Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 71 , Issue 5
Showing 1-37 articles out of 37 articles from the selected issue
  • Hideo Kurosawa, Sensuke Ogoshi
    1998 Volume 71 Issue 5 Pages 973-984
    Published: 1998
    Released: February 01, 2006
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    Recent developments in the understanding of some fundamental reactions undergone by group 10 metal allyl and propargyl (2-propynyl) complexes are described. Emphasis was placed on the bonding-reactivity relationship of these complexes which are relevant as key intermediate models in transition metal catalyzed transformations of allylic and propargylic substrates as well as related transformations involving unsaturated hydrocarbons. The specific complexes surveyed include group 10 metal complexes of allyl and propargyl ligands bound to the metal both in η1- and η3-fashions. Specific reactions to be discussed include oxidative addition, nucleophilic and electrophilic attack at the allyl or propargyl ligands, and reductive elimination of the allyl ligands.
  • Masahiro Irie, Kingo Uchida
    1998 Volume 71 Issue 5 Pages 985-996
    Published: 1998
    Released: February 01, 2006
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    A new class of thermally irreversible and fatigue resistant photochromic molecules named diarylethenes has been developed. Theoretical consideration based on the state correlation diagrams of electrocyclic reactions revealed that the thermal irreversibility is attained by introducing aryl groups that have low aromatic stabilization energy. According to the molecular design principle thermally irreversible photochromic diarylethenes having heterocyclic five-membered rings, such as furan, thiophene (or benzothiophene), or thiazole rings, have been newly synthesized. Among them, diarylethenes having benzothiophene aryl groups showed an excellent fatigue resistant property. They underwent photochromic cycles more than 1.0 × 104 times. The absorption maxima of the closed-ring forms varied from 425 to 828 nm depending on the aryl groups, substituents of the aryl groups, and the substitution position of the aryl groups to the ethane moiety. The response times of both cyclization and ring-opening reactions were less than 10 ps in solution as well as in a crystalline phase. The chemical and thermal control of photochromic reactivity was achieved by introducing intramolecular hydrogen bonding groups or oligothiophene aryl groups to the diarylethenes. Some of the dithienylperfluorocyclopentene derivatives were found to show photochromic reactivity in the crystalline phase. The reactivity was dependent on the conformation and molecular packing in the crystals.
  • Akiko Kobayashi, Akihito Miyamoto, Reizo Kato, Akane Sato, Hayao Kobay ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 997-1006
    Published: 1998
    Released: February 01, 2006
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    β-[(CH3)4N][Pd(dmit)2]2 is isomorphic to [(CH3)4N][Ni(dmit)2]2, which is the first pure π acceptor molecular conductor exhibiting a superconducting transition. The crystal structure at low temperature, pressure dependence of the resistivity and the magnetic susceptibility of β-[(CH3)4N][Pd(dmit)2]2 were examined. The general features of the phase diagram of β-[(CH3)4N][Pd(dmit)2]2 resemble those of the organic superconductors. At ambient pressure, the resistivity increases gradually with lowering temperature. A superconducting transition was observed at 6—9 kbar. The highest Tc was 6.5 K. Between 5 and 6.3 kbar, a characteristic rapid resistivity decrease was observed at the small temperature range above the offset temperature of the superconducting transition. Although the resistivity is not zero, this temperature region can be regarded as a “pre-superconducting region.” Above 9 kbar the metallic state is stabilized down to low temperature. Above 5 kbar, most of the crystals exhibited resistivity anomalies around 60 K, which may be ascribed to the metal-insulator transition of the domains with α-type structure (α-[(CH3)4N][Pd(dmit)2]2), which became mixed in with the crystals of β-[(CH3)4N][Pd(dmit)2]2. The resistivity data of the highly conducting state were very noisy in the pressure range where the superconducting transition could be observed.
  • Ali Maghari, Hassan Behnejad
    1998 Volume 71 Issue 5 Pages 1007-1011
    Published: 1998
    Released: February 01, 2006
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    Intermolecular potential-energy functions are given for helium–heavier-noble gas interactions directly from the inversion of experimental reduced viscosity collision integrals obtained from the corresponding-states correlation. The results are in excellent agreement with the potentials proposed by L. J. Danielson and M. Keil.
  • Swarna M. Patra, Rama K. Mishra
    1998 Volume 71 Issue 5 Pages 1013-1017
    Published: 1998
    Released: February 01, 2006
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    A computer program based on a divide-and-conquer algorithm was used to numerically split a univariate polynomial into factors depicting the various parts of Eπ (π: electronic energy) and K (total Kekulé structure count) of the benzenoid graphs. A multivariate regression equation is suggested, taking n, m, and Ki as the independent variables and Eπ (total) as the dependent variable; n, m, and Ki are the number of vertices, edges, and the fraction of the total K, respectively. A satisfactory correlation coefficient (R2 > 0.99) was obtained.
  • Yoshio Sugiyama
    1998 Volume 71 Issue 5 Pages 1019-1023
    Published: 1998
    Released: February 01, 2006
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    Irreversible reactions of poly(methyl methacrylate) radicals generated from the polymerization of methyl methacrylate (MMA) and structures of the produced stable polymer radicals in the frozen state have been investigated by Electron Spin Resonance (ESR). The stable polymer radicals were produced through disproportionation and addition reactions of poly(MMA) radicals. The structure of stable polymer radicals was also determined by the simulation of the ESR spectrum.
