Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 57 , Issue 11
Showing 1-50 articles out of 73 articles from the selected issue
  • Yoshio Yamada, Minoru Shiraishi, Takeshi Furuta, Toshio Yamakawa, Yuzo ...
    1984 Volume 57 Issue 11 Pages 3027-3031
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    The effect of hydrogenation of carbonized pitch on its solubility in quinoline was investigated in connection with structural changes of the pitch during carbonization. Naphtha-tar pitch (NTP) and acenaphthylene were carbonized at 673 and 703 K, respectively, for various periods of time. The pitches thus heat-treated were hydrogenated by BenKeser reaction and the amount of quinoline insolubles (QI) in the hydrogenated pitch was determined. An acenaphthylene pitch (ACP) heat-treated for 24 h was rendered completely soluble into quinoline by the hydrogenation, whereas a considerable amount of insolubles was left in the case of NTP treated for longer residence times than 8 h. This can be explained in terms of the difference in interaction among aromatic molecules constituting the QI components derived from NTP and ACP. ACPs doped with elemental sulfur left a significant quantity of QI after the hydrogenation. The addition of sulfur is considered to form crosslinking bonds between aromatic molecules through hydrogen abstraction by the sulfur. When QI separated from carbonized NTP was hydrogenated, the degree of conversion into quinoline solubles (QS) was low as compared with that for the whole sample of the same NTP. The presence of QS in the pitch plays a very important role for the hydrogenation.
  • Noriyuki Sotani, Noritetsu Yoshida, Yoji Kawamoto, Shozo Kishimoto, Ma ...
    1984 Volume 57 Issue 11 Pages 3032-3035
    Published: 1984
    Released: June 27, 2006
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    The decomposition process of orthorhombic hydrogen molybdenum bronze, H0.30MoO3, was studied by the temperature programmed decomposition (TPD) technique in vacuo and in helium gas. The only gas liberated during the decomposition was H2O and no other gas was detected. The TPD spectrum above 150 °C was composed of three bands (PII, PIII, and PIV). The PII band corresponded to the process from H0.30MoO3 to H0.21MoO2.95 without any structural change. The PIII band corresponded to the process from H0.21MoO2.95 to H0.06MoO2.88 with the structural change and the PIV band, to the process from H0.06MoO2.88 to MoO2.85.
  • Masahiko Hasunuma, Keiko Okada, Yoshifumi Kato
    1984 Volume 57 Issue 11 Pages 3036-3042
    Published: 1984
    Released: June 27, 2006
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    The (f,f*) transitions of europium tris(bromate) enneahydrate crystal between 12000 and 20000 cm−1 were measured at 95 K by laser-excited fluorescence spectroscopy. The crystal field components of the ground (7F0.1···6) and the excited states (5D0.1) participating in the transitions were analyzed in terms of the tensor-operator method. Besides electric-dipole transitions, a number of magnetic-dipole transitions were detected in compliance with the selection rule. The theory could reproduce the observed wavenumbers and intensities both for the σ- and π-transitions. The population ratio of the 5D0 to the 5D1 was estimated to be 14.1 from the intensity calculations and the observed results. The result suggests that mixing of g-orbitals is significant for the forced electric-dipole transitions.
  • Kikujiro Ishii, Kyuya Yakushi, Haruo Kuroda, Hiroo Inokuchi
    1984 Volume 57 Issue 11 Pages 3043-3047
    Published: 1984
    Released: June 27, 2006
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    Crystal absorption spectra of the two modifications of the perylene-TCNQ (7,7,8,8-tetracyanoquinodimethan) complex were derived from reflection spectra by the Kramers-Kronig transformation and are discussed in relation to the differences in the crystal structures. The spectral response of photoconduction does not show any efficient photocarrier generation in the lowest charge-transfer band region in either modification. However, the rise of the photocurrent of both modifications was found to obey an empirical equation, Y(EEth)2.5, where Y is the quantum yield of the photocarrier generation, E is the photon energy, and Eth is the threshold energy. Eth of the two modifications is almost the same and falls in the energy region a little above the lowest charge-transfer band. Efficiencies of the carrier generation, on the other hand, are quite different for the two modifications. These photoelectrical characters are discussed in connection with the optical spectra and also with the data of photoelectron emission.
  • Isao Oonishi, Shoji Fujisawa, Junji Aoki, Yuji Ohashi, Yoshio Sasada
    1984 Volume 57 Issue 11 Pages 3048-3051
    Published: 1984
    Released: June 27, 2006
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    Crystals of the title compound, C21H12O, are orthorhombic, belong to the space group Pn21a, have lattice constants of a=14.227(3), b=15.551(4), c=12.436(3) Å, and also have Z=8. The structure was determined using the direct method and was refined by using a full-matrix least-squares method to an R value of 0.106 on the basis of 1964 reflections with |Fo|>3σ(|Fo|). The molecules is slightly distorted from the planar conformation owing to a steric repulsion between the O and H atoms. The molecules are stacked in pairs and two pairs with different overlapping modes are randomly arranged with different populations. It has been qualitatively explained that the populations of disordered molecules reflect the difference in their lattice energies.
  • Noriyuki Kato, Tetsuo Miyazaki, Yukihiro Kawai, Kenji Fueki
    1984 Volume 57 Issue 11 Pages 3052-3057
    Published: 1984
    Released: June 27, 2006
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    The decay-rate constants, k, of dipentyl disulfide anions or benzyl radicals in 1-propanol and ethanol were measured over a temperature range of 107–230 K by pulse- and γ-radiolysis method. The decay-rate constants were found to range over nine orders of magnitude. The decay kinetics is a composite first-order reaction. Since the decay rates of reaction intermediates observed are diffusion-controlled, the decay-rate constants represent directly the rates of molecular transport in the supercooled liquids. It was found that the temperature dependence of the decay-rate constants could be expressed by the following equation.
    log\frackT=−\fracATTg+B,
    where T is the absolute temperature, A and B are constants. Tg is the glass transition temperature. The molecular diffusion of the ions or radicals in the supercooled liquids was completely suppressed at the glass transition temperature. The temperature dependence of the decay-rate constant was compared with that of the viscosity of the matrix. It was found that the temperature, at which the molecular diffusion is completely suppressed is much higher than the temperature at which the viscosity is infinite.
  • Junichi Furukawa, Shigeo Murata, Minoru Sakiyama, Syûzô Se ...
