Akihiro Takahashi

The proximal heme axial ligand plays an important role in tuning the reactivity of oxoiron(IV) porphyrin π-cation radical species (compound I) in enzymatic and catalytic oxygenation reactions. To reveal the essence of the axial ligand effect on the reactivity, we investigated it from a thermodynamic viewpoint. Compound I model complexes, (TMP(+•))Fe(IV)O(L) (where TMP is 5,10,15,20-tetramesitylporphyrin and TMP(+•) is its π-cation radical), can be provided with altered reactivity by changing the

To study the effect of axial ligands on the electronic structure and reactivity of compound I of peroxidases and catalases, oxoiron(IV) porphyrin pi-cation radical complexes with imidazole, 2-methylimidazole, 4(5)-methylimidazole, and 3-fluoro-4-nitrophenolate as the axial ligands were prepared by ozone oxidation of iron(III) complexes of 5,10,15,20-tetramesitylporphyrin (TMP) and 2,7,12,17-tetramethyl-3,8,13,18-tetramesitylporphyrin (TMTMP). These complexes were fully characterized by absorptio

The oxoiron(IV) porphyrin π-cation radical complex (compound I) has been identified as the key reactive intermediate of several heme enzymes and synthetic heme complexes. The redox properties of this reactive species are not yet well understood. Here, we report the results of a systematic study of the electrochemistry of oxoiron(IV) porphyrin π-cation radical complexes with various porphyrin structures and axial ligands in organic solvents at low temperatures. The cyclic voltammogram of (TMP)Fe(

This study presents an experimental investigation of the contribution of non-plastic fines to the development of seepage-induced internal instability and its impact on the undrained mechanical response of gap-graded sands. The purpose of the laboratory tests is to observe the internal instability of two key microstructures: (1) an underfilled microstructure in which the coarser particles control the stress transfer and (2) an overfilled microstructure in which the finer particles play a primary

An experimental investigation of multiple seepage-induced suffusion and its impact on the mechanical responses of internally unstable gap-graded soil, with a fines content of 25%, is presented in this paper. Using a modified triaxial erosion apparatus, with a redesigned seepage control system, erosion tests under multiple seepage conditions, as well as undrained monotonic and cyclic compression tests, are performed. It is found that multiple seepages cause an eroded mass without a marked change

It is well known that soils are prone to spatial non-uniformity, which affects evaluations of slope stability and failure mechanisms. This paper presents a probabilistic slope stability evaluation, considering the 3D spatial variation in the soil properties, by the random limit equilibrium method (RLEM). Specifically, 3D random fields of cohesion c, friction angle ϕ, and soil unit weight γ are generated using a fast Fourier transform. The RLEM is applied to evaluate the effects of the 3D spatial

Activation parameters for epoxidation and allylic hydroxylation reactions of cyclohexene with FeIVO(TMP)*+Cl (1) were determined. Within the experimental temperature range, the epoxidation reaction was enthalpy-controlled (i.e., DeltaH > -TDeltaS), while the allylic hydroxylation reaction was entropy-controlled (i.e., -TDeltaS > DeltaH). An unexpectedly large contribution of the entropy term for the allylic hydroxylation reaction indicated that the free energy of activation, DeltaG, rather than

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLoose-Fit Polyrotaxane Composed of γ-Cyclodextrin and Single Poly(Ethyelene Glycol) Chain: Making Room in γ-CD Cavity for Additional Inclusion ComplexationAkihiro Takahashi†, Ryo Katoono†‡, and Nobuhiko Yui*†‡View Author Information† School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292, Japan‡ JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan*Corresponding author