  • A. Ramesh, M. S. Subramanian
    1998 Volume 71 Issue 5 Pages 1025-1030
    Published: 1998
    Released: February 01, 2006
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    A simple and selective solvent-extraction method has been devised for the separation of SeIV and TeIV, not only from each other, but also from the other accompanying elements. 2,3,5-Triphenyltetrazolium chloride has been used as an extractant for the quantitative extraction of TeIV and SeIV from bromide and thiocyanate medium, respectively. The formed ion-pair complex of TeIV and SeIV can be quantitatively extracted into a dichloromethane and 1 : 1 cyclohexanol–toluene solvent mixture, respectively. The optimum conditions have been evaluated based on a critical study of the acid concentration, extractant concentration, period of equilibration, effect of dilution and effect of the solvent. Water was used for the stripping of tellurium, while a fresh solution of sodium hypobromite was used for selenium. This separation procedure in conjunction with the developed methods was applied to an analysis of the selenium and tellurium content of copper concentrate, incineration ash and In–Sb alloy samples.
  • Manabu Harata, Koji Hasegawa, Koichiro Jitsukawa, Hideki Masuda, Hisah ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1031-1038
    Published: 1998
    Released: February 01, 2006
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    Copper complexes of a tripodal tetradentate ligand, N-(2-pyridylmethyl)bis(6-pivalamido-2-pyridylmethyl)amine (Hbppa), have been prepared as a model of metal centers of mononuclear copper enzymes; their structures and properties have been examined together with those having several secondary ligands by electronic absorption, ESR and FAB mass spectral, cyclic voltammetric, and X-ray diffraction methods. The complexes, [Cu(Hbppa)](ClO4)2 and [Cu(Hbppa)(N3)]ClO4·H2O, were obtained as single crystals, whose crystal structures revealed square-planar and trigonal-bipyramidal geometries, respectively. The electronic absorption and ESR spectra for the CuII(Hbppa)–X systems (X = no, Cl, Br, I, N3, and CH3COO) allowed us to conclude that the complexes form several coordination geometries, such as square-planar, square-pyramidal, and trigonal-bipyramidal, depending upon the solvents (MeOH, MeCN). The redox potentials of [Cu(Hbppa)Cl]Cl in MeCN, THF, MeOH, and CH2Cl2 showed quasi-reversible CuI/CuII couples in the range of −0.056 — +0.085 V vs. Ag/AgCl at room temperature. The addition of dioxygen to the Cu(I)–Hbppa, which was prepared from [Cu(MeCN)4]PF6 and Hbppa (1 : 1) in EtCN at −78 °C, resulted in a graduate absorption spectral change with two well-separated absorption maxima at 665 (ε = 162 M−1 cm−1) and 837 nm (ε = 305 M−1 cm−1) and an intense band at 375 nm (ε = 641 M−1 cm−1) as a shoulder. Simultaneous ESR experiments of the same complex solution exhibited a silent spectrum, indicating that the complex is diamagnetic. A similar electronic absorption spectral change was observed in MeOH with absorption peaks at 387 nm (ε = 843 M−1 cm−1), 640 (ε = 183 M−1 cm−1) and 828 (ε = 289 M−1 cm−1), although the ESR spectrum did not continue to be completely silent. Increasing the temperature of the solution up to room temperature demonstrated the formation of [Cu(Hbppa)(OH)] species, whose X-ray structure was [Cu(Hbppa)(OH)]PF6·H2O. The reaction of the [Cu(Hbppa)]ClO4–sodium benzoylformate system with dioxygen in DMF resulted in production of carbon dioxide and benzoic acid, as analyzed by GC and HPLC.
  • Hiroaki Isago, Clifford C. Leznoff, Matthew F. Ryan, Robert A. Metcalf ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1039-1047
    Published: 1998
    Released: February 01, 2006
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    The title complex, [Co(odmbpc)], which is a single isomer and is highly soluble in common organic solvents, has been prepared and investigated electrochemically and spectroelectrochemically in dichloromethane solutions. The cyclic voltammograms of this complex at a concentration of ca. 6 × 10−5 mol dm−3 exhibited two reversible reduction waves at E1/2 = −0.67 V (vs. ferrocenium+/ ferrocene) and −1.74 V, which were attributed to cobalt-centered and triple-bond-centered (in a peripheral substituent) reductions, respectively, and three quasi-reversible oxidation waves at 0.26, 0.46, and 0.74 V, the former two and the latter one of which were attributed to phthalocyanine-chromophore-centered and cobalt-centered oxidations, respectively. Some of these assignments were supported by the electronic absorption spectra of the electro-generated species. The first reduction wave was not observed at 6 × 10−4 mol dm−3 until the applied potential was swept to the second reduction wave. Nevertheless, under the same conditions, the controlled-potential electrolyses in an optically transparent thin-layer electrode at potentials around the first reduction wave gave rise to drastic spectral changes without any preliminary electrolysis at potentials around the second reduction wave. Such strange phenomena are discussed in terms of molecular aggregation of the complexes in solutions. The peripheral alkynyl group has been found to be slightly electron-donating.
  • Takumi Konno, Keiji Tokuda, Tomoya Suzuki, Ken-ichi Okamoto
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1049-1054
    Published: 1998
    Released: February 01, 2006
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    Novel S-bridged CoIIIAgI3CoIII pentanuclear complexes, [Ag3{Co(aet)3}2]3+ (1) and [Ag3{Co(L-cys-N,S)3}2]3− (2), were prepared by reacting fac(S)-[Co(aet)3] (aet = 2-aminoethanethiolate) or ΔLLL-fac(S)-[Co(L-cys-N,S)3]3− (L-cys = L-cysteinate) with Ag+ in a ratio of 2 : 3. The crystal structure of 1(BF4)3 was determined by X-ray crystallography. 1(BF4)3·H2O, chemical formula C12H38B3N6OF12S6Co2Ag3, crystallizes in the orthorhombic space group Pnma with a = 16.397(2), b = 13.239(2), c = 15.803(4) Å, V = 3430.5(9) Å3, Z = 4, and R = 0.066. In 1 the two thiolato S atoms from two octahedral fac(S)-[Co(aet)3] units coordinate to each of three Ag atoms, such that the three S–Ag–S linkages form a triple helical structure. 1 gave only racemic isomer, ΔΔ and ΛΛ, which were optically resolved by cation-exchange column chromatography, while the ΔLLLΔLLL isomer was selectively formed for 2 with a retention of the absolute configuration of the starting ΔLLL-fac(S)-[Co(L-cys-N,S)3]3−. 1 was converted to the S-bridged tricobalt(III) complex [Co{Co(aet)3}2]3+ by a reaction with I in the presence of Co2+, accompanied by an intermolecular exchange and racemization of the Δ/Λ-fac(S)-[Co(aet)3] units. The electronic absorption and CD spectral properties of 1 and 2 are also reported.
