Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 69 , Issue 3
Showing 1-40 articles out of 40 articles from the selected issue
  • Mikiya Kato, Toshiaki Fukui, Yoshiharu Doi
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 515-520
    Published: 1996
    Released: June 20, 2006
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    Pseudomonassp. 61-3 accumulated poly(3-hydroxyalkanoates), P(3HA), in nitrogen-free media containing medium- and long-chain alkanoic acids or plant oils. The polyesters of 3HA units of even carbon numbers ranging from C4 to C12 were produced from the alkanoic acids of even carbon numbers, while those produced from the alkanoic acids of odd carbon numbers contained 3-hydroxybutyrate (3HB) and 3HA units of odd carbon numbers of C5 to C11. The strain produced simultaneously P(3HB) homopolymer and a random copolymer of 3HA units of C4 to C12 within cells from the alkanoic acids of even carbon numbers, while a copolymer of 3HB and 3-hydroxyvalerate was formed with a random copolymer of 3HA units from the alkanoic acids of odd carbon numbers. The results suggest that Pseudomonas sp. 61-3 has two types of PHA synthases with different substrate specificities.
  • Anil Kumar Bajpai, Manjulata Rajpoot
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 521-527
    Published: 1996
    Released: June 20, 2006
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    The adsorption measurements of sulfamethoxazole (SM) onto an alumina surface have been done at room temperature with an object to study the mode of SM adsorption at the solution–alumina interface. It is found that the adsorption isotherm is of the Langmuir type, showing a uni-layer formation of the SM molecules on the alumina surface. The adsorption is pH-dependent and found to increase with increasing pH of the medium. The adsorption is quite sensitive to the presence of Cl and SO42− ions also and shows much interesting variation with increasing concentrations of the added anions. The adsorption also decreases with increasing temperature of the adsorption medium. Various kinetic and adsorption parameters such as the adsorption coefficient, rate constants for the adsorption and desorption, and surface coverage have been evaluated with the help of a proposed kinetics scheme.
  • Xin Xu, Nanqin Wang, Qianer Zhang
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 529-534
    Published: 1996
    Released: June 20, 2006
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    After exploring the underlying physics of the cluster-surface analogy, we propose the concept of “metallic atom”. The importance of employing a metallic cluster in the cluster modeling of chemisorption is illustrated with some case studies.
  • Nobuaki Washida, Takashi Imamura, Hiroshi Bandow
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 535-541
    Published: 1996
    Released: June 20, 2006
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    Ozone destruction by CFC’s (CFCl3 and CF2Cl2), BFC’s (CF3Br and C2F4Br2), HCFC’s (CH3CCl2F, CF3CHCl2, and CF3CHFCl), and CH3Br was demonstrated using a 6-m3 evacuable photochemical chamber equipped with UV-enhanced Xe arc lamps. The decay of ozone by a catalytic cycle involving Cl or Br atoms released from the photolysis of halocarbons by UV light was evident, although the chain length was far less than that in the real stratosphere: It was about 8 for CFCl3 and 40 for CF3Br. The rates of ozone decomposition were faster in the BFC’s than in the CFC’s. According to a box-model simulation, in the CFCl3 system 90% of the catalytic cycle proceeds from reactions of Cl + O3 → ClO + O2 and ClO + O → Cl + O2. On the other hand, in the CF3Br system 90% of the catalytic cycle is governed by the following reactions: Br + O3 → BrO + O2 and BrO + BrO → 2Br + O2. The HCFC’s and CH3Br can destroy the ozone with sufficient potential as CFC’s and BFC’s when they enter the stratosphere.
  • Sanyo Hamai
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 543-549
    Published: 1996
    Released: June 20, 2006
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    2-Methylnaphthalene (MN) exhibits MN excimer fluorescence in both β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) neutral aqueous solutions. β-CD forms a 1 : 1 inclusion complex with MN, which self-associates to form a 2 : 2 inclusion complex emitting the MN excimer fluorescence. In 0.4 mol dm−3 NaOH solutions, no excimer fluorescence has been observed, indicating that the 2 : 2 inclusion complex dissociates to two 1 : 1 inclusion complexes because of an electrostatic repulsion between the negatively charged hydroxy groups of the two β-CD molecules contained in the 2 : 2 inclusion complex. For the γ-CD–MN system as well as the β-CD–MN system, the excimer fluorescence can be explained in terms of the formation of a 2 : 2 inclusion complex through a self-association of 1 : 1 inclusion complexes.
  • Tsutomu Asano, Kevin Cosstick, Hiroyuki Furuta, Kohei Matsuo, Hitoshi ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 551-560
    Published: 1996
    Released: June 20, 2006
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    Effects of pressure on thermal Z/E isomerization of substituted N-benzylideneanilines and azobenzenes were studied in 2-methyl-2,4-pentanediol. Pressure dependence of the Z/E isomerization of a substituted azonaphthalene was also studied in glycerol triacetate. From the results in this and earlier papers, the following conclusions were reached. 1) It is possible to cast slow thermal reactions into the state of fluctuation control in highly viscous liquid phase realized by a combination of a viscous liquid and high pressure. 2) The viscosity dependence of the rate constant can be rationalized by the two-dimensional reaction-coordinate model developed by Sumi but not by the Grote–Hynes’ theory of frequency-dependent friction. Namely, the energy-barrier crossing takes place after the solvent molecules are rearranged to accommodate the transition state. 3) Whether the solvent rearrangement involves chemical transformations with appreciable energy increases depends on the nature of the reaction and the solvent.
