CO2-Induced Spin-State Switching at Room Temperature in a Monomeric Cobalt(II) Complex with the Porous Nature |
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| Authors: | Dr Manabu Nakaya Dr Wataru Kosaka Prof Dr Hitoshi Miyasaka Yuki Komatsumaru Dr Shogo Kawaguchi Dr Kunihisa Sugimoto Dr Yingjie Zhang Dr Masaaki Nakamura Leonard F Lindoy Prof Dr Shinya Hayami |
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| Institution: | 1. Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto, 860-8555 Japan;2. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 Japan;3. Diffraction & Scattering Division Japan, Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198 ( Japan;4. Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC, NSW, 2232 Australia;5. School of Chemistry, The University of Sydney, Sydney, NSW, 2006 Australia |
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| Abstract: | CO2-responsive spin-state conversion between high-spin (HS) and low-spin (LS) states at room temperature was achieved in a monomeric cobalt(II) complex. A neutral cobalt(II) complex, CoII(COO-terpy)2]⋅4 H2O ( 1⋅4 H2O ), stably formed cavities generated via π–π stacking motifs and hydrogen bond networks, resulting in the accommodation of four water molecules. Crystalline 1⋅4 H2O transformed to solvent-free 1 without loss of porosity by heating to 420 K. Compound 1 exhibited a selective CO2 adsorption via a gate-open type of the structural modification. Furthermore, the HS/LS transition temperature (T1/2) was able to be tuned by the CO2 pressure over a wide temperature range. Unlike 1 exhibits the HS state at 290 K, the CO2-accomodated form 1⊃CO2 (P =110 kPa) was stabilized in the LS state at 290 K, probably caused by a chemical pressure effect by CO2 accommodation, which provides reversible spin-state conversion by introducing/evacuating CO2 gas into/from 1 . |
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| Keywords: | carbon dioxide cobalt(II) ions hydrogen bonding π–π stacking spin-state change |
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