Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 72 , Issue 11
Showing 1-30 articles out of 30 articles from the selected issue
  • Yasuo Wakatsuki, Teiji Chihara
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2357-2363
    Published: 1999
    Released: May 01, 2005
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    As a molecular model for heterogeneous catalysis effected by fine metal particles, the reactions of NO, SO2, and SO with hexanuclear ruthenium clusters have been investigated in detail. One typical reaction of gaseous NO with anionic cluster is a redox-type reaction to give an one-electron oxidation product in which the original cluster framework is retained. The other typical reaction is observed in the reaction of neutral clusters with NO leading to partially degraded products, to which not only NO, but also an NO2 unit are coordinated. When a μ2,η3-allyl ligand is present in NO or SO2 coordinated hexanuclear carbonyl clusters, variable temperature 1H NMR spectra of the allyl terminal protons provide a good methodology to observe the fluxional behavior brought about by rapid migration of the NO and SO2 ligands over the metal atoms in the cluster core. Stepwise reduction of cluster-bound SO2 to SO and finally to S has been realized by the successive action of a Lewis acid and then CO or H2.
  • Takashi Ito
    1999 Volume 72 Issue 11 Pages 2365-2377
    Published: 1999
    Released: May 01, 2005
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    Versatile reactions of tetrahydridomolybdenum, [MoH4(dppe)2] (1, dppe = Ph2PCH2CH2PPh2), one of the typical polyhydrido complexes, are shown. It releases one or two moles of dihydrogen on irradiation or heating in solution to give a coordinatively unsaturated intermediate {MoH2(dppe)2} (A) and/or {Mo(dppe)2} (B) which reacts with (1) methacrylic esters to cause olefinic C–H bond activation, (2) allyl carboxylates to give an carboxylato-κ2O complex and propene as a result of C–O bond activation, (3) β-diketones and catechols to give chelated diketonato and catecholato derivatives, respectively, (4) cyclic imines and amides to cleave their N–H bonds to give N-acylamido complexes, or finally (5) aryl silanes to give a novel hydrido-silyl complex which has a quinquedentate ligand comprising a P∼P∼Si∼P∼P framework. The last complex was further investigated in view of the reactivity resulting from its unique structure. Most of these reaction products are characterized spectroscopically as well as by X-ray crystallography.
  • Kouichi Hirata, Yoshinori Kobayashi, Cai-Lin Wang
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2379-2382
    Published: 1999
    Released: May 01, 2005
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    Positron lifetime measurements have been carried out to study formation and annihilation of ortho-positronium (o-Ps) in a series of fluorinated benzene derivatives. The o-Ps lifetimes (τ3) are longer than those expected from Tao’s empirical relationship for hydrocarbons, τ3−1 (ns−1) = 0.061σ0.5, where σ is the surface tension of the liquids in units of mN m−1. It was found that there is a rather good correlation between the o-Ps intensity I3 and the dipole moment for the fluorinated compounds.
  • Kenji Katayama, Tsuguo Sawada, Isao Tsuyumoto, Akira Harata
    1999 Volume 72 Issue 11 Pages 2383-2388
    Published: 1999
    Released: May 01, 2005
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    The energy transfer dynamics at gold/NaCl aq (0—0.5 M) interfaces was investigated using our recently developed surface plasmon resonance transient reflecting grating (SPR-TRG) method. We focused on two exponential decays in the SPR-TRG signals. The two decays correspond to the relaxation of hot electrons and interfacial heat transfer, respectively. The intensity of each decay changes systematically with increases in the concentration of NaCl, i.e., the former becomes smaller and the latter becomes larger. Considering the relation between the intensity and the dynamics, we concluded that there is some interaction between the hot electrons and the adsorbate on the interface and that the following temperature rise in gold after relaxation of the hot electrons becomes large. This conclusion shows that an ultrafast energy transfer processes by hot electrons exists, and that the process is hindered by the adsorbate. Finally, we discuss the ultrafast energy transfer in relation to the hot electrons and adsorbate on a molecular scale.