  • Seiji Yamasaki, Hisao Tsutsumi
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 561-564
    Published: 1996
    Released: June 20, 2006
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    The so-called 1,3 : 2,4-di-O-benzylidene-D-sorbitol (D-DBS) can cause the gelation of alcoholic solvents. The thermal behavior of a 1 wt% D-DBS/ethylene glycol gel was studied using thermal, optical, mechanical, and spectroscopic measurements. Changes in the optical and mechanical properties were observed at around 45 and 80 °C. Upon heating, the diameter of the spherulitic texture in the gel decreased above around 45 °C and disappeared at around 80 °C. In a thermal analysis, an endothermic peak was observed at around 80 °C, which agreed with the gel state-isotropic solution phase-transition point. The aggregated structure of D-DBS in ethylene glycol was studied, using UV absorption and circular dichroism (CD) measurements. The relative orientation of the benzene rings changed above 45 °C, due to the hypochromism of the UV absorptions. The gel showed a temperature dependence of the CD spectra. With increasing temperature, the value of the molar ellipticities increased at 27—82 °C, and drastically decreased at 82—93 °C, indicating that the aggregated structure underwent a change at between 45—80 °C and disappeared above 80 °C. The macroscopic level, as well as the optical and mechanical properties were related to the change in the aggregated structure formed by D-DBS.
  • Shinzo Kohjiya, Yasuhiro Takada, Kenji Urayama, Yasuyuki Tezuka, Akino ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 565-574
    Published: 1996
    Released: June 20, 2006
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    The size distribution of polymer clusters in the pre-gel state was investigated as a function of the conversion by gel permeation chromatography (GPC) in order to elucidate the process of polysiloxane network formation. Polysiloxane networks were synthesized by hydrosilylation between a bifunctional monomer and a tri- or tetrafunctional crosslinker. Experimental chromatograms for the pre-gel system were compared with a theoretical one based on the distribution for the mean-square radius of gyration (<S2>) of polymer clusters predicted by the Flory–Stockmayer theory and the Gaussian chain statistics. Experimental chromatograms at high conversion showed a longer tailed distribution in the large <S2> region compared with a theoretical one. A comparison of experimental chromatograms with theoretical ones suggests the structure of a precursor network in which branched clusters are linearly linked.
  • Yoko Sonoda, Suehiro Iwata
    1996 Volume 69 Issue 3 Pages 575-579
    Published: 1996
    Released: June 20, 2006
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    A hypothesis for the mechanism forming CH3NH2 and CH3OH in interstellar space is examined with the ab initio MO calculations. In the hypothesis, both of CH3NH2 and CH3OH are assumed to be formed via two steps, radiative association reaction and dissociative recombination reaction. The calculations support the possibility of the two-step mechanism for CH3OH, but the first step radiative association reaction for CH3NH2 is proved to be unfavorable. Based on the calculational results, an alternative reaction mechanism is proposed.
  • Satoshi Kusakabe, Miwa Arai
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 581-588
    Published: 1996
    Released: June 20, 2006
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    The partition equilibrium of tetrabutylammonium salts Bu4NX, where X is N3, NO3, SCN, ClO4, and picrate ion, has been measured between water and 1,2-dichloroethane at 298 K. The distribution ratio of these salts can be explained in terms of the extraction of an ion pair (the extraction constant is defined as Kex = [Bu4N+X]org/[Bu4N+]aq[X]aqf±2) and the dissociation and dimerization of the ion pairs in the organic phase. The hydration number of the salt in the organic phase, nh, seems similar among dissociated, ion-paired, and dimerized species. The free energy of phase transfer corrected for the hydration effect in the organic phase, −RT(ln Kexnh), may be correlated with the Gibbs free energy of hydration of the anions in the aqueous phase.
  • Kazuharu Yoshizuka, Hiroshi Kosaka, Takaaki Shinohara, Keisuke Ohto, K ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 589-596
    Published: 1996
    Released: June 20, 2006
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    Phosphoric esters having bis(4-ethylcyclohexyl) (D4ECHPA) and bis(4-cyclohexylcyclohexyl) (D4DCHPA) groups as the alkyl substituents were synthesized in order to investigate their selectivity in the extraction of rare earth elements from acidic nitrate media, together with the apparent molecular weights of the extractants in toluene, the acid dissociation constants and the aqueous distribution coefficients of the extractants. These extractants were found to exist as dimeric species in toluene. The acid dissociation constants of the extractants are nearly the same as that of bis(2-ethylhexyl) hydrogenphosphate (D2EHPA), which is a typical commercial acidic phosphorus extractant. The aqueous distribution coefficients of the extractants become greater in the order D4ECHPA > D2EHPA > D4DCHPA. From the concentration dependencies of the hydrogen ion and extractant on the distribution ratio of rare earth elements, it was concluded that the rare earth elements (M3+) were extracted with D4ECHPA and D4DCHPA (HR) as M(HR2)3 in the organic phase; also, the extraction equilibrium constants (Kex) were evaluated. The extraction equilibrium constants of rare earth elements become greater in the order D4DCHPA > D4ECHPA > D2EHPA. It was very noticeable that the separation factor between HoIII and GdIII, β(Ho/Gd), and β(Yb/Y) with D4ECHPA, and β(Ce/La), β(Pr/La), and β(Ho/Gd) with D4DCHPA are significantly greater than those with D2EHPA. The structural effects of the extractant on the selectivity of rare earth elements are discussed in terms of the molecular modelling. Furthermore, we found that the loading capacity of NdIII with these extractants is excellent compared with that of D2EHPA, due to preventing gelation of the organic phase.
  • Isao Sanemasa, Yue Wu, Takayuki Sato, Kaoru Samejima, Yuuki Koide, Nor ...
