1997 Fiscal Year Final Research Report Summary
DEVELOPMENT OF MOLECULE-BASED FERROMAGNETS UTILIZING STABLE ORGANIC RADICALS OR PYRIMIDINE-TRANSITION METAL COMPLEXES
| Project/Area Number |
08454218
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機能・物性・材料
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| Research Institution | THE UNIVERSITY OF ELECTRO-COMMUNICATIONS |
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Principal Investigator |
NOGAMI Takashi THE UNIVERSITY OF ELECTRO-COMMUNICATIONS,PROFESSOR, 電気通信学部, 教授 (80029280)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIDA Takayuki THE UNIVERSITY OF ELECTRO-COMMUNICATIONS,ASSOCIATE PROFESSOR, 電気通信学部, 助教授 (00232306)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Molecule-based ferromagnet / Transition-metal complex / Magnetic property / Crystal structure / Ferromagnetic interaction / Weak ferromagnetism / SQUID measurement / Stable organic radical |
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| Research Abstract |
(1) Magnetic Properties of Organic Radicals
Magnetic properties of 165 kinds of TEMPO derivatives (ArCH=N-TEMPO,Ar=aryl group) were studied by SQUID Intermolecular ferromagnetic interactions were found for 52 radicals. Thus, the intermolecular ferromagnetic interaction were found to be not a rare phenomenon. Eight kinds of radicals showed bulk ferromagnetic transitions below 0.4 K.We proposed that the ferromagnetic interaction was caused by the spin-polarization mechanism via beta-hydrogens. This mechanism was supported by MO calculations and NMR measurements. Spontaneous magnetization was observed below T_c by means of zero-field muSR measurements. In order to elevate the transition temperatures, magnetic properties of pi-conjugated NO radicals were studied. NO radicals possessing acridine skeleton showed the intermolecular ferromagnetic interaction which was caused through the overlaps of pi-electron clouds (McConell model).
(2) Magnetic Properties of Pyrimidine-Transition Metal Complexes
In order to study the magnetic interactions of transition-metal ions coordinated to meta-positions of an aromatic ring, magnetic properties of various pyrimidine-transition metal complexes were studied. It was found that coordination modes rather than coordination positions (meta-position) determine the magnetic interactions. In the case of Cu^<2+> an axial/equatorial coordination gave rise to the ferromagnetic interaction, and an equatorial/equatorial coordination did the antiferromagnetic interaction. When we adopted inorganic anions of small sizes, sevral complexes showed the behavior of a weak ferromagnetism. (pyrimidine)_2CoX_2 (X=Cl, Br) has a chiral crystal structure, and showed the behavior of the weak ferromagnetism.
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[Publications] T.Nogami, T.Ishida, M.Yasui, F.Iwasaki, N.Takeda, M.Ishikawa, T.Kawakami, and K.Yamaguchi: "Proposed Mechanism of Ferromagnetic Interaction of Organic Ferromagnets : 4-Arylmethyleneamino-2,2,6,6-tetramethyl-piperidin-1-oxyls and Related Compounds" Bull.Chem.Soc.Jpn.69. 1841-1848 (1996)
Description
「研究成果報告書概要(欧文)」より
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[Publications] K.Togashi, R.Imachi, K.Tomioka, H.Tsuboi, T.Ishida, T.Nogami, N.Takeda, and M.Ishikawa: "Organic Radicals Exhibiting Intermolecular Ferromagnetic Interactions with High Probability : 4-Arylmethyleneamino-2,2,6,6-tetramethylpiperidin-1-oxyls and Related Compounds" Bull.Chem.Soc.Jpn.69. 2821-2830 (1996)
Description
「研究成果報告書概要(欧文)」より
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