  • Minoru Satoh, Yasunori Ohba, Mikio Hoshino, Shiro Konishi, Fujio Ebina ...
    1999 Volume 72 Issue 11 Pages 2389-2394
    Published: 1999
    Released: May 01, 2005
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    The porphyrinato copper cation radical complexes were examined by EPR spectroscopy. The cation radical complexes having bulky peripheral substituents are present as monomers in fluid solution and show EPR spectra due to intramolecular spin coupling between the spins on copper and on the porphyrin ring. The cation radical complexes, having no such substituents, form a dimer in solution. On the other hand, when they are oxidized in frozen solution by γ-ray irradiation, the cation radical complexes are always formed as a monomer, showing a triplet state EPR due to the intramolecular spin coupling. The zero field splitting and spin exchange parameters, |D| and 2J, obtained from EPR measurements were classified into two groups by their magnitudes. The tetraphenylporphyrinato copper(II) cation radical complex, [CuII(tpp)]+, has a small |D| and a small negative 2J value, while the octaethylporphyrinato copper(II) cation radical complex, [CuII(oep)]+, has a large |D| and a large negative 2J value. The other porphyrinato copper(II) cation radical complexes are classified into one of these two type of complexes. These classifications can be related to the electronic configuration of the porphyrin cation radicals. These |D| and 2J values also suggest that the triplet state monomer complexes of porphyrinato copper(II) cation must be deformed from the planar structure.
  • Yoshinori Nibu, Noriaki Fujii, Hiroko Shimada
    1999 Volume 72 Issue 11 Pages 2395-2401
    Published: 1999
    Released: May 01, 2005
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    Cold ions of tetrafluorobenzene isomers were produced by pulsed glow discharge in a supersonic free jet and the electronic spectra due to D2–D0 transitions were observed. The vibrational frequencies of the ions were determined for the ground and electronically excited states through observations of the fluorescence excitation and dispersed fluorescence spectra under collision-free conditions. The vibronic bands observed in the spectra were assigned to totally symmetric vibrations. The difference in the vibrational frequencies between the ion and neutral molecules is very small in spite of the ejection of an electron from the π orbital. A very small frequency change is observed in the electronic excited state of the ions. The frequencies observed for the ions show that the bonding π orbitals are less effective for chemical bonds of the molecules. The electronic spectra of the 1,2,4,5-tetrafluorobenzene cation, whose neutral parent molecule is distorted in the S1 state along the fluorine-wagging normal mode, gave no sign of such a structural change in the electronic excited D2 state.
  • Shinsaku Fujita
    1999 Volume 72 Issue 11 Pages 2403-2407
    Published: 1999
    Released: May 01, 2005
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    A new and simple procedure for counting isomers derived from non-rigid parent molecules has been developed by the combination of the promolecule concept with the characteristic-monomial method. This procedure has been applied to the enumeration of diphenylmethanes, 2,2-diphenylpropanes, and 2,2-dimethylpropanes, after the characteristic monomial tables for the point groups C2v and C3v have been prepared.
  • Shinsaku Fujita
    1999 Volume 72 Issue 11 Pages 2409-2416
    Published: 1999
    Released: May 01, 2005
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    The unit-subduced-cycle-index method and the characteristic-monomial method have been applied to the combinatorial enumeration of ferrocene derivatives. The enumeration has been itemized with respect to formulas as well as to symmetries, where the symmetry of each derivative is characterized by a factor group Dh/C and its subgroups. The chirality/achirality of ligands and of ferrocene derivatives has been discussed.
