Papers by Norimichi Kojima
Molecular crystals and liquid crystals science technology. Section A, Molecular crystals and liquid crystals (CD-ROM), 2002
We have investigated the spin-crossover behavior for one-dimensional complexes [Fe (trz) 3 (RSO 3... more We have investigated the spin-crossover behavior for one-dimensional complexes [Fe (trz) 3 (RSO 3) 2 (trz= triazole) and two-dimensional mixed-valence complexes (C n H 2n+ 1) 4 N [Fe II Fe III (dto) 3](dto= C 2 O 2 S 2). For the case of [Fe (4-NH 2 trz) 3](RSO 3) 2, we have ...
Crystals, 2020
A transparent film allowing tunable multicolor emission based on a composite of an organometallic... more A transparent film allowing tunable multicolor emission based on a composite of an organometallic compound and a cation-exchange membrane has been developed, in which the cyclometallated iridium(III) complex [IrIII(4Py-ppy)3] (=tris[2-(2-pyridinyl-κN)-4-(4-pyridinyl)phenyl-κC]iridium) (1) with pH-dependent emission wavelengths has been incorporated into Nafion by cation exchange. Soaking Nafion in the solution of 1 for 24 h and exposed to buffers at pH 2, 4, and 10 resulted in maximum emission wavelengths of 587, 560, and 503 nm, respectively. The photophysical properties of 1@Nafion were also enhanced, as its maximum emission wavelength was more blue-shifted than those of 602, 564, and 503 nm in the solutions. The emission quantum yields (Φ) and lifetimes (τ) of 1@Nafion prepared under an acidic condition were up to Φ = 1.8% and τ = 0.11, 0.92 μs, which are considerably higher than the corresponding solutions of Φ = 0.5% and τ = 0.02, 0.18 μs. This is attributed to the fact that 1 ...
Related Article: G.Saito, H.Izukashi, M.Shibata, K.Yoshida, L.A.Kushch, T.Kondo, H.Yamochi, O.O.D... more Related Article: G.Saito, H.Izukashi, M.Shibata, K.Yoshida, L.A.Kushch, T.Kondo, H.Yamochi, O.O.Drozdova, K.Matsumoto, M.Kusunoki, K.Sakaguchi, N.Kojima, E.B.Yagubskii|2000|J.Mater.Chem.|10|893|doi:10.1039/a908670f
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2005
Molecular Crystals and Liquid Crystals, 1996
Angewandte Chemie, 2020
A proton-electron coupling system, exhibiting unique bistability or multistability of the protona... more A proton-electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials on the basis of proton dynamics. In this paper, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling with spin transition. Although the multi-step transition with hysteresis has been observed in various systems (e.g., valence tautomerism), the corresponding behavior of proton transfer has not been reported in crystalline systems; thus, the described iron(II) complex is the first example. Furthermore, because proton transfer occurs only in one of the two ligands and p electrons redistribute in it, the dipole moment of the iron(II) complexes changes with the proton transfer, wherein the total dipole moment in the crystal was canceled out owing to the antiferroelectric-like arrangement. This study shows the potential for using the proton transfer phenomenon in the materials science field.
Chemistry Letters, 2011
ABSTRACT We newly synthesized transparent films composed of pHsensitive spin-crossover complex [F... more ABSTRACT We newly synthesized transparent films composed of pHsensitive spin-crossover complex [FeII(diAMsar)] (diAMsar: 1,8-diaminosarcophagine) and an ion-exchange polymer, Nafion, having different colors corresponding to proton concentration. The UVvis spectroscopic measurements revealed that the films, which were provided under pH 4, 7, and 10 conditions, showed the spin state depending on pH.
Current Inorganic Chemistry, 2016
THE REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY, 1998
We have performed the single crystal X-ray structure analysis of the three-dimensional halogen-br... more We have performed the single crystal X-ray structure analysis of the three-dimensional halogen-bridged mixedvalence compound, Cs2AuIAuIIICl6 under high pressures up to 18 GPa. The high pressure apparatus used is a diamond-anvil-cell with helium gas as an inert and hydrostatic pressure-transmitting medium. The pressure dependence of the unit cell parameters indicates a structural phase transition from tetragonal to cubic at 12.5 GPa. The high pressure phase has a space group, Pm3m.