    1984 Volume 57 Issue 11 Pages 3058-3061
    Published: 1984
    Released: June 27, 2006
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    Standard enthalpies of combustion and of sublimation at 298.15 K were determined and standard enthalpies of formation in crystalline and gaseous states were derived for N,N-dimethyl-3- and N,N-dimethyl-4-nitroanilines by calorimetric measurements. Stabilization energies due to the intramolecular interaction between substituents were evaluated and discussed for these compounds and 3- and 4-nitroanilines.
  • Yoshiro Ito, Shigeyoshi Arai
    1984 Volume 57 Issue 11 Pages 3062-3065
    Published: 1984
    Released: June 27, 2006
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    Excited diatomic molecules of krypton and xenon in 13Σu+ states, Kr2* and Xe2*, were produced by irradiating krypton and xenon in the presence of an excess of argon with short electron-beam pulses. The kinetic behaviors of Kr2* and Xe2* (monitored by near-IR absorption spectrophotometry) are explained quantitatively in terms of mechanisms involving three-body association and radiative decay. The rate constants were found to be (6.5±0.8)×10−33 cm6s−1 for Kr*+Kr+Ar→Kr2*+Ar and (1.6±0.3)×10−32 cm6 s−1 for Xe*+Xe+Ar→Xe2*+Ar. The rate constants for the quenching reactions of Kr2* were determined for Xe, H2, O2, N2, CO, and NO.
  • Yoshio Nosaka, Yutaka Ishizuka, Kohji Norimatsu, Hajime Miyama
    1984 Volume 57 Issue 11 Pages 3066-3069
    Published: 1984
    Released: June 27, 2006
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    Ammonia was formed photocatalytically from an aqueous solution of azide ion by using illuminated Pt/TiO2 semiconductor powder. The reaction products, NH3, N2, and small amounts of N2O and NO3, were detected. Hydrogen, O2 and N2H4 were not formed in the primary reaction products. From these results, together with photoelectrochemical measurements, a mechanism of the ammonia formation from azide ion and water is presented.
  • Midori Takimoto, Akio Takenaka, Yoshio Sasada
    1984 Volume 57 Issue 11 Pages 3070-3073
    Published: 1984
    Released: June 27, 2006
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    3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide has been synthesized as a model for studying the interaction between cyclic ureide and adenine, and its crystal structure examined. The crystals are monoclinic, the space group P21/c, with unit-cell dimensions of a=10.861(1), b=12.766(1), c=9.753(1) Å, β=91.10(1)°, and Z=4. The ureide moiety is hydrogen bonded to adenine with NH···N(1) (2.903(3) Å) and O···HN(6) (2.955(3) Å). A comparison of the hydrogen bonding patterns of the related compounds with adenine suggests that cyclic ureide anticonvulsant drugs possess the capability of interacting with N(1) and N(6) sites of adenine.
  • Kenjiro Hayashi, Yoshiaki Sasaki, Shigehiro Inomata, Takagimi Yanagida ...
    1984 Volume 57 Issue 11 Pages 3074-3076
    Published: 1984
    Released: June 27, 2006
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    The overall formation constants, β3, of cadmium(II) and zinc(II) complexes with alkyl xanthates (O-alkyl dithiocarbonates) were determined by polarography in the 1:1 v/v water–N,N-dimethylformamide mixture. The values of these constants increase in the order, methyl<ethyl<propyl<butyl<2-methylpropyl<1-methylethyl xanthate. This order agrees entirely with the order of the basicity of alkyl xanthates determined by using the kinetic parameter of the acid decomposition of xanthates.
  • Hiroyuki Nariai, Yoshitaka Masuda, Eiichi Sekido
    1984 Volume 57 Issue 11 Pages 3077-3082
    Published: 1984
    Released: June 27, 2006
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    Bivalent metal complexes of cobalt(II), nickel(II), copper(II), and zinc(II) with 2-methyl-8-quinolinol (2MeHql) were prepared. Their properties, such as those shown by thermogravimetry (TG) and differential thermal analysis (DTA), X-ray diffraction, magnetic susceptibility, and the optical spectra, were measured and compared with those of 8-quinolinolato complexes. All the metal complexes prepared here are monohydrates, whereas their 8-quinolinolato complexes are dihydrates. The methyl group at the 2-position of the quinoline ring caused a shift of about 40–80 °C in the dehydration temperature, and, as a result of the dehydration, a dimer anhydrate was produced. The dimer-formation conditions were established in chloroform and dioxane solutions. However, the addition of such basic solvents as pyridine, water, and methanol cleaved the bridge linkages in complexes and produced a distorted octahedral configuration by solvent-binding in the axial position. The existence of a copper complex with a dimer structure such as has been shown in other metal complexes was not verified in any of the solvents used here.
  • Tatsuya Sekine, Kazuho Inaba
    1984 Volume 57 Issue 11 Pages 3083-3087
    Published: 1984
    Released: June 27, 2006
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    The ligand of tris(β-diketonato)iron(III) with acetylacetone (Hacac), trifluoroacetylacetone (Htfa), or 2-thenoyltrifluoroacetone (Htta) in carbon tetrachloride was exchanged with another ligand among these. The rate was measured in order to learn about the reaction mechanism in this medium; one in which no intermediates with the solvent molecules were expected. From the dependence of the rate on the particular leaving and entering ligand and from the values of ΔH\ eweq and ΔS\ eweq, it was concluded that in an exchange involving [Fe(acac)3] there is always a proceeding dissociative mechanism and for [Fe(tta)3] and [Fe(tfa)3] with Hacac there is an interchange mechanism. Exchanges with a fluorinated β-diketone is thought to have a character intermediate to these two mechanisms.
  • Minoru Ishii
    1984 Volume 57 Issue 11 Pages 3088-3093
    Published: 1984
    Released: June 27, 2006
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    The mixed ligand complex {N-(2-aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) was prepared. Of the five possible geometrical isomers, two were isolated by column chromatography; their formation ratio was ca. 6:4. Both isomers were completely resolved by chromatography. Their configurations were assigned to the meridional type on the basis of electronic, infrared, and circular dichroism spectroscopy, and the X-ray analysis data.