  • Nahoko Iimura, Keiju Sawada, Yuji Ohashi, Hirotaka Hirata
    1999 Volume 72 Issue 11 Pages 2417-2422
    Published: 1999
    Released: May 01, 2005
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    Water-insoluble drugs, 1-(2,4,6-trihydroxyphenyl)-1-propanone (flopropione) and 4-chloro-m-cresol, formed crystalline complexes with cationic surfactants, such as hexadecyl-, tetradecyl-, dodecyl-, and decyltrimethylammonium bromides, in a solubilized solution system when the solutions were kept at temperatures lower than 288 K and the solubilities of the crystalline complexes were significantly greater than those of only the drugs. Moreover, the complex crystals were more thermostable than only the drugs. The crystal structures of three complexes (4-chloro-m-cresol and hexadecyltrimethylammonium bromide (I), flopropione and tetradecyltrimethylammonium bromide (II), and flopropione and hexadecyltrimethylammonium bromide (III)) were analyzed by the X-ray diffraction method. These complexes were composed of the surfactant and drug molecules in a ratio of 1 : 1 (III) or 2 : 1 (I or II). In each crystal, the drug molecule was sandwiched by the alkyl chains of the surfactant molecules; the hydroxy group of the drug made a hydrogen bond with the bromide anion. Those structural characteristics were similar to those of the complexes between the surfactants and aromatic compounds. Such intermolecular interactions were responsible for the increased solubility and thermal stability of the complex.
  • Naoki Yoneyama, Akira Miyazaki, Toshiaki Enoki, Eiji Ogura, Yoshiyuki ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2423-2428
    Published: 1999
    Released: May 01, 2005
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    We have investigated the physical properties of a new charge transfer salt based on an asymmetric donor 4,5-dibromo-4′,5′-ethylenedioxy-tetrathiafulvalene (EDO-TTFBr2) whose crystal structure contains a weakly dimerized donor stacking structure. This salt is considered to be in a Mott insulating state in the vicinity of the metal-insulator boundary, taking account of the highly conductive semiconducting behavior and the feature of the susceptibility explained by the one-dimensional Heisenberg antiferromagnet model with an S = 1/2 localized spin per dimer and a large exchange interaction of about −190 K. The large exchange interaction and the exceptionally small resistivity (0.06 Ω cm at room temperature) originate from the strong inter-dimer transfer integral. The results of the ESR not only suggest an antiferromagnetic transition at 37 K, but also reflect the one-dimensional electronic state giving a negligible contribution to the spin-lattice relaxation process.
  • Hiroaki Horiuchi, Akinobu Yokawa, Tetsuo Okutsu, Hiroshi Hiratsuka
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2429-2435
    Published: 1999
    Released: May 01, 2005
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    Electronic structure and photodynamics of flav-3-en-2-ol have been studied by steady-state and time-resolved absorption measurements, and by semi-empirical MO calculations. The photo-ring-opening reaction to produce 2-hydroxychalcone has been determined to be a monophotonic process with the quantum yield of 0.29. The precursor to 2-hydroxychalcone has been assigned to the ground-state enol-form by nanosecond laser flash photolysis study at room temperature and steady-state photolysis study at 77 K. The efficiency of the tautomerization from the ground-state enol-form to keto-form of 2-hydroxychalcone has been estimated to be unity. The enol-form is transformed into 2-hydroxychalcone with the rate constant of 3.2 × 104 s−1 in neat acetonitrile, and this process is accelerated by protic molecules. The PM3 calculation of flav-3-en-2-ol showed that the dissociative potential surface in the first excited singlet-state is responsible for the ring-opening reaction.
  • Yoichi Kikuchi, Mitsuru Kubota, Kiyoshi Sawada
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2437-2443
    Published: 1999
    Released: May 01, 2005
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    The partition equilibria of alkali metal picrates with or without a series of poly(oxyethylene) derivatives (POE compound, S) into 4-methyl-2-pentanone (MIBK) have been studied at 25.0 °C. The thermodynamic constants of the distribution and ion-pair formation in the water-saturated MIBK of ion pairs of alkali metal picrates (M+·Pic), and , and the POE compounds-M+ complexes with Pic (SM+·Pic), and , were determined. From these data, the partition coefficients of M+ and Pic, , and the thermodynamic formation constants of the POE compounds-M+ complexes in MIBK, , were evaluated. The interionic distances, a, of ion pairs were estimated from the ion-pair formation constants, and . These results were compared with those in an inert solvent, 1,2-dichloroethane (1,2-DCE). The complex formation constants, , in MIBK are much smaller than those in 1,2-DCE, and their differences among alkali metal ions are small. The donating ability of the solvent has large effects on the stability of the complexes, whereas the polarity (dielectric constant) of the solvent is not very effective. A small metal ion, particularly lithium ion, is strongly hydrated in water-saturated MIBK. Hydration to the lithium ion brings about a serious structural change in the POE compound complex.
