Volume 54, Issue 8 pp. 2534-2537
Communication

A 36-Fold Multiple Unit Cell and Switchable Anisotropic Dielectric Responses in an Ammonium Magnesium Formate Framework

Ran Shang

Ran Shang

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

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Prof. Zhe-Ming Wang

Corresponding Author

Prof. Zhe-Ming Wang

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)Search for more papers by this author
Prof. Song Gao

Corresponding Author

Prof. Song Gao

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)Search for more papers by this author
First published: 13 January 2015
Citations: 95

This work was supported by the NSFC (Grants 21171010, 21290170, 21290171, and 21321001), the National Basic Research Program of China (Grant 2013CB933401).

Graphical Abstract

Multiply the unit cell: An ammonium Mg formate framework has a rare three-dimensional binodal framework with long cavities accommodating 1,3-propanediammonium and water. The framework displays a phase transition at 275 K to give a 36-fold multiple unit cell and anisotropic switchable dielectric responses.

Abstract

An ammonium Mg formate framework, prepared by using di-protonated 1,3-propanediamine (pnH22+), has a rare three-dimensional binodal (412⋅63)(49⋅66)3 Mg-formate framework with elongated cavities accommodating pnH22+⋅⋅⋅H2O⋅⋅⋅pnH22+ assemblies. It displays a para-electric to antiferroelectric phase transition at 275 K, with a 36-fold multiple unit cell from the high-temperature cell of 1703 Å3 to the low-temperature one of 60 980 Å3. The change results from the disorder–order transition of the pnH22+ cations and H2O molecules. The motions of these components freeze in a stepwise fashion on going from the high-temperature disorder state to the low-temperature ordered state, triggering the switch from high to low dielectric constants, and the spatial limitation of such motions contributes the strong dielectric anisotropy.

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