  • Tsutomu Mizuta, Ken-ichi Sasaki, Hiromi Yamane, Katsuhiko Miyoshi, Hay ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1055-1064
    Published: 1998
    Released: February 01, 2006
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    The chromatographic resolution of a diastereomeric mixture of Λ-ob3-, Δ-ob3-, Λ-lel3-, and Δ-lel3-[Co(chxn)3]3+ (chxn = trans-1,2-diaminocyclohexane) was carried out on an ion-exchange column using bis(μ-tartrato)diantimonate(III), [Sb2(d-tart)2]2− as a resolving reagent. The resulting elution order of Λ-ob3 > Λ-lel3 > Δ-lel3 > Δ-ob3 was interpreted on the basis of an association model in which lone-pairs on three oxygen atoms of [Sb2(d-tart)2]2− form triple hydrogen bonds with three N–H groups directed along the C3-axis of [Co(chxn)3]3+. Since the three N–H groups of the Λ-ob3 isomer have a right-handed helicity, they form the strongest linear hydrogen bonds with the three lone-pairs of [Sb2(d-tart)2]2−, which are also spirally oriented in the same sense, whereas those of the two lel3 isomers having practically no such helicity form weaker hydrogen bonds, and those of the Δ-ob3 isomer having the opposite helicity have the hydrogen bonds much damaged. To obtain structural evidence for the above association model, crystal structures of diastereomeric salts, Λ-ob3-[Co(chxn)3]X[Sb2(d-tart)2nH2O, X = Cl (1) and ClO4 (2) have been determined by single-crystal analyses. The crystal data are as follows: 1 is orthorhombic, with a space group P212121, Z = 4, a = 10.823(2), b = 17.901(7), c = 21.477(6) Å, V = 4161(2) Å3, and R = 0.057; 2 is monoclinic with a space group P21, Z = 4, a = 13.338(2), b = 17.119(3), c = 18.060(3) Å, β = 98.31(1)°, V = 4080(1) Å3, and R = 0.049. In both crystals, [Sb2(d-tart)2]2− approaches Λ-ob3-[Co(chxn)3]3+ along the C3-axis of the complex to form multiple hydrogen bonds, as expected, and one of the contact modes found in 2 is close to our proposed association model.
  • Katsumi Chikama, Kiyoharu Nakatani, Noboru Kitamura
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1065-1070
    Published: 1998
    Released: February 01, 2006
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    An electron-transfer (ET) reaction between decamethylferrocene in a single tributyl phosphate (TBP) droplet and hexacyanoferrate(III) in the surrounding water phase was investigated by laser trapping, microspectroscopic, and electrochemical techniques. The interfacial ET rate constant (kobs) was inversely proportional to the droplet radius (r) at > 5 μm, but deviated from a linear relationship between kobs and r−1 at r < 5 μm. The characteristic droplet-size effect was independent of the Galvani potential between the TBP and water phases. The results are discussed in terms of the physical properties of the micrometer-sized TBP droplet/water interface.
  • Masanobu Watanabe, Akira Nagasawa, Masaru Sato, Izumi Motoyama, Toshio ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1071-1079
    Published: 1998
    Released: February 01, 2006
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    The crystal form of the salt [{C5H4(CH3)2}2Fe–Hg–Fe{C5H4(CH3)2}2Hg(BF4)2, 1], prepared by a reaction of tetramethyl[2]ferrocenophane and Hg(CN)2 in ethanol containing HBF4, is triclinic, space group , a = 9.315(3), b = 12.823(4), c = 14.108(5) Å, α = 106.055(2), β = 100.253(2), γ = 94.460(2)°, Z = 2 and the final R = 0.059 and Rw = 0.072. Two ferrocene moieties are coordinated to the Hg atom from the opposite side, and the previously proposed Fe–Hg–Fe bridged structure has been verified. The structural feature of the cation is found in the conformation of the ferrocene moiety around the Fe–Hg–Fe bond. In order to reduce the steric hindrance between the Hg and ferrocene moieties, each moiety rotates largely with respect to the other (the torsion angle of the Cpcnt–Fe(1)···Fe(2)–Cpcnt is 75(1)° and Cpcnt is defined as the centroid of the Cp-ring). The mean Fe–Hg distance is 2.598(8) Å and the Fe–Hg–Fe bond angle is 176.4(1)°. The two C5H4 rings are greatly tilted, the mean tilting angle between them being 33.72°. Analogous Hg(II) salts of ruthenocene (2) and osmocene (3) were prepared by a similar method. Crystal 2 is monoclinic, space group P21/a, a = 9.633(1), b = 18.864(3), c = 13.388(1) Å, β = 94.161(9)°, Z = 4 and the final R = 0.058 and Rw = 0.072. The mean Ru–Hg distance is 2.661(2) Å and the Ru–Hg–Ru bond angle is 174.4(1)°; the mean tilting angle between the C5H4-planes is 27.39°. The structure of the cation is very similar to that of 1 (the torsion angle of the Cpcnt–Ru(1)···Ru(2)–Cpcnt is 70(1)°).
