| Co-Investigator(Kenkyū-buntansha) |
OHBA Masaaki Kyushu University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (00284480)
TAKAHASHI Kazuhiro Kyushu University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00216706)
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| Research Abstract |
1. Macrocyclic Dinuclear Mn Complexes as Functional Mn Catalases
Dinuclear MnィイD22ィエD2(II, II) complexes of Macrocyclic ligands derived from the [2 : 2] condensation between 2, 6-diformyl-4-methylphenol and diamine (ethylenediamine, trimethylenediamine, tetramethylenediamine) showed a Mn-catalase like activity to disproprtionate hydrogen peroxide into dioxygen and water. The reaction mixture assumed a deep purple color and showed a characteric absorption at 530 nm having v(Mn=O) vibration modes of ca. 730 cmィイD1-1ィエD1 separation. A frozen reaction mixture showed EPR signals characteristic of MnィイD22ィエD2(II, III). Mixed-valence MnィイD22ィエD2(II, III) complexes have been isolated that a catalase-like activity similar to that of the corresponding dinuclear MnィイD22ィエD2(II, II) complex. An intermolecular of hydrogen peroxide decomposition by the interconversion of MnィイD22ィエD2(II, II)/MnィイD22ィエD2(II, IV) is inferred for the complexes.
2. Macrocyclic CoィイD1IIィエD1MィイD1IIィエD1 Complexes with 'Co(sal
… More
en)' in A Macrocyclic Framework
Dinuclear CoィイD1IIィエD1MィイD1IIィエD1 Complexes [CoM(L)(AcO)]CIOィイD24ィエD2 and [CoM(L)(NCS)]CIOィイD24ィエD2 (M=Mn, Fe, Co) have been obtained where LィイD12-ィエD1 is a heterodinucleating macrocyclic ligand derived by the 2 : 1 : 1 condensation of 2, 6-diformyl-4-methylphenol, ethylenediamine and diethylenetriamine and has two dissimilar NィイD22ィエD2OィイD22ィエD2 and NィイD23ィエD2OィイD22ィエD2 metal-binding sites sharing the phenolic oxygens. The Co resides in the NィイD22ィエD2OィイD22ィエD2 site and assumed a 'Co(salen)'-like geometry. The oxygenation at the 'Co(salen)' site is influenced by the dinuclear core structure and the nature of the adjacent MィイD1IIィエD1 ion. In the acetate complexes the acetate bridge prohibits an intramolecular oxygenation to provide an intermolecular peroxo dimer, {MィイD1IIィエD1CoィイD1IIIィエD1-O-O-CoィイD1IIIィエD1MィイD1IIィエD1}. Stable peroxo complexes have been isolated for M=Co and Mn and crystallographycally characterized. When no additional bridge exists and the second MィイD1IIィエD1 is susceptible to oxydation, an intramolecular peroxo complex is formed that is readily converted into a CoィイD1IIIィエD1MィイD1IIIィエD1 species by hydrolysis or solvolysis. An analogous CoィイD1IIィエD1CuィイD1IィエD1 complex was very sensitive to dioxygen and readily converted into a CoィイD1IIIィエD1CuィイD1IIィエD1 species through an intramolecular peroxide complex..
3. Heterodinuclear Complexes of Dinucleating with N(anime)ィイD22ィエD2OィイD22ィエD2 and N(imine)ィイD22ィエD2OィイD22ィエD2 Sites
New phneol-based dinucleating macrocycles with N(amine)ィイD22ィエD2OィイD22ィエD2 and N(imine)ィイD22ィエD2OィイD22ィエD2 metal-binding sites have been developed for the study of heterodinuclear complexes. The ligands show site-selectivity of metal ions depending upon a synthetic method, the nature of the counter ion used and the cavity sizes of the macrocycles. The mononuclear CuィイD1IIIィエD1 complex has the metal in the N(imine)ィイD22ィエD2OィイD22ィエD2 site and generally accommodates the second MィイD1IIィエD1 ion in the aminic site. PbィイD1IIィエD1CuィイD1IIィエD1 complexes with Pb in the aminic site and Cu in the iminic site have been derived as precursors which were converted into CuィイD1IIィエD1MィイD1IIィエD1 complexes (with Cu in the aminic site and M in the iminic site) in the transmetallation of the Pb for MィイD1IIィエD1 ion. Coordination-position isomers have been derived by the two synthetic methods. They were characterized by different physicochemical properties. Less
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