  • Hiroshi Kawaguchi, Takashi Okamoto, Keisuke Miura, Tokuo Shimizu, Taka ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2445-2449
    Published: 1999
    Released: May 01, 2005
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    A method for the determination of indium at ng dm−3 levels in water sample is described. Indium is extracted into carbon tetrachloride as an ion pair of (5-sulfo-8-quinolinolato) indate(III) anion with tetradecyldimethylbenzylammonium chloride, and subsequently back-extracted into 0.3 cm3 of a nitric acid solution. The back-extracted solution, containing 100 μg cm−3 of palladium as a matrix modifier, is suitable for the determination of indium by electrothermal atomic absorption spectrometry. The extraction behavior of the ion associate was also compared with that of the 8-quinolinolato complex. The detection limit (3σ) for indium is 0.28 ng dm−3, based on a 2000-fold preconcentration. The proposed method is applicable to the determination of indium at ng dm−3 levels in water sample.
  • Kazuo Eda, Takayoshi Ito, Noriyuki Sotani
    1999 Volume 72 Issue 11 Pages 2451-2457
    Published: 1999
    Released: May 01, 2005
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    A hydrogen-insertion process by spillover on alkali metal decamolybdates was investigated in situ. Hydrogens were inserted, leading to the formation of OH groups. The insertion induced dehydration (release of the crystallization water of the molybdates), which resulted in distortions in the Mo–O framework. The dehydration behaviour varied depending on the kinds of decamolybdates or the manners in which the decamolybdates have crystallization-water species. Furthermore, structural changes of the resultant compounds with heat-treatments in N2 were also investigated. It was then confirmed that these compounds could become starting materials, leading to the formation of alkali metal molybdenum bronzes at lower temperatures, ca. 200 K below those used in ordinary syntheses.
  • Toshio Nakamura, Kaori Makino, Masashi Yanagisawa, Takahiro Miyasaka
    1999 Volume 72 Issue 11 Pages 2459-2462
    Published: 1999
    Released: May 01, 2005
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    The potentiometric response behavior of an electrode, which consists of a non-plasticized carboxyl-modified polyacrylamide polymer (PAA) coupled to benzo-12-crown-4 (PAA–B12C4) to Li+, Mg2+, and Ca2+ in such aprotic solvents as acetonitrile (AN), propylene carbonate (PC), and γ-butyrolactone (GBL), were examined. The electrode showed a Nernstian response to Li+ and Ca2+ in AN, and Li+, Mg2+, and Ca2+ in PC and a near-Nernstian response to Mg2+ in GBL. From the response to Ca2+ it could be confirmed that the membrane potential was mainly established at the polymer membrane–solution interface. The electrode was applied to a study of their complexing with such other basic aprotic solvent molecules (D) as N,N-dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide. The successive complex formation constants (βi) and Gibbs energies of transfer (ΔGtr(j)) of Li+ in AN and Mg2+ in PC in relation to such D were obtained.