    1996 Volume 69 Issue 3 Pages 597-603
    Published: 1996
    Released: June 20, 2006
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    Upon introducing the vapor of binary mixtures of trimethylbenzene (TMB) or trichlorobenzene (TCB) isomers into an α-cyclodextrin (α-CyD) aqueous solution, and circulating it in a closed system, CyD was precipitated with the isomers. In (1,3,5–1,2,3 or 1,2,4,)-TMB systems of various mixing ratios, the mole fraction of 1,3,5-TMB in the total TMBs precipitated was considerably lower than that of 1,2,3- or 1,2,4-TMB: selective precipitation of 1,2,3- or 1,2,4-TMB occurred in the presence of 1,3,5-TMB. The concentration of α-CyD in the supernatant aqueous solution was determined as a function of the isomer mixing ratio. The selectivity was rather poor in the cases of TCB systems. Ternary mixtures of TMB isomers were also studied to a less extent. The solubility product constants at 25 °C were proposed for TMB and TCB precipitates with α-CyD.
  • Mala Nath, Savita Goyal, George Eng, D. Whalen
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 605-612
    Published: 1996
    Released: June 20, 2006
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    Some new organotin(IV) complexes of the general formula, RnSnCl4−n·L [where n = 3, R = CH3 or C6H5; n = 2, R = C6H5; L = Schiff bases derived from the condensation of 2-amino-5-(o-methoxyphenyl)-1,3,4-thiadiazole with salicylaldehyde (L-1), 2-hydroxy-1-naphthaldehyde (L-2), 2′-hydroxyacetophenone (L-3), benzyl methyl ketone (L-4), acetylacetone (L-5), and 2-furancarbaldehyde (L-6)] have been synthesized and characterized by elemental analyses, molar conductances, electronic, infrared, far-infrared, 1H and 119Sn NMR and Mössbauer spectral studies. Thermal studies of three complexes, viz., Ph3SnCl(L-2), Me3SnCl(L-4), and Ph3SnCl(L-5) have been carried out in the temperature range 25—1000 °C using TG, DTG, and DTA techniques. All these complexes decompose gradually with the formation of SnO2 as an end product. In vitro antimicrobial activity of the ligands and their complexes has also been determined against Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus Penicillin resistance (2500 units), Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii, Trichophyton mentagrophytes, and Aspergillus fumigatus.
  • Masaru Kimura, Kyouko Seki, Hitomi Horie, Keiichi Tsukahara
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 613-617
    Published: 1996
    Released: June 20, 2006
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    It was found that peroxodiphosphate ions (denoted by PDP and meaning all forms of P2O84−, HP2O83−, H2P2O82−, etc.) were formed by the oxidation of the phosphinate ion (PH2O2) by molecular oxygen (O2) using trace amounts of the copper(II) ion as a catalyst in aqueous solutions. The formation rate was dependent on the acidity being maximum at around pH 3.5, and was inhibited by the presence of radical scavengers or a complex-forming substance of ethylenediaminetetraacetic acid (EDTA). The formation of PDP was not observed when ions such as IrIV and CeIV were used in place of the copper(II) ion. Thus, this reaction is specific only for the copper(II) ion, which can be easily reduced to Cu+ by the phosphinate ion, where the reduced species are capable of reacting with molecular oxygen to efficiently produce the superoxide of O2−• or HO2. After some PDP had been formed in the presence of air or oxygen, if the reacting solution was changed to be anaerobic by bubbling nitrogen through the solution, the PDP began to decompose according to the first-order rate law with respect to the concentrations of PDP. The kinetics and mechanisms for not only the formation, but also the decomposition of PDP, are presented.
  • Toru Ozeki, Hirohiko Adachi, Shigero Ikeda
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 619-625
    Published: 1996
    Released: June 20, 2006
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    The dissolved structures of the mononuclear molybdate species, MoO42−, HMoO4, and H2MoO4, in aqueous solution were estimated by optimizing their structure models so that their UV-vis absorption spectra were well reproduced by the DV- molecular orbital calculation. In this paper it is proposed that the former two species are tetrahedral ions, and the last is a distorted octahedral species. Using the values of the bond order obtained by a Mulliken population analysis the reason why the dimolybdate anion Mo2O72− does not exist, in contrast with the presence of the well-known dichromate anion Cr2O72−, has been explained. The key species which plays an important role in condensation reactions of molybdate system is not the HMoO4 ion, but the H2MoO4 with very weak Mo–OH bonds.
  • Kiyoshi Tsuge, Hideo Imoto, Taro Saito
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 627-636
    Published: 1996
    Released: June 20, 2006
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    Hexanuclear chromium cluster complexes [Cr6E8(PR3)6] (E = S, PR3 = PEt3, PMe3; E = Se, PR3 = PEt3, PMe3, PMe2Ph) were prepared by the reaction of anhydrous chromium dichloride, a trialkylphosphine, and either NaSH or Na2Se in methanol. The complexes comprised the Cr6 octahedra with eight face-bridging chalcogen atoms and six terminal phosphine ligands. Though the overall ligand arrangements were the same, the symmetry of the central Cr6 octahedra was Oh in PEt3 complexes, but distorted to D3d and D2h in PMe3 and PMe2Ph complexes, respectively. Because of a weakness of the metal–metal interaction, the steric and electronic effect complementarily caused a variation in the chromium octahedra. The electronic effect was analyzed by molecular-orbital calculations using the DV- method.