    The crystal form of 3 is triclinic, space group , a = 9.823(1), b = 11.194(1), c = 12.241(1) Å, α = 113.822(8), β = 95.828(8), γ = 90.104(8)°, Z = 2 and the final R = 0.030 and Rw = 0.032. The mean Os–Hg distance is 2.69(2) Å and the Os–Hg–Os angle is 170.1(3)°. The most interesting structural difference of 3 compared with 1, 2 is found to be the conformation of the osmocene moieties around the Os–Hg–Os bond. The two moieties are coordinated to Hg in parallel, and the torsion angle of Cpcnt–Os(1)···Os(2)–Cpcnt is negligible (2(1)°) so as to reduce the steric hindrance between the cations and the PF6 anions.
  • Minori Uehara, Mika Urade, Atsuko Ueda, Narumi Sakagami, Yuriko Abe
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1081-1088
    Published: 1998
    Released: February 01, 2006
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    The effects of divalent metal ions (M2+ = Mn2+, Co2+, Ni2+, Cu2+, and Zn2+ ions) on the catalase-like activities of mononuclear Schiff base Mn(III) complexes, such as [Mn(salen)Cl] (H2salen: N,N′ -ethylenebis(salicylideneamine)), [Mn(saltn)Cl] (H2saltn: N,N′-propane-1,3-diylbis(salicylideneamine)), [Mn(saltnOH)Cl] (H2saltnOH: N,N′-(2-hydroxypropane-1,3-diyl)bis(salicylideneamine)), and [Mn(saltnOCOPh)Cl] (H2saltnOCOPh: N,N′-(2-benzoyloxypropane-1,3-diyl)bis(salicylideneamine)), in N,N-dimethylformamide (DMF) have been reported. Except for the Cu2+ ion, H2O2 decomposition was depressed in the presence of M2+ = Mn2+, Co2+, Ni2+, and Zn2+ ions because [Mn(salen)]+reacted with M2+ to give dinuclear Mn(III)–M(II) and trinuclear Mn(III)2–M(II) complexes inactive toward H2O2 in DMF. For the Cu2+ ion, the dinuclear complexes with the salen and saltnOCOPh ligands showed high activities, although the trinuclear complexes were inactive toward H2O2. The ESR spectra suggested that the intramolecular electron transfer from Cu(II) to Mn(III) on the dinuclear Mn(III)–Cu(II) complex partly occurs to produce a dinuclear Mn(II)–Cu(III) complex active toward H2O2. During H2O2 decomposition including the radical reaction path, [Cu(salR)] (R = en, tnOCOPh) and Mn2+ were produced accompanying metal substitution by Cu2+ on the dinuclear complex. To clarify the substituted product, the preparation and an X-ray crystal structure analysis of [Cu(saltnOCOPh)] were carried out. Three independent [Cu(saltnOCOPh)] complexes (CuA, CuB, and CuC) were present along with an intermolecular π–π stacking interaction between benzene rings on the salicylidenediamine moiety and benzene ring on the benzoyloxy group in the crystal. The geometries around the coppers in both CuA and CuC are more distorted toward tetrahedral from square plane than that in CuB. No stacking interaction between benzene rings on [Cu(saltnOCOPh)] occurs in DMF solution.
  • Sui Wen Lin, Young Chul Kim, Wataru Ueda
    1998 Volume 71 Issue 5 Pages 1089-1094
    Published: 1998
    Released: February 01, 2006
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    SrBi3O4Cl3 with the X1X2 structure, in which metal–oxygen sheets were separated by single chlorine layers and double chlorine layers alternately, has been prepared and tested as a catalyst for the oxidative dehydrogenation of ethane. SrBi3O4Cl3 crystallized in space-group I4/mmm with lattice parameters of a = 3.9370(1), c = 27.0177(7) Å. The structure was refined by a Rietveld analysis, which showed that between two Bi(1) and Bi(2) sites, the former being of Bi in the metal–oxygen sheet faced the single chlorine sheet and the later faced the double chlorine sheet, strontium ions occupied the Bi(2) site only, and did not occupy the Bi(1) site. The SrBi3O4Cl3 catalyst showed a good catalytic performance for the oxidative dehydrogenation of ethane. Particularly, a high selectivity to ethene of more than 90% was obtained. Based upon an investigation of the potential role of chlorine during the cource of the reaction, it was apparently shown that a role of surface chlorine species was important, rather than gas-phase chlorine, for the reaction. It is considered that the high selectivity to ethene can be attributed to the fact that the chlorine radical mechanism operates on the catalysts, and that the surface chlorine blocks the formation of active-oxygen species to prevent destructive oxidation reactions.
  • Kazuo Ogawa, Isao Yamazaki, Toshiaki Yoshimura, Shin Ono, Seichi Renga ...
    1998 Volume 71 Issue 5 Pages 1095-1100
    Published: 1998
    Released: February 01, 2006
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    The protective effect of guanidine hydrochloride (Gu-HCl) on the retrogradation of waxy corn starch (WCS) gel was studied using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and solid-state 1H nuclear magnetic resonance (NMR). The areas of the endothermic peaks on DSC curves attributed to re-gelatinization of WCS gels became small and shifted to lower temperature with increasing Gu-HCl contents; finally, the endothermic peak for WCS gel containing 40% Gu-HCl disappeared, indicating that the WCS gel remained in the gelatinized state.
    The solid-state 1H NMR and FT-IR spectra for retrograded WCS gels showed significant changes compared with those for gelatinized WCS gels. In the process of retrogradation, these spectral changes should imply the formation of intra- and intermolecular hydrogen bonds of WCS and the increase of free water molecules. However, the 1H NMR and FT-IR spectra for a WCS gel containing 40% Gu-HCl did not show such changes along with the progress of retrogradation. From these results, we found that the retrogradation of starch can be protected by the addition of hydrogen bond-breaking materials, such as Gu-HCl.
