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Three-Step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex |
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| Authors: | Takumi Nakanishi Yuta Hori Shuqi Wu Hiroyasu Sato Atsushi Okazawa Prof Norimichi Kojima Yusuke Horie Hajime Okajima Prof Akira Sakamoto Yoshihito Shiota Prof Kazunari Yoshizawa Prof Osamu Sato |
| Institution: | 1. Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan;2. Institute for Materials Chemistry and Engineering & IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan
Center for Computational Sciences, University of Tsukuba, Tsukuba, 305-8577 Japan;3. Rigaku Corporation, 3-9-12 Matsubaracho, Akishima, Tokyo, 196-8666 Japan;4. Department of Basic Science, Graduation School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 Japan Current address: Division of Chemistry, Institution of Liberal Education, Nihon University School of Medicine, 30-1 Oyaguchi Uemachi, Itabashi-ku, Tokyo, 173-8610 Japan;5. Department of Basic Science, Graduation School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 Japan;6. Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5258 Japan |
| Abstract: | A proton–electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials based on proton dynamics. Herein, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling with spin transition. Although the multi-step transition with hysteresis has been observed in various systems, the corresponding behavior of proton transfer has not been reported in crystalline systems; thus, the described iron(II) complex is the first example. Furthermore, because proton transfer occurs only in one of the two ligands and π electrons redistribute in it, the dipole moment of the iron(II) complexes changes with the proton transfer, wherein the total dipole moment in the crystal was canceled out owing to the antiferroelectric-like arrangement. |
| Keywords: | hydrazone complexes proton transfer spin crossover solid-state chemistry switchable materials |