  • Masaharu Murata, Shinji Hijiya, Mizuo Maeda, Makoto Takagi
    1996 Volume 69 Issue 3 Pages 637-642
    Published: 1996
    Released: June 20, 2006
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    The surface templated resins for three different metal ions such as Cu2+, Zn2+ or Cd2+ as the template guest were prepared by emulsion polymerization using oleyl phenyl hydrogenphosphate as a host surfactant, sodium dodecyl sulfate (SDS) as a co-surfactant and divinylbenzene as a resin matrix-forming monomer. The Cu2+-imprinted resin adsorbed Cu2+ much more effectively than did the nonimprinted, the Zn2+- and Cd2+-imprinted ones. On the other hand, the Cd2+-imprinted resin showed a more highly effective binding to Cd2+ than those of the Cu2+-imprinted, Zn2+-imprinted, and nonimprinted resins. In fact, the Cu2+-imprinted resin did not adsorb any significant amount of Cd2+. The selective feature of the surface templated resins to the target ion was thus successfully demonstrated. The template-dependent selectivity should be ascribed to a favorable placement of the surface-anchored metallophilic groups for multidentate coordination to the specific metal ion.
  • Farooque MD. Akhter, Masakazu Hirotsu, Isamu Sugimoto, Masaaki Kojima, ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 643-653
    Published: 1996
    Released: June 20, 2006
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    Photolysis of trans(t-N,S)-[Co{S(O)2CH2COO-S,O}(tren)]+ (1, t–N = tertiary amine nitrogen; tren = tris(2–aminoethyl)amine) with visible light yielded two complexes, orange and red. The molecular structure of the orange complex perchlorate was determined by the X-ray method to be cis(t-N,O(S))-[Co{OS(O)CH2COO-O,O}(tren)]ClO4·H2O (2, O(S) = oxygen of sulfinate group); geometrical isomerization as well as linkage isomerization took place upon photolysis. A mechanism for the geometrical isomerization was proposed. The red complex, which was assigned as trans(t-N,O(S))-[Co{OS(O)CH2COO-O,O}(tren)]+ (3), is thermally unstable and reverts to the starting complex. This observation is in accord with molecular mechanics calculations, which estimate the starting complex to be more stable. The kinetic studies were performed using the HPLC method in the temperature range 28—70 °C, giving ΔH = 100 kJ mol−1 and ΔS = −23 J K−1 mol−1. Photolysis of a cobalt(III) complex containing the L-cysteinesulfinate-S,N ligand, cis(t-N,S)-lsqb;Co{S(O)2CH2CH(COOH)NH2-S,N}(tren)]2+ (4) with visible light provided two types of linkage isomers, cis(t-N,O(C))-[Co{NH2CH(CH2SO2)COO-N,O}(tren)]+ (4b, O(C) = oxygen of carboxylate group) with an uncoordinated sulfinate group, and a pair of diastereomers of cis(t-N,O(S))-[Co{OS(O)CH2CH(COOH)NH2-O,N}(tren)]2+ (4a). The molecular structures of the perchlorate of 4b and the bromide of 4a with the (S)-sulfur atom have been determined by X-ray diffraction. Isomerization (epimerization) from 4a-R to 4a-S was studied in the temperature range 55—75 °C, giving ΔH = 105 kJ mol−1 and ΔS = −20 J K−1 mol−1. Photolysis of trans(t-N,S)-[Co{S(O)2CH2CH(COOH)NH2-S,N}(tren)]2+ (5) yielded six products. Three of them were the same as those obtained by the photolysis of 4, indicating that geometrical isomerization took place.
  • Masanori Wada, Shuichi Hayase, Masanobu Fujiwara, Tetsuji Kawaguchi, T ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 655-664
    Published: 1996
    Released: June 20, 2006
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    The X-ray crystal structure of the title compound, Φ3PSe [Φ = 2,6-(MeO)2C6H3], showed that the P=Se bond distance [2.136(2) Å] was the longest among those of the reported triarylphosphine selenides, that the P–C bond distances [av. 1.839 Å] were longer than those of triphenylphosphine selenide, and that all the P···O interatomic distances [2.794—3.189 Å] were shorter than the sum of the van der Waals radii, implying a direct electron-donative interaction from the methoxy oxygen atom to the phosphorus atom. Some chemical evidence also showed that the P=Se bond was weaker than that of triphenylphosphine selenide. Alkyl halides, RX, reacted with Φ3PSe to give a mixture of alkylselenophosphonium salts, [Φ3P–SeR]X, and alkylphosphonium salts, [Φ3P–R]X, while they reacted with PhΦ2PSe to give [PhΦ2P-SeR]X almost selectively. Measurements of the reaction rates of Ph3−nΦnPY (n = 0—3; Y = none, O, S, Se) with butyl bromide in acetonitrile showed that the rate decreased in the order of Y = none > Se > S > O and n = 3 > 2 > 1 > 0. Benzylselenophosphonium salts, [Φ3P–SeCH2C6H4Z-4]Cl (Z = H, Me, Cl) and [PhΦ2P–SeCH2Ph]Cl, reacted easily with aqueous sodium hydroxide or with aqueous tin(II) chloride to give the diselenides, (4-ZC6H4CH2Se)2, and most of ArΦ2P [Ar = Φ or Ph] was recovered after these reactions. These properties of [ArΦ2P–SeR]X, as well as of ArΦ2PSe, were discussed in terms of the electronic effect and/or steric effect of methoxy groups at 2,6-positions.
  • Hideaki Kanno, Junko Yamamoto, Shunji Utsuno, Junnosuke Fujita
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 665-671
    Published: 1996
    Released: June 20, 2006
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    Two new chromium(III) complexes, [Cr(4,4′-X2bpdo)3]3+ (X = MeO or EtO; bpdo = 2,2′–bipyridine 1,1′-dioxide), were prepared. These complexes form two diastereomers, lel3(Δ(λλλ), Λ(δδδ)) and lel2ob(Δ(λλδ), Λ(δδλ)), which were separated and resolved by an SP-Sephadex column chromatographic method using achiral eluting agents, such as Na2SO4 or NaCl. The isomers isomerized to each other (lel3lel2ob) fairly rapidly in water along with changes in the absorption spectra, and then racemized very slowly (Δ Λ). These reactions, including conformational (δ λ) and configurational (Δ Λ) changes, are independent of H+ and free ligand concentrations, and are supposed to proceed by an intramolecular mechanism. For a series of [Cr(4,4′-X2bpdo)3]3+ (X = H, Me, MeO, EtO), both the rates of isomerization and racemization are remarkably reduced along with an increase in the electron-releasing ability of the 4,4′-X2 substituents on bpdo.
