Papers - Yoshioka, Naoki

Synthesis of Boron–Imidazole Complexes and Studies on their Multi-Stimuli-Responsive Fluorescence Properties

Miura Y., Mohri K., Funayama D., Yoshioka N.

European Journal of Organic Chemistry 27 ( 46 )  2024.12

ISSN  1434193X

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Organoboron complexes represented by BODIPY are one of the candidates for fluorescent skeletons exhibiting good fluorescence properties in the solution. However, because most BODIPY have high planar skeletons and small Stokes shifts, their fluorescence is quenched in the solid state. Therefore, numerous approaches were challenged to prepare the solid state fluorescent BODIPYs. On the other hand, an alternative approach to developing solid state fluorophores involves imidazole-boron complexes. Herein, imidazole-based boron complexes featuring the imidazo[1,2-c][1,3,2]diazaborole skeleton were synthesized. This skeleton comprised two fused five-membered rings and could introduce substituent at the 2-, 3-, 5-, and 6-positions. The boron complexes with aryl groups at the 3,5,6-positions exhibited fluorescence in both the solution and solid states. These compounds exhibited Stokes shifts exceeding 120 nm, effectively suppressing self-absorption. DFT calculations suggested that the large Stokes shift could be attributed to the planarization of π-conjugation upon excitation. In the solid state, the complexes displayed mechanofluorochromism, with the altered fluorescence color being recovered upon annealing at 150 °C. Compounds with two or three methoxy groups underwent a phase transition to a glass state, resulting in long-wavelength fluorescence. Furthermore, they demonstrated mechanochromism, thermochromism, and thermofluorochromism in the solid state, indicating their potential as scaffolds for multifunctional fluorophores.

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Hydrogen-Bonded Cyclic Tetramer Formation of a Pyridylethynylimidazole-Based Fluorophore

Miura Y., Murai K., Ando N., Yoshioka N.

Chemistryselect 9 ( 38 )  2024.10

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Supramolecular have promising application prospects owing to their catalytic, self-healing, and stimulus-responsive functions. Pyridylethynylimidazole-based supramolecular synthons with fluorescent properties have been developed. 4-(2-Pyridylethynyl)-5-arylethynyl-1H-imidazole derivatives 1 with different substituents at the 4- and 5-positions of the imidazole skeleton were prepared using a step-by-step Sonogashira coupling reaction. The fluorescence maxima of phenyl- and methoxyphenyl-substituted derivatives 1a and 1c were independent of solvent polarity. On the other hand, ester- and cyano-substituted 1b and 1d showed bathochromically shifted fluorescence maxima in highly polar solvents. In crystals, the 4-(2-pyridylethynyl)-5-arylethynyl-1H-imidazole derivatives formed a supramolecular cyclic tetramer structure via two hydrogen bonds: one was between N─H in imidazole and N in pyridine, and the other was between C─H in imidazole and N in imidazole. Introducing the pyridine ring as a hydrogen bond acceptor, in addition to the imidazole ring, promoted the unique cyclic tetramer structure formation.

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A Nitronyl Nitroxide-Substituted Benzotriazinyl Tetraradical**

Tretyakov E.V., Zayakin I.A., Dmitriev A.A., Fedin M.V., Romanenko G.V., Bogomyakov A.S., Akyeva A.Y., Syroeshkin M.A., Yoshioka N., Gritsan N.P.

Chemistry A European Journal 30 ( 8 )  2024.02

ISSN  09476539

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High-spin organic tetraradicals with significant intramolecular exchange interactions have high potential for advanced technological applications and fundamental research, but those synthesized to date possess limited stability and processability. In this work, we have designed a tetraradical based on the Blatter's radical and nitronyl nitroxide radical moieties and successfully synthesized it by using the palladium-catalyzed cross-coupling reaction of a triiodo-derivative of the 1,2,4-benzotriazinyl radical with gold(I) nitronyl nitroxide-2-ide complex in the presence of a newly developed efficient catalytic system. The molecular and crystal structure of the tetraradical was confirmed by X-ray diffraction analysis. The tetraradical possesses good thermal stability with decomposition onset at ∼150 °C under an inert atmosphere and exhibits reversible redox waves at −0.54 and 0.45 V versus Ag/AgCl. The magnetic properties of the tetraradical were characterized by SQUID magnetometry of polycrystalline powders and EPR spectroscopy in various matrices. The collected data, analyzed by using high-level quantum chemical calculations, confirmed that the tetraradical has a triplet ground state and a nearby excited quintet state. The unique high stability of the prepared triazinyl-nitronylnitroxide tetraradical is a new milestone in the field of creating high-spin systems.

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Thermosalient Effect of 5-Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole without Phase Transition

Miura Y., Takeda T., Yoshioka N., Akutagawa T.

Crystal Growth and Design 22 ( 10 ) 5904 - 5911 2022.10

ISSN  15287483

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5-Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole 1 exhibited a thermosalient effect without phase transition. The crystal of 1 was jumped by heating to about 80 °C using a hot plate. No phase transition peak was observed at this temperature range according to DSC measurement, unlike renowned thermosalient crystals. Variable-temperature X-ray crystal structure analyses revealed that anisotropical cell constant expansion resulting from the torsion angle change between the imidazole group and carbonyl moiety induced unit cell constant expansion and the thermosalient effect.

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4-Arylethynyl-5-fluorobenzoyl-1-methylimidazole Exhibiting Self-Recovering Mechanofluorochromism and Forming Fluorescence Molecular Glass

Youhei Miura,Kazuki Murai, Kazufumi Yamada, Naoki Yoshioka

Bulletin of the Chemical Society of Japan (公益社団法人 日本化学会)  94 ( 10 ) 2444 - 2450 2021.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00092673

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4-Arylethynyl-5-fluorobenzoyl-1-methyl-1H-imidazoles exhibited self-recovering mechanofluorochromism and formed a glass state. Although the solid sampleof the anisyl-substituted 1a and dimethoxyphenyl-substituted 1b exhibited no and blue f luorescence, respectively, they exhibited bluish-green fluorescence after grinding. These compounds recovered the color of their fluorescence after approximately 20s and after 20h, respectively. Both compounds exhibited non-crystalline samples after melting and rapid cooling to room temperature. Based on thermal analysis, it was found 1a and 1b were supercooling liquid and glass, respectively, at room temperature. Both non-crystalline samples exhibited fluorescence at a wavelength longer than that of the solid state. DFT calculations indicated that the bluish-green fluorescence of the ground and noncrystalline samples was derived from the twisted intramolecular charge transfer excitation state.

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V-shaped fluorophores with a 1-methyl-4,5-bis(arylethynyl)imidazole skeleton displaying solid-state fluorescence, acid responsiveness, and remarkable fluorescence solvatochromism

Miura Y., Kobayashi K., Yoshioka N.

New Journal of Chemistry (New Journal of Chemistry)  45 ( 2 ) 898 - 905 2021.01

ISSN  11440546

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Novel V-shaped fluorophores with an imidazole skeleton composed of arylethynyl moieties were developed. Their HOMO-LUMO energy gaps were well controlled by the introduction of electron-withdrawing or -donating groups in the aryl moiety. Compounds with different substituents at the 4- and 5-positions were selectively synthesized exploiting the difference in reactivity between the iodo and bromo groups. All compounds synthesized displayed fluorescence not only in solution but also in the solid state. The compound with a donor-acceptor structure displayed a fluorescence maximum with a wavelength over 500 nm and a large Stokes shift of about 150 nm, due to its intramolecular charge transfer character. In the solid state, the synthesized compounds have planar structures, indicating an expansion of π-conjugation. Upon exposure of the compounds in the solid state to acid vapor, the fluorescence of the compounds with acceptor groups was quenched, and that of the others shifted to longer wavelengths.

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Unique Superparamagnetic‐like Behavior Observed in Non‐π‐delocalized Nitroxide Diradical Compounds Showing Discotic Liquid Crystalline Phase

TAKEMOTO YUSA, ZAYTSEVA ELENA, SUZUKI KATSUAKI, YOSHIOKA NAOKI, TAKANISHI YOICHI, FUNAHASHI MASAHIRO, YUCHIDA OSHIAKI, AKITA TAKUYA, PARK JAYEONG, SATO SHUICHI, CLEVERS SIMON, COQUEREL GÉRARD, AZHUKIN DMITRII G., SHIMONO SATOSHI, SUGIYAMA MASAHITO, TAKAHASHI HIROKI, YAMAUCHI JUN, TAMURA RUI

Chemistry A European Journal (Wiley)  24 ( 65 ) 17293 - 17302 2018.10

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09476539

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© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A unique superparamagnetic-like behavior and a large “positive magneto-LC effect” were observed in the solid phases and the hexagonal columnar (Col h ) liquid crystalline (LC) phase, respectively, of novel achiral non-π-delocalized nitroxide diradical compounds (R,S)-1, which showed polymorphism in the solid phases (solids I and II). The SQUID magnetization measurement revealed that (1) (R,S)-1 containing a small amount of racemic diastereomers (R*,R*)-1 possessed an unusual and large temperature-independent magnetic susceptibility (χ TIM >0) component in the original nanocrystalline solid I that was responsible for the observed superparamagnetic-like behavior under low magnetic fields and did not arise from the contamination by extrinsic magnetic metal or metal ion impurities, besides ordinary temperature-dependent paramagnetic susceptibility (χ para >0) and temperature-independent diamagnetic susceptibility (χ dia <0) components, (2) a large increase in molar magnetic susceptibility (χ M ) (positive magneto-LC effect) that occurred at the solid I-to-liquid crystal transition upon heating was preserved as an additional χ TIM increase in the resulting polymorphic nanocrystalline solid II by cooling, and (3) such unique magnetic phenomena were induced by thermal processing for (R,S)-1 or by adding a small amount of (R*,R*)-1 to (R,S)-1 as the impurity.

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Magneto-Structural Correlation of Cyano-Substituted 3-tert-Butyl-1-phenyl-1,2,4-benzotriazin-4-yl: Spin Transition Behaviour Observed in a 6-Cyano Derivative

TAKAHASHI YUSUKE, TSUCHIYA NAOYA, MIURA YOUHEi, YOSHIOKA NAOKI

New Journal of Chemistry (New Journal of Chemistry)  42 ( 12 ) 9949 - 9955 2018.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  11440546

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New cyano-substituted 3-tert-butylbenzotriazinyls, 7CN and 6CN, were synthesized and their spectroscopic properties and magneto-structural correlation were investigated. The radical 7CN formed a 1D columnar structure and displayed an antiferromagnetic interaction along the column (J = -15.8 cm^-1). The 6-cyano substituted radical 6CN also formed a 1D columnar structure and exhibited a reversible spin transition at ca. 284 K in the range of 6 K. The molecular arrangements in the high-temperature phase (300 K) and low-temperature phase (263 K) were evaluated by X-ray crystallographic analysis and the molecules slightly rotated while remaining in the 1D columnar structure, resulting in a phase transition. The spin transition behaviour was caused by the structural phase transition, which was consistent with the DSC and computational studies.

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Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives

TAKAHASHI YUSUKE, MATSUHASHI RYO, MIURA YOUHEI, YOSHIOKA NAOKI

Chemistry A European Journal (Wiley)  24 ( 31 ) 7939 - 7948 2018.05

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09476539

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Three hetero-biradical derivatives, with the structure of a back-to-back connected benzotriazinyl and tetramethyl or tetraethylisoindoline N-oxyl sharing a common benzo ring, 1-tBu, 1-Ph, and 2-tBu, were synthesized and characterized by single-crystal X-ray analyses, variable-temperature magnetic susceptibility studies, and DFT calculations. Although these radical derivatives form a columnar or chained assembly in the solid state, magnetic measurements of diluted samples in the polymer matrices and computational result simply that the magnetic properties of the polycrystalline sample can be explained by a two-spin system with an intramolecular antiferromagnetic interaction. The moderately strong intramolecular antiferromagnetic interactions can be interpreted by a through-bond interaction through the nonconjugated framework and/or through-space interactions based on molecular orbital theory. The strong distance dependency between the N-O spin site and vinylic carbon atoms indicates that the orbital interaction plays an important role in the intramolecular magnetic interaction.

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5,12-Diacetyl-5,12-dihydroquinoxalino[2,3-b]quinoxalines; Their Solid State Fluorescence, AIE Properties, and Orbital Switching by Substituent Effect

MIURA YOUHEi, YOSHIOKA NAOKI

Chemistry An Asian Journal (Wiley-VCH)  13 ( 13 ) 1683 - 1687 2018.05

Research paper (scientific journal), Joint Work, Accepted,  ISSN  18614728

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The compound 5,12-diacetyl-5,12-dihydroquinoxalino[2,3-b]quinoxaline 1a and its derivatives were prepared, and their solid and solution state spectroscopic properties were studied; 1a shows stronger fluorescence in solution than in the solid state due to aggregation caused by self-quenching. Phenyl or alkoxy substituted derivatives 1b–d show solid state fluorescence with moderate quantum yields of about Φ = 0.12~0.15, although these are 0.01~0.07 in solution. The spectroscopic properties of alkoxy substituted derivatives were hardly changed compared to 1a and 1b, although 1a and 1b have similar absorption and fluorescence maxima in solution and in the solid state. DFT calculations indicate that orbital switching occurs between HOMO and HOMO-1 and HOMO-2 due to orbital interactions with introduced substituents. Crystal structure analysis revealed that the molecules have bent structures around tertiary nitrogen atoms and form a characteristic dimeric structure.

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In Silico Study, Synthesis, and Cytotoxic Activities of Porphyrin Derivatives

KURNIAWAN FRANSISKA, MIURA YOUHEI, KARTASASMITA EMRAN RAHMANA, YOSHIOKA NAOKI, MUTALIB ABDUL, TJAHJONO DARTONO H.

