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Open AccessArticle

Hydrogen-Bonding Assembly of Coordination Polymers Showing Reversible Dynamic Solid-State Structural Transformations

1
Institute for Molecular Science, Nishigounaka 38, Myoudaiji, Okazaki 444-8585, Japan
2
Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
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Daiichi Kigenso Kagaku Kogyo Co., Ltd., 1-6-38 Hirabayashi-minami, Suminoe-ku, Osaka 559-0025, Japan
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Department of Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
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Institute of Pulsed Power Science, Kumamoto University, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
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XRD Application & Software Development, X-ray Instrument Division, Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196-8666, Japan
*
Authors to whom correspondence should be addressed.
Present address: Toyota Central R and D Labs. Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan.
Inorganics 2018, 6(4), 115; https://doi.org/10.3390/inorganics6040115
Received: 24 September 2018 / Revised: 18 October 2018 / Accepted: 18 October 2018 / Published: 21 October 2018
(This article belongs to the Special Issue Self-Assembly of Supramolecular Coordination Compounds)
We herein report the synthesis, single-crystal structures of coordination polymers, and structural transformations of complexes employing 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile (tdpd2−) and pyrazine (pyz) as bridging ligands. {[M(H2O)4(pyz)][M(tdpd)2(pyz)]·6(H2O)}n, [1·10H2O and 2·10H2O where M = Co (1) and Zn (2)], consists of two types of crystallographically independent one-dimensional (1D) structures packed together. One motif, [M(tdpd)2(pyz)]2− (A), is an anionic infinite pyz bridged 1D array with chelating tdpd2− ligands, and the other motif is a cationic chain, [M(H2O)4(pyz)]2+ (B), which is decorated with four terminal water molecules. The 1D arrays (A) and (B) are arranged in parallel by multi-point hydrogen-bonding interactions in an alternate (A)(B)(A)(B) sequence extending along the c-axis. Both compounds exhibit structural transformations driven by thermal dehydration processes around 350 K to give partially dehydrated forms, 1·2H2O and 2·2H2O. The structural determination of the partially dehydrated form, 2·2H2O, reveals a solid-state structural transformation from a 1D chain structure to a two-dimensional (2D) coordination sheet structure, [Zn2(tdpd)2(H2O)2(pyz)]n (2·2H2O). Further heating to 500 K yields the anhydrous form 2. While the virgin samples of 1·10H2O and 2·10H2O crystallize in different crystal systems, powder X-ray diffraction (PXRD) measurements of the dehydrated forms, 1·2H2O and 2·2H2O, are indicative of the same structure. The structural transformation is irreversible for 1·10H2O at ambient conditions. On the other hand, compound 2·10H2O shows a reversible structural change. The solid-state structural transformation for 1·10H2O was also confirmed by monitoring in-situ magnetic susceptibility, which is consistent with other thermally-induced measurements. View Full-Text
Keywords: cobalt; zinc; pyrazine; coordination polymer; metal–organic framework; 1D array; solid-state structural transformation cobalt; zinc; pyrazine; coordination polymer; metal–organic framework; 1D array; solid-state structural transformation
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MDPI and ACS Style

Kumagai, H.; Yagishita, S.; Kanazashi, K.; Ishii, M.; Hayami, S.; Konaka, H.; Ishikawa, R.; Kawata, S. Hydrogen-Bonding Assembly of Coordination Polymers Showing Reversible Dynamic Solid-State Structural Transformations. Inorganics 2018, 6, 115.

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