in C₁ symmetry. X-ray crystallography shows that each of them contains a similar {Mn^III₈O₁₃} unit, four marginal Mn^III ions, and two linear {Ln^III₃} units with parallel or perpendicular orientation for high- and low-symmetry cores, respectively. For [Gd^III₆Mn^III₁₂], the distinct spins of the {Mn^III₈O₁₃} unit lead to different spin ground states (S_T = 23 for the high-symmetry one and S_T = 16 for the low-symmetry one), and significant magnetocaloric effects are observed in a wide temperature range [full width at half-maximum (FWHM) of 鈭捨?i>S_m > 18 K] that can maximizes the refrigerant capacity, which may be attributed to the ferromagnetic interactions. By replacement of isotropic Gd^III with anisotropic Tb^III, they behave as single-molecule magnets, with the high-symmetry one possessing a larger effective barrier (36.6 K) than the low-symmetry one (19.6 K).