Pharmaceuticals (MDPI)  11 ( 1 ) UNSP8 2018.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1427-8247

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Five known porphyrins, 5,10,15,20-tetrakis(p-tolyl)porphyrin (TTP), 5,10,15,20-tetrakis(p-bromophenyl)porphyrin (TBrPP), 5,10,15,20-tetrakis(p-aminophenyl)porphyrin (TAPP), 5,10,15-tris(tolyl)-20-mono(p-nitrophenyl)porphyrin (TrTMNP), 5,10,15-tris(tolyl)-20-mono(p-aminophenyl)porphyrin (TrTMAP), and three novel porphyrin derivatives, 5,15-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-10,20-di(p-tolyl)porphyrin (DBECPDTP), 5,10-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-15,20-di-(methylpyrazole-4-yl)porphyrin (cDBECPDPzP), 5,15-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-10,20-di-(methylpyrazole-4-yl)porphyrin (DBECPDPzP), were used to study their interaction with protein targets (in silico study), and were synthesized. Their cytotoxic activities against cancer cell lines were tested using 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide (MTT) assay. The interaction of porphyrin derivatives with carbonic anhydrase IX (CAIX) and REV-ERBβ proteins were studied by molecular docking and molecular dynamic simulation. In silico study results reveal that DBECPDPzP and TrTMNP showed the highest binding interaction with REV- ERBβ and CAIX, respectively, and both complexes of DBECPDPzP-REV-ERBβ and TrTMNP-CAIX showed good and comparable stability during molecular dynamic simulation. The studied porphyrins have selective growth inhibition activities against tested cancer cells and are categorized as marginally active compounds based on their IC50.

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Synthesis and Magnetic Properties of Stable Radical Derivatives Carrying a Phenylacetylene Unit

MIYASHIRO SHOGO, ISHII TOMOAKI, MIURA YOUHEI,YOSHIOKA NAOKI

Molecules (MDPI)  23 ( 2 ) No. 371 2018.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1420-3049

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A nitronyl nitroxide derivative, 2-phenylethynyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide (1), and two verdazyl derivatives carrying a phenylacetylene unit, 1,5-diphenyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (2) and 1,5-diisopropyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (3), were synthesized and their packing structures were studied by X-ray crystallographic analysis and magnetically characterized in the solid state. While 1 and 3 had an isolated doublet spin state, 2 formed an antiferromagnetically coupled pair (2J/kB = −118 K). Density functional theory (DFT) calculations reveal that the spin density polarized in the phenyl group decreases as the dihedral angle between the phenyl ring and radical plane increases.

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Magnetic Interaction Observed in Hetero Biradical Derivatives Containing a 2,2,5,5-Tetramethylpyrrolin-1-yloxyl Unit as a Localized Spin Center

TAKAHASHI YUSUKE, MIURA YOUHEI,YOSHIOKA NAOKI

ChemPhysChem (Wiley)  19 ( 2 ) 175 - 179 2018.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1439-7641

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The magneto‐structural correlation of hetero biradical derivatives containing a 2,2,5,5‐tetramethylpyrrolin‐1‐yloxyl unit as a localized spin center and a verdazyl or nitronyl nitroxide radical is reported. The magnetic susceptibility measurement revealed that the verdazyl attached biradical 1 exhibits ferromagnetic interaction, whereas antiferromagnetic interaction is observed for nitronyl nitroxide attached biradical 2. An EPR study in toluene glass matrix suggests that both 1 and 2 have a ground triplet state. DFT calculations predict that there is intramolecular ferromagnetic interaction for both biradicals. The computation also suggests that the intramolecular magnetic interaction is weaker with larger dihedral angle between pyrroline ring and verdazyl ring/O−N−C−N−O plane of nitronyl nitroxide. The computations of model compounds 3 and 4 suggest that spin polarization on vinylic moiety without distribution of SOMO might be an essential condition for the intramolecular ferromagnetic interaction.

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Computational study of imidazolylporphyrin derivatives as a radiopharmaceutical ligand for melanoma

Kurniawan F., Kartasasmita R., Yoshioka N., Mutalib A., Tjahjono D.

Current Computer-Aided Drug Design (Current Computer-Aided Drug Design)  14 ( 3 ) 191 - 199 2018

ISSN  15734099

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© 2018 Bentham Science Publishers. Background: Melanoma is the most aggressive type of skin cancer. Metastatic melanoma is extremely difficult to treat with current therapy methods such as surgery. On the other hand, it is a good opportunity to develop a radiopharmaceutical using a radionuclide such as Technetium (Tc) for diagnostic and Rhenium (Re) for therapeutic purposes. T3,4BCPP has been be used as a radioimaging agent for melanoma cancers experimentally. The aim of the present research was to design new imidazolylporphyrin derivatives with better selectivity and higher affinity than those of T3,4BCPP by molecular modeling. Methods: Eight types of Re-and Tc-labeled imidazolylporphyrins were docked to Fibroblast Growth Factor Receptor 1 (FGFR1, PDB ID: 5AM6) using AutoDock 4.2. FGFR1 was simulated by Molecular Dynamic (MD) simulation for 30 ns using NAMD 2.10 at 37 °C. The obtained conformations were then applied in a molecular docking simulation. Dovitinib (natural ligand of FGFR1), Re-and Tc-T3, 4BCPP were used as references. Results: The MD simulation resulted in an RMSD of 3.8 Å. From all the studied imidazolylporphyrin derivatives, Tc-cD3, 4BCPMIP and Re-cD3, 4BCPIP had the best docking parameter. Tc-cD3, 4BCPMIP had a free binding energy of 4.06 kcal/mol, while that of Re-cD3, 4BCPIP was 4.35 kcal/mol. Conclusion: It is concluded that cD3,4BCPMIP and cD3,4BCPIP are two potential candidate ligands for a melanoma radiopharmaceutical kit.

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A Selective Distance-Based Paper Analytical Device for Copper(II) Determination Using a Porphyrin Derivative

PRATIWI RIMADANI, NGUYEN MICHAEL P., IBURAHIM SLAMET, YOSHIOKA NAOKI, HENRY CHARLES S., TJAHJONO DARTONO H.

Talanta (Elsevier)  174   493 - 499 2017.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0039-9140

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Meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin sulfonate (TDMPzP), a water-soluble porphyrin derivative, was synthesized and used as a colorimetric reagent for Cu2+ detection on a microfluidic paper-based analytical device (mu PAD) using distance-based quantification. TDMPzP showed a high selectivity for Cu2+ detection in aqueous solutions. When Cu2+ was added to the TDMPzP under acidic conditions, a color change from green to a pink was observed by the naked eye. Under optimized conditions, the application of this system to a distance-based mu PAD exhibited good analytical response. The presence of common metal ions (Al3+, Fe3+, Mg2+, Co2+, Mn2+, Zn2+, Pb2+, Cd2+, Sn2+, and Ni2+) did not interfere with Cu2+ detection within reasonable tolerance ratios. The lowest concentration of copper that could be measured was 1 mg L-1 (1 ppm) which meets the requirements for drinking water contamination regulations from the US Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines for drinking water. Real drinking water samples were analyzed to confirm the practical application of this system and the results showed good agreement with ICP-MS data. This distance-based mu PAD based on TDMPzP for Cu2+ detection is convenient and effective for real-time drinking water analysis.

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Synthesis and Physicochemical Properties of Methoxy-Substituted Diphenyldihydroacridine and Its Si and Ge Bridged Analogues and Corresponding Nitroxide Radical Derivatives

SUZUKI RYOTA, TADA REIKI, MIURA YOUHEI, YOSHIOKA NAOKI

Journal of Molecular Structure 1106   399 - 406 2016.02

Research paper (scientific journal), Joint Work, Accepted

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Three dihydroacridine analogues, 2,7-dimethoxy-9,10-dihydro-9,9-diphenylacridine (1-C), 2,8-dimethoxy-10,10-diphenyl-5,10-dihydrophenazasiline (1-Si), and 2,8-dimethoxy-10,10-diphenyl-5,10-dihydrophenazagermine (1-Ge), and corresponding nitroxide radical derivatives, 2,7-dimethoxy-9,10-dihydro-9,9-diphenylacridine-10-oxyl (2-C), 2,8-dimethoxy-10,10-diphenyl-5,10-dihydrophenazasiline-5-oxyl (2-Si), and 2,8-dimethoxy-10,10-diphenyl-5,10-dihydrophenazagermine-5-oxyl (2-Ge) were synthesized in order to study the effect of the Si and Ge bridging atoms on the physicochemical properties of the diaryl nitroxide radical derivatives. These derivatives were stable in non-halogenated solvents and in the solid state. Their structures were crystallographically analyzed and UV-vis, fluorescence, EPR, and cyclic voltammetry measurements were performed to investigate the physicochemical properties of the dihydroacridine analogues and nitroxide radical derivatives.

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Synthesis of Ester-Substituted Dihydroacridine Derivatives and Their Spectroscopic Properties

SUZUKI RYOTA, TADA REIKI, HOSODA TAKUMI, MIURA YOUHEI, YOSHIOKA NAOKI

New Journal of Chemistry 40 ( 3 ) 2920 - 2926 2016.01

Research paper (scientific journal), Joint Work, Accepted

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Three dihydroacridine derivatives, 2,7-bis(4-methoxycarbonylphenyl)-9,9-diphenyl-9,10-dihydroacridine (1), 2,8-bis(4-methoxycarbonylphenyl)-10,10-diphenyl-5,10-dihydrophenazasiline (2), and 2,7,9,9-tetraphenyl-9,10-dihydroacridine (3), were prepared and their spectroscopic properties were investigated. These compounds exhibited relatively high quantum yields in a range of solvents. The emission spectra of 1 and 2 displayed large solvatochromic shifts, while the fluorescence solvatochromic behavior was not observed in 3. The intramolecular charge transfer (CT) process from the electron donating moiety at the NH site to the electron withdrawing ester moiety occurs in the excited states of 1 and 2. The increase in the dipole moment induced by the CT process was determined to cause the positive fluorescence solvatochromism. The differences between the excited and ground state dipole moments based on the Lippert-Mataga expression were estimated. The effect of the push-pull substitution in the dihydroacridine pi-conjugated system was also discussed using a computational method.

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Effects of Cyano, Ethynyl and Ethylenedioxy Groups on the Photophysical Properties of Carbazole-Based Porphyrins

MAEDA CHIHIRO, KURIHARA KOSUKE, MASUDA MOTOKI, YOSHIOKA NAOKI

Organic & Biomolecular Chemistry 13 ( 46 ) 11286 - 11291 2015.09

Research paper (scientific journal), Joint Work, Accepted

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The synthesis and photophysical properties of cyano and ethynyl substituted carbazole-based porphyrins were investigated. The introduction of ethynyl groups induced red shifts, while that of cyano groups induced blue shifts of their absorption bands, which was supported by MO calculations. Ethylenedioxy-appended porphyrins were also prepared via a coupling reaction. The conjugated and electronic substituent effects on the photophysical properties of the carbazole-based porphyrins have been elucidated by using both experimental results and calculations. Among these porphyrins, the ethylenedioxy-appended selenaporphyrin displayed intensified and red-shifted absorption in the NIR region up to 1178 nm.

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π-Stacked Structure of Thiadiazolo-Fused Benzotriazinyl Radical: Crystal Structure and Magnetic Properties

MIURA YOUHEI, YOSHIOKA NAOKI

Chemical Physics Letters (Elsevier)  626 ( 17 ) 11 - 14 2015.04

Research paper (scientific journal), Joint Work, Accepted

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A novel benzotriazinyl radical with a 2,1,3-thiadiazolo fused ring (1,3-diphenyl-1,2-dihydro-[1,2,5]thiadiazolo[3′,4′:3,4]benzo[1,2-e]-1,2,4-triazine-2-yl; NSNBT) was prepared and characterized by ESR measurement, cyclic voltammetry, and X-ray crystallographic analysis. By a detailed study of bond lengths and angles, it was found that the molecular structure of NSNBT borrows characteristics both from 2,1,3-benzothiadiazole and from the unsubstituted benzotriazinyl radical, and the central phenyl ring presents a phenanthrene-type bond alternation. Molecules were shown to be arranged in a π-stacked columnar structure, with columns connected to each other through sulfur-sulfur interactions in the crystal. It exhibited strong antiferromagnetic interactions (J/kB = -434 K) derived from its dimer structure.

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Synthesis and Properties of the 3-tert-Butyl-7-trifluoromethyl-1,4-dihydro-1-phenyl-1,2,4-benzotriazin-4-yl Radical

TAKAHASHI YUSUKE, MIURA YOUHEI, YOSHIOKA NAOKI

New Journal of Chemistry 39 ( 6 ) 4783 - 4789 2015.04

Research paper (scientific journal), Joint Work, Accepted

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A novel benzotriazinyl radical, 3-tert-butyl-7-trifluoromethyl-1,4-dihydro-1-phenyl-1,2,4-benzotriazin-4-yl (2), was prepared and its magneto-structural correlation was investigated. An X-ray crystallographic analysis revealed that 2 forms a 1D column assembly, however, pi-pi interaction was not the driving force of the column structure. The magnetic susceptibility obeyed the Curie-Weiss law with C = 0.369 emu K mol(-1) and theta = +0.7 K. The thermal behavior of wmT was described using the 1D ferromagnetic chain model with J/k(B) = +0.91 K.

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Wurster's Blue-type Cation Radicals Framed in a 5,10-Dihydrobenzo[a]indolo[2,3-c]carbazole (BIC) Skeleton: Dual Electrochromism with Drastic Changes in UV/Vis/NIR and Fluorescence

SUZUKI TAKANORI, SAKANO YUTO, TOKIMIZU YUSUKE, MIURA YOUHEI, KATOONO RYO, FUJIWARA KENSHU, YOSHIOKA NAOKI, FUJII NOBUTAKA, OHNO HIROAKI

Chemistry An Asian Journal (Willey)  9 ( 7 ) 1841 - 1846 2014.06

Research paper (scientific journal), Joint Work, Accepted

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Electron-donating dihydrobenzindolocarbazoles (BICs) 1 a-c, which adopt planar disk-shaped geometries, were prepared by gold(I)-catalyzed cyclization as a key step. Due to the presence of a 1,4-phenylenediamine (PD) moiety in the framework, they undergo reversible one-electron oxidation to the corresponding Wurster's Blue (WB)-type species that exhibits NIR absorptions up to λ=1200 nm. In the case of the N,N'-dimethyl derivative, cation radical 1 c(+.) is stable enough to be isolated as a salt and X-ray analysis indicated paraquinoid-type bond alternation in the WB core unit, whereas the bond lengths in the peripheral benzene rings are identical to those in the neutral donor. Upon electrochemical interconversion, the redox pairs of 1 a-c and 1 a-c(+.) exhibited an electrochromic response in the UV/Vis/NIR region, which was accompanied by a drastic change in the fluorescence spectrum because only neutral donors 1 a-c are highly emissive (Φ(F) : 0.7-0.8).

