Papers - Yoshioka, Naoki

Light-Induced Mixed-Valence State of FeII[Fe(CN)5NO]・xH2O

MORIOKA YOSHIYUKI, HISAMITSU TAKA-AKI, INOUE HIDENARI, YOSHIOKA NAOKI, TOMIZAWA HIROSHI, MIKI EI-ICHI

Bulletin of the Chemical Society of Japan 71 ( 4 ) 837 - 844 1998.04

Research paper (scientific journal), Joint Work, Accepted

　View Summary

A long-living metastable state is produced in FeII[Fe(CN)5NO]·xH2O by an irradiation of 488 nm light at 200 K. A strong near-infrared band of about 10000 cm−1 and a ν(CN) band at 2070 cm−1 that newly appear in the metastable state point to development of the mixed-valence state analogous to Prussian blue. An iron-to-nitrosyl charge transfer in pentacyanonitrosylferrate(2−), [Fe(CN)5NO]2−, explains the formation of the mixed-valence state, because the charge transfer causes a pair of iron(II) and iron(III) atoms bridged by CN− that has the same local structure as Prussian blue. In addition to the formation of the metastable state, the prolonged irradiation causes an irreversible change of FeII[Fe(CN)5NO]·xH2O and leads to the formation of a photoproduct. The photoproduct also has infrared spectra characteristic of the mixed-valence state. Mössbauer spectra of the photoproduct show that a low-spin iron ion in pentacyanonitrosylferrate(2−) is divalent and a high-spin iron outside of pentacyanonitrosylferrate(2−) is trivalent. Therefore, the charge-transfer between the two non-equivalent iron ions is thought to follow the intra-molecular charge transfer in pentacyanonitrosylferrate(2−).

• Access to Document (DOI)

Reversed-Phase High-Performance Liquid Chromatography of Iron(II) and Copper(II) Chelates with 4,7-diphenyl-1,10-phenanthroline disulfonate

MUDASIR, ARAI MEIKO, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Chromatography A 799 ( 1-2 ) 171 - 176 1998.03

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The chromatographic behaviour of negatively-charged iron(II) and copper(II) chelates with 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) disulfonate (BPS) on a reversed-phase Inertsil ODS-2 column was studied by using methanol–water (60:40, v/v) containing 0.02 M tetramethylammonium bromide (TMAB) and 0.025 M tris(hydroxymethyl)aminomethane (Tris)–HCl at pH 7.5 as a mobile phase. The possibility that the hydrophilic Tris–HCl buffer also serves as a counter ion together with TMAB was briefly discussed. Chromatographic parameters influencing the separation of the chelates were optimized. The method was successfully applied to indirectly determine iron(II) and iron(III) contents in natural water. Nickel(II) ion and possibly organic pollutants interfere with the present method.

• Access to Document (DOI)

Synthesis and Magnetic Property of Stable Organic Radicals Bearing Imidazole Ring

YOSHIOKA NAOKI, IRISAWA MUNETOSHI, MOCHIZUKI YUICHIRO, AOKI TAKASHI, INOUE HIDENARI

Molecular Crystals and Liquid Crystals Science and Technology. Section A. 306   403 - 408 1997.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Three imidazole derivatives with stable radical groups at 2-position were prepared and their magnetic property were characterized. The effect of NH hydrogen bonding site was also discussed.

• Access to Document (DOI)

Synthesis and Magnetic Properties of　Metal Complexes with Chelating Nitronyl Nitroxide and Imino Nitroxide

YOSHIOKA NAOKI, IRISAWA MUNETOSHI, AOKI TAKASHI, AIZAWA NAOYUKI, INOUE HIDENARI, OHBA SHIGERU

Molecular Crystals and Liquid Crystals Science and Technology Section A 306   397 - 402 1997.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Several metal complexes of chelating pyridyl nitronylnitroxide, imidazolyl nitronylnitorxide, and imidazolyl iminonitroxide were synthesized and their magnetic properties were characterized.