  • Hiroyuki Noda, Hiroaki Ohya, Hitoshi Kamada
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2463-2468
    Published: 1999
    Released: May 01, 2005
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    The oxygen reduction ability of hydroxo(protoporphyrinato)iron(III) (HEM) adsorbed on powdery supports in the presence of cysteine was investigated using a Clark-type oxygen electrode. All of the oxygen consumption rates for HEM adsorbed on powdery supports having different surface basicity values (CaO > MgO > TiO2) were larger than the cases of HEM in aqueous solution and of MgO suspension without HEM in the presence of cysteine. Maximum oxygen consumption rate was obtained in the case of the HEM/MgO system. This result suggests that the optimum surface basicity of powdery support is necessary to achieve efficient oxygen consumption. From the measurements for ESR and Raman spectra of the HEM/MgO system, we confirmed the change for the iron valence of HEM from III to II in the presence of cysteine. The production of cystine through the dimerization of cysteinyl radicals in the reaction mixture was also confirmed by the measurements of ESR spectra and capillary electrophoresis (CE). A possible mechanism for accelerating the oxygen consumption rate of the HEM/MgO system in the presence of cysteine is discussed, concerning the effect of the catalytic ability of MgO on the turnovers of iron valence.
  • Masafumi Unno, Daisuke Ishii, Hideyuki Matusmoto
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2469-2473
    Published: 1999
    Released: May 01, 2005
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    The isomerization of the sesquichalcogenides Thex4M4E6 (Thex = 1,1,2-trimethylpropyl, 1: M = Si, E = S; 2: M = Si, E = Se; 3: M = Ge, E = S; 4: M = Ge, E = Se) with the “double-decker”-type structures (Thex2M2E2)2E2, (1dd4dd) to the corresponding compounds with the adamantane-type structures Thex4M4E6 (1ad4ad) was studied. The skeletal rearrangement has been observed to be reversible in the case of sesquichalcogenides 1, 2, and 4; for 1 and 4, the isomerization has reached an equilibrium with preference for adamantane-type structures 1ad and 4ad, respectively, while the equilibrium in 2 has lain more to “double-decker”-type 2dd. On the other hand, the isomerization of 3dd to 3ad has been observed to be irreversible under the condition employed. In the temperature ranges 433—453 K (1dd), 373—393 K (3dd), and 358—383 K (4dd), the equilibrium has followed reversible first-order kinetics. The thermodynamic parameters determined for the forward isomerization, the “double-decker”-type structures (dd) → adamantane-type structures (ad), are as follows: for 1dd1ad, Ea = 35.9 ± 0.1 kcal mol−1, ln A = 30.8 ± 0.2 s−1, ΔH = 35.0 ± 0.1kcal mol−1, ΔS = −0.044 cal mol−1 K−1; for 3dd3ad, Ea = 35.9 ± 0.1 kcal mol−1, ln A = 38.3 ± 0.2 s−1, ΔH = 34.6 ± 0.1 kcal mol−1, ΔS = 13.7 cal mol−1 K−1; for 4dd4ad, Ea = 32.3 ± 0.1 kcal mol−1, ln A = 35.7 ± 0.1 s−1, ΔH = 31.7 ± 0.3 kcal mol−1, ΔS = 10.4 cal mol−1 K−1. The X-ray structure of new sesquichalcogenide 2ad is also reported.
  • Yuji Matsushima, Hidetoshi Kikuchi, Mitsunari Uno, Shigetoshi Takahash ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2475-2482
    Published: 1999
    Released: May 01, 2005
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    Norbornene as well as its 5,6-disubstituted derivatives and oxa-norbornene undergoes a novel cyclopropanation with propargyl alcohol in methanol containig cationic (η5-cyclopentadienyl)tris(acetonitrile)ruthenium complexes as catalysts to give exo-3-acetyltricyclooctane derivatives. Cyclopentadienylruthenium catalysts having an electron-withdrawing substituent on the Cp ligand exhibited the highest activity and the cyclopropanation proceeded even at −20 °C. On the basis of a deuterium labeling experiment, a reaction mechanism involving a ruthenacycle intermediate is proposed.