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Introduction of Three Aryl Groups to Benzotriazinyl Radical by Suzuki-Miyaura Cross-coupling Reaction

TAKAHIASHI YUSUKE, MIURA YOUHEI, YOSHIOKA NAOKI

Chemistry Letters (Chemical Society of Japan)  43   1236 - 1238 2014.05

Research paper (scientific journal), Accepted

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A new radical, 7-phenyl-1,3-bis(4-biphenylyl)-1,4-dihydro-1,2,4-benzotriazin-4-yl (2), was prepared from the iodo group-substituted benzotriazinyl radical 1 with phenyltriolborate salt by the Suzuki–Miyaura cross-coupling reaction at room temperature. An X-ray crystal structural analysis clarified its crystal structure. ESR measurements and DFT calculations revealed that its unpaired electron was more delocalized over the molecule than that of Blatter’s radical due to the substituent effect.

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Synthesis of Carbazole-Based Heterocore-Modified Porphyrins

MAEDA CHIHIRO, MASUDA MOTOKI, YOSHIOKA NAOKI

Organic & Biomolecular Chemistry (Chemical Society)  12   2656 - 2662 2014.02

Research paper (scientific journal), Joint Work, Accepted

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Cu(I)-mediated annulation reaction of a 1,1′-(1,3-butadiyne)-8,8′-(2,5-thiophene)-bridged carbazole dimer 10 with amines provided the N-substituted carbazole-based isophlorines 11a–11c. A similar annulation reaction with selenium in the presence of hydrazine monohydrate afforded hetero-core-modified isophlorine 12. The oxidation of 12 generated the corresponding 21-selena-23-thiaporphyrin 13, which exhibited NIR absorption. The intramolecular charge transfer from Se to S was confirmed by the 1H NMR results along with DFT calculations.

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Effective pi-Extension of Carbazole-Based Thiaporphyrins by Peripheral Phenylethynyl Substituents

MAEDA CHIHIRO, MASUDA MOTOKI, YOSHIOKA NAOKI

Organic Letters (American Chemical Society)  15 ( 14 ) 3566 - 3569 2013.07

Research paper (scientific journal), Joint Work, Accepted

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Several tetrakis(phenylethynyl)- and (phenylethynylphenylethynyl)-substituted carbazole-based thiaporphyrins were synthesized. These π-extended porphyrins display remarkably intensified and red-shifted absorption bands in the NIR region up to 1126 nm due to perturbation by the phenylethynyl substituents.

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Synthesis of Carbazole-Based Selenaporphyrin via Annulation

MASUDA MOTOKI, MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic Letters (American Chemical Society)  15 ( 3 ) 578 - 581 2013.01

Research paper (scientific journal), Single Work, Accepted

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Cu(I)-mediated alkoxylation of doubly 1,3-butadiyne-bridged carbazole dimer 1, followed by acid-catalyzed cyclization, provided furan-bridged carbazole dimer 3, while annulation reaction of 1 with selenium in the presence of hydrazine monohydrate provided selenophene-bridged carbazole dimer 5a. Oxidation of isophlorin 5a afforded carbazole-based selenaporphyrin 5b, which possessed distinct aromaticity and produced intensified and red-shifted absorption bands in the near-IR region.

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Peripherally Ethynylated Carbazole-Based Core-Modified Porphyrins

MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic & Biomolecular Chemistry 10   5182-5185 2012.05

Research paper (scientific journal), Single Work, Accepted

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Peripherally ethynylated carbazole-based core-modified porphyrins were synthesized by sequential metal-catalyzed coupling and annulation reactions. Experimental results and DFT calculations both confirm that the π-conjugated networks of the resulting porphyrins effectively delocalize over the entire macrocycle, including the ethynyl substituent groups.

Magnetic Tuning of All-Organic Binary Alloys between Two Stable Radicals

SEBER GONCA , FREITAS S. RAFAEL, MAGUE T. JOEL, PADUAN-FILHO ARMANDO, GRATENS XAVIER, BINDILATTI VALDIR, OLIVEIRA NEI FERNANDES JR., YOSHIOKA NAOKI, LAHTI M. PAUL

Journal of the American Chemical Society 134 ( 8 ) 3825-3833 2012.04

Research paper (scientific journal), Joint Work, Accepted

Synthesis and Characterization of Novel Fused Porphyrinoids Based on Cyclic Carbazole[2]indolones

MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic Letters (American Chemical Society)  14 ( 8 ) 2212 - 2125 2012.04

Research paper (scientific journal), Single Work, Accepted

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The carbazole- and indolone-based porphyrinoids 3 and 4 were synthesized by stepwise transition-metal-catalyzed coupling reactions. Palladium metalation of 4 produced 4Pd, which exhibits near-infrared absorption.

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Theoretical Study of Intermolecular Magnetic Interaction of Chromium(V)-Nitrido Complex Self-Assembly with Tetradentate Schiff Base Ligand

MATSUOKA NAOKI, YOSHIOKA NAOKI

Chemical Physics Letters 523   65-68 2012.01

Research paper (scientific journal), Joint Work, Accepted

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A theoretical study of the intermolecular magnetic interaction of [CrN(salpn)] is discussed based on DFT calculations. The close contact between the 2p orbitals on the axial nitrogen and other 3d orbitals besides the 3dxy orbital on the adjacent chromium is effective for ferromagnetic coupling. The magnetic interaction is rationally explained by the significantly large spin polarization of the axial nitrogen.

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Theoretical Study of Magnetic Properties of Oxovanadium(IV) Complex Self-Assemblies with Tetradentate Schiff Base Ligands

MATSUOKA NAOKI, TSUCHIMOTO MASANOBU, YOSHIOKA NAOKI

The Journal of Physical Chemistry B 115 ( 26 ) 8465 - 8473 2011.07

Research paper (scientific journal), Joint Work, Accepted

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he theoretical study of the magnetic properties of oxovanadium(IV) complex self-assemblies with tetradentate Schiff base ligands is discussed on the basis of DFT calculations. Large negative spin densities are found on the axial oxygens of the various oxovanadium(IV) complexes. The relationship between the effective exchange parameters Jab and the geometrical parameters for these complexes was studied by changing the position of the neighboring molecules for the purpose of clarifying the mechanism of the ferromagnetic coupling. The intermolecular ferromagnetic interaction of the oxovanadium(IV) complexes with tetradentate Schiff base ligands is significantly affected by the formation of polymeric octahedral structures in the solid state. The overlap between the 2p orbitals of the axial oxygen and the 3d orbitals of the adjacent vanadium is effective for the ferromagnetic coupling. On the other hand, the effect of overlap between the vanadium 3dxy orbitals is too small to lead to magnetic coupling. It was revealed that the intermolecular ferromagnetic interaction of the polynuclear oxovanadium(IV) complexes is significantly affected by the spin polarization on the axial oxygen.

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Synthesis of Carbazole-Containing Porphyrirnoids by a Multiple Annulation Strategy: A Core-Modified and pi-Expanded Porphyrin

MAEDA CHIHIRO, YONEDA TOMOKI, ARATANI NAOKI, YOON MIN-CHUL, LIM JONGMIN, KIM DONGO, YOSHIOKA NAOKI, OSUKA ATSUHIRO

Angewande Chemie-International Edition 50 ( 25 ) 5691 - 5694 2011.06

Research paper (scientific journal), Joint Work, Accepted

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Going around in circles: The copper(I)-mediated annulation of a doubly 1,3-butadiyne-bridged carbazole dimer with amines or Na2S provides isophlorins containing carbazole or thiophene-carbazole moieties, respectively (see scheme). Oxidization of the thiophene-containing isophlorin with MnO 2 gives the corresponding porphyrin, which displays distinct aromaticity and remarkably intensified and red-shifted absorption bands in the near IR region.

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Spectroscopic Studies on the Thermodynamic and Thermal Denaturation of the CT-DNA Binding of Methylene Blue

Mudasir, Wahyuni Tri Endang, Tjahjono H. Daryono, YOSHIOKA NAOKI, INOUE HIDENARI

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy 77 ( 2 ) 528 - 534 2010.10

Research paper (scientific journal), Single Work, Accepted,  ISSN  1386-1425

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The ct-DNA binding properties of methylene blue (MB) including binding constant, thermodynamic parameter and thermal denaturation (T(m)) have been systematically studied by spectrophotometric method. The binding of MB to ct-DNA is quite strong as indicated by remarkable hypochromicity, red shift and equilibrium binding constant (K(b)). Van't Hoff plot of 1/T versus lnK(b) suggests that the MB dye binds exothermically to ct-DNA which is characterized by large negative enthalpy and entropy changes. According to polyelectrolyte theory, the charge release (Z) when ct-DNA interacts with MB is +1.09 which corresponds very well to the one positive charge carried by the MB dye. The K(b) at a low concentration of salt is dominated by electrostatic interaction (90%) while that at a high concentration of salt is mostly controlled by non-electrostatic process (85%). However, the stabilization of the DNA binding event in both cases is governed by non-electrostatic process. A moderate stabilization of double helix ct-DNA occurs when the MB dye binds to ct-DNA as indicated by the increase in T(m) of ct-DNA of about 5.5 degrees C in the presence of MB. This suggests that MB dye possibly binds to ct-DNA via electrostatic and intercalation modes.

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Binding of Nickel(II) Tetrakis(dimethylpyrazolium-4-yl)porphyrin to Poly(dG-dC)(2) and Poly(dA-dT)(2)

Tjahjono Daryono HADI, SUHENDAR, PERMANA BENNY, YOSHIOKA NAOKI, INOUE HIDENARI

Journalof Porphyrins and Phthalocyanines 14 ( 4 ) 305 - 313 2010.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1088-4246

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The interaction of nickel(II) complex of cationic porphyrins bearing five-membered rings, meso-tetrakis(1,2-dimethylpyrazolium-4-yl) porphyrinatonickel(II) (NiPzP), with synthetic polynucleotides poly(dG-dC) 2 and poly(dA-dT) 2 has been characterized by viscometric, visible absorption, CD and MCD spectroscopic, and melting temperature measurements. The nickel(II) complex NiPzP is intercalated into poly(dG-dC) 2 but outside bound to the major groove of poly(dA-dT) 2. The binding constants of NiPzP to poly(dG-dC) 2 and poly(dA-dT) 2 are in the order of 10 6 M -1 and comparable to those of other reported cationic metalloporphyrins. The binding process of NiPzP to poly(dG-dC) 2 and poly(dA-dT) 2 is endothermic and entropically driven.

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Magnetic Property and Crystal Structure of Bis[N-(4-chlorophenyl)salicylideneaminato]oxovanadium (IV)

MATSUOKA NAOKI, KAWAMURA HIROSHI, YOSHIOKA NAOKI

Chemical Physics Letters (ELSEVIER SCIENCE INC)  488 ( 1-3 ) 32 - 37 2010.03

Research paper (scientific journal), Joint Work, Accepted

Synthesis and DNA-Binding Properties of Water-Soluble Cationic Pyropheophorbides Derived from Chlorophyll a/b

TAIMA HIDETOSHI, YOSHIOKA NAOKI, INOUE HIDENARI

Organic & Biomolecular Chemistry (Royal Society of Chemistry)  7 ( 6 ) 1176 - 1183 2009.06

Research paper (scientific journal), Joint Work, Accepted

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A series of mono-, di-, tetra-and hexacationic esters of pyropheophorbide a/b have been designed and synthesized to explore the intercalation of their phorbine ring between the base pairs of double-helical DNA and the influence of their peripheral substituents on the DNA interactions. Mono-(1), di-(2, 3) and tetra-(4, 5) cationic pyropheophorbides are soluble as an oligomeric aggregate in HEPES buffer, but hexa-(6) cationic pyropheophorbide is soluble as a monomer at lower concentrations. The interaction of these cationic pyropheophorbide derivatives with DNA has been investigated by DNA unwinding assay,fluorescence energy transfer, and measurements of the melting temperature of the double-helical DNA and visible absorption spectra. Dicationic 2 and 3 bind outside the double-helical DNA without and/or with self-aggregation and with self-aggregation, respectively, because they cannot intercalate between the base-pairs due to their aggregation. On the other hand, tetracationic 4 and 5 and hexacationic 6 intercalate between the base pairs of the double-helical DNA. The binding mode of the cationic pyropheophorbides a/b is strongly dependent on the number and position of the cationic peripheral substituents of the pyropheophorbides.

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Electronic Structures and Magnetic Properties of Copper(II) Complexes with Axially Coordinated Nitronyl Nitroxide Radicals

MATSUOKA NAOKI, YOSHIOKA NAOKI

Polyhedron (PERGAMON-ELSEVIER SCIENCE LTD)  28 ( 9-10 ) 1875 - 1879 2009.06

Research paper (scientific journal), Joint Work, Accepted

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Electronic structures and magnetic properties of Cu(II) complexes with axially coordinated nitronyl nitroxide radicals are discussed on the basis of computational study using density functional theory (DFT) calculation. The tendency of the effective exchange integrals J is examined by changing the position of the nitronyl nitroxide moiety. The spin density distributions for these complexes are also estimated in order to understand the mechanism of the ferromagnetic interaction. The relationship between the geometrical parameters and the magnetic interaction indicates the delocalization of the unpaired electron from the π* orbital of the nitronyl nitroxide group to the 3dz2 atomic orbital of the Cu(II) ion. On the other hand, there is practically no dependence of the overlap between the 3dx2-y2 atomic orbital of the Cu(II) ion and the π* orbital of the nitronyl nitroxide group on the magnitude of the ferromagnetic coupling. It is revealed that the delocalization mechanism is important for the ferromagnetic properties in Cu(II) complexes with axially coordinated nitronyl nitroxide radicals.