  • Kingo Uchida, Yuichi Kido, Tadatsugu Yamaguchi, Masahiro Irie
    1998 Volume 71 Issue 5 Pages 1101-1108
    Published: 1998
    Released: February 01, 2006
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    Non-symmetric diarylethenes that have a 1-benzothiophene ring on one end and a 2-thienyl or 3-thienyl group on the other end of the double bond of maleimide were synthesized in order to study the effects of the substitution position of the thiophene ring on the absorption bands and the reactivities. The open-and closed-ring forms of N-cyanomethyl-2-(2,4-dimethyl-5-phenyl-3-thienyl)-3-(2-methoxy-1-benzothiophen-3-yl)maleimide showed absorption bands at 420 and 563 nm in hexane, respectively. When 3-thienyl was changed to 2-thienyl, the absorption bands of N-cyanomethyl-2-(3,4-dimethyl-5-phenyl-2-thienyl)-3-(2-methoxy-1-benzothiophen-3-yl)maleimide shifted to 448 nm (the open-ring form) and 487 nm (the closed-ring form), respectively. The cyclization and ring-opening quantum yields were also dependent on the substitution position. The cyclization yield decreased from 0.30 to 0.03 by changing the position from 3- to 2-thienyl, while the ring-opening yield increased from 0.03 to 0.13. No absorption spectral change by photoirradiation was observed for N-cyanomethyl-2,3-bis(3,4-dimethyl-5-phenyl-2-thienyl)maleimide, which has two 2-thienyl groups.
  • Ryuzo Yoshioka, Kimio Okamura, Shin-ichi Yamada, Ken-ichi Aoe, Tadamas ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1109-1116
    Published: 1998
    Released: February 01, 2006
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    In the optical resolution by diasteromeric salt formation of DL-leucine with (S)-(−)-1-phenylethanesulfonic acid (PES), the less-soluble L-Leu·(−)-PES salt preferentially crystallized from acetonitrile–methanol and, in contrast, the same resolution from acetonitrile–water afforded the monohydrated D-salt [D-Leu·(−)-PES·H2O]. The role of the water of crystallization formed during this resolution system has been explored through a comparison of the crystalline characteristics of D-, monohydrated D-, and L-Leu·(−)-PES by thermoanalysis (DSC) and spectroscopy. The DSC indicated that D-Leu·(−)-PES had a polymorphic form with the water of crystallization; that is, D-Leu·(−)-PES·H2O was thoroughly dehydrated at 60—90 °C and simultaneously converted into the D-Leu·(−)-PES form. However, L-Leu·(−)-PES does not have the water of crystallization even in 75% relative humidity. Detailed comparisons among the X-ray crystal structures of three salts have revealed that in all of the salts the conformations of the PES anion and the Leu cation, respectively, were approximately the same, and their crystal structures comprised specific interaction modes having characteristic hydrogen-bond networks. In particular, in D-Leu·(−)-PES·H2O the PES and Leu ions are cross-linked to each other through water molecules. These observations suggested that the water of crystallization, together with the formation of a stable crystal-packing mode by cross-linking the PES and Leu ions, presumably plays an important role in the selective crystallization in the resolution.
  • Masayuki Takeuchi, Tomoyuki Imada, Seiji Shinkai
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1117-1123
    Published: 1998
    Released: February 01, 2006
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    5,10,15,20-Tetrakis[3- and 4-(dihydroxyboryl)phenyl]porphinatoiron(III)s (1a and 1b, respectively) were synthesized and the saccharide-binding ability of their μ-oxo dimers was investigated. The saccharide-binding process with boronic acids can be conveniently monitored by CD spectroscopy. The μ-oxo dimer of 1b with 4-(hydroxyboryl) groups can bind glucose and galactose among monosaccharides with extremely high selectivity and sensitivity (association constants 104—105 dm3 mol−1), whereas that of 1a with 3-(hydroxyboryl) groups shows only a weak affinity with these monosaccharides. A similar trend was also observed for disaccharides. The origin of the CD activity in 2b can be ascribed to the formation of 1 : 1 μ-oxo dimer/saccharide complexes, in which two porphyrin rings are chirally bridged by one saccharide molecule. The CD sign is well-correlated with the absolute configuration of these saccharides. Thus, the present paper demonstrates that the μ-oxo dimer of 1b, which is formed in a self-assembled manner in aqueous alkaline solution, acts as an excellent pair of artificial “sugar tweezers”.
  • Haruhiko Tomoda, Shojiro Saito, Koji Araki, Shinsaku Shiraishi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1125-1135
    Published: 1998
    Released: February 01, 2006
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    A series of 2-, 3-, or 4-substituted pyrido[1′,2′ : 1,2]imidazo[4,5-b]quinoxalines (PIQs) were synthesized in moderate-to-good yields by the reactions of 2-amino-3-chloroquinoxalines (ACQs) with substituted pyridines, and the structures were established. The reactions of ACQs with 3-phenoxycarbonyl and 3-benzoylpyridines gave the corresponding 2-substituted PIQs, while those with 3-methyl, 3-ethyl, 3-benzyl, 3-phenyl, 3-ethoxycarbonyl, and 3-acetylpyridines gave the corresponding 4-substituted PIQs. PIQ derivatives having substituents at the 2,4,8, and/or 9-positions were also studied. The spectroscopic and electrochemical properties of a series of PIQs derivatives were studied. PIQ showed a strong green fluorescence at 481.5 and 505 nm (Φ = 0.40) in ethanol. The introduction of substituents at the 3 position of PIQ altered the color of the fluorescence from blue to green without deteriorating the high quantum yield of PIQ. All of the derivatives showed strong (blue to orange) fluorescence in both solution and the solid state.