  • Minoru Ishii, Shoichi Sato, Yoshihiko Saito, Masayoshi Nakahara
    1984 Volume 57 Issue 11 Pages 3094-3098
    Published: 1984
    Released: June 27, 2006
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    The crystal structure of (−)474CD mer-[Co{N-(2-aminoethyl)-1,3-propanediamine}(diethylenetriamine)]I3·H2O has been determined by means of X-ray diffraction. The crystal is monoclinic, with a space group of P21, a=9.662(2), b=14.602(2), c=8.201(3), β=112.87(4)°, and Z=2. The structure was solved by the Patterson-Fourier method and refined by the full-matrix least-squares method, which yielded an R value of 0.060 for the 2441 observed reflections. Each ligand molecule acts as a terdentate with meridional configurations. The absolute configuration of the coordinated asymmetric nitrogen atom in N-(2-aminoethyl)-1,3-propanediamine was determined to be R. The six-membered chelate ring in N-(2-aminoethyl)-1,3-propanediamine adopts a chair conformation, and the conformation of the five-membered chelate ring is δ. The conformations of the two five-membered chelate rings formed by diethylenetriamine are δ and λ, and the N(secondary)-H bond is oriented toward the six-membered chelate ring formed by N-(2-aminoethyl)-1,3-propanediamine.
  • Yoshihiro Kudo, Noboru Yoshida, Taira Imamura, Masatoshi Fujimoto
    1984 Volume 57 Issue 11 Pages 3099-3103
    Published: 1984
    Released: June 27, 2006
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    The formation of a new N,N-bidentate complex of nickel(II) perchlorate with an N,N,O-terdentate ligand, 4-(4-methyl-2-pyridylazo)resorcinol (4-MePAR), was first detected in dioxane spectrophotometrically. The stability of the N,N-bidentate species in dioxane is strongly affected by the presence of a proton acceptor such as water, ethanol, imidazole, and Cl, which promote the coordination of the ortho phenolic oxygen in the ligand to form the N,N,O-terdentate complex. The new complex was isolated from dioxane solution and identified to be an N,N-bidentate complex salt, [Ni(4-mepar)2](ClO4)2, having two counter ions, ClO4. A distortedplanar configuration of the complex was suggested on the basis of IR, X-ray photoelectron spectroscopic, and magnetic measurements.
  • Takumi Konno, Ken-ichi Okamoto, Jinsai Hidaka
    1984 Volume 57 Issue 11 Pages 3104-3110
    Published: 1984
    Released: June 27, 2006
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    Five optically active cobalt(III) complexes of [Co(bidentate-N,Se)(en)2] type were prepared; here bidentate-N,Se denotes 2-aminoethaneselenolato (aes), 2-aminoethaneselenenato (aesee), 2-(methylseleno)ethylamine (mseea), 2-(ethylseleno)ethylamine (eseea), and 2-(benzylseleno)ethylamine (bseea). These complexes were characterized from their absorption, CD and 1H NMR spectra. Of these complexes, the crystal structure of (+)500CD-[Co(mseea)(en)2](ClO4)3 was determined by the X-ray diffraction method. The red plate crystal was orthorhombic, space group P212121, a=12.220(15), b=19.224(7), c=8.977(11) Å, Z=4, and the final R value was 0.087. The coordinated selenium atom takes the (R) configuration for the Λ isomer. The absorption and CD spectra of the five complexes are discussed in comparison with those of the corresponding cobalt(III) complexes containing a coordinated sulfur atom.
  • Mikako Kanesaka, Ken-ichi Okamoto, Masayo Nomoto, Jinsai Hidaka
    1984 Volume 57 Issue 11 Pages 3111-3116
    Published: 1984
    Released: June 27, 2006
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    [Co(R,S-sexidentate-N2,S2,O2)] and [Co(R-terdentate-N,S,O)(S-terdentate-N,S,O)] type complexes, including the title complex cation, [Co(R,S-ebp)]+, were prepared and resolved. The crystal structure and absolute configuration of the (+)560CD-[Co(R,S-ebp)]+ isomer were determined by X-ray diffraction. The complex cation has an [S] configuration. The R,S-ebp coordinates as a sexidentate, of which two sulfur donor atoms take selectively R(S). The absorption and CD spectra are discussed in comparison with those of the related complexes.
  • Michinori Oki, Manabu Ohira
    1984 Volume 57 Issue 11 Pages 3117-3121
    Published: 1984
    Released: June 27, 2006
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    The coordinated form of [o-(diethylaminomethyl)phenyl]halodimethyl(or diphenyl)stannanes was found to exhibit dynamic behaviors in their 1H NMR spectra. Examination of a series of halogen compounds by total line shape analysis of the diastereotopic methylene proton signals revealed that, at 10 °C, the rates of dissociation were 11.7, 22.9, 28.6, and 73.3 s−1 for fluoro, chloro, bromo, and iodo compounds, respectively: The results are in conformity with the expectation from the electronegativity of halogens. The relatively small differences in the activation parameters in the whole series may include contribution by solvation energies. The diphenyl compound exhibited fast exchange rates relative to the corresponding dimethyl compound. This was attributed to the steric factor rather than the pπ-dπ interaction.
  • Seiji Yasuda
    1984 Volume 57 Issue 11 Pages 3122-3124
    Published: 1984
    Released: June 27, 2006
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    Spectral changes in the P Kα and P Kβ X-ray emission lines of solid organic phosphorus compounds were measured with a two-crystal X-ray spectrometer. The P Kα line shifted to higher energies with an increasing number of oxygen atoms attached directly to a phosphorus atom. Similar shifts were found in the P Kα satellites, which were always 1.5–2.0 times larger than those of the parent Kα line. There was no simple correlation for relating the P Kβ1 shift to the phosphorus form. The P Kβ profiles of organic phosphorus seemed to be characterized by the surrounding atoms or groups. The appearance of the Kβ′ band offered possible evidence for the existence of phosphorus-oxygen bonding in the samples.
  • Yoshito Wakui, Katsunori Yano, Yoshiharu Nakano, Kousaburo Ohashi, Kat ...