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Enantioselective DNA Binding of Iron(II) Complexes of Methyl-Substituted Phenanthroline

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Inorganic Biochemistry (ELSEVIER SCIENCE INC)  102 ( 8 ) 1638 - 1643 2008.08

Research paper (scientific journal), Single Work, Accepted

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The enantioselective binding of [Fe(4,7-dmp)(3)](2+) (dmp: 4,7-dimethyl-1,10-phenantroline) and [Fe(3,4,7,8-tmp)(3)](2+) (tmp: 3,4,7,8-tetramethyl-1,10-phenanthroline) to calf-thymus DNA (ct-DNA) has been systematically studied by monitoring the circular dichroism (CD) spectral profile of the iron(II) complexes in the absence and presence of ct-DNA. The effect of salt concentration and temperature on the degree of enantioselectivity of the ct-DNA binding of the iron(II) complexes, i.e. the molar ratio of Delta- to Lambda-enantiomer in the solution or vice versa has been rigorously evaluated. It is noticeable that Delta-[Fe(4,7-dmp)(3)](2+) and Lambda-[Fe(3,4,7,8-tmp)(3)](2+) are preferentially bound to ct-DNA as reflected in their opposite CD spectral profiles. The preferential binding of the A-enantiomer of [Fe(3,4,7,8-tmp)(3)](2+) to ct-DNA compared to that of the A-enantiomer is associated with the bulkiness of the ancillary ligands due to substitution of four hydrogen atoms in 1,10-phenanthroline for four methyl groups. The determination of enantiomeric inversion constant (K-inv) at various salt concentrations has revealed that the degree of enantioselectivity is salt concentration dependent, indicating that electrostatic interaction is involved in the enantioselective binding of the iron(II) complexes to ct-DNA. Although [Fe(4,7-dmp)(3)](2+) and [Fe(3,4,7,8-tmp)(3)](2+) exhibit an opposite pattern in the CD spectra, the degree of their enantioselectivity (K-inv) is not different from each other significantly. A thermodynamic study on the enantioselective binding of [Fe(4,7-dmp)(3)](2+) to ct-DNA using the van't Hoff plot of lnK(inv) versus 1/T has demonstrated that the enthalpy change (Delta H-o) in the inversion process from the Lambda- to Delta-enantiomer of [Fe(4,7-dmp)(3)](2+) ct-DNA is positive, indicating that the process is endothermic and thus entropically driven. @ 2008 Elsevier Inc. All rights reserved.

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DNA Binding of Iron(II)-Phenanthroline Complexes: Effect of Methyl Substitution on Thermodynamic Parameters

MUDASIR，YOSHIOKA NAOKI,INOUE HIDENARI

Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences (VERLAG Z NATURFORSCH)  63 ( 1 ) 37 - 46 2008.01

Research paper (scientific journal), Joint Work, Accepted

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The influence of methyl substitution on the thermodynamic parameters for the binding of [Fe(DMP)(3)](2+) and [Fe(TMP)(3)](2+) (DMP = 4,7-dimethyl-1,10-phenanthroline, TMP = 3,4,7,8-tetramethyl-1,10-phenanthroline) to calf thymus DNA (ct-DNA) has been studied by determining their equilibrium binding constants (K-b) at various salt concentrations and temperatures. Kb of the iron(II) complexes to ct-DNA decreases with the salt concentration in the solution, suggesting considerable electrostatic interaction in the ct-DNA binding of the iron(II) complexes. In contrast, Kb of the DNA binding increases with temperature, indicating that the DNA binding reaction of the complex is endothermic and entropically driven. The evaluation of the non-electrostatic binding constant (K-t(0)) based on polyelectrolyte theory has revealed that the K-t(0) portions of the total binding constant (Kb) are relatively large and reach 46.4% for [Fe(DMP)3]2+ at [Na+] = 0.075 m and 43.9% for [Fe(TMP)(3)](2+) at [Na+] = 0.100 M. The contribution of non-electrostatic binding free energy (Delta G(t)(0)) to total binding free energy change (AGO) is extremely large, L e. > 90 % for both iron(II) complexes at [Na+] = 0.05 M, suggesting that the stabilization of the DNA binding is mainly contributed from the non-electrostatic process. The effect of methyl substitution on electrostatic (AGO and non-electrostatic (Delta G(t)(0)) binding free energy changes has been systematically evaluated using the quantity of Delta Delta G(pe)(0) and Delta Delta G(t)(0) relative to that of the parent iron(II) complex, [Fe(phen)(3)](2+). The results indicate that the substitution of hydrogen atoms in the phen ligand by methyl groups decreases slightly the electrostatic binding free energy changes, but tremendously increases the non-electrostatic ones to yield net binding free energy changes which are more favorable for the ct-DNA binding.

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An Organic Radical Solid Solution with Strong Ferromagnetic Exchange

MURATA HIDENORI, MAGUE T. JOEL,ABOAKU SAFO, YOSHIOKA NAOKI, LAHTI M. PAUL

Chemistry of Materials (AMER CHEMICAL SOC)  19 ( 17 ) 4111 - 4113 2007.08

Research paper (scientific journal), Joint Work, Accepted

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A nearly equimolar solid solution alloy is formed between two benzimidazole-2-yl-nitronylnitroxides, one aryl fluorinated, one not. The crystal packing of the alloy is similar to those of the components, but with randomized lattice site occupation by the two radicals. The chainlike 1D ferromagnetic exchange behavior observed in the alloy is similar to the behaviors exhibited by the individual pure components.

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Base-Specific and Enantioselective Studies for the DNA Binding of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine

MUDASIR, WIJAYA KARNA,WAHYUNI TRI ENDANG, INOUE HIDENARI, YOSHIOKA NAOKI

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy (PERGAMON-ELSEVIER SCIENCE LTD)  66 ( 1 ) 163 - 170 2007.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1386-1425

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Base specificity and enantioselectivity for the DNA binding of [Fe(phen)(2)(dppz)](2+) (phen = 1, 10-phenanthroline and dppz =dipyrido[3,2-a:2,3'c]phenazine) have been studied by determining the equilibrium binding constant (K-b) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)(2)], poly[(dG-dC)(2)] and poly[(dI-dC)(2)] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)(2)(dppz)](2+) prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)(2)] and poly[(dI-dC)(2)] rather than into the G-C sequences of poly[(dG-dC)21 or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppZ)]21 is base-dependent in nature. The A-enantiomer of [Fe(phen)2(dppz)]2, is preferentially intercalated into the base pairs of poly[(dG-dC)21 or ct-DNA as indicated by its CD spectral profiles. On the other hand, the A-enantiomer of [Fe(phen)2(dppZ)]2, is favorably intercalated into poly[(dA-dT)(2)] or poly[(dI-dC)(2)] as suggested by the opposite CD spectral profile. This preferential binding of A-[Fe(phen)(2)(dppz)](2+) for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non intercalated)phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (K-inv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron
(II) complex.

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Synthesis and Structures of Vanadium-Cerium Trinuclear Complexes with Schiff-Base Ligands

TSUCHIMOTO MASANOBU, ISHII TOSHIO, IMAOKA TAKANE, YAMAMOTO KIMIHISA, YOSHIOKA NAOKI, SUNATSUKI YUKINARI

Bulletin of the Chemical Society of Japan (CHEMICAL SOC JAPAN)  79 ( 9 ) 1393 - 1397 2006.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0009-2673

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A vanadium(V)-cerium(IV) trinuclear complex, [{(VO2)-O-V(L-1)}(2)Ce-IV](1) (H3L1: N,N'-bis-3-ethoxysalicylidene-2-hydroxy-1,3-propanediamine),was prepared by the reaction of [(VO)-O-IV(acac)(2)] and [Ce-III(acac)(3)](.)3H(2)O with H3L1 in CH3CN, followed by oxidation of the product in air. The structure of complex 1 was determined by X-ray
crystal structure analysis. The complex has a V-V-Ce-IV-V-V trinuclear structure with two dioxovanadium(V) moieties on each side of the cerium(IV) moiety. Complex I has two L-1 ligands to form a trinuclear structure. The basal oxo atoms of the dioxovanadium(V) moieties are coordinated to the cerium atom with Ce-O distances of 2.322(3) and 2.343(3) angstrom. The apical two non-coordinating oxo atoms are
oriented to the same direction to form an endo structure. IR data of complex 1 show V=O stretching bands at 975 cm(-1) for the apical non-coordinated oxo atoms and 802 cm(-1) for the basal coordinated oxo atoms. The cyclic voltammogram of complex I in CH3CN shows a quasi-reversible two-electron redox couple with E-1/2 = -0.60 V vs Fc/Fc(+).

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DNA-Binding Properties and Photocleavage Activity of Cationic Water-Soluble Chlorophyll Derivatives

TAIMA HIDETOSHI, OKUBO AKIHIRO, YOSHIOKA NAOKI, INOUE HIDENARI

Chemistry-A European Journal (WILEY-V C H VERLAG GMBH)  12 ( 24 ) 6331 - 6340 2006.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0947-6539

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Three cationic water-soluble chlorin e(6) derivatives, that is,6a-,gamma b-,7c-tris(2-trimethylammonioethyl)chlorin e6 (1), 6a-gamma b-,7c-tris(3-methylpyridiniummethyl)chlorin e6 (2), and 6a-,gamma b-,
7c-tris(2-trimethylammonioethyl)-2-(3-trimethylammonioprop-l-enyl)chlorin e(6) (3), have been designed and synthesized to allow the study of their DNA-binding and -photocleavage activities. The DNA-unwinding assay, measurements of melting temperatures of double-stranded DNA, and the induced CD and visible absorption spectra have revealed that 1 and 3 are intercalated into the base pairs of the double-helical DNA, while 2 is bound to outside the minor groove of the double-helical DNA. The cationic water-soluble chlorin e(6) derivatives effectively cleave the double-helical DNA under photo-irradiation and the DNA-photocleavage activity increases in the order 3 > 1 > 2. The DNA-binding and -photocleavage characteristics of the three cationic water-soluble chlorin e6 derivatives are influenced by aspects of their molecular structure, such as the kind, number, and position of the cationic substituents.

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Binding of Tetrakis(pyrazoliumyl)porphyrin and its Copper(II) and Z0inc(II) Complexes to Poly(dG-dC)(2) and Poly(dA-dT)(2)

TJAHJONO H. DARYONO, KARTASASMITA E. RAHMANA, NAWAWI AS’ARI, MIMA SHUNSUKE, AKUTSU TAKEHIRO, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Biological Inorganic Chemistry (SPRINGER)  11 ( 4 ) 527 - 538 2006.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0949-8257

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Interactions of cationic porphyrins bearing five-membered rings at the meso position, meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin(MPzP; M is H-2, Cu-II or Zn-II), with synthetic polynucleotides poly(dG-dC)(2) and poly(dA-dT)(2) have been characterized by viscometric, visible absorption, circular dichroisim and magnetic circular dichroism spectroscopic and melting temperature measurements. Both H(2)PzP and CuPzP are intercalated into poly(dG-dC)(2) and are outside-bound to the major groove of poly(dA-dT)(2), while ZnPzP is outside-bound to the minor groove of poly(dA-dT)(2) and surprisingly is intercalated into poly(dG-dC)(2). The binding constants of the porphyrin and poly(dG-dC)(2) and poly(dA-dT)(2) are on the order of 10(6) M-1 and are comparable to those of other cationic porphyrins so far reported. The process of the binding of the porphyrin to poly(dG-dC)(2) and poly(dA-dT)(2) is exothermic and enthalpically driven for H(2)PzP, whereas it is endothermic and entropically driven for CuPzP and ZnPzP. These results have revealed that the kind of the central metal ion of metalloporphyrins influences the characteristics of the binding of the porphyrins to DNA.

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Salt-Dependent Binding of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine to Calf Thymus DNA

Mudasir, Wijaya Kama, Wahyuni Tri Endang, Yoshioka Naoki, Inoue Hidenari

Biophysical Chemistry (ELSEVIER SCIENCE BV)  121 ( 1 ) 44 - 50 2006.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0301-4622

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The salt-dependent binding of racemic iron(II) mixed-ligand complex containing 1,10-pherianthroline (phen) and dipyrido[3,2-a:2',3'-c]phenazine (dppz), [Fe(phen)(2)(dppz)](2+) to calf thymus DNA (ct-DNA)has been characterized by UV-VIS spectrophotometric titration. The
equilibrium binding constant (K-b) of the iron(II) complex to ct-DNAdecreases with the salt concentration in the solution. The slope, SK=(delta log K-b/delta log [Na2+]) has been found to be 0.49, suggesting that, in addition to intercalation, considerable electrostatic interaction is also involved in the ct-DNA binding of [Fe(phen)(2)(dppz)](2+). The calculation of non-electrostatic binding constant (K-t degrees) based on polyelectrolyte theory has revealed that the non-electrostatic contribution to the total binding constant (K-b) increases significantly with the increase in [Na+] and reaches 36% at 0.1 M NaCl. On the other hand, the contribution of the non-electrostatic binding free energy (Delta(G) under bar (t)degrees) to the total binding free energy change (Delta G degrees) is considerably large, i.e. 87% at [Na+]=0.1 M, suggesting that the stabilization of the DNA binding is mostly due to the contribution of non-electrostatic process. Moreover, the effect of specific ligand substitutions on Delta G degrees has been rigorously evaluated using the quantity Delta Delta G(t)degrees, i.e. the difference in Delta G(t)degrees relative to that of the parent iron(II) complex,
[Fe(phen)(3)](2+), indicating that each substitution of phen by dip and dppz contributes 7.5 and 17.5 kJ mol(-1), respectively to more favorable ct-DNA binding.

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Synthesis and magnetic properties of 2,2,4-and 2,2,6-triphenyl-1,2-dihydroquinoline-N-oxyl derivatives

Yao Masaru, Shibuya Hideki, Kato Takashi, Inoue Hidenari, Yoshioka Naoki

Polyhedron (PERGAMON-ELSEVIER SCIENCE LTD)  24 ( 16-17 ) 2828 - 2834 2005.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0277-5387

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The synthesis and magnetic properties of two novel aromatic Ar-oxyl radicals based on the quinoline skeleton, 2,2,4-triphenyl-1,2-dihydroquinoline-N-oxyl (1) and 2,2,6-triphenyl-1,2-dihydroquinoline-N-oxyl (2) are described. ESR measurements and DFT calculations for 1 and 2 revealed that their spins were delocalized over the pi-systems. Based on the SQUID measurement, 1 exhibited a weak antiferromagnetic interaction in its crystal. For 2, two crystalline phases were obtained, and the alpha-phase of 2
exhibited a paramagnetic behavior; however, the beta-phase of 2 showed a weak ferromagnetic interaction. The observed ferromagnetic interaction was analyzed by a dimer model, and the singlet-triplet gap was estimated to be 2J = +2.5 cm(-1).

