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Simultaneous Spin-Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′-Tetracyano-p-quinodimethane |
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| Authors: | Dr Ryuta Ishikawa Shuya Ueno Shoei Nifuku Dr Yoji Horii Dr Hiroaki Iguchi Prof Yuji Miyazaki Prof Motohiro Nakano Prof Shinya Hayami Dr Shohei Kumagai Dr Keiichi Katoh Prof Zhao-Yang Li Prof Masahiro Yamashita Prof Satoshi Kawata |
| Institution: | 1. Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180 Japan;2. Research Center for Structural Thermodynamics, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043 Japan;3. Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aza-Aoba Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 Japan;4. Department of Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555 Japan;5. Department of Advanced Materials Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8561 Japan;6. School of Materials Science and Engineering, Nankai University, Tianjin, 300350 P. R. China;7. Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aza-Aoba Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 Japan
World Premier International Research Center Initiative, Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577 Japan School of Materials Science and Engineering, Nankai University, Tianjin, 300350 P. R. China |
| Abstract: | The reaction of Fe(OAc)2 and Hbpypz with neutral TCNQ results in the formation of Fe2(bpypz)2(TCNQ)2](TCNQ)2 ( 1 ), in which Hbpypz=3,5-bis(2-pyridyl)pyrazole and TCNQ=7,7′,8,8′-tetracyano-p-quinodimethane. Crystal packing of 1 with uncoordinated TCNQ and π–π stacking of bpypz− ligands produces an extended two-dimensional supramolecular coordination assembly. Temperature dependence of the dc magnetic susceptibility and heat capacity measurements indicate that 1 undergoes an abrupt spin crossover (SCO) with thermal spin transition temperatures of 339 and 337 K for the heating and cooling modes, respectively, resulting in a thermal hysteresis of 2 K. Remarkably, the temperature dependence of dc electrical transport exhibits a transition that coincides with thermal SCO, demonstrating the thermally induced magnetic and electrical bistability of 1 , strongly correlating magnetism with electrical conductivity. This outstanding feature leads to thermally induced simultaneous switching of magnetism and electrical conductivity and a magnetoresistance effect. |
| Keywords: | conducting materials iron semiconductors spin crossover TCNQ |