  • Takeru Iwamura, Ikuyoshi Tomita, Masato Suzuki, Takeshi Endo
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1137-1144
    Published: 1998
    Released: February 01, 2006
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    The hydrogen-transfer polymerization of N-acryloyl-N′-p-tolylsulfonylurea (1) prepared by the reaction of p-tolylsulfonyl isocyanate with acrylamide, was carried out at 80 °C for 24 h in N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (MeCN), and toluene containing N-phenyl-2-naphthylamine (1 mol%) as a radical inhibitor using t-BuOK or 1,3-diazabicyclo[5.4.0]undec-7-ene (DBU) (3 mol%) as an initiator. Polymers obtained by t-BuOK in polar solvents were composed of the hydrogen-transfer polymerization unit selectively, while those afforded by t-BuOK in less polar solvents or by DBU were composed of both the hydrogen-transfer and the vinyl polymerization units. Although N-acryloyl-N-methyl-N′-p-tolylsulfonylurea (2) prepared by the reaction of p-tolylsulfonyl isocyanate with N-methylacrylamide, gave low molecular-weight compounds (68) via the generation of the sulfonyl isocyanate, N-acryloyl-N′-methyl-N′-p-tolylsulfonylurea (3) underwent the selective hydrogen-transfer polymerization.
  • Tomomi Kinoshita, Masaya Fujita, Hideyuki Kaneko, Ken’ichi Takeu ...
    1998 Volume 71 Issue 5 Pages 1145-1149
    Published: 1998
    Released: February 01, 2006
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    The ionization-potential and oxidation-potential values have been examined as stability parameters in the gas and solution phase, respectively, for cyclopentadienide ions with from one to four condensed aromatic rings. They indicate that, without solvation effects, the condensed aromatic rings intrinsically stabilize the cyclopentadienide ion in solution as well as in the gas phase, and that an apparent destabilization effect by the aromatic rings in solution is most probably ascribed to a decrease in the stabilizing solvation effects due to charge delocalization on the carbanions. Theoretical investigations from governing orbital interactions using the frontier orbital theory demonstrate that the essential stability of the cyclopentadienide ions is dependent on the structure, itself.
  • Akiko Kitamura, Taira Kiyota, Sannamu Lee, Gohsuke Sugihara
    1998 Volume 71 Issue 5 Pages 1151-1158
    Published: 1998
    Released: February 01, 2006
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    We previously designed and synthesized five N- and C-termini-free amphiphilic α-helical model peptides (Hel series) with a systematically varied hydrophobic–hydrophilic balance (HHB) that showed hemolytic activity, but no antimicrobial activity. However, an N-acetylated and C-amidated model peptide, peptide 3 [S. E. Blondelle and R. A. Houghten, Biochemistry, 31, 12688 (1992)], similar to a Hel series peptide, Hel 9-9, whose hydrophobic and hydrophilic amino acid residues and areas are equal in the α-helical structure, have exhibited both hemolytic and antimicrobial activities. Thus, to investigate the N- and C-terminal effect of the Hel series peptides on their antimicrobial activity, we designed and synthesized three peptides (Cap-Hel series), both termini-blocked by N-acetyl and C-amide groups. Their interaction mode with membranes was examined through reverse-phase high-performance liquid chromatography and circular dichroism spectroscopy as well as measurements of the hemolytic activity, antimicrobial activity, and membrane-clearing ability. No essential difference was found in either the terminal-free or -protected peptides, indicating that acetylation of the N-terminal and amidation of C-terminal did not affect their intrinsic antimicrobial activity in spite of a considerable change in the binding properties to lipids and hemolytic activities.
  • Takayuki Arai, Kazuo Shinozuka, Hiroaki Sawai
    1998 Volume 71 Issue 5 Pages 1159-1169
    Published: 1998
    Released: February 01, 2006
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    New simple bleomycin (BLM) model compounds, which bear a carbamide (1), bulky t-butyl (2), simple alkyl (3), or amino group (4) around the sixth coordination site, have been synthesized in order to study the effect of the distal substituents on the redox reaction and oxygen activation ability of the iron complexes. The carbamide group in 1 lowers the pK values of the all-amino donors of the ligand, which enhances complex formation. The oxygen activation ability of the Fe(II) complexes of 1, 2, 3, and 4, is 74, 69, 43, and 41%, respectively, of that of BLM. The rate of reduction of the Fe(III) complexes of the model compounds and BLM with a reducing agent is more than ten-times lower than that of the oxygenation and activation of the corresponding Fe(II) complexes, indicating the low turnover of the iron complexes of the model compounds and BLM in the reversible redox reaction.
  • Nobuo Kato, Feng Li, Akira Mori, Hitoshi Takeshita
    1998 Volume 71 Issue 5 Pages 1171-1180
    Published: 1998
    Released: February 01, 2006
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    Cotylenins and fusicoccins, fungal diterpenoid glycosides, are know to have identical, yet unique, plant growth-regulating activities. These compounds widen the stomatal pore, stimulate cell enlargement, break seed dormancy, and stimulate rhizogenesis. Because of these plant-hormone like activities, fusicoccin, a representative of this family, has been widely utilized in plant physiology. During the course of our study on the structure-activity relationships of this class of compounds, 9-deoxy-15-hydroxycotylenol and its 15-methoxymethyl ether were synthesized in order to clarify the role of the 9α-hydroxy group of cotylenol, a common aglycon of cotylenins. Since these cotylenol analogs retained germination-stimulating activity on lettuce seeds, it has been clarified that the 9α-hydroxy group of cotylenol is not essential for its biological activities. This finding is informative in designing useful tools for targeting the 14-3-3 protein, which has recently been identified as the binding protein of fusicoccin.