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Synthesis of Cationic Water-Soluble Esters of Chlorin e(6)

Taima Hidetoshi, Okubo Akihiro,Yoshioka Naoki, Inoue Hidenari

Tetrahedron Letters (PERGAMON-ELSEVIER SCIENCE LTD)  46 ( 24 ) 4161 - 4164 2005.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0040-4039

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Two esters of chlorin e(6) have been synthesized by esterification with aminoalcohols via the formation of acid chloride using oxalyl chloride and converted to the corresponding cationic water-soluble esters of chlorin e(6). The visible absorption and circular dichroism spectra
have revealed that these two cationic chlorin e(6) esters synthesized are readily soluble in water as a monomer.

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Formation of a One-Dimensional Stacking Structure of pi-Conjugated Nitroxyl Radical Bearing a 1,2,5-Thiadiazole Ring and its Magnetic Property

Yao Masaru, Asakura Satoshi, Abe Masahiro, Inoue Hidenari, Yoshioka Naoki

Crystal Growth & Design (AMER CHEMICAL SOC)  5 ( 2 ) 413 - 417 2005.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1528-7483

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A novel stable organic radical,7,7-diphenyl-6,7-dihydro[1,2,5]thiadiazolo[3,4-f]quinoline-6-oxyl (1),forms a one-dimensional columnar structure consisting of slipped,pi-stacks, which is in contrast to dimer formation of the isoelectronic benzologue,3,3-diphenyl-3,4-dihydrobenzo[f]quinoline-4-oxyl (2). Magnetic susceptibility of 1 obeyed an antiferromagnetic chain model with J =-47 cm(-1), while 2 behaved as an isolated doublet spin state even in the dimer.

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Novel Aromatic N-oxyl Radical Based on the Benzo[g]quinoline Skeleton: Synthesis and Intermolecular Ferromagnetic Interaction

Yao Masaru, Inoue Hidenari, Yoshioka Naoki

Chemical Physics Letters (ELSEVIER SCIENCE BV)  402 ( 1-3 ) 11 - 16 2005.01

Research paper (scientific journal), Single Work, Accepted,  ISSN  0009-2614

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A novel stable organic radical,2,2-diphenyl-1,2-dihydrobenzo[g]quinoline-N-oxyl (2), has been synthesized and structurally characterized in order to examine the ring
extension effect on the known derivative, 2,2-diphenyl-1,2-dihydroquinoline-N-oxyl (1). Based on SQUID measurement, 2 exhibited a ferromagnetic interaction obeying the Bleaney-Bowers equation with 2J = +4.6 cm(-1). The X-ray analysis revealed an intermolecular edge-edge association of the aryl ring and N-oxyl moiety in the crystal of 2. The bifurcated edge-edge contacts between the alpha-spin site (nitroxyl O atom) and the beta-spin site (aryl-H atoms) are responsible for the ferromagnetic interaction of 2.

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Amphiphilic meso-Disubstituted Porphyrins: Synthesis and the Effect of the Hydrophilic Group on Absorption Spectra at the Air-Water Interface

Yao Masaru, Iwamura Yuko,Inoue Hidenari, Yoshioka Naoki

Langmuir (AMER CHEMICAL SOC)  21 ( 2 ) 595 - 601 2005.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0743-7463

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Five amphiphilic meso-disubstituted porphyrins bearing one polar group were synthesized. and their monolayer films were prepared. Their limiting molecular areas obtained from pi-A isotherms were 0.5-0.6nm(2), which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air-water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of hydrophilic groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of hydrophilic substituents on the absorption Spectra of disubstituted porphyrin monolayers is discussed.

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An Ideal One-Dimensional Antiferromagnetic Spin System Observed in Hydrogen-Bonded Naphth[2,3-d]imidazol-2-yl Nitronyl Nitroxide Crystal:The Role of the Hydrogen Bond

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Journal of Physical Chemistry B 108 ( 20 ) 6144 - 6151 2004.05

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(naphth[2,3-d]imidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide (4), has been designed, synthesized, and structurally characterized to examine the effects of ring extension on 2-(benzimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide (2). 4 forms four-centered intramolecular and intermolecular hydrogen bonds, and the hydrogen bonds are repeated along the c-axis to form a one-dimensional chain structure. This hydrogen-bonding motif contrasts that of 2, which forms three-centered intramolecular and intermolecular hydrogen bonds. The magnetic susceptibility measurement of 4 reveals that an antiferromagnetic interaction is dominant between spins, and the magnetic behavior is reproduced by the Bonner-Fisher model with J = −14 cm-1. Because each hydrogen-bonded chain is well isolated, a magnetic interaction pathway was thought to exist along the chain direction. Two interaction pathways have been assumed:  (i) through-space interaction between the O atoms of the nitroxide and (ii) through the NH···ON intermolecular hydrogen bond. We have concluded that pathway (i) is predominant, by considering the identical magnetic data between the NH nondeuterated and deuterated samples. The hydrogen bond mainly has a role in crystal scaffolding.

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DNA-Binding Properties of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine

MUDASIR, WIJAYA, Karna, YOSHIOKA NAOKI, INOUE HIDENARI

Zeitschrift für Naturforschung B (VERLAG Z NATURFORSCH)  59 ( 3 ) 310 - 318 2004.03

Research paper (scientific journal), Joint Work, Accepted

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An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2’,3’- c]phenazine (dppz), [Fe(phen)2(dppz)]2+, has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen)2(dppz)]2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (Δ Tm = 21 °C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen)2(dppz)]2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative TΔ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen)2(dppz)]2+. This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ -enantiomer indicates that Δ -[Fe(phen)2(dppz)]2+ is preferentially bound to ct-DNA

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Metamagnetic Behavior Observed in Purely Organic 5-Azaindol-2-yl Nitronyl Nitroxide Brick-Wall Architecture

NAGASHIMA HIDEAKI, FUJITA SHIN'YA, INOUE HIDENARI, YOSHIOKA NAOKI

Crystal Growth & Design 4 ( 1 ) 19 - 21 2004.01

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(5-azaindol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoline-1-oxyl-3-oxide (3), forms a two-dimensional brick-wall architecture based on hydrogen bonding and π-stacking. Low-temperature magnetization curves reveal an S-shape dependence on the applied field below ca. 3.0 K, which could be interpreted as metamagnetic behavior.

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Interaction of Dicationic Bis(imidazoliumyl)porphyrinatometals with DNA

Yamamoto Tomoko, Tjahjono Hadi Daryono, Yoshioka Naoki, Inoue Hidenari

Bulletin of the Chemical Society of Japan 76 ( 10 ) 1947-1955 - 1955 2003.10

Research paper (scientific journal), Joint Work, Accepted

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A pair of dicationic metalloporphyrins with only two meso-substituents, i.e. copper(II) and zinc(II) complexes of 5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrin (H2-1), have been synthesized by insertion reaction of the metal ions. Interactions of [5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrinato]copper(II) (Cu-I) and [5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrinato]zinc(II) (Zn-1) with calf thymus DNA (CT-DNA) and double-helical synthetic polynucleotides ([poly(dA-dT)]2 and [poly(dG-dC)]2) have been studied by melting temperature, viscometric, visible absorption, CD and MCD spectroscopic measurements. The copper(II) complex, Cu-1, intercalates into the base pairs of DNA such as CT-DNA, [poly(dA-dT)]2 and [poly(dG-dC)]2 to stabilize the DNA duplex due to its high affinity for them. In contrast, the zinc(II) complex, Zn-1, binds edge-on to CT-DNA, [poly(dA-dT)]2 and [poly(dG-dC)]2 as an outside binder. The binding constant of Cu-1 to DNA is in the order of 106 M-1 in a phosphate buffer (pH 6.8) at 25 °C, while that of Zn-1 ranges from 104 to 10 5 M-1 under the same experimental conditions. The binding of Cu-1 and Zn-1 to DNA is entropically driven, although that of H 2-1 is enthalpically driven. As a result, it has been revealed that the kind of central metal ions in dicationic metalloporphyrins influences the binding properties of the dicationic porphyrin to DNA.

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Synthesis, Solution ESR Spectra, and Solid-State Magnetic Property of Thieno[3,4-d]imidazol-2-yl Nitronyl Nitroxide

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Polyhedron 22 ( 14-17 ) 1823 - 1827 2003.07

Research paper (scientific journal), Joint Work, Accepted

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2-(Thieno[3,4-d]imidazol-2-yl)-1,3-dihydro-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (2) was designed and synthesized. Compound 2 was stable in a solid state but unstable in organic solvents. Solution ESR spectra showed that small spin densities locate on the four methyl groups and the thieno[3,4-d]imidazole ring, though most of spin densities localized on the ONCNO moiety. Magnetic susceptibility measurement showed that antiferromagnetic interaction is dominant which could be fitted to the Bonner–Fisher model with J=−8.8 cm−1.

A new nitronyl nitroxide derivative carrying thieno[3,4-d]imidazole ring was designed and synthesized. It was stable in a solid state but unstable in organic solvents. Solution ESR spectra showed that small spin densities locate on the four methyl groups and the thieno[3,4-d]imidazole ring. Magnetic susceptibility measurement showed that antiferromagnetic interaction is dominant which could be fitted to the Bonner–Fisher model with J=−8.8 cm−1.

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Synthesis and Physicochemical Properties of Some 5,15-Diarylporphyrin Derivatives

YAO MASARU, KAMISHIRO MASAFUMI, INOUE HIDENARI, YOSHIOKA NAOKI

Polyhedron 22 ( 14-17 ) 2281 - 2285 2003.07

Research paper (scientific journal), Joint Work, Accepted

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Several derivatives of meso-5,15-diarylporpyrins (1–4) and their metal complexes were prepared and their physicochemical properties were studied. Their magnetic properties were characterized by SQUID magnetometer. The temperature dependence of the molar magnetic susceptibility of the copper and vanadyl complex of 5,15-diphenylporphyrin (1-Cu, 1-VO) obeyed the Curie law and were almost identical with those of corresponding meso-tetraphenyl derivatives. In addition to the magnetic properties of disubstituted porphyrins, the properties of Langmuir film of meso-disubstituted porphyrins 2-H2 were investigated by π–A isotherms and visible absorption spectra.

meso-Diphenylmetalloporpyrins (M=Cu, VO) were prepared and their magnetic properties were characterized. These derivatives obeyed the Curie law and were almost identical with those of corresponding meso-tetraphenyl derivatives. Prepared amphiphilic diarylporphyrin showed a large red shift pattern in the visible absorption spectrum at air–water interface, compared with in the solution.

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Theoretical study on magnetic properties of imidazolyl nitronyl nitroxide derivatives

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Synthetic Metals 137 ( 1-3 ) 1257 - 1258 2003.04

Research paper (scientific journal), Joint Work, Accepted

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imidazol-2-yl nitronyl nitroxideとbenzimidazol-2-yl nitronyl nitroxideは、水素結合により連鎖構造を形成し、前者は強い反強磁性、後者は強磁性相互作用が存在する。構造－磁性相関より、磁気的相互作用として水素結合を介する経路と、空間を介した磁気軌道の接近による経路が考えられる。DFT計算を活用してこれら２つのラジカル分子では、磁気軌道の直積的な接近が主要な経路であることを明らかにした。

Coexistence of an Antiferromagnetically Coupled Dimer and Isolated Paramagnetic Spin in 4-Azaindol-2-yl Nitronyl Nitroxide Crystal

NAGASHIMA HIDEAKI, HASHIMOTO NORIKO, INOUE HIDENARI, YOSHIOKA NAOKI

New Journal of Chemistry (Royal Society of Chemistry)  27 ( 5 ) 805 - 810 2003.04

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(4-azaindol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoline-1-oxyl-3-oxide was synthesized and its magneto-structual correlation is discussed.

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Effect of Hydrophilic Group on Absorption Spectra of meso-Disubstituted Porphyrin LB Films

YAO MASARU, ISHIDA NAOMI, INOUE HIDENARI, YOSHIOKA NAOKI

Synthetic Metals 137 ( 1-3 ) 917 - 918 2003.04

Research paper (scientific journal), Joint Work, Accepted

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両親媒性基を導入したmeso-２置換ポルフィリン誘導体を合成し、これを膜物質とするLB膜を作製した。膜の光吸収特性に及ぼす、導入置換基の効果を各種分光法を用いて明らかにした。

ESR Study and Deuteration Effect on the Magnetic Property of Hydrogen-Bonded Benzimidazole Nitronyl Nitroxide

NAGASHIMA HIDEAKI, IRISAWA MUNETOSHI, YOSHIOKA NAOKI, INOUE HIDENARI

Molecular Crystals and Liquid Crystals 376 ( 1 ) 371 - 376 2002.03

Research paper (scientific journal), Joint Work, Accepted

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A solution ESR spectral investigation on 2-(benzimidazol-2-yl)-4,4,5,5-tetramethyl-1 H -imidazoline-1-oxyl-3-oxide (=BIm-NN) and a magnetic susceptibility measurement of its −(N)H deuterated sample (BIm-NN-d 1 ) were carried out. A moderate amount of spin density was observed in benzimidazole ring bearing a hydrogen-bonding site. There was no appreciable difference in the temperature dependence of magnetic susceptibility between BIm-NN and BIm-NN-d 1 .

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Self-Assembly of a Porphyrin Array via the Molecular Recognition Approach: Synthesis and Properties of a Cyclic Zinc(II) Porphyrin Trimer Based on Coordination and Hydrogen Bonding

IKEDA CHUSAKU, TANAKA YUICHI, FUJIHARA TAKESHI, ISHII YOKO, USHIYAMA TAKESHI, YAMAMOTO KIMIHISA, YOSHIOKA NAOKI, INOUE HIDENARI

Inorganic Chemistry 40 ( 14 ) 3395 - 3405 2001.08

Research paper (scientific journal), Joint Work, Accepted

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Self-assembly of [5-(pyrazol-4-yl)-10,20-bis(p-tolyl)-15- (2-ethoxycarbonylphenyl)porphyrinato]-zinc(II) (1), designed to have both a coordination site and a hydrogen bonding site, leads to a stable cyclic trimer array where coordination of the pyrazole nitrogen to the zinc(II) ion as well as hydrogen bonding between carbonyl oxygen and pyrazole NH holds each zinc(II) porphyrin. The recognition event for pyrazole has been confirmed preliminarily in the model studies using [5-(2-ethoxycarbonylphenyl)tris(p-tolyl)porphyrinato]-zinc(II) (3). The zinc(II) porphyrin 3 has large affinity for pyrazole due to the hydrogen bond between pyrazole and the 2-ethoxycarbonyl group in addition to the coordination bonding accompanied by the conformational change of the ethoxycarbonyl group in the coordination process. The 1H NMR, IR, and UV−vis spectra of 1 and its ESI-MS and VPO measurements have revealed the cyclic trimer structure with an overall association constant of 6.0 × 1013 M-2 at 22 °C. The contribution of the hydrogen bond to the total free energy change in trimer formation is estimated to be 7.5 kcal/mol based on a reference trimer system without a hydrogen bonding site. The trimer geometry causes characteristic exitonic interaction between porphyrin units to yield a broad Soret band which is deconvoluted into four components by UV−vis and MCD spectral analyses. Electrochemical measurements have shown that only the first ring-oxidation process proceeds stepwise in the trimer.