    1984 Volume 57 Issue 11 Pages 3125-3129
    Published: 1984
    Released: June 27, 2006
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    A new ligand, 3-(1-naphthyl)-2,4-pentanedione, was prepared. Concentration proton-dissociation constants of 3-aryl-2,4-pentanedione (aryl group; phenyl, 2,4-dinitrophenyl, and 1-naphthyl) and concentration stability constants of some bivalent metal chelates of 3-aryl-2,4-pentanedione were determined in a 75% v/v 1,4-dioxane–water medium containing 0.05 mol dm−3 sodium perchlorate by a pH-titrimetric method. The dissociation constant (pKa) of 3-(2,4-dinitrophenyl)-2,4-pentanedione, 2,4-pentanedione, 3-phenyl-2,4-pentanedione, and 3-(1-naphthyl)-2,4-pentanedione were found to be 8.87, 10.93, 11.50, and 11.71, respectively. The order of acidity in 2,4-pentanedione was explained by the field effect of the aryl group. The stability constants of the bivalent metal chelates of these ligands were in accord with the Irving-Williams series. The stepwise stability constant of the chelate increased with an increasing pKa value of 3-aryl-2,4-pentanedione. This result cannot be explained by the steric and solvation effect of an aryl substituent.
  • Kousaburo Ohashi, Kiichiro Nagashima, Rumiko Seita, Katsumi Yamamoto
    1984 Volume 57 Issue 11 Pages 3130-3133
    Published: 1984
    Released: June 27, 2006
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    The solvent extraction of molybdenum(VI) with 1,5-diphenylcarbazone (Hdpco) into chloroform, benzene, or tributyl phosphate (tbp) was studied. The molar ratio of molybdenum(VI): 1,5-diphenylcarbazone in the complex extracted into chloroform or benzene in the range from 1.0 mol dm−3 HNO3 to pH 1.9 was found to be 1:2. The extracted complex was estimated to be MoO2(dpco)2. On the other hand, molybdenum(VI) may be extracted into tbp as a mixture of MoO2(dpco)2 and MoO2(dpco)(OH)(tbp). The extraction constants, Kex(=[MoO2(dpco)2]o/[Mo(OH)6][Hdpco]o2), were determined to be 7.9×106 and 3.8×108mol−2dm6 for chloroform and benzene respectively. A black complex formulated as MoO2(dpco)2·5H2O was formed. Molybdenum(VI) can be determined over the range from 1.50 to 19.0 μg/10 cm3 within a relative error of ±4%. The interference of diverse ions will be described.
  • Masatatsu Suzuki, Akira Uehara
    1984 Volume 57 Issue 11 Pages 3134-3138
    Published: 1984
    Released: June 27, 2006
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    Reaction of copper(II) ion with hexacyanoferrate(II) ion, [Fe(CN)6]4−, in an aqueous solution containing such an amine as en (1,2-ethanediamine), tn (1,3-propanediamine), dien (bis(2-aminoethyl)amine), or dpt (bis(3-aminopropyl)amine), gave two types of complexes: Double complex salts, [Cu(en or tn)2]2[Fe(CN)6nH2O(n=5–8), and cyanide-bridged complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O. The infrared spectra of the complexes in the νCN region revealed that the complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, contain cyanide bridges, while in [Cu(en or tn)2]2[Fe(CN)6nH2O, no cyanide bridge is present. The thermal reactions of the complexes in the solid state were investigated by means of derivatography under dynamic conditions (D conditions). It was found that dehydration from [Cu(en)2Fe(CN)6nH2O resulted in formation of cyanide bridge in the apical position of square planer [Cu(en)2]2+. For [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, dehydration resulted in the formation of additional cyanide bridges. All the complexes showed metal to metal (iron(II) to copper(II)) charge-transfer transitions (MMCT) in the near ultraviolet or visible region. The complexes, [Cu(en or tn)2]2[Fe(CN)6nH2O, exhibited the outer sphere iron(II) to copper(II) charge-transfer bands (OSMMCT) in the near ultra-violet region. [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O and the dehydrated complexes prepared by thermal reaction showed the inner-sphere iron(II) to copper(II) charge transfer bands (ISMMCT) in the visible region. A good correlation was observed between the energies of the MMCT and the d-d band maxima of copper(II) ions.
  • Masamichi Atoh, Kazuo Kashiwabara, Haruko Ito, Tasuku Ito, Junnosuke F ...
    1984 Volume 57 Issue 11 Pages 3139-3146
    Published: 1984
    Released: June 27, 2006
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    Dianionocobalt(III) complexes of the [CoX2(edpp)2]+-type (X=Cl, Br I, NCO, NCS, N3, NO2) have been prepared, where edpp is (2-aminoethyl)diphenylphosphine. The corresponding [CoX2(en)(dppe)]+ complexes are rather unstable and have been obtained only for X=Cl, Br, and NCS, where en and dppe denote ethylenediamine and 1,2-bis(diphenylphosphino)ethane, respectively. Except for the NCS complex of edpp, only one geometrical isomer has been obtained for all the complexes. Two geometrical isomers of [Co(NCS)2(edpp)2]+ have been isolated, and crystal structures of trans(NCS,NCS),cis(P,P)-[Co(NCS)2(edpp)2]Br·3H2O·(CH3)2CO and cis(NCS,NCS),trans(P,P)-[Co(NCS)2(edpp)2]Br·CH3OH have been determined by X-ray analyses. The NCS ions in these complexes coordinate to the cobalt(III) ion through their nitrogen atoms with nearly linear Co–N–C–S fragments. The Co–P distances in the isomers are similar to one another, but the average Co–NH2 and Co–NCS distances in the trans(NCS,NCS) isomer (2.010 and 1.882 Å) are longer and shorter than those of the cis(NCS,NCS) isomer (1.970 and 1.960 Å), respectively. Absorption spectra of all the complexes in solution have been recorded and the results compared with those of related dianionocobalt(III) complexes.
  • Michio Nakamura, Hisashi Okawa, Sigeo Kida, Seizo Misumi
    1984 Volume 57 Issue 11 Pages 3147-3151
    Published: 1984
    Released: June 27, 2006
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    Lanthanoid complexes with 1-l-menthyloxy-3-benzoylacetone, [Ln(l-moba)3(H2O)n] (Ln=La, Pr, Nd, Eu, Dy, Ho, Tm; n=0, 1, or 2), have been synthesized and characterized by elemental analyses, molecular weight determinations, and electronic, circular dichroism, and luminescence spectra. The molecular weight determinations suggest that the complexes are in a monomer-dimer equilibrium in nondonating solvents while they are monomeric in donating solvents. The complexes exhibit fairly intense circular dichroisms at the f-f band region, demonstrating the stereoselective formation of an enantiomer. The stereoselectivities have been discussed in terms of the intramolecular interligand CH/π-interaction operating between the phenyl and the menthyl groups of the ligands. [Eu(l-moba)3(H2O)] shows luminescence at the 5D07F1 and 5D07F2 transitions in benzene. Based on the concentration dependence of the luminescence, it is demonstrated that dimerization facilitates nonradiative relaxation and greatly reduces the quantum efficiency of luminescence.