Crystal structures, gas storage and magnetic properties of lanthanide-organic frameworks built up from dicarboxylates, [Ln2(2,5-pydc)2(2,5-pipdc)(H2O)2]n (Ln = Ce, Pr, Eu) and (H2pip)n[Ln2(2,6-pydc)4(H2O)2]n (Ln = Ce, Pr, Eu, Sm) Polyhedron
Chemistry Letters, 2018
A molecular salt with a bulky cation and anion, (H 2 bipip)-(H) 2 [Fe(CN) 6 ] (1) (H 2 bipip 2+ :... more A molecular salt with a bulky cation and anion, (H 2 bipip)-(H) 2 [Fe(CN) 6 ] (1) (H 2 bipip 2+ : 4,4¤-bipiperidine-1,1¤-diium), has been prepared. The salt comprises protons (H +) as counter cations. Single-crystal X-ray structure analysis revealed that the proton is trapped between two cyanido ligands of [Fe(CN) 6 ] 4¹ anions, forming a very short N£H + £N hydrogen bond.
New Journal of Chemistry, 2018
A new triplet biradical having two chelatable nitroxide sites and a strong intramolecular ferroma... more A new triplet biradical having two chelatable nitroxide sites and a strong intramolecular ferromagnetic coupling through a “meta–para” bipyridyl linker.
Le Journal de Physique Colloques, 1988
A metamagnetic transition was found in CsFeCl3.2H2O with anomalous relaxation at 14 T when the ex... more A metamagnetic transition was found in CsFeCl3.2H2O with anomalous relaxation at 14 T when the external magnetic field is applied parallel to the 1D-magnetic chain of the *axis. A metastable state and hysteresis, which was not observed in the steady field, appeared at the transition in the pulsed field measurement.
Current Inorganic Chemistry, 2013
Physical Review B, 1985
Polarized absorption spectra of the one-dimensional (1D) ferromagnet CsFeC13 have been investigat... more Polarized absorption spectra of the one-dimensional (1D) ferromagnet CsFeC13 have been investigated from 3000 to 400 nm from 15 to 295 K. Several weak bands are seen at the low-energy sides of the C, E, and F bands, whose temperature dependence of intensity agrees with that predicted for the 1D ferromagnet: This is the first observation of hot magnon sideband in CsFeC13. It turns out that (1) the parity-forbidden but spin-allowed 3 band arises not only from the vibration-assisted electric dipole transition but also from the magnetic dipole transition and (2) the parity-and spinforbidden 8-I' bands arise not only from the intrachain ferromagnetic spin-exchange-induced electric dipole transition in two adjacent Fe + ions, giving rise to hot magnon sidebands, but also from the magnetic dipole transition in a single Fe + ion. All the 3-G absorption bands are attributed to the Fe + crystal-field energy state of the d electronic configuration. It is revealed by a computer analysis that an absorption band attributable to the T2~(I') state is obscured by the sharply structured E and F bands.
Topics in Applied Physics, 2021
Journal of the Magnetics Society of Japan, 1987
Optical absorption spectra corresponding to the 6Al9+4T29(D) transition in CSMnCl; 2H 2 0 and (CH... more Optical absorption spectra corresponding to the 6Al9+4T29(D) transition in CSMnCl; 2H 2 0 and (CH3)2NH2MnCl302H20 were investigated under magnetic fields. In these compounds, a sharp exciton line in the lowest energy region of this transition was split by the applied field perpendicular to the spin direction. From the analysis of the spin configuration, it was proved to be a Davydov splitting induced by the field. The field induced Davydov splitting can be explained by the fact that in an external magnetic field perpendicular to the spin direction, spins cant towards the field so as to remove the prohibition of the inter-sublattice exciton transfer. The field dependence of this splitting was explained by the exciton transfer due to the anisotropic exchange interaction.
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Papers by Norimichi Kojima