| Co-Investigator(Kenkyū-buntansha) |
ISHIDA Hiroyuki Okayama University, Graduate School of Natural Science and Technology, Professor, 大学院自然科学研究科, 教授 (70193331)
SUNATSUKI Yukinari Okayama University, Advanced Science research Center, Assistant, 自然生命科学研究支援センター, 助手 (80362987)
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| Budget Amount *help |
¥15,300,000 (Direct Cost: ¥15,300,000)
Fiscal Year 2006: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥12,300,000 (Direct Cost: ¥12,300,000)
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| Research Abstract |
Lanthanide (Ln) metal ions have a large ground-state spin and a strong easy axis magnetic anisotropy, and most of their magnetic interactions with the 3d-transition metal ions are ferromagnetic. All these properties are favorable for 3d-4f complexes to behave as single molecule magnets (SMMs). Polynuclear 3d-4f complexes will meet the requirement to be identified as SMMs by a smaller number of metal ions than the 3d-transition metal clusters. Therefore, 3d-4f complexes are strong candidates for SMMs. In the first year, we have prepared di-, tri-, and tetranuclear Ni^<II>-Ln^<III> complexes by the use of the "complexes as ligands" strategy, and we could control the nuclearity of the complexes by the selection of the additional ligand on the Ln^<III> ion. We used [Ni(HL^1)] (H_3L^1 = 1,1,1-tris(N- salicylideneaminomethyl)ethane) as a complex ligand. The ac susceptibility measurements of the dinucler complex, [(NiL)Dy(hfac)_2(EtOH)] (Hhfac = hexafluoroacetylacetone) revealed that this complex behaves as an SMM at low temperatures. However, it was not easy to prepare trinuclear Ni-Ln-Ni complexe, since the bridging ability of the phenolate oxygen atoms is low. In the second year, we added methoxy groups on the benzene rings of the ligand to increase the stability of the trinuclear complexes, since Ln^<III> ions have a strong affinity toward oxygen. By using [Co^<II>(L^2)]- as a ligand complex, we obtained the trinuclear Co^<II>-Dy^<II>-Co^<II>, [Co(L^2)_2Dy]NO_3. This complex also behaves as an SMM, and has a higher blocking energy barrier than [(NiL)Dy(hfac)_2(EtOH)].
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