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Stress-Induced Ligand Field Distortion and Consequent Multi-Mode Spin Crossover Behavior in Fe(phen)2(NCS)2 and Fe[HB(pz)3]2

TSUCHIYA NAOKO, TSUKAMOTO ATSUSHI, OHSHITA TADASHI, ISOBE TETSUHIKO, SENNA MAMORU, YOSHIOKA NAOKI, INOUE HIDENARI

Solid State Sciences 3 ( 6 ) 705 - 714 2001.08

Joint Work, Accepted

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Changes in the nature of spin crossover caused by mechanical stressing exerted on the crystalline powders were studied for FeII(phen)2(NCS)2 (phen = 1,10-phenanthroline) and FeII[HB(pz)3]2 (pz = pyrazol-1-yl) by means of a multi-component fitting of the temperature dependence of magnetic susceptibility. The analysis revealed the development and broadening of the ligand field distribution as a consequence of mechanical stressing. This was confirmed by the broadening of Mössbauer and far-infrared spectra.

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Ligand-Exchange Reaction between Tris(1,10-phenanthroline)metal(II) and　Tris(4,7-diphenyl-　1,10-phenanthroline)metal(II) Ions

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Coordination Chemistry 52 ( 4 ) 333 - 344 2001.07

Research paper (scientific journal), Joint Work, Accepted

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The ligand exchange reaction between [M(phen)3]2+ and [M(DIP)3]2+ (where M is the same and M = FeII or NiII, phen = 1,10-phenanthroline, DIP = 4,7-diphenyl-1,10-phenanthroline) has been investigated by reversed phase ion-paired chromatography (RP-IPC). The effect of pH and solvent on the ligand-exchange reaction is studied by monitoring the variation in chromatograms with time after mixing. The results have shown that the ligand exchange reaction between [M(phen)3]2+ and [M(DIP)3]2+ takes place in the pH range of 3–8 and the rate of reaction for nickel(II) complexes is about two times slower than that for iron(II) complexes. Experiments on the effect of various solvents on the ligand-exchange reaction have revealed that the rate of reaction is enhanced by the solvent in the following order: (CH3)2CO > CHCl3 ≥ CH2Cl2 > CH3CN > CH3OH. Elemental analysis and UV-visible spectroscopy confirmed that the products obtained from the ligand-exchange reaction are mixed-ligand complexes containing phen and DIP ligands, i.e., [M(phen)2(DIP)]2+ and [M(phen)(DIP)2]2+.

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Metallopyrazoliumylporphyrins with Calf Thymus DNA

TJAHJONO H. DARYONO, MIMA SHUNSUKE, AKUTSU TAKEHIRO, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Inorganic Biochemistry 85 ( 2-3 ) 219 - 228 2001.06

Research paper (scientific journal), Joint Work, Accepted

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The interaction of transition metal complexes of cationic porphyrins bearing five membered rings, meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin (MPzP, M=MnIII, NiII, CuII or ZnII), with calf thymus DNA (ctDNA) has been studied. Metalloporphyrins NiPzP and CuPzP are intercalated into the 5′GC3′ step of ctDNA. MnPzP is bound edge-on at the 5′TA3′ step of the minor groove of ctDNA, while ZnPzP is bound face-on at the 5′TA3′ step of the major groove of ctDNA. The binding constants of the metalloporphyrins to ctDNA range from 1.05×105 to 2.66×106 M−1 and are comparable to those of other reported cationic porphyrins. The binding process of the metallopyrazoliumylporphyrins to ctDNA is endothermic and entropically driven. These results have revealed that the kind of central metal ions of metalloporphyrins influences the binding characteristics of the porphyrin to DNA.

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Synthesis and Magnetic Properties of Nitronyl Nitroxide Radicals Carrying a Purine Ring

NAGASHIMA HIDEAKI, YOSHIOKA NAOKI, INOUE HIDENARI

Polyhedron 20 ( 11-14 ) 1151 - 1155 2001.05

Research paper (scientific journal), Joint Work, Accepted

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2-(Purin-8-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide (Pu-NN) was designed and synthesized. Two crystalline phases (α- and β-phases) exhibiting different IR spectral patterns at the νNH region were obtained depending on the crystallizing condition. The temperature dependences of the magnetic susceptibility of these two phases followed Curie–Weiss law with θ=−5.7 K (α-phase) and θ=−0.3 K (β-phase) implying intermolecular antiferromagnetic interaction, which were quite different from that of parent benzimidazole derivative, 2-(benzimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H- imidazolyl-1-oxyl-3-oxide that formed a 1-D ferromagnetic chain induced by an intermolecular hydrogen bonding.

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Synthesis and Magnetic Properties of a Polymeric Nitridochromium(V) Complex with a Tetradentate Schiff Base Ligand

TSUCHIMOTO MASANOBU, YOSHIOKA NAOKI, OHBA SHIGERU

European Journal of Inorganic Chemistry 2001 ( 4 ) 1045 - 1049 2001.03

Research paper (scientific journal), Joint Work, Accepted

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A novel polymeric nitridochromium(V) complex with a Schiff base ligand [CrN(salpn)] [H2(salpn) = N,N′‐disalicylidene‐1,3‐propanediamine] was prepared by photolysis of an azidochromium(III) complex in acetonitrile. X‐ray crystal structure analyses of the starting material {(CH3)2NH2}2[CrCl2(salpn)]Cl (1) and the polymeric complex [CrN(salpn)] (3) were carried out. The orange complex 3 has a linear ···Cr≡N···Cr≡N··· chain structure with the N···Cr distance being 2.508(2) Å. Magnetic data show that 3 has a ferromagnetic intermolecular interaction in the chains (J = +8.4 cm−1).

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Synthesis and Magnetic Properties of Nitronyl Nitroxide radicals Carrying a Purine Ring

吉岡 直樹

Polyhedron 20   1151-1155 2001.03

Research paper (scientific journal), Single Work, Accepted

Formation of Cyclic Trimers and Tetramers of Zinc(II) Pyrazolylporphyrins by Mutual Coordination

IKEDA CHUSAKU, NAGAHARA NORIKO, YOSHIOKA NAOKI, INOUE HIDENARI

New Journal of Chemistry 24   897 - 902 2000.09

Research paper (scientific journal), Joint Work, Accepted

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The self-assembly of zinc(II) porphyrins bearing a pyrazole substituent are reported. 1H NMR, UV/Vis and VPO measurements indicate the formation of a cyclic trimer of zinc(II) pyrazol-4-ylporphyrin and a tetramer of zinc(II) 3,5-dimethypyrazol-4-ylporphyrin by mutual coordination.

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Synthesis and DNA-Binding Properties of Cationic Bisdiazolium Porphyrins

TJAHYONO H. DARYONO, YAMAMOTO TOMOKO, ICHIMOTO SUMITO, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of the Chemical Society, Perkin Transactions 1 2000 ( 18 ) 3077 - 3081 2000.08

Research paper (scientific journal), Joint Work, Accepted

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A pair of 5,15-bisdiazoliumylporphyrins with only two meso-substituents, 5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrin 1b and 5,15-bis(1,2-dimethylpyrazolium-4-yl)porphyrin 2b, has been synthesized. The crowded porphyrin 1b intercalates between base pairs of DNA to stabilize the duplex DNA to thermal denaturation due to its high affinity for DNA. The binding of porphyrin 1b to DNA is an exothermic interaction and enthalpically driven. Porphyrin 1b interacts more strongly with poly(dA-dT)2 than with poly(dG-dC)2, and the interaction is more favorable or selective to AT-rich sites than to GC-rich sites.

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Mechanochemical Reaction of Polymeric Oxovanadium(IV) Complexes with Schiff Base Ligands Derived from 5-Nitrosalicylalde and Diamines

TSUCHIMOTO MASANOBU, HOSHINA GAKUSE, YOSHIOKA NAOKI, INOUE HIDENARI, NAKAJIMA KIYOHIKO, KAMISHIMA MAYOMI, KOJIMA MASAAKI, OHBA SHIGERU

Journal of Solid State Chemistry 153 ( 1 ) 9 - 15 2000.08

Research paper (scientific journal), Joint Work, Accepted

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Light brown [VO(5-NO2salen)]·2H2O (1; H2(5-NO2 salen)=N,N′-di-5-nitrosalicylidene-1,2-ethanediamine) and orange [VO(5-NO2sal-meso-stien)]·0.5H2O (2; H2(5-NO2sal-meso-stien)=N,N′-di-5-nitrosalicylidene-(R,S)(S,R)-1,2-diphenyl-1,2-ethanediamine) which have linear chain structures in the solid state turn dark brown and yellow-brown, respectively, when ground thoroughly in mortars. The IR spectra of 1 and 2 in Nujol mulls show strong V=O stretching bands at 875 and 905 cm−1, respectively. On the other hand, the spectra of the finely ground complexes in Nujol mulls show very weak V=O stretching bands. X-ray powder diffraction patterns of the ground complexes scarcely show diffraction peaks. The spectroscopic and magnetic data suggest that the linear chain structures in the crystals of 1 and 2 are destroyed on grinding to yield the fragments of the polymeric chains.

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Optical Studies of the Monolayer Films of Diazole-Containing Porphyrins at the Air-Water Interface

IKEDA CHUSAKU, TAKASHIMA YUFUKO, IRIE TAKESHI, YOSHIOKA NAOKI, INOUE HIDENARI

Molecular Crystals and Liquid Crystals Science and Technology. Section A. 342 ( 1 ) 81 - 86 2000.08

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Optical properties of the monolayers of 5-(1-methyliniidazol-2-yl)- 10,15,20-tris(p-octyloxy-phenyl)porphyrin, 5-(1-methylpyrazol-4-yl)-10,15,20-tris(p-octyloxyphenyl)porphyrin and their zinc(II) complexes have been studied. The π-A isotherms and UV-vis spectra have revealed that the zinc(II) complexes form coordination assemblies between peripheral nitrogen atom and central zinc(II) ion at the air-water interface with very tight molecular packing.

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Thermal Decomposition of Prussian Blue Analogues of the Type Fe[Fe(CN)5NO]

INOUE HIDENARI, NARINO SHUICHI, YOSHIOKA NAOKI, FLUCK EKKEHARD

Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences 55   685 - 690 2000.08

Research paper (scientific journal), Joint Work, Accepted

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The structure and properties of the thermal decomposition products of Fe[Fe(CN)5NO] · x H2O (x = 5 ~ 6) have been studied by Mössbauer and FT-IR spectroscopy, X-ray diffraction, and conductivity measurements. The valence state and coordination environment of the iron ions change dramatically when the nitrosyl ligand is eliminated by heat-treatment under vacuum at 200 °C. The dark blue product obtained by heat-treatment under vacuum at 250 °C is characteristic of the mixed-valence state in Prussian blue analogues. The electrical conductivity of the dark blue product is higher by a factor of 103 than that of the starting material because of the mixed-valence state between Fe(III)[Fe(II)(CN)5] and Fe(II)[Fe(III)(CN)5]. Heat-treatment under vacuum at 350°C yields a new product Fe(II)[Fe(II)(CN)4] the crystal structure of which is different from that of the starting material. The electrical conductivity of the decomposition product obtained at 350 °C is about 105 times higher than that of the starting material.

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DNA Binding of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and 4,7-Diphenyl-1,10-phenanthroline

Mudasir, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Inorganic Biochemistry 77 ( 3-4 ) 239 - 247 1999.11

Research paper (scientific journal), Joint Work, Accepted

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Absorption spectroscopy and circular dichroism (CD) have been used to characterize the DNA binding of [Fe(phen)3]2+, [Fe(phen)2(DIP)]2+ and [Fe(phen)(DIP)2]2+ where phen and DIP stand for 1,10-phenanthroline and 4,7-diphenyl-1,10-phenanthroline, respectively. Both [Fe(phen)3]2+ and [Fe(phen)2(DIP)]2+ bind weakly to calf thymus DNA (CT-DNA) in an electrostatic mode, while [Fe(phen)(DIP)2]2+ binds more strongly to CT-DNA, possibly in an intercalation mode. The hypochromicity, red shift and Kb increase in the order [Fe(phen)3]2+<[Fe(phen)2(DIP)]2+<[Fe(phen)(DIP)2]2+ in accordance with the increase in size and hydrophobicity of the iron(II) complexes. The thermodynamic parameters obtained suggest that the DNA binding of both [Fe(phen)3]2+ and [Fe(phen)2(DIP)]2+ is entropically driven, while that of [Fe(phen)(DIP)2]2+ is enthalpically driven. A strong CD spectrum in the UV and visible region develops upon addition of CT-DNA into the racemate solution of each iron(II) complex (Pfeiffer effect). This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one of the DNA-complex diastereomers. The striking resemblance of the CD spectral profiles to those of the pure Δ-enantiomer indicates that the Δ-enantiomer of the iron(II) complexes is preferentially bound to CT-DNA. The mechanism of the development of Pfeiffer CD is proposed on the basis of kinetic studies on the DNA binding of the racemic iron(II) complexes.

