| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Methanemonooxygenase (MMO), one of the Non-heme metalloenzyme, draws much attention due to its high ability on oxygenation of alkanes giving alcohols under mild conditions. Dendrimers having a structure with regularly branching form are spherical single molecular, which resembles to micells, and show characteristic behavior. Although we have already developed good catalysts for alkane oxygenations, the catalytic system had a defect that the catalysts showed high activity only in chlorinated solvents. Introducing dendrons to our ruthenium complexes having high catalytic ability on alkane oxygenation, the solubility of the catalyst is able to be freely controlled and realizes excellent models of MMO.
Dendrimer-type ruthenium complexes have been synthesized. One has tetradentate ligand, tris (pyridylmethyl) amine (TPA), and the other has both terdentate ligand, terpyridine, and, bidentate ligand, bipyridine. Dendrons of benzylether type were introduced to their pyridyl groups. First, second, and third generation of the dendrimers were prepared and it was found that they have catalytic ability on alkane oxygenation.
In the present catalysts the key inetermediate is assumed to be a five-coordinated species. In general, ruthenium complexes are known to show photochemical activity such as isomerization and/or ligand substitution under irradiation with dissociative mechanism. Preliminary experiments revealed that the ruthenium complexes prepared above showed an activity on photochemical isomerization and/or ligand substitution with good quantum yield.
Further, formation of possible five-coordinated species was observed on irradiation of the complexes in chlorinated solvent. The reaction of the five-coordinated intermediate and pyridine N-oxide gave new spieces showing similar UV spectra to those of oxoruthenium complexes reported in literatures. Further studies are in progress.
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