  • Masaaki Tabata, Jun Nishimoto, Akiko Ogata, Tohru Kusano, Nurun Nahar
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 673-677
    Published: 1996
    Released: June 20, 2006
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    A water-soluble porphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2obtpps4−; H2P4−) was synthesized and the equilibrium constants have been determined for the reaction of H2obtpps4− with lithium(I), cadmium(II), and mercury(II) at 25 °C in I = 0.1 mol dm−3 (NaNO3). The protonation constants of H2obtpps4− were found to be 104.83 ± 0.04 mol−1 dm3, 101.96 ± 0.06 mol−1 dm3, and 10−10.02 ± 0.02 mol dm−3 for K1 = [H3P3−][H+]−1[H2P4−]−1, K2 = [H4P2−][H+]−1[H3P3−]−1, and K−1 = [HP5−][H+][H2P4−]−1, respectively. The porphyrin reacted with lithium(I) in alkaline aqueous solution to form LiP5−, of which formation constant was 10−18.81 ± 0.02 mol dm−3 for KLiP = [LiP5−][H+]2[Li+]−1[H2P4−]−1. Sodium and potassium ions did not form their complexes under the same experimental conditions. The equilibrium constants for the formation of cadmium(II) and mercury(II) porphyrins defined by KMP = [MP4−][H+]2[M2+]−1[H2P4−]−1, M = Cd2+; Hg2+, were 10−8.60 ± 0.13 mol dm−3 and 100.12 ± 0.06 mol dm−3 for KCdP and KHgP, respectively. Mercury(II) also forms homodinuclear porphyrin, Hg2P, and the value was 103.57 ± 0.03 mol−1 dm3 for KHg2P = [Hg2P2−][Hg2+]−1[HgP4−]−1. The octabromo groups lower the basicity of the porphyrin, which results in the formation of lithium(I) porphyrin.
  • Masahiro Mikuriya, Mika Fukuya
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 679-683
    Published: 1996
    Released: June 20, 2006
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    A dinuclear oxovanadium(IV) complex with 2,6-bis(salicylideneaminomethyl)-4-methylphenol (H3L), [(VO)2(L)(CH3O)(dmso)] (1) (dmso = dimethyl sulfoxide), has been synthesized and characterized by infrared and electronic spectra, and by the temperature dependence of magnetic susceptibilities (80—300 K). The molecular structure of 1 was determined by single-crystal X-ray structure analysis. The two octahedral vanadium ions are bridged by a phenoxo-oxygen of L, a methoxo ion, and a dimethyl sulfoxide and have syn oxo configuration. The magnetic property was discussed in relation to the crystal structure.
  • Habib Firouzabadi, Alireza Sardarian, Hasan Badparva
    1996 Volume 69 Issue 3 Pages 685-691
    Published: 1996
    Released: June 20, 2006
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    Tetrabutylammonium periodate is able to oxidize alcohols to their carbonyl compounds, α-hydroxy ketones to α-diketones, α-hydroxy carboxylic acids to the carbonyl compounds (accompanied with decarboxylation), thiols to disulfides, thioethers to sulfoxides in CHCl3 and CH3CN in the presence of AlCl3 and BF3·Et2O as catalysts.
  • Toshiyuki Urano, Hideki Nagasaka, Makoto Shimizu, Shigeru Takahara, Ts ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 693-700
    Published: 1996
    Released: June 20, 2006
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    The sensitization mechanisms of ketocoumarin dyes with a radical-generating reagent, 10,10′-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one] (KCD-J), 7,7′-bis(diethylamino)-3,3′-carbonyldicoumarin (KCD-DA) with 3,3′,4,4′-tetrakis(t-butyldioxycarbonyl)benzophenone (I) in poly(methyl methacrylate) film containing dimethyl phthalate (DMP) as a plasticizer have been investigated by laser flash photolysis using a total reflection cell. The fluorescence of the dyes was efficiently quenched by I in PMMA containing 50 wt% of DMP (film A) against total solid with static quenching distances of 12.5 and 12.7 Å for KCD-J and KCD-DA. The static quenching distance was around 1.5 times longer than that in PMMA. The decay time of the triplet in a film A was slightly quenched by I with a kq of less than 1.5 × 106 mol−1 dm3 s−1 for KCD-J and KCD-DA.
    These results show that a static singlet sensitization from the fluorescent excited dyes to I is the predominant process in film A, suggesting the same predominant static singlet sensitization process in a PMMA film containing acrylate monomer, and the static quenching distance is increased by incorporation of DMP into PMMA film.
  • Yasumasa Fukushima
    1996 Volume 69 Issue 3 Pages 701-708
    Published: 1996
    Released: June 20, 2006
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    Four 18-residue amphiphilic peptides were designed and synthesized, and their helix-sheet conformational transitions were investigated by circular dichroism (CD) in aqueous solution at different pH, peptide concentration and ionic strength as well as in a water/HFIP mixture. The α-helical conformations existed as monomeric states, while the β-sheet structures were formed by the aggregation of approximately 6 monomeric peptides for Peptide I, II, and III. The conformational transitions were provided by the self-association and dissociation of each peptide. The aggregated β-sheet structures would be stabilized by intermolecular hydrophobic interactions and complementary ionic bonds in addition to the conventional hydrogen bonds. In contrast, the formation of α-helical conformations would be caused by intramolecular electrostatic interactions between charged residues and the intrinsic high α-helix propensities of constituent amino acids in addition to hydrogen bonds. These peptides could be useful models for studying the factors governing the stability of secondary and tertiary structures as well as conformational transitions for comprehending the principles of how proteins fold into native states.