  • Hitoshi Takeshita, Akira Mori, Satoshi Nakamura
    1984 Volume 57 Issue 11 Pages 3152-3155
    Published: 1984
    Released: June 27, 2006
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    Starting from the photocycloaddition of methyl 2,4-dioxopentanoate with 4-isopropenyltoluene, isolaurene was synthesized, and its further conversion to 5-cuparenone constituted the formal synthesis of cuparene. For the first time, the proto-(2+2)π cycloadduct, a β-keto cyclobutanol derivative, has been isolated from the product mixture.
  • Hitoshi Takeshita, Hideshi Motomura, Hiroaki Mametsuka
    1984 Volume 57 Issue 11 Pages 3156-3159
    Published: 1984
    Released: June 27, 2006
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    Upon MCPBA-oxidation, several 8H-cyclohepta[b]thiophen-8-ones yielded the 8H-cyclohepta[b]thiophen-8-one 1,1-dioxides and their epoxides. The latters were shown to be convertible to several ring-contracted derivatives, the benzo[b]thiophene 1,1-dioxides and/or their corresponding phenol and salicylaldehyde derivatives.
  • Tsutomu Nonaka, Shuta Kihara, Toshio Fuchigami, Manuel M. Baizer
    1984 Volume 57 Issue 11 Pages 3160-3166
    Published: 1984
    Released: June 27, 2006
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    It was confirmed that cyclic and acyclic sulfates of diols and monoalcohols could be reduced at cathodes in nonaqueous solvents. The reduction products were greatly affected by the molecular structures of the sulfates. The reduction of the cyclic sulfates of 1,2-diols yielded the corresponding alkenes and disulfate dianions of the parent diols in high yields and current efficiencies were based on one-electron reduction. On the other hand, the cyclic sulfates of 1,3- and 1,4-diols were also reduced by one-electron transfer under similar conditions, but the cycloalkanes expected were not formed and the products were cyclic ethers along with acyclic alkane or unsaturated alcohol. The reduction of the cyclic sulfate of hydrated formaldehyde, which is regarded as a 1,1-diol, did not give any identified products except for a small amount of methane. Finally, acyclic dialkyl sulfates were reduced by one-electron transfer to give complicated mixtures consisting of monomeric alkanes and alkenes, dimeric alkanes, ethers, and/or alkyl metals. Based on the results obtained, the mechanism of reduction of sulfates (mainly cyclic sulfates of 1,2-diols) is discussed.
  • Masahiro Tamura, Hiroshi Nishizaki, Chiemi Miyazaki, Hideo Okai
    1984 Volume 57 Issue 11 Pages 3167-3172
    Published: 1984
    Released: June 27, 2006
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    A mixture of N-(L-α-aspartyl)- and N-(L-β-aspartyl)-β-D-glucopyranosylamine was obtained by the condensation of N-(benzyloxycarbonyl)-L-aspartic anhydride with β-D-glucopyranosylamine. Attempts to separate the mixture by using cation-exchange chromatography, a copper(II) complex, and fractional recrystallization were carried out. These separations gave good yields of the desired β-amine.
  • Yuichiro Haramoto, Koji Akazawa, Hiroyoshi Kamogawa
    1984 Volume 57 Issue 11 Pages 3173-3176
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    2-Substituted-5-(p-substituted phenyl)-1,3-dithianes (8), new liquid crystals, were synthesized. The mesomorphic properties of these compounds were compared with those of the corresponding 2-(p-substituted phenyl)-5-alkyl-1,3-dithianes (9). The main difference found between these two liquid-crystal compounds was that some of 8 exhibited both monotropic nematic and smectic liquid-crystal phases but 9 exhibited only the monotropic nematic phase. This difference seems to originate in somewhat increased lateral interactions between molecules. Even for the three-ring compounds, many of them exhibited the monotropic liquid-crystal behavior. This should mean that these 1,3-dithiane compounds strongly tend to exhibit the monotropic liquid-crystal behavior.
  • Yorihiro Yamamoto, Noriyuki Saeki, Schunichi Haga, Etsuo Niki, Yoshio ...
    1984 Volume 57 Issue 11 Pages 3177-3181
    Published: 1984
    Released: June 27, 2006
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    Decompositions of methyl linoleate hydroperoxide (LOOH) induced by di-t-butyl diperoxyoxalate and cobalt ions were investigated in benzene at 50 °C under vacuum to elucidate the degradation mechanism. The major products were dimer (LOOL), oxodiene, hydroxydiene and epoxyhydroxyene (and/or epoxyoxoene). It was suggested that these products were formed by the recombination of L· and LOO· radicals, β-scission of LO· radical, hydrogen abstraction of LO· radical, and intramolecular epoxidation of LOO· radical, respectively. The decomposition of methyl linolenate hydroperoxide (L′OOH) was also studied. The major products were dimer, oxotriene, hydroxytriene, and thiobarbituric acid reactive substances, which were suggested to be formed by the intramolecular cyclization of L′OO· radical.
  • Shigeru Kobayashi, Tsunehiko Fukuda, Hidefumi Yukimasa, Masahiko Fujin ...
