Development of New Molecular Catalysts for Dioxygen Activation and Biomimetic Fuel Cell

Cytochrome c oxidase （CcO）是一个家庭enzymes，which metabolite dioxygen to water by an efficient foul -electron reduction pathway with concomitanttranslocation of proton through membranes in mitochondria. The enzyme contains heme（hemea_3）（his）_3Cu(cu_b), and his -cross linked type at the active site. the exact functions, however，这些组件作为一个良好的其dioxygen reduction mechanism. The enzyme也有一些互动the similarity of its reaction with one at the O2 electrode of a fuel cell. Thus他们首先examined the preparation of heme-Cu complexes and tried to clarify their reactivity witho_2 as well as the structure of the resultant peroxy complexes. Tris(pyridylmethyl)amine-tetherediron porphyrin reacted with O2 to give the corresponding peroxo complex in a quite high我们obtained its single crystals and its X-ray crystallographic analysis showed the peroxocomplex taking μ-η^2:η^1 structure. This was the first example of the structuraMore l determination of hetro -dimetallic peroxo complexes. Howerver，the peroxo complexes stable and only showed gradual decomposition to the corresponding μ-oxoone.In order to simulate the dioxygen reaction at the enzyme, the remaining residuesTyr-His and His as an axial ligand to heme a_3are considered to be important. We have prepared an elaborate model，其中所有组件在CcO active site. This model exhibited an interesting reaction：First, it gave the corresponding peroxo complex [Fe^<III>- o_2 -Cu^<II>], possibly μ-1,2 form，at a low temperature. It gradually converted to the superoxy one [Fe^<III>- o_2 /Cu^I]，where the Cu ion was Cu^I. Since peroxy-to-superoxy transformation has never been reported so farthis is a new reaction. this reaction partly simulates the early stage one of o_2 reaction in theenzyme . thus,the Tyr group in the Tyr- his crosslink could play an important role for stabilization of thesuperoxy complex in the enzyme as a H+ donor. the success of the O2 complex at the accurate activesite model opens the new way to clarify its further reaction. Less

Cytochrome c oxidase (CcO) is known to be a family of enzymes, which metabolite dioxygen to water by an efficient four-electron reduction pathway with concomitant translocation of proton through membranes in mitochondria. The enzyme contains heme(hemea_3), (his)_3Cu(Cu_B), and His-cross linked Tyr at the active site. The exact functions, however, of these components as well as its dioxygen reduction mechanism. The enzyme is also interested on the similarity of its reaction with one at the O2 electrode of a fuel cell. Thus, theWe first examined the preparation of heme-Cu complexes and tried to clarify their reactivity with O_2 as well as the structure of the resultant peroxy complexes. Tris(pyridylmethyl)amine-tethered iron porphyrin was reacted with O2 to give the corresponding peroxo complex in a quite high stability. We obtained its single crystals and its X-ray crystallographic analysis showed the peroxo complex taking μ-η^2:η^1 structure. This was the first example of the structura … More l determination of hetero-dimetallic peroxo complexes. Howerver, the peroxo complexes were stable and only showed gradual decomposition to the corresponding μ-oxo one.In order to simulate the dioxygen reaction at the enzyme, the remaining residues, Tyr-His and His as an axial ligand to heme a_3, are considered to be important. We have prepared an elaborate model, which bears all components at the CcO active site. This model exhibited an interesting reaction : First, it gave the corresponding peroxo complex [Fe^<III>-O_2-Cu^<II>], possibly μ-1,2 form, at a low temperature. It was gradually converted to the superoxy one [Fe^<III>-O_2・/Cu^I], where the Cu ion was Cu^I. Since peroxy-to-superoxy transformation has never been reported so far, this is a new reaction. This reaction partly simulates the early stage one of O_2 reaction in the enzyme. Thus, the Tyr group in the Tyr-His crosslink could play an important role for stabilization of the superoxy complex in the enzyme as a H+ donor. The success of the O2 complex at the accurate active site model opens the new way to clarify its further reaction. Less