  • Akihiko Ishii, Takashi Ishida, Naoko Kumon, Nobuo Fukuda, Hiroyuki Oya ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 709-717
    Published: 1996
    Released: June 20, 2006
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    The title compound 1 was synthesized by the reaction of 2,4,6-tri-t-butylphenyllithium with O-ethyl thioformate or that of 2,4,6-tri-t-butylbenzaldehyde hydrazone with disulfur dichloride in the presence of triethylamine. The thioaldehyde 1 is a purple crystalline compound which is thermally quite stable; only around 200 °C it underwent intramolecular cyclization to give 6,8-di-t-butyl-3,4-dihydro-4,4-dimethyl-1H-2-benzothiopyran 9. The X-ray crystallographic analysis of 1 revealed that the thioformyl group is almost perpendicular to the aromatic ring. The reaction of 1 with 1-cyano-1-methylethyl radicals afforded 9, while that with t-butyl radicals gave 1,3,5-tri-t-butyl-2-t-butylthiomethylbenzene and t-butyl 2,2-dimethyl-1-(1,3,5-tri-t-butylbicyclo[2.2.0]hexa-2,5-dien-2-yl)propyl sulfide in addition to 9. Some Grignard reagents and organolithiums reacted with 1 gave carbophilic, thiophilic, double addition products and some others depending on the kind of the organometallic reagents. Hydrazine and butylamine reacted with 1 very readily to give the corresponding hydrazone and imine, respectively.
  • Soichiro Watanabe, Toshio Yamamoto, Takayuki Kawashima, Naoki Inamoto, ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 719-724
    Published: 1996
    Released: June 20, 2006
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    The title thioaldehyde 1 undergoes [4 + 2] cycloaddition with 2,3-dimethyl-1,3-butadiene at 160 °C and [3 + 2] cycloadditions with diphenylnitrilimine and mesitonitrile oxide at room temperature. The intermediary cycloadduct with mesitonitrile oxide undergoes cycloreversion to give 2,4,6-tri-t-butylbenzaldehyde and mesityl isothiocyanate as the final products. Oxidation of 1 with m-chloroperbenzoic acid (mCPBA) and dimethyldioxirane (9) gives a mixture of (E)- and (Z)-isomers of the corresponding S-oxides (sulfines), the former and the latter being kinetically and thermodynamically controlled products, respectively. Although both (E)- and (Z)-sulfines are not further oxidized by mCPBA, the (Z)-sulfine is oxidized with 9 to give 7-oxa-8-thia-2,4,6-tri-t-butylbicyclo[4.3.0]nona-2,4,9-triene 8,8-dioxide and 6,8-di-t-butyl-3,4-dihydro-4,4-dimethyl-1H-2-benzothiopyran 2,2-dioxide, both of which are intramolecular cyclization products of an intermediary thioaldehyde dioxide (sulfene).
  • Kazuo Morisaki, Shoichiro Ozaki
    1996 Volume 69 Issue 3 Pages 725-734
    Published: 1996
    Released: June 20, 2006
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    A novel series of hybrid L-ascorbic acid (vitamin C) derivatives linking other biologically active substances glycolic acid, myo-inositol, and α-tocopherol (vitamin E) at the C-2 or C-3 hydroxyl group were synthesized, and their thermal stability and inhibitory activities against tyrosinase-catalyzed melanin formation, active oxygen species (AOS), and free radicals were evaluated in vitro. Among these derivatives, 2-O-carboxymethylascorbic acid had high thermal stability as well as moderate inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals compared to other typical inhibitors and scavengers. On the other hand, 3-O-carboxymethylascorbic acid was markedly unstable in aqueous solution. The 2-O-carbonylmethyl derivatives linking myo-inositol or vitamin E were susceptible to degrading, however the vitamin E derivative had stronger inhibitory activities against AOS and free radicals than free vitamin C.
  • Yutaka Ukaji, Masanori Miyamoto, Miho Mikuni, Susumu Takeuchi, Katsuhi ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 735-742
    Published: 1996
    Released: June 20, 2006
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    Palladium-catalyzed asymmetric intra- and intermolecular bis(alkoxycarbonylation) reactions of homoallylic alcohols in the presence of copper(I) triflate were achieved by using the chiral bioxazoline ligand, (S,S)-4,4′-dibenzyl-4,4′,5,5′-tetrahydro-2,2′-bioxazole, under normal pressure of carbon monoxide and oxygen at 25 °C to give the corresponding optically active γ-butyrolactones in 19—65% ee.
  • Morifumi Fujita, Akira Shindo, Akito Ishida, Tetsuro Majima, Setsuo Ta ...
    1996 Volume 69 Issue 3 Pages 743-749
    Published: 1996
    Released: June 20, 2006
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    Photooxygenation of 1,1-diarylethylene occurs efficiently using 10-methylacridinium ion as a photocatalyst to yield the 1,2-dioxane and/or the diaryl ketone depending on the substituents on the aryl groups. The reaction mechanism is revealed based on the dependence of the quantum yields on the concentrations of the alkene and oxygen, the fluorescence quenching of 10-methylacridinium ion by the alkene, and the direct detection of reactive intermediates by applying laser flash spectroscopy as well as pulse radiolysis. The photooxygenation proceeds via photoinduced electron transfer from the alkene to the singlet excited state of 10-methylacridinium ion. The alkene radical cation formed by the photoinduced electron transfer reacts with alkene to give the 1,4-dimer radical cation, which then reacts with oxygen to produce the oxygenated 1,6-radical cation. The subsequent one-electron reduction of the 1,6-radical cation results in formation of the 1,6-biradical which cyclizes to yield 1,2-dioxane derivative or fragmentates to yield diaryl ketone. When the 1,6-biradical is reduced by the alkene itself, the alkene radical cation is regenerated to repeat the radical chain process.