    1984 Volume 57 Issue 11 Pages 3182-3196
    Published: 1984
    Released: June 27, 2006
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    ω-(1,4-Benzoquinon-2-yl)alkanoic acids, 2-[10-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)decyl]-3-hydroxytetracosanoic acid, all-trans-5,9,13,17-tetramethyl-4,8,12,16-octadecatetraenoic acid, and stearic acid were coupled to the 6-O-position of the carbohydrate moiety of muramyl dipeptide alkyl esters, and 6-O-aminoacylmuramyl dipeptide methyl esters. The aminoacyl residues used were Gly, Leu, Ahx, and Aud. New synthetic methods were developed for ω-(1,4-benzoquinon-2-yl)alkanoic acids such as 22-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)docosanoic acid, and the α-branched ω-(1,4-benzoquinone-2-yl) β-hydroxy acid, 2-[10-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)decyl]-3-hydroxytetracosanoic acid. The effects of the resulting quinonyl, multiprenylacetyl, and stearoylmuramyl dipetides on the induction of delayed-type hypersensitivity to ABA-Tyr in guinea pigs and the tumor(meth-A)-suppressive activity in syngeneic BALB/c female mice were measured. The results revealed that all these muramyl-dipeptide derivatives retained the adjuvant activity whereas the potent tumor-suppressive activity was observed only in quinonylmuramyl dipeptides, indicating that the 5,6-dimethoxy-3-methyl-1,4-benzoquinone ring is a requisite for the manifestation of the tumor-suppressive activity. The lipophilicity-hydrophilicity balance of the molecule was also important. Among the compounds tested, N-acetyl-6-O-[10-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)decanoyl]muramyl-L-valyl-D-isoglutamine methyl ester showed the most potent tumor-suppressive activity. This compound also showed tumor-regressive activity in guinea pigs, and hence is a good candidate for further studies.
  • Yasuo Ariyoshi
    1984 Volume 57 Issue 11 Pages 3197-3202
    Published: 1984
    Released: June 27, 2006
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    A series of twenty four analogues of L-α–Asp–Gly–Gly–OMe has been synthesized in relation to structural features of sweet peptides. The rule in the structure-taste relationships of dipeptides is held in the sweet aspartyl tripeptide esters. In order for the aspartyl tripeptide esters to be sweet, the second amino acid must have a D-configuration and a small, compact alkyl group (Me, Et, or i-Pr) at R2. An L-configuration of the third amino acid is required for a potent sweet taste. It has been concluded that the small alkyl group at R2 participates in binding with the receptor through a hydrophobic interaction and increases the sweetness potency.
  • Kaoru Harada, Toratane Munegumi
    1984 Volume 57 Issue 11 Pages 3203-3209
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Asymmetric catalytic hydrogenations of chiral pyruvamides were carried out using palladium on charcoal (Pd-C) as a catalyst to give lactamides with the diastereoisomeric purities (d.p.) of up to 62%. It was found that there was a linear correlation between the d.p. and the dielectric constant of the solvents used in the hydrogenations of chiral pyruvamides. The results were explained by employing the chelation model and the adsorption of the phenyl group in the substrate molecule on the catalyst. The temperature effect on the d.p. of the product was also examined. The catalytic hydrogenations of chiral benzoylformamides were also performed to give low d.p. presumably, the chelation complexes of the substrates could not take a predominant conformation with the catalyst.
  • Makoto Tamaki
    1984 Volume 57 Issue 11 Pages 3210-3220
    Published: 1984
    Released: June 27, 2006
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    According to a primary structure proposed for an antibiotic peptide, gratisin, four peptides containing respectively partial sequences, L-Phe–L-Pro–L-Tyr, D-Phe–L-Pro–L-Tyr, L-Phe–L-Pro–D-Tyr, and D-Phe–L-Pro–D-Tyr, were synthesized by a liquid phase method. Among them, cyclo(–L-Val–L-Orn–L-Leu–D-Phe–L-Pro–D-Tyr–)2 showed the strongest activity against the Gram-positive microorganisms tested. The activity toward Bacillus subtilis was similar to that of gramicidin S. Therefore, it is quite possible that natural gratisin is identical to this peptide. To facilitate a further investigation of the structure-activity relationship, four additional analogs were prepared. The results of their antibiotic activities showed that an interchange of D-Phe residues with D-Tyr residues caused the decrease of activity, and that the hydroxyl group of D-Tyr residues had no important role in this activity. The peptides possessing partial sequences, D-Phe–D-Tyr–L-Pro and L-Pro–D-Phe–D-Phe, exhibited strong activity. These facts show that the positions of Pro residues are not restricted to 5 and 5′ for the exhibition of the activity. The CD spectra of these synthetic peptides in an aqueous solution reflected the partial sequences around Pro residues, which affect largely the conformation of these synthetic antibiotics. The temperature dependence of these CD spectra indicated that the conformation of biologically active peptides is more stable than those of less active peptides.
  • Otohiko Tsuge, Eiji Wada, Shuji Kanemasa, Hirohiko Sakoh
    1984 Volume 57 Issue 11 Pages 3221-3233
    Published: 1984
    Released: June 27, 2006
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    Multiple Diels-Alder reaction of bis(silyloxy) cross-conjugated trienes is presented. Two trienes, 3-benzylidene- and 3-(methoxymethylene)-2,4-bis(trimethylsilyloxy)-1,4-pentadiene, undergo two sequential Diels-Alder cycloadditions with a variety of dienophiles forming hydronaphthalene rings. Some characteristics of this reaction have been discussed in terms of stereo-, regio-, and chemoselectivity. It is proposed that this process is referred to as “diene-transmissive Diels-Alder reaction”.
  • Otohiko Tsuge, Shuji Kanemasa, Hirohiko Sakoh, Eiji Wada
    1984 Volume 57 Issue 11 Pages 3234-3241
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Cross type of diene-transmissive Diels-Alder cycloaddition has been demonstrated by using two bis-silyloxy cross-conjugated trienes. The first cycloaddition stage of cross reaction, which has to be highly selective in the formation of mono-cycloadducts, has been performed by the reactions of an activated triene with cyclic olefins or those of trienes with acyclic olefins.The secod cycloadditions with a variety of dienophiles provide cross types of bis-adducts. The characteristics of these cross reactios are discussed.
  • Seijiro Matsubara, Noriyuki Tsuboniwa, Yoshitomi Morizawa, Koichiro Os ...
    1984 Volume 57 Issue 11 Pages 3242-3246
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Treatment of α-bromo carbonyl compounds with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnCl2 and Et2AlCl affords enolates which react with ketone or aldehyde to give β-hydroxy carbonyl compounds in good to excellent yields. The reactions proceed similarly with the reagents which are generated from R3PbLi (R=Ph, n-Bu) and Et2AlCl. Catalysis by the added Pd(PPh3)4 complex promotes the reduction effectively and improves the yields of the desired adducts. The regio- and stereoselectivities are disclosed.