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Magnetic Properties of Nitronyl Nitroxide Derivatives Bearing N-H Site: an Approach to Ferromagnetic Self-Assemblies Using Hydrogen Bond

YOSHIOKA NAOKI, MATSUOKA NAOKI, IRISAWA MUNETOSHI, OHBA SHIGERU, INOUE HIDENARI

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Vol. 334 ( 1 ) 239 - 246 1999.11

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Abstract
Nitronyl nitroxide derivatives bearing NH site, imidazolyl-2-nitronyl nitroxide (Im-NN), 4(5)-methyl-imidazolyl-2-nitronyl nitroxide (MeIm-NN), and benzimidazolyl-2-nitronyl nitroxide (BIm-NN) were synthesized, and were self-assembled by hydrogen bonding at NH site with nitrogen atom on imidazole ring or oxygen atom of nitroxide moiety. Ferromagnetic intermolecular interactions were observed in MeIm-NN and BIm-NN. The magnetic interaction can be rationally explained by McConnell model.

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Cationic porphyrins bearing diazolium rings: synthesis and their interaction with calf thymus DNA

TJAHJONO H. DARYONO, YOSHIOKA NAOKI, INOUE HIDENARI

Biochimica et Biophysica Acta 1472 ( 1-2 ) 333 - 343 1999.10

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Two novel cationic porphyrins bearing five-membered rings at the meso-positions, meso-tetrakis(1,3-dimethylimidazolium-2-yl)porphyrin (H2TDMImP) and meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin (H2TDMPzP), have been synthesized. These two compounds interact with calf thymus DNA (CTDNA) in different binding modes from that of meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (H2TMPyP). H2TDMImP outside binds to the minor groove of CTDNA while H2TDMPzP intercalates into CTDNA. These two novel cationic porphyrins strongly bind to CTDNA even at high ionic strength and the binding constant of H2TDMPzP to CTDNA is comparable to that of H2TMPyP. The binding of H2TDMImP to CTDNA is enthalpically driven. The favorable free energy changes in binding of H2TDMPzP to CTDNA come from the large negative enthalpy changes accompanied by small positive entropy changes.

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Self-Assembly of Monopyrazolylporphyrins by Hydrogen Bonding in Solution

IKEDA CHUSAKU, NAGAHARA NORIKO, MOTEGI EIKO, YOSHIOKA NAOKI, INOUE HIDENARI

Chemical Communications Vo1 1999   1759 - 1760 1999.09

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The self-associated structures of two noble meso-(monopyrazolyltritolyl)porphyrins synthesized via their NH-protected precursors have been studied by 1H NMR, FT-IR and ESI MS measurements; meso-(pyrazol-4-yl)porphyrin and meso-(3,5-dimethylpyrazol-4-yl)porphyrin form a dimer and a tetramer, respectively, in solution due to intermolecular hydrogen bonding between pyrazole units.

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Iron(II) and Nickel(II) Mixed-Complexes Containing 1,10-Phenanthroline and 4,7-Diphenyl-1,10-phenanthroline

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Transition Metal Chemistry Vol. 24 ( 2 ) 210 - 217 1999.06

Research paper (scientific journal), Joint Work, Accepted

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Two types of mixed-ligand complexes, i.e. [M(phen)2 (dip)]2+ and [M(phen)(dip)2]2+ (M = iron(II) and nickel(II); phen = 1,10-phenanthroline and dip = 4,7-diphenyl-1,10-phenanthroline) have been prepared from their related tris-complexes, [M(phen)3]2+ by ligand substitution, and isolated by semi-preparative HPLC. Elemental and chromatographic analyses confirm the purity of the isolated complexes while u.v./vis and i.r. spectra were used to identify and characterize them. 1H-n.m.r. and room temperature Mössbauer spectra of the iron(III) complexes were also measured and the results are discussed. In addition, our preliminary results on hypochromicity in the MLCT band and circular dihroism (CD) emerging in the u.v./vis region upon addition of CT(calf thymus)-DNA to the racemic complexes indicated that the iron(II) mixed-ligand complexes interact with CT-DNA.

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Polymerization of (p-Vinylphenyl) hydrogalvinoxyl and Formation of a Stable Polyradical Derivative

KANEKO TAKASHI, TATSUMI HIROYUKI, AOKI TOSHIKI, OIKAWA EIZO, YOSHIOKI HAJIME, YOSHIOKA NAOKI, TSUCHIDA EISHUN, NISHIDE HIROYUKI

Journal of Polymer Science, Part A Polymer Chemistry 37 ( 2 ) 189 - 198 1999.01

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4‐[(3,5‐Di‐tert‐butyl‐4‐hydroxyphenyl)(3,5‐di‐tert‐butyl‐4‐oxo‐cyclohexa‐ 2,5‐dienylidene)methyl]styrene (abbreviated as (p‐vinylphenyl)hydrogalvinoxyl) was polymerized using AIBN as an initiator to give a bright yellow polymer with Mw = 3.2 × 104. The polymer was oxidized to give the corresponding polyradical derivative, whose spin concentration could be increased up to about 70 mol % depending on oxidative conditions. ESR signal line‐width in the solid state was greatly increased below 200 K for the polyradical with a high spin concentration (> 50 mol %). The magnetization and magnetic susceptibility indicated weak antiferromagnetic interaction among the radical sites.

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Magnetic Properties of Polynuclear Oxovanadium(Ⅳ) Complexes with Tetradetate Schiff Base Ligands

TSUCHIMOTO MASANOBU, YOSHIOKA NAOKI

Chemical Physics Letters 297 ( 1-2 ) 115 - 120 1998.11

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Temperature dependence measurements of magnetic susceptibilities and low-temperature magnetization of tetradentate Schiff base–oxovanadium(IV) complexes, [VO(salpn)] (1), [VO(5-NO2salen)]·2H2O (2), and [VO(3-EtOsal-meso-stien)]·H2O (3) were carried out. Orange 1 and brown 2, which take linear chain structures (VO⋯VO⋯) in the solid state, show dominant ferromagnetic intermolecular interactions (J=+5.2 and +5.7 cm−1, respectively) on which very weak antiferromagnetic interactions between the chains are superimposed. However, green 3, which takes a fairly elongated linear chain structure (V⋯O distance: 4.060(2) Å) in the crystal, shows an isolated doublet state.

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Magnetic Properties of Nitronyl Nitroxide Derivatives Bearing N-H Site: An Approach to Ferromagnetic Self-Assemblies Using Hydrogen Bond

Naoki Yoshioka, N. Matsuoka, Munetoshi Irisawa, Shigeru Ohba, Hidenari Inoue

Molecular Crystals and Liquid Crystals 334   239-246 1998.10

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N-H水素結合部位を有するニトロニルニトロキシドラジカルの磁気特性に対するイミダゾール導入置換基の影響を報告した。（９頁）

Mossbauer Spectroscopic Characterization of the Light-Induced Mixed-Valence State in Fe[Fe(CN)5NO]・xH2O

INOUE HIDENARI, YOSHIOKA NAOKI, MORIOKA YOSHIYUKI

Hyperfine　Interactions (C) 3   113 - 116 1998.08

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Fe[Fe(CN)5NO]・xH2Oに光照射した際に観測される磁気特性の変化を報告した.

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

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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−).

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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

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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.

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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

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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.

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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

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

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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

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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).

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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

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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.

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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

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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.

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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

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

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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Poly (phenylvinylene) and Poly(phenylenevinylene) with Nitroxide Radicals

NISHIDE HIROYUKI, KANEKO TAKASHI, KUZUMAKI YOSHIHIRO, YOSHIOKA NAOKI, TSUCHIDA EISHUN

Molecular Crystals and Liquid Crystals, Section A. 232 ( 1 ) 143 - 150 1993.12

Research paper (scientific journal), Joint Work, Accepted

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Poly(phenylvinylene) and poly(phenylenevinylene) with tert-butyInitroxide as a built-in radical group were synthesized. Precursor polymers were obtained by the polymerization of the corresponding acetylene and styrene derivatives by Rh and Pd catalysts. They were soluble in common solvents and their chemical oxidation under moderate condition gave the corresponding polyradicals.

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Poly[[4-(N-tert-butyl-N-hydroxyamino)phenyl]acetylene] and the Magnetic Property of its Radical　Derivative

NISHIDE HIROYUKI, KANEKO TAKASHI, YOSHIOKA NAOKI, AKIYAMA HARUHISA, IGARASHI MASUKAZU, TSUCHIDA EISHUN

Macromolecules 26 ( 17 ) 4567 - 4571 1993.08

Research paper (scientific journal), Joint Work, Accepted

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[4-(N-tert-Butyl-N-hydroxyamino)phenyl]acetylene (7) was synthesized and polymerized to yield a solvent-soluble polyacetylene: poly [[4-(N-tert-butyl-N-hydroxyamino)phenyl] acetylene] (8). Oxidation of the polymer gave its radical derivative: the ESR spectrum showed a broad signal only in the delta ms = ±1 region, and magnetic measurement with a SQUID magnetometer revealed an antiferromagnetic through space interaction.

Polymerization and Photoinitiation Behavior in the Light-Cured Dental Composite Resins

FUJIMORI YUKIO, KANEKO TAKASHI, KAKU TAKAHIKO, YOSHIOKA NAOKI, NISHIDE HIROYUKI, TSUCHIDA EISHUN

Polymers for Advanced Technologies 3 ( 8 ) 437 - 441 1992.12

Research paper (scientific journal), Joint Work, Accepted

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The polymerization behavior and photoinitiation process in the visible light‐cured dental composite resins were studied using ESR and IR spectroscopies. The concentration of methacryl propagating radical corresponded to the transmittance of irradiated light. While the radical was stable and long‐lived in the cured resin, its concentration quickly decreased in the oral cavity due to the ventilation of atmospheric oxygen accompanied by respiration. Camphorquinone radical in the presence of tertiary amine easily initiated the radical polymerization. A decrease in monomer consumption was explained by the inhibition effect of oxygen in the photoinitiation process. Post‐curing by the residual radical proceeded effectively in the deeper part of the resin.

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Synthesis and Magnetic Property of Polyacetylene Bearing pi-Conjugated Bis (diphenylene) phenylallyl Radical

NISHIDE HIROYUKI, YOSHIOKA NAOKI, SAITOH YUKOH, GOTOH RITSUKO, MIYAKAWA TAKESHI, TSUCHIDA EISHUN

Journal of Macromolecular Science-Pure and Applied Chemistry A29 ( 9 ) 775 - 786 1992.07

Research paper (scientific journal), Joint Work, Accepted

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m- and p Bis(diphenylene)propenylphenylacetylene (m-, p-8) were synthesized and polymerized with WCI6, MoCl5, and Rh catalyst, yielding solvent-soluble poly(phenylacetylene)s bearing a π-conjugated bis(di-phenylene)propenyl groups (m-, p-7a). The polymers gave their polyanion derivatives, which were electrolytically and chemically oxidized to yield the corresponding polyradicals (m-, p-7b). The polyradicals were chemically very stable due to the resonance stabilization of an unpaired electron whose spin concentration could be increased up to ca. 2 × 1023 spins per molar monomer unit. ESR spectroscopy suggested an antiferro-magnetic interaction between unpaired electrons.

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Poly[(p-ethynylphenyl)hydrogalvinoxyl]　and its Polyradical Derivative with High Spin Concentration

YOSHIOKA NAOKI, NISHIDE HIROYUKI, KANEKO TAKASHI, YOSHIKI HAJIME, TSUCHIDA EISHUN

Macromolecules 25 ( 15 ) 3838 - 3442 1992.07

Research paper (scientific journal), Joint Work, Accepted

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[4-[(3,5-Di-tert-butyl-4-hydroxyphenyl) (3,5-di-tert-butyl -4-oxocyclohexa-2,5-dien-1-ylidene) -methyl]pheny l ]acetylene (6), was synthesized and polymerized to yield a solvent-soluble polyacetylene poly-[[4-[3,5-di-tert -butyl-4-hydroxyphenyl) (3,5-di-tert-butyl-4 -oxocyclohexa-2,5-dien-1-ylidene) methyl]phenyl ] acetylene] (5a). The polymer gave its polyradical derivative 5b through the chemical oxidation with active PbO2. 5b was stable, whose spin concentration could be increased up to 4.8 × 1023 spins per molar monomer unit. ESR analysis indicated localization of unpaired electrons in the galvinoxyl residue. ESR analysis also suggested an exchange-narrowing and interpolymer dipole-dipole interaction.

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歯科用高分子中でのラジカル生成量と硬化特性

藤森行雄、加来恭彦、吉岡直樹、西出宏之、土田英俊

高分子論文集 49 ( 6 ) 509 - 512 1992.06

Research paper (scientific journal), Joint Work, Accepted

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光硬化型歯科用コンポジットレジン中のアクリレートモノマーの重合挙動を, 硬化体中に残存するラジカル濃度とモノマー二重結合のESR及びIR定量から考察した. 光照射により硬化体中にはメタクリル生長ラジカルが検出され, その濃度は光到達度に対応した. 生長ラジカルは極めて安定に硬化体中に残存したが, 温度が高く換気十分な口腔内では速やかに減少した. 一方, モノマー二重結合消費率は硬化体表面では酸素により, また深部では低い光透過により減少した. 重合率の経時変化から, 残存ラジカル種の後反応によって硬化体深部で重合が進行し, 硬度が維持されていることが示された.

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Effect of Ultrasonic Irradiation on　Luminescence Properties of Lanthanide-Polyelectrolyte Complexes

KIDO JUNJI, OKAMOTO YOSHIO, YOSHIOKA NAOKI, NISHIDE HIROYUKI, TSUCHIDA EISHUN

Polymer 33 ( 11 ) 2273 - 2276 1992.03

Research paper (scientific journal), Joint Work, Accepted

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Luminescence properties of Tb3+ - or Eu3+-polycarboxylate complexes in aqueous solution were investigated. The excitation bands near 300 nm for terbium- or europium-polyacrylate solutions were drastically enhanced by the addition of hydroxyl-radical generating reagents as well as ultrasonic irradiation. These spectral changes were attributed to the energy transfer from chromophore molecules formed by the hydroxyl radicals generated in both systems.

