Tunable Synchronicity of Molecular Valence Tautomerism with Macroscopic Solid-Liquid Transition by Molecular Lattice Engineering |
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| Authors: | Mayumi Chida Satoru Takahashi Ryunosuke Konishi Dr Takeshi Matsumoto Dr Akinobu Nakada Dr Masanori Wakizaka Dr Wataru Kosaka Prof Hitoshi Miyasaka Prof Ho-Chol Chang |
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| Institution: | 1. Department of Applied Chemistry Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga Bunkyo-ku, Tokyo, 112-8551 Japan;2. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 Japan |
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| Abstract: | The combination of a cobalt-dioxolene core that exhibits valence tautomerism (VT) with pyridine-3,5-dicarboxylic acid functionalized with chains bearing two, four, or six oxyethylene units led to new complexes ConEGEspy (n = 2, 4, and 6). These complexes commonly form violet crystals of the low-spin (ls)-CoIII(nEGEspy)2(3,6-DTBSQ)(3,6-DTBCat)] (ls-CoIII], 3,6-DTBSQ = 3,6-di-tert-butyl semiquinonato, 3,6-DTBCat = 3,6-di-tert-butyl catecholato). Interestingly, violet crystals of Co2EGEspy in the ls-CoIII] transitioned into a green liquid, accompanied by an almost complete VT shift (94 %) to the high-spin (hs)-CoII(nEGEspy)2(3,6-DTBSQ)2] (hs-CoII]) upon melting. In contrast, violet crystals of Co4EGEspy and Co6EGEspy in the ls-CoIII] exhibited partial VT (33 %) and only a 9.3 % VT shift after melting, respectively. These data demonstrate the tunability of the synchronicity of the molecular VT and macroscopic solid-liquid transitions by optimizing the tethered chains, thus establishing a new strategy for coupling bistable molecules with the macroscopic world. |
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| Keywords: | cobalt crystal engineering N O ligands phase transitions valence isomerization |
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