  • Kazuo Okumura, Taishi Suzuki, Yutaka Nakamura, Chung-gi Shin
    1999 Volume 72 Issue 11 Pages 2483-2490
    Published: 1999
    Released: May 01, 2005
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    The first total synthesis of a macrocyclic antibiotic, micrococcin P1 (1), was achieved. This antibiotic has a unique structure and is constructed of four components called Fragments A, B, C, and D. In particular, the structures of the central pyridine skeleton (Fragment A) and the exocyclic side-chain (Fragment D) of 1 are slightly different from those of a similar antibiotic, micrococcin P (2). By various chemical modifications of the synthetic method for 2, the synthesis of the central 2,3,6-tris(substituted thiazolyl)pyridine segment [Fragment A—C] 15 from ethyl 2-[6-dimethoxymethyl-2-(1-ethoxyvinyl)-3-pyridyl]thiazole-4-carboxylate (9), followed by coupling of 15 with the Fragments B and D moieties, synthesized independently, gave the protected Fragment A-B-C-D segment. Final intramolecular cyclization by using (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate as a condensing agent under high-dilution conditions and then deprotection of all the protecting groups with trifluoroacetic acid were effected successfully to give the expected synthetic 1.
  • Mitsuaki Ide, Masaya Nakata
    1999 Volume 72 Issue 11 Pages 2491-2499
    Published: 1999
    Released: May 01, 2005
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    2-Substituted 1,3-dithiane derivatives, (S)-1-(t-butyldiphenylsiloxy)-2-(1,3-dithian-2-yl)propane (9), (S)-1-(t-butyldimethylsiloxy)-2-(1,3-dithian-2-yl)propane, 1-(t-butyldiphenylsiloxy)-2-(1,3-dithian-2-yl)-2-methylpropane, and 1,2-bis(t-butyldiphenylsiloxy)-3-(1,3-dithian-2-yl)propane, were subjected to lithiation in THF with n-BuLi at room temperature (r.t.); the resulting anions reacted with 2,3-disubstituted oxirane, trans-2-methyl-3-(triphenylmethoxymethyl)oxirane (22), at r.t., giving the coupling products in satisfactory yield. On the other hand, the lithium salt formed in ether from (S)-2-(1,3-dithian-2-yl)-1-(4-methoxybenzyloxy)propane with n-BuLi at r.t. reacted with 22 at r.t. in the presence of hexamethylphosphoric triamide to afford the coupling product in moderate yield. In addition, a mixed organometallic reagent, n-BuLi / Bu2Mg, was found to be an effective metallation reagent for 9 and the resulting anion reacted with 22 to afford the coupling product in good yield.
  • Mitsuaki Ide, Keiji Tsunashima, Masaya Nakata
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2501-2507
    Published: 1999
    Released: May 01, 2005
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    The anion derived from 2-substituted 1,3-dithiane derivative, (S)-2-[2-(t-butyldiphenylsiloxy)-1-methylethyl]-1,3-dithiane, with n-BuLi at room temperature (r.t.) in THF was subjected to coupling with 2,3-disubstituted oxirane, (2S,3S)- or (2S,3R)-2,3-epoxy-1-(triphenylmethoxy)butane, at r.t., giving the coupling products in satisfactory yield. These coupling products were subjected to de-dithioacetalization, and the resulting carbonyl compounds were stereoselectively reduced to afford four stereoisomers of 6-(t-butyldiphenylsiloxy)-3,5-dimethyl-1-(triphenylmethoxy)hexane-2,4-diol.
  • Takeo Yamaguchi, Yoichi Furukawa, Shigeyuki Terada
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2509-2513
    Published: 1999
    Released: May 01, 2005
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    The structure of spectrin in aqueous solutions or erythrocyte ghosts was characterized by using a fluorophore, N-(1-pyrenyl)iodoacetamide (NPIA). The excimer fluorescence of NPIA was clearly observed in isolated spectrin, but not in other proteins such as actin, bovine serum albumin, and lysozyme. The excimer disappeared upon addition of sodium dodecyl sulfate, but reappeared by dialysis. Further, the excimer appeared in spectrin extracts from ghosts labeled at 37 °C with NPIA. Interestingly, no such excimer in spectrin extracts appeared upon pretreatment of ghosts with diamide, and then N-ethylmaleimide. However, when such double-treated ghosts were exposed to dithiothreitol before NPIA labeling, the excimer fluorescence reappeared. Further, excimer fluorescence was observed in ghosts which were pretreated above 30 °C, especially at 50 °C, and then labeled at 0 °C with NPIA. The data of nondenaturing polyacrylamide gel electrophoresis and CD spectra showed marked changes in the structure of spectrin at 50 °C. We thus suggest that the excimer fluorescence of NPIA is useful to monitor the structural changes of spectrin.