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Poly[(3,5-di-tert-butyl-4-hydroxyphenyl)acetylene] and Its Polyradical Derivative

NISHIDE HIROYUKI, YOSHIOKA NAOKI, INAGAKI KATSUNARI, KAKU TAKAHIKO, TSUCHIDA EISHUN

Macromolecules 25 ( 2 ) 569 - 575 1992.01

Research paper (scientific journal), Joint Work, Accepted

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(3,5-Di-tert-butyl-4-hydroxyphenyl)acetylene (8) was synthesized and polymerized with WCIs and MoCl5, giving a novel and solvent-soluble conjugated polymer, poly[(3,5-di-tert-butyl-4-hydroxyphenyl)acetylene] (3). Visible absorption of the polymer indicated a fairly long π-conjugated system along the main chain. The polymer yielded its polyanion 10 and polyradical derivative 4 after the treatment of its solution with an alkali and oxidizing reagent, respectively. The polyradical 4 was surprisingly stable, and spin concentration was increased up to 2.3 × 1023 spins/molar (hydroxyphenyl)acetylene residue. ESR spectra of the polyradical 4 in solution suggested that the formed unpaired electrons were delocalized along the polyacetylene main chain. 4 was also very stable even in solid state. Spin-exchange interaction observed in 4 strongly depended on its spin concentration. Antiferromagnetic interaction between the unpaired electrons was suggested from the temperature dependency of the ESR signal intensity.

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Synthesis and Magnetic Properties of Conjugated Stable Polyradicals

NISHIDE HIROYUKI, YOSHIOKA NAOKI, KAKU TAKAHIKO, YAMAZAKI MASANORI, TSUCHIDA EISHUN

Journal of Macromolecular Science-Chemistry 28 ( 11-12 ) 1177 - 1187 1991.12

Research paper (scientific journal), Joint Work, Accepted

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ynthesis and magnetic properties of π-conjugated stable polyradicals bearing a polyacetylene backbone are described. 2,6-Di-tert-butyl-4-ethynylphenol (8) and 4-ethynylphenylhydrogalvinoxyl (9) are polymerized with W, Mo chloride or Rh complex to yield their polyacetylene derivatives with molecular weight of ca. 10^4, while 2-ethynylphenalenone (10) gives only its oligomer. The polymers are soluble in common solvents and converted to the corresponding conjugated polyradicals via heterogeneous chemical oxidation using PbO2 or alkaline K3Fe(CN)6. The polyradicals with extremely high spin concentration (up to 4.8 × 10^23 spins/monomer mol) are obtained by regulating the oxidative conditions. The polyradicals are quite stable in solution and even in the solid state because of resonance stabilization and/or a steric effect of the substituents. Magnetic interactions between the unpaired spins in the conjugated stable polyradicals are discussed.

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UPS Spectra of the Polyacetylene Derivatives Carrying Stable Radical Substituents

YOSHIOKA NAOKI, NISHIDE HIROYUKI, KAKU TAKAHIKO, KANEKO TAKASHI, TSUCHIDA EISHUN, NARIOKA SATORU, SEKI KAZUHIKO

Polymer Journal 23 ( 7 ) 921 - 924 1991.07

Research paper (scientific journal), Joint Work, Accepted

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側鎖に安定有機ラジカルを有するポリアセチレンの光電子スペクトルの解析結果について報告した。

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Magnetic Properties of Conjugated Phenoxy Polyradicals

NISHIDE HIROYUKI, YOSHIOKA NAOKI, TSUCHIDA EISHUN

Journal of Macromolecular Science-Chemistry 27 ( 9-11 ) 1261 - 1273 1990.11

Research paper (scientific journal), Joint Work, Accepted

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Formation and magnetic properties of ?r-conjugated phenoxy radicals bearing a porphyrin macrocycle or a polyacetylenic backbone are described. Tetrakis(3,5-di-t-butyl-4-hydroxyphenyl)porphinatometals (7-M) [M = Zn(II), VO(II), and Cu(II)] were oxidized to give the corresponding stable monoradical and biradical. Magnetic properties of the radical species depend on the magnetic orbital of the central metal ion. ESR hfs structure reveals that the biradical for 7-Zn and -VO are in the triplet (S = 1) and quartet state (S = 3/2), respectively. Poly(3,5-di-t-butyl-4-hydroxyphenylacetylene) (8) and poly(pethynylphenylhydrogalvinoxy1) (9) with molecular weights of %lo4 are characterized. ESR spectra with hyperfine structure for 8 indicate that the phenoxy radicals are conjugated with the polyacetylenic main chain over ~7 monomer units as a“neutral soliton.” Formed polyradicals for 8 and 9 are surprisingly stable, even in the solid state, due to resonance stabilization and/or steric effect of the conjugated main chain. An antiferromagnetic interaction is observed for oxidized 8 with a spin concentration above 10 mol%.

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Poly(p-ethynylphenyl)galvinoxyl: Formation of a New Conjugated Polyradical with an Extraordinarily High Spin Concentration

NISHIDE HIROYUKI, YOSHIOKA NAOKI, KANEKO TAKASHI, TSUCHIDA EISHUN

Macromolecules 23 ( 20 ) 4487 - 4488 1990.10

Research paper (scientific journal), Joint Work, Accepted

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This paper describes the synthesis of poly-[4-[(3,5-di-tert-butyl-4-hydroxyphenyl) (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-yldene) methyl]phenylacetylene] (abbreviated as poly[(p-ethylphenyl)hydrogalvinoxyl]) (4) and also the formation of its polyradical macromolecule, 5, through chemical oxidation. 5 is one of the model polymers with an indirect magnetic interaction; the unpaired electron is mainly localized at the phenylgalvinoxyl side chain, whose spin density is distributed mainly over the galvinoxyl substituent, but also over the phenyl ring to some extent by a spin polarization mechanism.

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Magnetic Interaction Observed in the Polyacetylenic Derivatives with High Spin Concentration

YOSHIOKA NAOKI, NISHIDE HIROYUKI, TSUCHIDA EISHUN

Molecular Crystals and Liquid Crystals 190 ( 1 ) 45 - 53 1990.10

Research paper (scientific journal), Joint Work, Accepted

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Electronic state and magnetic interaction of π-conjugated phenoxy radicals bearing a polyacetylenic backborn are described. Poly(3,5-di-t-butyl-4-hydroxyphenylacetylene) (7a) and poly(p-ethynyl-phenylhydrogalvinoxyl) (8a) with molecular weight ca. 10^4 are characterized. ESR spectra with hyperfine structure for the chemically oxidized 7b indicate that the phenoxy radical conjugates through the polyacetylenic main chain over ca. 7 monomer units as a “neutral soliton.” Polyradicals 7b and 8b are surprisingly stable even in the solid state, because of a resonance stabilization and/or a steric effect of the conjugated main chain. An antiferromagnetic interaction is observed for 7b with spin concentration above 10 mol%. Mechanism of the magnetic interaction is discussed.

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Electrical Conductive and Magnetic Properties of Conjugated Tetrathiolate Nickel Polymers

YOSHIOKA NAOKI, NISHIDE HIROYUKI, INAGAKI KATSUNARI, TSUCHIDA EISHUN

Polymer Bulletin (Springer)  23 ( 6 ) 631 - 636 1990.06

Research paper (scientific journal), Joint Work, Accepted

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Three tetrathiolate (tetrathiafulvalenetetrathiolate, ethylenetetrathiolate, and butadienetetrathiolate) nickel polymers are prepared. The polymers contain mixed valence Ni ions and are ESR active based on low-spin d8 Ni (III) species. Magnetic susceptibility measurement in the range of 30–60 K suggests and antiferromagnetic interaction between the Ni ions in the polymers. Below 30K a weak ferromagnetic interaction is observed. Chemically oxidized polymers are ESR inactive, while electrical conductivity is greatly enhanced.

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UV Curing of Acrylate Monomers Activated with Resol Resin

YOSHIOKA NAOKI, Dwi Wahini Nurhajati, NISHIDE HIROYUKI, TSUCHIDA EISHUN, KASAI MASANORI

Journal of Photopolymer Science and Technology 2 ( 2 ) 231 - 236 1989.06

Research paper (scientific journal), Joint Work, Accepted

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UV Curing behavior of acrylate monomers in the presence of resol is described. A thin layer consist of resol, monofunctional acrylate (ECA), and hexafunctional acrylate (DPCA-60) gives the crosslinked polymer under UV irradiation. IR spectra of the crosslinked polymer show characteristic absorptions due to both resol and acrylate with a decrease of v C=C′ which indicates the additional polymerization takes place in this system. The curing is accelerated by addition of alkali, which suggests the phenol structure is active site for the polymerization. Among several kinds of alkali investigated, Ba(OH)2 is most effective for the reaction from the point of insoluble polymer yield. Consumption of acrylate double bond in the insoluble polymer ranges above 60% which decreases slowly with an increase in the DPCA-60 content due to steric hindrance. The synergic effect of Ba(OH)2 appears when it is added 0.1mol% for hydroxy group in the resol. UV irradiation leads to color change of the cured layer from pale yellow to reddish violet (λmax =570nm) with an appearance of ESR signal at g =2.004, which indicates the formation of phenoxy radical. The phenoxy radical formed in the resol should be an active site for UV polymerization of this system.

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Coordination Structure and Magnetic Property of Poly(pyridilenemethylidenen nitriloiron)s

NISHIDE HIROYUKI, YOSHIOKA NAOKI, TSUCHIDA EISHUN, INOUE HIDENARI

Journal of Polymer Science, Part A, Polymer Chemistry Edition 27 ( 2 ) 497 - 505 1989.01

Research paper (scientific journal), Joint Work, Accepted

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Poly[bis(2,6‐pyridinediylmethylidenenitrilohexamethylenenitrilomethylidene)iron sulfate] was said to be a ferromagnetic compound by earlier investigators. This polymer and its derivatives are carefully reprepared and their unusual magnetic property is reinvestigated spectroscopically. The counter anion species and spacer length of the polymers affect their coordination structure and magnetism. Mössbauer spectroscopy and x‐ray diffractometry on the polymers indicate that their unusual magnetic property is caused by the ferromagnetic iron oxide slightly formed in the polymers.

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Poly[(3,5-di-tert-butyl-4-hydroxyphenyl)acetylene]: Formation of a Conjugated Stable Polyradical

NISHIDE HIROYUKI, YOSHIOKA NAOKI, INAGAKI KATSUNARI, TSUCHIDA EISHUN

Macromolecules 21 ( 10 ) 3119 - 3120 1988.10

Research paper (scientific journal), Joint Work, Accepted

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description is given of the synthesis of poly[(3,5-di-tert-butyl-4-hydroxyphenyl)acetylene] (1) and the formation of its polyradical. Experimental data shows that the absorption intensity of the oxidized 1 solution suggests formation of the phenoxy radical of 1 in high concentration and stays constant upon standing at room temperature over a day. This radical formation of 1 is in contrast to the radical formation of the corresponding low molecular phenols, e.g. 3,5-di-tert-butyl-4-hydroxycinnamate; the latter had been reported to give bisquinone methides irreversibly. The sterically crowded structure of 1 probably suppresses bond formation between unpaired electrons.

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Complexation of Gadolinium Ion with Poly(methacrylic acid)s and Magnetic Properties of the Complexes

YOSHIOKA NAOKI, NISHIDE HIROYUKI, TSUCHIDA EISHUN

Inorganica Chemica Acta 128 ( 1 ) 135 - 138 1987.04

Research paper (scientific journal), Joint Work, Accepted

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The complexation of gadolinium (Gd3+) ion with poly(methacrylic acid) and its copolymers was studied. Poly(methacrylic acid-co-acrylamide) formed the tris(carboxylate)-coordinate gadolinium complex with an extra large complex formation constant, while poly(methacrylic acid) formed the biscoordinate complex. Transparent and flexible film containing a high proportion of Gd ion was prepared by casting the complex solution of poly(methacrylic acid-co-methylacrylate). The complexed Gd ion was uniformly dispersed in the film and showed paramagnetism. The formation and magnetic properties of the polymer-Gd complexes are discussed in comparison with those of the corresponding iron complexes.

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Complexation Constants of Lanthanide Ions with Poly (Methacrylic Acid) and Its Copolymers

NISHIDE HIROYUKI, IZUSHI TADAHIKO, ARAI AKEMI,TSUCHIDA EISHUN

Journal of Macromolecular Science-Chemistry (Taylor & Francis)  24 ( 3-4 ) 343 - 351 1987.03

Research paper (scientific journal), Joint Work, Accepted

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Complexation of some lanthanide ions with poly(methacry1ic acid) and its copolymers was studied by potentiometric titration. Poly [methacrylic acid-co-oligo(ethy1ene oxide)rnethacrylate] and poly(methacrylic acid-co-acrylamide) formed tris-carboxylate coordinate lanthanide complexes with large overall complexation constants, while poly(methacrylic acid)s and copolymer with higher content of the methacrylic acid residue formed bis-coordinate ones. It was concluded that the comonomer residues in the copolymer chains decreased the steric hindrance for the complexation and/or acted as co-coordinating groups of the carboxylic group to lanthanide ions. Very large positive and favorable entropy changes were observed for the complexation with poly(methacry1ic acid) and its copolymers. This contribution of thermodynamic parameters to the complexation was contrary to that for the analogous monomeric methacrylic acid complex and is assumed to be induced by dehydration of the polymers through the lanthanide ion complexation.

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Complexation of Europium Ion with Poly(Methacrylic Acid)s and Fluorescent Property of the Complexes

NISHIDE HIROYUKI, IZUSHI TADAHIKO, YOSHIOKA NAOKI, TSUCHIDA EISHUN

Polymer Bulletin (Springer)  14 ( 5 ) 387 - 392 1985.11

Research paper (scientific journal), Joint Work, Accepted

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The complexation of europium ion(Eu3+) with poly(methacrylic acid) and its copolymers was studied. Poly(methacrylic acid-co-acrylamide) formed the tris(carboxylate)-coordinate Eu complex with extra large overall complexation constant while poly(methacrylic acid)s did the bis-coordinate ones. Transparent and flexible film containing much Eu ion was prepared by casting the complex solution of poly(methacrylic acid-co-methylacrylate). On exposure to ultraviolet light (393 nm), the film relatively strongly fluorescenced a red color based on the tris-coordinate and uniformly dispersed Eu complex.

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ポリメタクリル酸－ガドリニウム錯体の合成と性質

吉岡直樹、出石忠彦、西出宏之、篠原　功、土田英俊、渡辺　強、近　桂一郎

高分子論文集 42 ( 5 ) 301 - 304 1985.05

Research paper (scientific journal), Joint Work, Accepted

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メタクリル酸-メチルアクリラート共重合体 (モル組成比約1: 3) とガドリニウムの錯体は, 溶媒キャスト法によりGd3+含量が多く, かつ柔軟で透明な膜を与えた. 錯形成したGd3+は常磁性 (室温, 2.7×10-2emu mol-1) で, 膜中に均一に分散していることを確認した。

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