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A Paramagnetic Compass Based on Lanthanide Metal-Organic Framework |
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| Authors: | Hao Jia Dr Baipeng Yin Jiaying Chen Prof Ye Zou Hong Wang Yu Zhang Prof Tongmei Ma Prof Qiang Shi Prof Jiannian Yao Prof Shuming Bai Prof Chuang Zhang |
| Institution: | 1. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190 China;2. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190 China
These authors contributed equally to this work.;3. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190 China School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510641 China These authors contributed equally to this work.;4. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190 China University of Chinese Academy of Sciences, Beijing, 100049 China;5. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510641 China |
| Abstract: | Macroscopic compass-like magnetic alignment at low magnetic fields is natural for ferromagnetic materials but is seldomly observed in paramagnetic materials. Herein, we report a “paramagnetic compass” that magnetically aligns under ～mT fields based on the single-crystalline framework constructed by lanthanide ions and organic ligands (Ln-MOF). The magnetic alignment is attributed to the Ln-MOF's strong macroscopic anisotropy, where the highly-ordered structure allows the Ln-ions’ molecular anisotropy to be summed according to the crystal symmetry. In tetragonal Ln-MOFs, the alignment is either parallel or perpendicular to the field depending on the easiest axis of the molecular anisotropy. Reversible switching between the two alignments is realized upon the removal and re-adsorption of solvent molecules filled in the framework. When the crystal symmetry is lowered in monoclinic Ln-MOFs, the alignments become even inclined (47°-66°) to the field. These fascinating properties of Ln-MOFs would encourage further explorations of framework materials containing paramagnetic centers. |
| Keywords: | Lanthanides Magnetic Anisotropy Magnetic Materials Metal-Organic Frameworks Paramagnetism |