  • Liangyou He, C. Akira Horiuchi
    1999 Volume 72 Issue 11 Pages 2515-2521
    Published: 1999
    Released: May 01, 2005
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    The reaction of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate (CS) in alcohols and acetic acid gave the corresponding alkyl esters of oxo acids (80—96%) and oxo acids (78—96%), respectively, by oxidative cleavage of the C(R)–C=O bond. In the case of 2-iodocycloalkanones in methanol, the dimethyl ester was obtained in good yield. A treatment of 5α-cholestan-3-one with CS in methanol produced 2-acetal 3-ester of 2,3-seco derivative in good yield. The effects of cerium(IV) and copper(II) salts are also discussed.
  • Kiyoshi Kanie, Katsuya Mizuno, Manabu Kuroboshi, Sadao Takehara, Tamej ...
    1999 Volume 72 Issue 11 Pages 2523-2535
    Published: 1999
    Released: May 01, 2005
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    Liquid crystals (LCs) containing a trifluoromethylamino group are prepared by the cross-coupling reaction of p-bromo-substituted-(hetero)aryl(trifluoromethyl)amines that are derived from the corresponding dithiocarbamates through oxidative desulfurization–fluorination. The novel LCs are shown to exhibit mainly a smectic phase over a wide range of temperatures. Their electro-optical properties as a component of nematic LCs are compared with those of the corresponding methylamines.
  • Fumihiko Andoh, Kanji Kubo, Tadamitsu Sakurai
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2537-2542
    Published: 1999
    Released: May 01, 2005
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    It was shown that despite the occurrence of a diffusion-limited triplet energy transfer between the title hydroxylamine 1 and benzophenone, triplet 1 decomposed inefficiently giving p-substituted N-(p-substituted benzylidene)benzylamine 2 and 1-naphthoic acid (3) as unimolecular radical elimination products. The logarithm of the kr/kd ratio (where kr is the rate constant for homolytic cleavage of the N–O bond in triplet 1 and kd is that for its deactivation) used as a measure of the triplet-state reactivities of 1, showed a negligible dependence on the substituent constant. This finding was explained in terms of a very small contribution of the ionic structure to the transition state for the N–O bond homolysis.
  • Shunji Ito, Noboru Morita, Toyonobu Asao
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2543-2548
    Published: 1999
    Released: May 01, 2005
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    The reaction of 1-azulenecarbaldehydes 9a and b with pyrrole (8) in acetic acid resulted in decarbonylation to afford azulenes even at room temperature in 49 and 78% yields, respectively. 1,3-Azulenedicarbaldehydes also reacted with 8 to give azulenes in 36 and 52% yields, respectively. This decarbonylation reaction was adopted to the selective synthesis of 3,3′-unsubstituted di(1-azulenyl)methane derivatives 7ad. Acid-catalyzed condensation of 9a and b with paraformaldehyde or benzaldehyde afforded 3,3′-methylenedi(1-azulenecarbaldehyde)s, following this decarbonylation reaction gave the desired 7ad as a sole product in 33—59% yields starting from 9a and b. Such decarbonylation is because of the ability of protonation of azulene ring in acidic condition and because of electron-donating properties of pyrrole ring. This reaction would serve as a new strategy for the protection of 1- and/or 3-positions of azulene ring.