  • Kohei Uosaki, Hideaki Kita
    1984 Volume 57 Issue 11 Pages 3247-3252
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Electroluminescence (EL) due to band-to-band transition was observed for n-GaAs in solutions containing peroxodisulfate ions. Digital simulation shows that the observed transient current and EL intensity stimulated by negative potential pulses can be explained by assuming that the surface concentration of S2O82− was zero during potential pulses and that the EL intensity was proportional to the surface concentration of SO4\ ewdot(generated by the one-electron reduction of S2O82−). Surface composition change seems to be the main reason for the relation between the potential and EL intensity. A hydrogen evolution reaction reduces the EL efficiency at relatively negative potentials. Although the potential and time had no observed effect on the shape of the EL spectra, the carrier concentration affected the peak position and the full width at half maximum (FWHM) of the EL spectra. For greater carrier concentrations, the wavelength of the EL peak became shorter and the FWHM became larger. These results agree with those reported regarding solid-state luminescence and can be explained by the filling of the conduction band states by electrons (Burnstein-Moss shift).
  • Naotoshi Nakashima, Kozo Morimitsu, Toyoki Kunitake
    1984 Volume 57 Issue 11 Pages 3253-3257
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    An azobenzene-containing chiral amphiphile showed a drastic enhancement of circular dichroism (CD) due to formation of the rigid bilayer assembly. The drastic CD change was caused by phase transition of the matrix bilayer in the case of mixed bilayers with dihexadecyldimethylammonium bromide, but was caused by phase transition of the chiral component in the case of the single component bilayer. Both CD and absorption spectra of the azobenzene-containing chiral bilayer were used for detecting phase separation of mixed membranes. It was pointed out that the CD technique is widely applicable to phase separation studies.
  • Fumio Kawaizumi, Nobuo Sasaki, Yasushi Ohtsuka, Hiroyasu Nomura, Yutak ...
    1984 Volume 57 Issue 11 Pages 3258-3261
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Using an isoperibol twin calorimeter the specific heat capacities of solutions of D-glucose and D-xylose dissolved in water–ethanol mixtures (10, 20, 30, and 50 wt% of ethanol) have been measured at temperature close to 30 °C and the apparent molar heat capacity of te solutes φCp has been calculated. Dependence of φCp upon solute concentration varied markedly with the solvent composition but the variation was similar for both solutes. The infinite dilution values of φCp° i.e. Cp,2 are higher for D-glucose than for D-xylose at any compositions of the solvent system. The Cp,2 decreased first noticeably with the amount of ethanol in the solvent, reaching a minimum value at approximately 20 wt% of ethanol, then it increased. Values of the parameter ΔCp,2=Cp,2Cp,2*, where Cp,2* is the specific heat capacity of the solute in the solid state, are negative in 10, 20, and 30 wt% of ethanol, while it is positive in 50 wt%. The values of ΔCp,2 have been discussed in its connection with the degree of structuring of the solvents.
  • Akiko Kobayashi, Takehiko Mori, Yukiyoshi Sasaki, Hayao Kobayashi, M. ...
    1984 Volume 57 Issue 11 Pages 3262-3268
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    The crystal structure determination of the title compound (abbreviated as α-LiPt(mnt) has been performed at room temperature and 153 K. The [Pt(mnt)2]n (mnt=1,2-dicyano-1,2-ethylenedithiolato, C4N2S22−) anions stack face-to-face along the c-axis with Pt···Pt distance of 3.6 Å. The room temperature structure and the average structure of the 153 K superstructure are almost the same. The room temperature conductivity of α-LiPt(mnt) is about 200 S cm−1, and the compound undergoes a metal-insulator transition (Peierls transition) at 220 K. In α-LiPt(mnt) the conduction pathway is through the ligand-centered π-system which is composed of predominantly S 3pz orbitals. Oscillation photographs about the c-axis show strong satellite spots on the layerlines of (0.41+n)c* and (0.59+n)c* (n=0, ±1, ±2, ···) The content of Li cation reveals that these satellite spots can be described as 2kF spots. The regular appearance of characteristic satellite reflections indicates that α-LiPt(mnt) has a sinusoidally modulated lattice. The wave vector of the lattice modulation wave is k=0.15b*+0.59c* and the amplitude of the lattice modulation wave is 0.045 aa+0.13bb+0.060cc Å. The overlap integrals along face-to-face stacking directions are much larger than the interstack overlap integrals and the resulting large anisotropy indicates that α-LiPt(mnt) is a one-dimensional metal.
  • Kinya Iijima, Nobuhiro Adachi, Shuzo Shibata
    1984 Volume 57 Issue 11 Pages 3269-3273
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    The molecular structure of trimethylamine–borane (CH3)3N·BH3 has been determined from gas electron-diffraction data with spectroscopic data. The molecular parameter values and their uncertainties are rg(B–H)=1.261±0.006 Å, rg(N–B)=1.656±0.002 Å, rg(C–N)=1.485±0.001 Å, rg(C–H)=1.108±0.002 Å, ∠HBH=112.8±0.4°, and ∠CNC=109.2±0.2°. The potential barrier around the N–B bond has been estimated to be larger than 5 kcal mol−1 (1 cal=4.183 J). The isotope effects on the B–D bond distance and the DBD angle have also been estimated to be −0.006 Å and 0.4°, respectively, in rα0 parameters.
  • Mitsutomo Tsuhako, Mayumi Fujimoto, Shigeru Ohashi, Hiroyuki Nariai, I ...
    1984 Volume 57 Issue 11 Pages 3274-3280
    Published: 1984
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    Phosphorylation of nucleosides with sodium cyclo-triphosphate (P3m) was studied under various conditions (mixing ratio of P3m to nucleoside, pH, reaction temperature and time). 1) Adenosine, cytidine, guanosine, and uridine were easily phosphorylated by P3m to form selectively nucleoside 2′-monophosphates, 3′-monophosphates, and 2′,3′-cyclic monophosphates. On the other hand, 2′-deoxyadenosine, 3′-deoxyadenosine, 2′-deoxycytidine, and thymidine could not be phosphorylated by P3m. 2) The phosphorylation of adenosine, cytidine, guanosine, and uridine varied strongly, depending on the reaction conditions; mixing ratio, pH, reaction temperature and time. Under conditions of a high mixing ratio of P3m to nucleoside (5:1–10:1), high pH (12–14), high temperature (70–100 °C) for a short time (1–2d) or low temperature (room temperature) for a long time (70–150 d), nucleoside 2′- and 3′-monophosphate could be obtained in high yield (about 50–100%). 3) At the initial stage of the phosphorylation reactions of adenosine, cytidine, and guanosine with P3m, nucleoside 2′,3′-cyclic monophosphates were formed, though a small amount (about 1–3%), but in the course of the reaction for a long time, they were hydrolyzed to nucleoside 2′- and 3′-monophosphates. 4) 2′-deoxyadenosine, 3′-deoxyadenosine, 2′-deoxycytidine, and thymidine could not be phosphorylated by P3m. This means that the presence of hydroxyl groups at the 2′- and 3′-positions of the ribose was necessary for the phosphorylation of nucleosides with P3m. 5) Phosphorylation of nucleosides with short-chain phosphates (ortho-, pyro-, and triphosphate) could not be observed at all. 6) The mechanism of formation of nucleoside 2′-monophosphates, 3′-monophosphates, and 2′,3′-cyclic monophosphates in the phosphorylation of nucleosides with P3m was discussed.