• Access to Document (DOI)

Dichlorobis[4,4,5,5-tetramethyl-2-(2-pyridyl)-4,5-dihydro-1H-imidazol-1- yloxy 3-oxide] copper (II) Bis 　(dichoromethane)Solvate

OHBA SHIGERU, KATO TAKANARI, YOSHIOKA NAOKI, INOUE HIDENARI

Acta Crystallographica, Section C 53   IUC9700004 1997.09

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The crystal of this Cu(II) complex is isostructural with those of Ni(II) and Mn(II) complexes having the same ligands [Luneau, et al. (1993). Inorg. Chem. 32, 5616-5622]. The bond distances between copper and nitroxide O atom is 2.319 (2) Å. Magnetic susceptibility measurement suggested that there is a weak ferromagnetic interaction between the copper ion and the coordinating nitroxide radicals (J = +8 cm-1).

• Access to Document (DOI)

Spectroscopic Properties of Chlorophylls and Their Derivatives, Influence of Molecular Structure on the Electronic State

NONOMURA YOSHIMUNE, IGARASHI SHIGEO, YOSHIOKA NAOKI, INOUE HIDENARI

Chemical Physics 220 ( 1-2 ) 155 - 166 1997.08

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The spectroscopic properties of chlorophylls (MgChl a and H2Chl a), metallochlorophyll a and b (MgChl a and b, M  Ni, Cu and Zn), zinc(II) pyromethylpheophoribide a (ZnPMP a) and zinc(II) chlorin e6 trimethyl ester (ZnChl e6 TME) were studied by circular dichroism (CD), magnetic circular dichroism (MCD), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electronic absorption spectra were assigned in terms of the spectral analysis of CD and MCD. The absorption maximum of the Qy band varied linearly with the electronegativity of the central metal M and the energy level of the macrocyclic π orbitals in MChl a. The semiempirical MO calculation demonstrated that the deviation of H2Chl a from the general trend is induced by rising of the energy levels of next HOMO and second next HOMO in H2Chl a. A comparison of the UVVIS and MCD spectral data in zinc(II) chlorophylls revealed that the substituents on the pyrrole β position and the ring V govern the position of the Q and B bands. The spectroscopic behavior was explained on the basis of the energy level of the macrocyclic π orbitals calculated by the conventional MO method.

• Access to Document (DOI)

Ion Paired Chromatography of　　 Iron(II, III), Nickel(II) and Copper(II) as Their 4,7-Diphenyl-1,10-Phenanthroline Chelates

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Talanta 44 ( 7 ) 1195 - 1202 1997.07

Research paper (scientific journal), Joint Work, Accepted

　View Summary

A reversed phase ion-paired chromatographic method that can be used to determine trace amounts of iron (II,III), nickel (II) and copper (II) was developed and applied to the determination of iron (II) and iron (III) levels in natural water. The separation of these metal ions as their 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) chelates on an Inertsil ODS column was investigated by using acetonitrile-water (80/20, v/v) containing 0.06 M perchloric acid as mobile phase and diode array spectrophotometric detection at 250-650 nm. Chromatographic parameters such as composition of mobile phase and concentration of perchloric acid in mobile phase were optimized. The calibration graphs of iron (II), nickel (II) and copper (II) ions were linear (r > 0.991) in the concentration range 0-0.5, 0-2.0 and 0-4.0 mug ml(-1), respectively. The detection limit of iron (II), nickel (II) and copper (II) were 2.67, 5.42 and 18.2 ng ml(-1) with relative standard deviation (n = 5) of 3.11, 5.81 and 7.16% at a concentration level of 10 ng ml(-1) for iron (II) and nickel (II) and 25 ng ml(-1) for copper (II), respectively. The proposed method was applied to the determination of iron(II) and iron(III) in tap water and sea water samples without any interference from other common metal ions.

• Access to Document (DOI)

Unusually Large Magnetic Interactions　Observed in Hydrogen-Bonded Nitronyl Nitroxides

YOSHIOKA NAOKI, IRISAWA MUNETOSHI, MOCHIZUKI YUICHIRO, KATO TAKANARI, INOUE HIDENARI, OHBA SHIGERU

Chemistry Letters 26 ( 3 ) 251 - 252 1997.03

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Two nitronyl nitroxide derivatives bearing imidazole and benzimidazole ring were prepared and their hydrogen-bonded structures and magnetic properties were characterized.