  • Takashi Mukawa, Yukihiko Inoue, Shinsaku Shiraishi
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2549-2556
    Published: 1999
    Released: May 01, 2005
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    The structure of the product obtained by the base-induced isomerization of the 1,3-dipolar cycloadduct of 2,5-di-t-butyl-p-benzoquinone with 2,6-dichlorobenzonitrile oxide was determined by X-ray analysis. The t-butyl group at the bridgehead position of the 1,3-dipolar cycloadduct migrated to the neighboring carbonyl carbon atom. This base-induced rearrangement took place with a bulky group, i. e., Et, i-Pr, t-Bu, and Bn at the bridgehead position of nitrile oxide-quinone cycloadducts in an alcoholic media. The driving force of this reaction is considered to be due to stabilization by aromatization from isoxazoline derivatives to isoxazole-fused p-quinol derivatives.
  • Isao Yamaguchi, Kohtaro Osakada, Takakazu Yamamoto, Motomi Katada
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2557-2562
    Published: 1999
    Released: May 01, 2005
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    The 1 : 2 polycondensation of 3,3′,4,4′-biphenyltetramine and 1,1′-ferrocenedimethanol catalyzed by [RuCl2(PPh3)3] gives ferrocenylene-containing polybenzimidazole 1, (Im–Fc–CH2–O–CH2–Fc)n (Im = [5,5′-bi(benzimidazole)]-2,2′-diyl, Fc = 1,1′-ferrocenediyl). The reaction involves 1 : 2 condensation of 3,3′,4,4′-biphenyltetramine and 1,1′-ferrocenedimethanol to make two imidazole rings and subsequent intermolecular dehydrating coupling of two CH2OH groups to form the CH2–O–CH2 linkage. Polymer 1 is soluble in DMF and DMSO and has molecular weights, Mn = 2.1 × 104 and Mw = 4.5 × 104, determined by GPC (polystyrene standards). Extremely broad 1H NMR signals and results of SQUID measurements showing paramagnetism of 1 suggest the presence of Fe(III) centers in the polymer. The content of Fe(III) is estimated as approximately 20% based on the Mössbauer spectrum of 1. An equimolar reaction of 1,2-diaminobenzene and 1,1′-ferrocenedimethanol in the presence of the Ru(II) catalyst gives bis[1′-(benzimidazol-2-yl)ferrocen-1-ylmethyl] ether. The model compound shows reversible oxidation and reduction peaks assigned to the Fe(II)/Fe(III) redox, whereas the Polymer 1 undergoes oxidation and subsequent irreversible deprotonation to give the electrochemically inert polymer.
  • Renzhi Ma, Ji Liang, Bingqing Wei, Bin Zhang, Cailu Xu, Dehai Wu
    1999 Volume 72 Issue 11 Pages 2563-2566
    Published: 1999
    Released: May 01, 2005
    JOURNALS RESTRICTED ACCESS
    Two kinds of block-type porous materials of carbon nanotubes were fabricated. One was fabricated by hot-pressing without any binding materials, the other was synthesized through carbonization of a cured mixture of carbon nanotubes and phenol-formaldehyde resin. The specific surface area and total volume of the open pores were measured. Both are suitable for fabricating polarizable electrodes of electric double-layer capacitors (EDLCs). In addition, the block-type carbon nanotube electrodes enable one to fabricate a box-type cell. A cell with large capacitance, 150 F at 1.0 V, was developed by using sulfuric acid as the electrolyte.
  • Hiroshige Matsumoto, Shuji Tanabe, Kenji Okitsu, Yuji Hayashi, Steven ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 11 Pages 2567-2571
    Published: 1999
    Released: May 01, 2005
    JOURNALS RESTRICTED ACCESS
    Decomposition of CO2 to CO and O2 in Ar stream has been investigated under atmospheric pressure by the use of a dielectric-barrier discharge plasma reactor. CO2 dissociation was found to proceed in accordance with the stoichiometry of 2 CO2 = 2 CO + O2 at considerable rates, which increased with increasing the input voltage, the CO2 concentration in Ar, and the heat of oxide formation of the corresponding metallic component used as the electrode. From kinetic and spectroscopic measurements, the major pathway of CO2 decomposition was speculated to be promoted by a synergetic effect between plasma excitations in the gas phase and catalytic actions of the electrode surface.
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