| Project/Area Number |
16074205
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KOJIMA Norimichi The University of Tokyo, Graduate School of Arts and Sciences, Professor (60149656)
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| Co-Investigator(Kenkyū-buntansha) |
ENOMOTO Masaya The University of Tokyo, Graduate School of Arts and Sciences, Assistant Professor (70345065)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥10,800,000 (Direct Cost: ¥10,800,000)
Fiscal Year 2007: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2006: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2005: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | organic-inotganic hybrid systen / charge transfer phase transition / ferroaagnetism / light-induced magnetism / mixed-valence complex / photoisomerization / spin crossover / coordination space / 光異性化 / 光磁性 / ヘテロ分子集合体 / 協同ヤーン・テラー効果 / インターカレーション |
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| Research Abstract |
Intercalation of photochromic molecule into magnetic system provides fascinating multi-functionalities such as photo-magnetism, which gains much attention for their application to devices. The main subjects in this project were the development of photo-induced spin-crossover phenomena at room temperature by using the photo-isomerization of intercalated molecule, and the development of the transformation of magnetism for two-dimensional ferromagnetic system coupled with photochromic molecule.
The outcomes of the title subject are as follows. (1) Iron mixed-valence complex, (n-C_3H_7)_4N[Fe^<II>Fe^<III>(dto)_3] (dto = C_2O_2S_2), shows the charge transfer phase transition coupled with spin and charge around 120 K and a ferromagnetic transition at 6.5 K. These phase transitions remarkably depend on the cation size. In order to control the magnetic properties in this system by means of photo-irradiation, we have synthesized (SP) [Fe^<II>Fe^<III>(dto)_3] (SP = spiropyran), and found that the
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UV irradiation changes the structure of spiropyran from the closed form to the open one in solid state. The photochromism of spiropyran in this system controls the ferromagnetic transition temperature and the coercive field as well as the charge transfer phase transition. Moreover, we have found that the photochromism of spiropyran in (SP) [Fe^<II>Fe^<III>(dto)_3] induces the charge transfer phase transition in [Fe^<II>Fe^<III>(dto)_3]_∞. (2) We have synthesized several organic-inorganic hybrid systems consisting of two-dimensional ferromagnets and photochromic diarylethenes. In the case of layered perovskite-type copper halides coupled with cationic diarylethene, we found that the isomerization of diarylethene controls the magnetic ordering temperature. In the case of cobalt hydroxide-based 2D ferromagnet (Co-LDHs), we found that the reversible photo-isomerization of anionic diarylethene takes place in solid state and the photo-isomerization from the open form to the close form induces the enhancement of Curie temperature from 9 K to 20 K. Less
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