• Access to Document (DOI)

Structure and Magnetic Property of 2-Imidazolylnitornyl Nitroxide and its Metal Complexes

YOSHIOKA NAOKI, IRISAWA MUNETOSHI, AIZAWA NAOYUKI, AOKI TAKASHI, INOUE HIDENARI, OHBA SHIGERU

Molecular Crystals and Liquid Crystals Science and Technology Section A 286-286   165 - 170 1996.11

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Structure and magnetic property of 2-(imidazole-2-yl)-4,4,5,5tetramethyl imidazoline-1-oxyl-3-oxide and its metal complexes are studied in order to identify structure-property relationship.

• Access to Document (DOI)

Preparation and Separation of　Metallobacteriochlorophyll a by Reversed-Phase High-Performance Liquid Chromatography

INOUE HIDENARI, NONOMURA YOSHIMUNE, ASHIZAWA AKIKO, TAJIMA IKUKO, MONURA MOTOKI, NAKAMURA NATSU, YOSHIOKA NAOKI

Chromatographia 43 ( 7-8 ) 361 - 364 1996.10

Research paper (scientific journal), Joint Work, Accepted

　View Summary

emi-preparative high-performance liquid chromatography has been used for the preparation of copper(II) bacteriochlorophyll a [Cu(II)-BCh]-a] and zinc(II) bacteriochlorophyll a [Zn(II)-BCh]-a]. Both compounds are separated on a reversed-phase Inertsil ODS-2 column using a mobile phase of acetone-methanol (25:75, v/v). The fractionated metallobacteriochlorophylls (M-Bchl-a) are identified by fast atom bombardment mass spectrometry. The spectroscopic parameters such as the wavelength of absorption maxima and the molar extinction coefficients are determined using pure M-Bchl-a obtained by preparative HPLC. The HPLC method proposed here has been demonstrated to be useful for the purification and determination of components of M-Bchl-a.

• Access to Document (DOI)

Ion-paired Chromatographic Separation　of Iron(II) Complexes of 1,10-Phenanthroline and Its Derivatives

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Analytical Letters 29 ( 12 ) 2239 - 2254 1996.09

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Iron(II) chelate complexes of 1,10-phenanthroline (Phen), 4,7-dimethyl-1,10-phenanthroline (DMPhen), 3,4,7,8-tetramethyl-1,10-phenanthroline (TMPhen) and 4,7-diphenyl(batho)-1,10-phenanthroline (DPPhen) were prepared and identified by means of absorption and infrared spectroscopy. The characteristic elution of these complexes on an Inertsil ODS column as well as their separation was investigated by ion-paired reversed phase chromatography. Some parameters influencing the separation such as composition of eluent, counter ion species and their concentrations were also studied. It was found that acetonitrile/water (80/20, v/v) containing 0.06 M HC1O4 gave the best separation for each complex.

• Access to Document (DOI)

Mechanochemical Effects on the Structures and Chemical States of [Fe(Phen)3] (NCS)2・H2O

TSUCHIYA NAOKO, ISOBE TETSUHIKO, SENNA MAMORU, YOSHIOKA NAOKI, INOUE HIDENARI

Solid State Communications 99 ( 8 ) 525 - 529 1996.08

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Changes in the structure and chemical bonding state of coordination complex crystal, iron(II) tris(1,10-phenanthroline) dithiocyanate (FPhN) by mechanical stress were studied by X-ray diffractometry and infrared spectroscopy. FPhN was completely amorphized after milling by a planetary ball-mill for 5 h. Amorphized FPhN recrystallized at 406 K, but no significant change in the thermal decomposition processes was observed. On amorphization, the ligand field strength of phenanthroline in FPhN was reduced and hence the transition from low spin (1A1g) to high spin (5T2g) occurred gradually on heating, as detected by the increase in the effective magnetic moment.

• Access to Document (DOI)

High-Performance Liquid Chromatographic Separation of Iron(III) Chlorophyllin

Y.Nonomura, M.Yamaguchi, T.Hara, K.Furuya, N.Yoshioka, H.Inoue

Journal of Chromatography A 721 ( 2 ) 350 - 354 1996.01

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The components of iron(III) chlorophyllin were separated by high-performance liquid chromatography on a reversed-phase Inertsil ODS column. Good retention was achieved with acetonitrile-phosphate buffer (pH 2) (60:40, v/v) containing 0.01 M tetramethylammonium chloride (TMACl) in studies of the chromatographic behaviour with various elution solvents and their mixtures. Three kinds of iron(III) chlorophyll derivatives, i.e., iron(III) pheophorbide a (Fe-Phed a), iron(III) chlorin e6 (Fe-Chl e6) and iron(III) chlorin e4 (Fe-Chl e4), were detected as major components. Standard materials for qualitative and quantitative analysis were derived from chlorophyll a which was extracted from spinach. The required compounds were prepared under strict conditions by the insert reaction of iron(II) chloride with pheophytins to avoid molecular degradation by light or molecular oxygen.