  • Mizue Fujio, Yoshihiro Saeki, Kenichiro Nakamoto, Sung Hong Kim, Zvi R ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 751-764
    Published: 1996
    Released: June 20, 2006
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    The solvolysis rates of (1-arylcyclobutyl)methyl and (1-arylcyclopropyl)methyl p-toluenesulfonates were measured in a wide variety of solvents. The aryl-assisted kΔ solvolysis of [1-(p-methoxyphenyl)cyclobutyl]methyl p-toluenesulfonate did not give a linear Winstein–Grunwald correlation using the 2-adamantyl-based YOTs scale, but did show dispersion for different binary solvent mixtures. An extended dual-parameter treatment, log (k/k80E) = mcYOTs + mΔYΔ, successfully correlated the present set of kΔ solvolyses with R > 0.995 and SD < 0.09. The blending parameter MΔ (= 0.51mΔ/(mc + 0.51mΔ)) increases monotonically with increased electron donation by the substituent, showing an increased dispersion of the YOTs plot with increasing anchimeric assistance. The solvolysis of (1-arylcycloalkyl)methyl p-toluenesulfonates demonstrates the varying extent of anchimeric assistance by the neighboring groups, from a completely synchronous aryl-assisted process for the p-methoxy derivative of (1-phenylcyclobutyl)methyl p-toluenesulfonate, via moderately to weakly aryl-assistance by the p-methyl derivative and the unsubstituted compound, to a completely aryl-unassisted kc process for the more electron-withdrawing aryl derivatives and the (1-arylcyclopropyl)methyl p-toluenesulfonates. The dual-parameter equation enables one to monitor the varying extent of anchimeric assistance in the transition state. From the results we propose a general solvolysis framework involving a continuous spectrum of kckΔ mechanisms for anchimerically assisted solvolysis.
  • Masaaki Sawa, Kenji Ogino, Waichiro Tagaki
    1996 Volume 69 Issue 3 Pages 765-774
    Published: 1996
    Released: June 20, 2006
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    The reactivities and the site-selectivities of the hydrolyses of ATP and UTP by the catalysts of the metal complexes of adenine-linked di-2-pyridylamine ligands, (Py)2N–(CH2)n–Ade (L: n = 3, 4, 5, and 6), were examined. It was found that these adenine–dipyridylamine coordinated Cu2+ complexes (with 2 : 1 ratios of [CuII(L)]2+ : ATP or [CuII(L)]2+ : UTP) were more reactive for the hydrolyses of ATP and UTP than the complexes of ligands containing other metal ions (Mg2+, Ni2+, and Zn2+) at 40 °C and pH 7.3 (HEPES buffer), as reflected in much higher product ratios of ADP/AMP and UDP/UMP than those of Cu2+ alone. The observed high reactivity and selectivity are interpreted in terms of the base-base stackings between an adenine moiety of ATP or an uracil moiety of UTP and an adenine of the ligands, and of the selective coordination of Cu2+ to oxide ions in phosphate residues in the ternary complexes of ligand–Cu2+–ATP. The Cu2+-complex of di-2-pyridylamine having no adenine moiety, which is the active center of [CuII(L)]2+, promoted the hydrolyses of ATP and UTP less efficiently than the aquacopper(II) ion. The number of spacer methylene groups of the ligands influenced the hydrolytic activity of the Cu2+-complexes of these adenine–dipyridylamine ligands. The complexes of [CuII(L-4)]2+ and [CuII(L-5)]2+ were the most reactive and site-selective for the hydrolyses of ATP and UTP, respectively.
  • Tadamitsu Sakurai, Tohru Nagaoka, Jun Kamiya, Hiroyasu Inoue
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 775-778
    Published: 1996
    Released: June 20, 2006
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    Substituent and temperature effects on the equilibrium constants for the triethylamine-catalyzed acyl exchange reactions of N-(substituted benzoyl)-O-acetyl-o-aminophenols have been investigated by 1H NMR spectroscopy. It was found that the standard enthalpy change ΔH° in acyl exchange processes, estimated from temperature dependence of the equilibrium constant, correlates well with the standard free energy change ΔG° which was used as a measure of the relative stability of isomer pairs, while the standard entropy change ΔS° is approximately constant (−6 ± 2 J K−1 mol−1) irrespective of the substituents in benzoyl introduced. The finding of enthalpy-controlled acyl exchange reactions confirms that the relative stability of a given isomer pair is determined by the difference in electrostatic force of attraction between the amide nitrogen with a partial positive charge and the ester carbonyl oxygen having a partial negative charge in both isomers.
  • Kazushi Kinbara, Kazuhiko Saigo
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 779-784
    Published: 1996
    Released: June 20, 2006
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    The solid-state EZ-isomerizability of α,β-unsaturated amides, which had low isomerizability in the solid state, was greatly improved by modifying their structure; EZ-isomerizability was attained by replacing the carbonyl group of the amides by a thiocarbonyl group as well as replacing the heterochiral N-substituent of the amides by a homochiral one. Crystallographic analyses have revealed that the isomerizability of α,β-unsaturated amides and thioamides in the solid state partially depends on their molecular conformation in crystal. In addition, it was found that the packing coefficient has a correlation with the isomerizability; a smaller value of the packing coefficient caused an increased formation of (Z)-isomers.