  • Juzo Nakayama, Nobuo Masui, Yoshiaki Sugihara, Akihiko Ishii
    1998 Volume 71 Issue 5 Pages 1181-1186
    Published: 1998
    Released: February 01, 2006
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    Reduction of 3,4-di(1-adamantyl)-1,2-dithiete (2) with LiEt3BH, followed by treatment with MeI, gave (E)-1,2-di(1-adamantyl)-1,2-bis(methylthio)ethene (7-E) in 87% yield. Configuration of the double bond part of 7-E was determined by X-ray diffraction analysis. Treatment of 2 with MeLi and then with MeI also gave the same alkene 7-E in 90% yield, whereas treatment of 2 with MeLi followed by acidification afforded thermally labile (E)-1,2-di(1-adamantyl)-2-methylthioethenethiol in a good yield. Reduction of 2 with LiEt3BH followed by treatment with CS2, SOCl2, and PhBCl2 gave 4,5-di(1-adamantyl)-1,3-dithiole-2-thione, 4,5-di(1-adamantyl)-1,2,3-trithiole 2-oxide, and 4,5-di(1-adamantyl)-2-phenyl-1,3,2-dithiaborole, respectively, in moderate yields. The CuCl(I)-catalyzed decomposition of Ph2CN2 in the presence of 2 afforded 4,5-di(1-adamantyl)-2,2-diphenyl-1,3-dithiole quantitatively, whereas that of tosyl azide produced 1,2-di(1-adamantyl)-2-(p-tolylsulfonyl)iminoethane-1-thione in 10% yield.
  • Teruo Maruta, Yoshiaki Sugihara, Sanae Tanaka, Akihiko Ishii, Juzo Nak ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1187-1192
    Published: 1998
    Released: February 01, 2006
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    6-Acetoxy-, 6-methoxy-, 6-azido-, and 6-(methylthio)dibenzo[d,g][1,3,6]trithiocins (13, 14, 17, and 18, respectively) were synthesized by reactions of 9aH-9,10-dithia-4b-thioniaindeno[1,2-a]indene chloride (4) with appropriate nucleophiles in good yields. The trithiocin 13 was also prepared by the Pummerer reaction of dibenzo[d,g][1,3,6]trithiocin 5-oxide (12) in 97% yield. In many reactions of 4 with nucleophiles, the trimeric partial hydrolysis product, bis{o-[(dibenzo[d,g][1,3,6]trithiocin-6-yl)thio]phenyl} sulfide (15), was formed either as the major or a minor product. Structure of 15 was determined by X-ray diffraction analysis. Meanwhile, heating 4 in boiling methanol or ethanol gave the hydrolysis product, bis(o-mercaptophenyl) sulfide (16), in good yields. Condensation of 16 with benzaldehyde and pivalaldehyde gave 6-phenyl- and 6-t-butyldibenzo[d,g][1,3,6]trithiocins in good yields.
  • Toshiaki Murai, Tatsuya Ezaka, Shinzi Kato
    1998 Volume 71 Issue 5 Pages 1193-1200
    Published: 1998
    Released: February 01, 2006
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    The reaction of lithium alkyneselenolates generated from terminal acetylenes, butyllithium, and selenium with amines and allylic bromides proceeded smoothly in THF at 67 °C to give 4-penteneselenoamides in moderate to high yields. The reaction may proceed via selenoketene intermediates bearing an allylic group, followed by the attack of amines to give the products. Aliphatic and aromatic acetylenes, silylacetylene, and enynes were employed as terminal acetylenes. One molar amount of secondary amines was effective, whereas an excess of primary amines was necessary. The reactions with 2-butenyl bromide exhibited high regioselectivity, although they gave the stereoisomeric mixtures. The reactions of silyl ethers of propargylic alcohols gave α,β-unsaturated selenoamides as a product.
  • Toshiyuki Kida, Yasuhiko Inoue, Wanbin Zhang, Yohji Nakatsuji, Isao Ik ...
    1998 Volume 71 Issue 5 Pages 1201-1205
    Published: 1998
    Released: February 01, 2006
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    Mono-6-O-acylated cycloinulohexaoses 1 and mono-6-O-alkylated cycloinulohexaoses 2 were prepareds by the reaction of cycloinulohexaose with long-chain acyl chlorides and long-chain alkyl bromides, respectively. These amphiphilic cycloinulohexaoses showed good water solubilities. The critical micelle concentration (cmc) of each amphiphilic compound, which was determined by a dye method, decreased along with an increase in the alkyl chain length. The micelle-forming ability of compound 2 was higher than that of compound 1 bearing the same carbon number in the hydrophobic part. The aggregation numbers of mono(6-O-tetradecanoyl)cycloinulohexaose 1b and mono(6-O-tetradecyl)cycloinulohexaose 2b, which were obtained with fluorescence measurements, were 4.8 and 6.5, respectively. The cmcs of compounds 1b and 2b were increased by the addition of either KCl, RbCl, or BaCl2, though they were decreased by the addition of LiCl or NaCl. These results indicate that compounds 1b and 2b complex with K+, Rb+, or Ba2+ in water, but negligibly with Li+ or Na+.
  • Yoji Umezawa, Sei Tsuboyama, Kazumasa Honda, Jun Uzawa, Motohiro Nishi ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1207-1213
    Published: 1998
    Released: February 01, 2006
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    The CH/π interaction is a weak molecular force occurring between CH groups and π-groups. A study was carried out by use of the Cambridge Structural Database in order to obtain insights into the nature of the CH/π interaction and to examine its role in the crystal packing. The proportion of organic molecules bearing at least one CH/π interaction in their crystal structures has been found considerable. The CH hydrogen atoms tend to point toward the center of the aromatic ring. A number of short CH/π distances have been shown in the crystal structures of organic compounds. Moreover, the mean CH/π distance decreases as the acidity of the CH group increases. These results suggest that the CH/π interaction is not simply due to the dispersion force but involves other types of interactions, which are orientation-dependent and effective at wider ranges. It was suggested that the CH/π interaction constitutes one of the important factors in controlling the crystal packing of molecules.