• Access to Document (DOI)

Axial Coordination of Phosphine or　Phosphite to Iron (III) Chlorophyll a

INOUE HIDENARI, AKAHORIHIROMI, OHNO YURI, NAKAZAWA KATSUO, NONOMURA YOSHIMUNE, YOSHIOKA NAOKI, HECKMANN GERNOT, FLUCK EKKEHARD

Zeitschrift für Naturforschung B 50 ( 8 ) 1222 - 1228 1995.08

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The adduct formation of iron(III) chlorophyll a with phosphines or phosphites has been studied by spectroscopic methods. The red-shift in the Soret and Q bands caused by the axial coordination of phosphine or phosphite to iron(III) chlorophyll a is an evidence for the autoreduction of the central iron(III) ion. The 31P{1H} NMR spectrum of bis-adducts measured in the presence of excess phosphine or phosphite ligands gave a single peak in the down field range compared to that of the corresponding free ligand. The ESR and X-ray photoelectron spectra have revealed that the central iron atom of the bis-adduct of iron chlorophyll a with phosphines or phosphites is divalent and in the low-spin state. The axial coordination of phosphine or phosphite influences the electronic configuration of the central iron atom and the macrocyclic chlorine ligand to induce the autoreduction of the central iron(III) ion.

• Access to Document (DOI)

Mossbauer Spectroscopic Characterization of Iron Methyl Pyropheophorbide a and Its Derivatives

INOUE HIDENARI, SOEDA KAORI, AKAHORI HIROMI, NINOMURA YOSHIMUNE, YOSHIOKA NAOKI

Hyperfine　Interactions 91 ( 1 ) 815 - 819 1994.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Two kinds of iron chlorophylls, i.e. (methyl pyropheophorbide a)iron(III) chloride and its bis-pyridine adduct, were prepared and characterized by57Fe Mössbauer spectroscopy. (Methyl pyropheophorbide a)iron(III) chloride gave an asymmetric quadrupole-split doublet typical of high-spin iron(III) chlorophylls, while its bis-pyridine adduct showed a symmetric quadrupole-split doublet characteristic of low-spin iron(II) chlorophylls. The isomer shift and quadrupole splitting obtained for (methyl pyropheophorbide a)iron(III) chloride and its bis-pyridine adduct have led to the following conclusions. The substitution of the bulky phytyl group for the methyl group hardly affects the electronic state of the iron(II,III) ion, but the elimination of the methoxycarbonyl group increases the planarity of the macrocyclic chlorin ligand.

• Access to Document (DOI)

ESR Studies on Distortion in the Macrocyclic Ring of Copper(II) Chlorophylls

NONOMURA YOSHIMUNE, YOSHIOKA NAOKI, INOUE HIDENARI

Inorganica Chimica Acta 224 ( 1-2 ) 181 - 184 1994.10

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The influence of distortion in the porphine ring on the electronic structure of the central metal ion was studied by means of the ESR spectra of copper(II) chlorophylls. A linear correlation between ESR parameters, i.e. g and A values, indicated that the electronic structure of the central copper(II) ion in CuChls is different from that in compounds having the regular porphine skeleton. The weakened CuN bond in CuChls was evidenced by a decrease in the bonding coefficient α2. These observations on the ESR parameters of CuChls were explained by a partially saturated and distorted macrocyclic structure.