  • Isao Tomita, Masaru Banju, Katsumi Noguchi, Toshihiro Nakamura
    1984 Volume 57 Issue 11 Pages 3281-3285
    Published: 1984
    Released: June 27, 2006
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    Forward and backward pH titration curves were measured for potassium-ion exchange on crystalline α-hafnium phosphate which had been prepared by the direct-precipitation method. Exchange in each direction proceeded in two steps, and the hysteresis was observed in the region of smaller loadings of the potassium ions. Exchange in the ternary H+–Li+–K+ system was also preliminarily investigated, the selectivity of the potassium and lithium ions was what would be expected from the results of the binary hydrogen ion-alkali metal ion systems.
  • Kiyoshi Otsuka, Seiichiro Yokoyama, Akira Morikawa
    1984 Volume 57 Issue 11 Pages 3286-3289
    Published: 1984
    Released: June 27, 2006
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    Steam reforming of CH4 and C2H4 or water gas shift reaction was allowed to occur through a wall of stabilized zirconia acting as hydrogen separator. The reactions proceed via transport of oxygen ions in the zirconia lattice from cathode to anode of the wall, accompanying an electron transfer in the reverse direction through the outer lead wire. Hydrogen without CO2, CO, or hydrocarbons can be obtained directly by each reaction at the cathode side. The rate of hydrogen production increases exponentially with a rise in applied potentials via chromel-constantan thermocouples. The presence of reducing gas such as CO, CH4, or H2 at the anode side will decrease considerably the applied potential required to produce hydrogen at the same rate. A tentative reaction mechanism is proposed on the basis of kinetic information of the reaction.
  • Masashi Iino, Minoru Matsuda
    1984 Volume 57 Issue 11 Pages 3290-3294
    Published: 1984
    Released: June 27, 2006
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    Coals were extracted with alcohol–benzene mixtures at room temperature. For coals of high oxygen content, Yallourn and Taiheiyo coals, the extraction yields for the mixtures were much greater than those for alcohols and benzene alone. This synergistic effect was more marked for less bulky alcohols: The order was methanol>ethanol>isopropyl alcohol>t-butyl alcohol. The degree of swelling and the apparent density of the coals in alcohols were measured. The results show that smaller alcohols may permeate into pores of the coals more extensively and cause greater swelling than larger alcohols. It is reasonable to consider that this swelling of the coals then facilitates the extraction with benzene or alcohol–benzene mixtures, which are better solvents in solubility for coal molecules than alcohols. For Shin-yubari coal having low oxygen content, no such a synergistic effect was observed, probably due to the lower degree of swelling of this coal.
  • Shinzaburo Ito, Masahide Yamamoto, Yasunori Nishijima
    1984 Volume 57 Issue 11 Pages 3295-3299
    Published: 1984
    Released: June 27, 2006
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    An unstable intramolecular excimer which is formed in an excited state of cis-1,2-di(2-naphthyl)cyclobutane is investigated. The excimer formation-rate constants and dissociation-rate constants in fluid solutions at low temperatures were determined by picosecond time-resolving measurements. The formation processes are interpreted in relation to the bending motion of the cyclobutane ring. Photophysical characteristics of unstable excimers are shown in this system.
  • Masayuki Umemoto, Taketora Ogata, Hiroko Shimada, Ryoichi Shimada
    1984 Volume 57 Issue 11 Pages 3300-3306
    Published: 1984
    Released: June 27, 2006
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    Assignments of the out-of-plane normal vibrations of [1H4]- and [2H4]pyrimidines were reexamined through studies of the polarized Raman, time-resolved phosphorescence and polarized dark sublevel phosphorescence spectra. The vibrational analyses of the phosphorescence spectra based on their polarization behavior indicate that the appearance of the strong 0-0 and totally symmetric vibronic bands in the dark sublevel phosphorescence spectra is attributed to the distortion of the molecular structure along the b1 normal coordinates in the lowest triplet state.
  • Naohide Matsumoto, Kazuhiro Kimoto, Akira Ohyoshi, Yonezo Maeda
    1984 Volume 57 Issue 11 Pages 3307-3311
    Published: 1984
    Released: June 27, 2006
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    Several iron(III) complexes with planar unsymmetrical quadridentate Schiff bases composed of 1:1:1 condensation products of acetylacetone, ethylenediamine, and each of salicylaldehyde and o-hydroxyacetophenone have been prepared and characterized, where the Schiff bases are abbreviated as [H2salacen] and [H2hapacen], respectively. The effective magnetic moment of [FeCl(hapacen)] increases gradually from 3.46 BM at 80 K to 5.31 BM at 301 K, and was interpreted by a spin-spin interaction model based on a binuclear structure with an antiferromagnetic interaction parameter of J=−10 cm−1 (S1=S2=5⁄2), while the magnetic moment for [FeCl(salacen)] is 5.86 BM at 80 K and 5.96 BM at 302 K, indicating that the complex is a monomeric species of high-spin type. The bis(imidazole)iron(III) complexes [Fe(im)2(salacen)]BPh4·CH3OH and [Fe(im)2(hapacen)]BPh4·2CH3OH showed a striking thermochromic behavior in various organic solvents, changing from dark red to green with decrease of the temperature. The complexes are essentially of low-spin type in solids, where im and BPh4 denote imidazole and tetraphenylborate, respectively. Electronic, 1H NMR (Evans method), and ESR spectra confirmed that the thermochromism is caused by spin-equilibrium between high-spin(S=5⁄2) and low-spin(S=1⁄2) states of iron(III).
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