  • Tsugio Kitamura, Masakatsu Yamane, Bian-Xiang Zhang, Yuzo Fujiwara
    1998 Volume 71 Issue 5 Pages 1215-1219
    Published: 1998
    Released: February 01, 2006
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    A parent 1-phenyl-1-benzothiophenium triflate was prepared by a direct phenylation of 1-benzothiophene with diphenyliodonium triflate in the presence of a catalytic amount of copper(II) acetate. Various substituted 1-phenyl-1-benzothiophenium triflates were successfully prepared by this method. The possible mechanism for the copper-catalyzed direct S-phenylation is discussed.
  • Yoshichika Kuroki, Kazuaki Ishihara, Naoyuki Hanaki, Suguru Ohara, His ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1221-1230
    Published: 1998
    Released: February 01, 2006
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    The total synthesis of spermidine and spermine alkaloids, (S)-(+)-dihydroperiphylline (1), (±)-buchnerine (2), (±)-verbacine (3), (±)-verbaskine (4), and (±)-verbascenine (5), is described. The construction of macrocyclic lactams has been efficiently accomplished by the metal-templated cyclization of triamino esters and tetraamino esters. It was also found that the antimony(III) ethoxide is useful as an intermolecular amidation catalyst.
  • Hiroyuki Suga, Xiaolan Shi, Toshikazu Ibata
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1231-1236
    Published: 1998
    Released: February 01, 2006
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    The reactions of substituted oxazoles with nitrosobenzene gave 2-phenyl-2,5-dihydro-1,2,4-oxadiazoles regioselectively through formal [3 + 2] cycloadditions proceeding via a ringopening of oxazoles by an attack of nitrosobenzene. The reactions with 1-chloro- and 1-methyl-4-nitrosobenzenes also produced the corresponding 2,5-dihydro-1,2,4-oxadiazoles regioselectivity.
  • Satoshi Sakaguchi, Susumu Kato, Takahiro Iwahama, Yasutaka Ishii
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1237-1240
    Published: 1998
    Released: February 01, 2006
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    Highly selective aerobic oxidation of isobutane to t-butyl alcohol was successfully achieved by the use of a radical catalyst, N-hydroxyphthalimide (NHPI) in the presence of Co(II) salt under relatively mild conditions. The oxidation of isobutane by NHPI combined with Co(acac)2 under a pressure of air (10 atm) in benzonitrile at 100 °C gave t-butyl alcohol in high yield (84%) along with acetone (13%). The reaction is thought to proceed via hydrogen abstraction from isobutane by the phthalimidooxyl radical (PINO), which seems to be a key active species. The formation of acetone can be explained by a partial β-scission of the t-butoxy radical, generated from the redox decomposition of t-butyl hydroperoxide by cobalt ion. Alkyl-substituted butanes and pentanes were difficult to be oxidized selectively under these conditions because of easy degradation to smaller fragments of the resulting alkoxyl radical intermediates.
  • Gaku Yamamoto, Katsuya Inoue, Hiroyuki Higuchi, Masami Yonebayashi, Yu ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 5 Pages 1241-1248
    Published: 1998
    Released: February 01, 2006
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    In N-phenyl-9-triptycylamine (6), “gear rotation” (GR) and “isolated rotation” (IR) have almost the same free-energy barriers of ca. 45.2 kJ mol−1, while the nitrogen inversion is fast throughout the whole temperature range and thus the nitrogen is regarded as planar on the NMR timescale. In N-methyl-N-phenyl-9-triptycylamine (7), the internal motions are fast on the NMR time scale even at the lowest attainable temperature. In N-benzyl-N-phenyl-9-triptycylamine (8), the GR process has a free-energy barrier of ca. 36 kJ mol−1 and the passing of the benzyl group over an o-benzeno group has a higher barrier than GR. N-2-Biphenylyl-9-triptycylamine (9), which is obtained during the course of the synthesis of 6, shows a dynamic behavior presumably ascribable to GR with the free-energy barrier of 70 kJ mol−1.
  • Kozo Iseda, Atsuya Towata, Eiji Watanabe, Mitsuharu Fukaya, Hiroshi Ta ...
    1998 Volume 71 Issue 5 Pages 1249-1253
    Published: 1998
    Released: February 01, 2006
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    Acetaldehyde, acetaldehyde diethyl acetal (acetal), ethylene, hydrogen, methane, and carbon dioxide were produced from neat ethanol over TiO2 powder without metal in an Ar atmosphere under light irradiation. The yields of these products decreased in the above order. The following observation was obtained by using a filter which cut light at wavelengths below 390 nm. The yield of carbon dioxide was slightly decreased. The yield of acetaldehyde was greatly decreased at the initial irradiation, while it was slightly decreased with continuing of irradiation. The yield of acetal somewhat decreased, and that of ethylene, methane, and hydrogen roughly decreased to 1/2, 1/5, and 1/10, respectively.
  • Manabu Kawasaki, Hirotsugu Kikuchi, Tisato Kajiyama
    1998 Volume 71 Issue 5 Pages 1255-1258
    Published: 1998
    Released: February 01, 2006
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    In order to clarify the rotational direction of molecular reorientation induced by a polarization inversion of ferroelectric liquid crystal (FLC), an electric current along the direction perpendicular to both an electric field and the smectic layer normal was measured for the first time for the FLC cell with a thickness of 50 μm. The electric current curve against time upon the application of an a.c. electric field with a form of triangular wave exhibited a peak attributed to a polarization inversion. The sign of the electric current peak value was inverted by the polarity inversion of an electric field, indicating that the LC molecules rotate in the same direction on the tilt cone upon polarity inversion, that is one-way rotation. The same result was given by polarizing optical microscope observation of the director change during the polarization inversion in a free-standing film. This result differs from that for a surface-stabilized FLC cell.
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