• Access to Document (DOI)

Determination of Copper(II) Chlorophyllin by Reversed - Phase High Performance Liquid Chromatography

INOUE HIDENARI, YAMASHITA HIROSHI, FURUYA KENJI, NONOMURA YOSHIMUNE, YOSHIOKA NAOKI, LI S

Journal of Chromatography A 679 ( 1 ) 99 - 104 1994.09

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Copper(II) chlorophyllin, consisting of copper(II) pheophorbide a, copper(II) chlorin e6, copper(II) rhodin g7 and copper (II) chlorin e4, was prepared and separated by semi-preparative high-performance liquid chromatography (HPLC). The components of copper(II) chlorophyllin were determined on a reversed-phase Inertsil ODS-2 column using a mobile phase of methanol-water (97:3, v/v) containing 1% (v/v) of acetic acid. Linear calibration plots were obtained for copper(II) chlorophyllin in the concentration range of 0–30 μg cm−3 with photometric detection at 407 or 423 nm. The detection limits of copper(II) pheophorbide a, copper(II) chlorin e6, copper(II) rhodin g7 and copper(II) chlorin e4 were 3.5, 1.5, 3.3 and 1.4 ng cm−3 with relative standard deviations (n = 10) of 1.8, 1.6, 5.2 and 3.6%, respectively. The reversed-phase HPLC method proposed here was demonstrated to be useful for the determination of the components of sodium copper(II) chlorophyllin.

• Access to Document (DOI)

Semiempirical Investigation of Stilbene-Linked Diradicals and Magnetic Study of Their Bis (N-tert-butylnitroxide) Variants

YOSHIOKA NAOKI, LAHTI M. PAUL, KANEKO TAKASHI, KUZUMAKI YOSHIHIRO, TSUCHIDA EISHUN, NISHIDE HIROYUKI

The Journal of Organic Chemistry 59 ( 15 ) 4272 - 4260 1994.07

Research paper (scientific journal), Joint Work, Accepted

　View Summary

he electronic states of open-shell stilbene diradicals were studied. Previously used semiempirical MO-CI methods were applied to stilbenes having dimethylene, dioxyl, and dinitroxide centers in o,o′-, o,m′-, o,p′-, m,m′-, m,p′-, and p,p′-substitution patterns, and the various singlet-triplet energy gaps were computed to predict qualitative ground state spin multiplicities. Singlet and triplet spin states were essentially degenerate in the m,m′-isomers of disjoint connectivity, while nondisjoint o,m′- and m,p′-isomers had triplet computed ground states. Nitroxide-based diradicals showed considerably smaller computational exchange coupling energies than did other diradical models studied. As a tests of these computations, stilbenes with two N-tert-butyl nitroxide groups at the o,m′-, m,m′-, and m,p′-positions were prepared, and their magnetic properties were studied by ESR and magnetic susceptibility measurements. The m,m′- and m,p′-isomers were found experimentally to have singlet and triplet ground states, respectively, in accord with the qualitative computed predictions.

• Access to Document (DOI)

Magnetic Characterization and Computational Modeling of Poly (phenylacetylene)s Bearing Stable Radical Groups

NISHIDE HIROYUKI, KANEKO TAKASHI, IGARASHI MASAKAZU, TSUCHIDA EISHUN, YOSHIOKA NAOKI, LAHTI M. PAUL

Macromolecules 27 ( 11 ) 3082 - 3086 1994.05

Research paper (scientific journal), Joint Work, Accepted

　View Summary

The magnetic properties of poly(phenylacetylene)s with radical groups at the paraposition, poly[(3,5-di-tert-butyl-4-oxyphenyl)acetylene] (l),poly[[4-[(3,5-di-tert-butyl-4-oxyphenyl)(3,5-di-tert-butyl4-oxocyclohexa-2,5-dien-l-ylidene)methyl]phenyl]acetylene](2) and poly[[4-(N-tert-butyl-N-oxyamino)-phenyl]acetylene](3), were studied with a SQUID magnetometer. The magnetization and magnetic susceptibility indicated unexpected antiferromagnetic interactions between the radical sites. The exchange interaction observed in these conjugated polyradicals was discussed in connection with their computationally modeled structures.

• Access to Document (DOI)

Theory and Experiment of Investigation of Exchange Interactions in Organic Molecules and Materials

LAHTI M. PAUL, LING CHRIS, YOSHIOKA NAOKI, ROSSITTO C. FRANK, VAN WILLIGEN HANS

Molecular Crystals and Liquid Crystals Science and Technology. Section A. 233 ( 1 ) 17 - 32 1993.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Intramolecular and intermolecular exchange in molecules and polymers is investigated computationally and experimentally, in order to identify structure-property relationships.

Theory and Experiment of Investigation of Exchange Interactions in Organic Molecules and Materials.

• Access to Document (DOI)