Hiroki Taniguchi 교수

A nickel-catalyzed intermolecular hydroacylation of methylenecyclopropanes (MCPs) has been developed. The reaction proceeds with stereospecific cleavage of the proximal C-C bond of the cyclopropane ring to give gamma,delta-unsaturated ketones with high diastereoselectivities. A nickel catalyst generated in situ from Ni(cod)(2) and P(n-Bu)(3) with a P/Ni ratio of 1:1 is effective for the hydroacylation, in which benzaldehyde derivatives, heteroaryl aldehydes, and aliphatic aldehydes react with MC

A lead-free ferroelectric: The occurrence of ferroelectricity is demonstrated in a silicate-based compound (Bi2SiO5, see picture), by direct observation of polarization switching. The mechanism of ferroelectricity in Bi2SiO5 has been studied by Raman scattering, transmission electron microscopy, X-ray powder diffraction, and first-principles calculations. The observed ferroelectricity stems from twisting of the one-dimensional SiO4 tetrahedral chain. As a service to our authors and readers, this

Abstract Systematic Raman scattering experiments were performed on Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) single crystals to resolve the low‐wavenumber dynamics in the crystal. Careful checking of the angular dependence of the Raman spectra indicated that the intense peak around 45 cm −1 , which always smears the low‐wavenumber spectra, stems from the F 2 g mode due to Mg:Nb = 1:1 chemically ordered Fm 3 m region. A proper scattering configuration for eliminating the strong F 2 g mode allowed the observati

Abstract New series of ferroelectric liquid crystals with several bond moments near the chiral part have been prepared. The position and the orientation of those bond moments are found to strongly influence the magnitude of the spontaneous polarization in these ferroelectric liquid crystals, and the spontaneous polarization as high as 240 nC/cm2 has been obtained.

The quantum ferroelectric phase transition of 18O-exchanged SrTiO3 (x% exchanged SrTiO3 is abbreviated as STO18-x) was investigated by Raman scattering as a function of x. The result indicates the ideal soft mode-type quantum ferroelectric phase transition of STO18-x, where the 18O exchange enhances the softening of the soft mode by the suppression of quantum fluctuation. In the vicinity of the quantum critical point (x approximately xc=33%), the system results in the ferroelectric-paraelectric

A mechanism for cation-substitution-induced suppression of ferroelectricity in a perovskite-type ferroelectric oxide, CdTiO${}_{3}$, has been elucidated in terms of the relationship between the covalency and the lattice dynamics. Raman scattering experiments and first-principles calculations clarified that a change in the covalency of Cd sites due to Ca substitution selectively decreases the frequencies of the modes associated with octahedral rotations whose axes are perpendicular to the spontan

The oxygen isotope effect on the soft-mode dynamics in quantum paraelectric $\mathrm{SrTi}{(^{18}\mathrm{O}_{x}^{16}\mathrm{O}_{1\ensuremath{-}x})}_{3}$ [STO18-$x$] is investigated by Raman scattering in terms of local symmetry breaking in the paraelectric phase. The exchange rates $x$ of the $^{18}\mathrm{O}$ atoms are 0.23 [STO18-23] and 0.32 [STO18-32], which are less than the critical value ${x}_{c}(=0.33)$. In STO18-32, whose exchange rate is just below ${x}_{c}$, the soft ${E}_{u}$ mode sh

Li2SrNb2O7 (LSNO) crystallizes in a structure closely related to n = 2 Ruddlesden–Popper-type compounds, which are generally formed by intergrowth of two-dimensional perovskite-type blocks and rocksalt-type layers. The present study demonstrates the coexistence of spontaneous polarization and an anti-ferroelectric-like nonlinear response in LSNO at 80 K, suggesting weak ferroelectricity below the phase transition temperature of 217 K. A combination of first-principles calculations and single-cry