  • Yoshifumi Koide, Hiroyuki Terasaki, Hirotaka Sato, Hideto Shosenji, Ki ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 785-790
    Published: 1996
    Released: June 20, 2006
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    Table-type chelating surfactants ([4]ArmX-R12, mX means the number of phosphates (P), carboxylic acid (Ac), and hydroxamic acid (Hx), respectively) have been derived from the calix[4]resorcinarene bearing tetradodecyl side chains ([4]Ar-R12), and applied to a collector of uranium flotation. The surface tension of the aqueous solution was 35 mN m−1 for [4]Ar5.6P-R6 (Rn means the alkyl chain length), 52 mN m−1 for [4]Ar5.9P-R12, 42 mN m−1 for [4]Ar8.0Ac-R12, and 48 mN m−1 for [4]Ar5.1Hx-R12. They formed UO2 complexes and floated the UO22+ from an aqueous solution by air-bubbling. Furthermore, [4]Ar5.9P-R12 and [4]Ar6.3P-R12 had competence to float the uranium from seawater. A trace amount of uranium in 450 cm3 of seawater was floated at 68—94% using 1—10 mg of [4]Ar5.9P-R12 or [4]Ar6.3P-R12. On the other hand, [4]Ar5.1Hx-R12 and [4]Ar8.0Ac-R12 brought about lower floatabilities. [4]ArmP-R12 could be recycled several times by dissolving the scum (uranium complex) in 5 mol dm−3 H2SO4.
  • Chieko Uchida, Yasuko Iizuka, Eido Ohta, Kaori Wakamatsu, Masanao Oya
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 791-796
    Published: 1996
    Released: June 20, 2006
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    High-purity N-carboxyl L-tryptophan anhydride (L-4-indoylmethyl-2,5-oxazolidinedione) was synthesized in good yield. Copolypeptides with a random sequence of L-trypophan (Trp) with glycine (Gly), L-alanine (Ala), L-α-amino-n-butyric acid (Abu), L-n-valine (Nval), L-n-leucine (Nleu), L-leucine (Leu), L-γ-methylglutamate (Glu(OMe)), and L-methionine (Met) were synthesized by the copolymerization of the corresponding N-carboxy-α-amino acid anhydrides (NCA) in solution. The rate of polymerization of Trp NCA was less than that of the other amino acid NCAs. The helix contents of the formed copolypeptides, estimated by the circular dichroism (CD) spectra, were remarkably decreased at a content of about 8% of Trp involved in poly(Trp-co-Nval) (poly(Trp,Nval)), poly(Trp-co-Leu) (poly(Trp,Leu)), poly(Trp-co-Nleu) (poly(Trp,Nleu)), and poly(Trp-co-Glu(OMe)) (poly(Trp,Glu(OMe))), but was not decreased at that percentage in poly(Trp-co-Met) (poly(Trp,Met)).
  • Kuniaki Takata, Yoshihisa Yamamoto, Toshikatu Sata
    1996 Volume 69 Issue 3 Pages 797-804
    Published: 1996
    Released: June 20, 2006
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    In order to prepare an excellent monovalent cation permselective cation exchange membrane, a polyethyleneimine (PEI) layer was formed with sulfonyl–amide bonding between PEI and sulfonyl chloride groups on one surface of the membrane. Two methods were tried: 1) one surface of the membrane reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed, and 2) after one surface of the sulfonyl chloride groups had been hydrolyzed, the other surface of the membrane was reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed. The cation exchange membranes, which had been prepared using both methods, had excellent monovalent cation permselectivity, low electrical membrane resistance and high current efficiency for the long-term electrodialytic concentration of seawater. The reacted amount of PEI on the membrane was about 10% of the cation exchange capacity.
  • Shigeru Kunugi, Masumi Yoshida
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 3 Pages 805-809
    Published: 1996
    Released: June 20, 2006
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    Thermolysin-catalyzed peptide condensation reactions from acylamino acids and amino acid amides were studied in an acetonitrile (MeCN)–water mixed solvent in a homogeneous system. A kinetic analysis of the condensation reaction was performed by taking into account the simultaneous, solvent-induced, gradual inactivation of the enzyme. Although the dependence on the concentration of the carboxyl component gave linear double-reciprocal plots, that on the amine component at 70% MeCN showed an apparent substrate inhibition profile. An analysis of the apparent Km and kcat parameters for both components at 40% MeCN indicated that the condensation reaction proceeded by a random Bi–Bi mechanism. The Km values were estimated to be 5.5 mM for Cbz–Phe and 110 mM for LeuNH2, and kcat was 4—5 s−1. The Km values for Cbz–Phe and LeuNH2 were also evaluated at 70% MeCN to be 5 and 100—150 mM, respectively. This indicates that the catalytic property of this enzyme is not significantly influenced by the existence of a higher concentration of such an organic solvent, except for the second nonproductive binding of the amine component.
  • Akira Adachi, Jun Yamauchi
    1996 Volume 69 Issue 3 Pages 811-814
    Published: 1996
    Released: June 20, 2006
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    The effect of oxygen on polypyrrole (PPy) doped with benzenesulfonate has been investigated by electric conductivity and electron spin resonance (ESR) measurements. There are two regions in the changes of the conductivity, the linewidth and the spin concentration with respect to the pressure of oxygen. When the pressure decreased in the range from ambient pressure to 0.2 Torr (region I), the conductivity increased consistently with the relationship of the Langmuir adsorption, in which we assumed that the amount of adsorption was in proportion to the inverse of conductivity. This effect was reversible with respect to the pressure, indicating physical adsorption in this region I. The oxygen desorption by reducing the pressure caused a rapid decrease of the linewidth as well as the spin concentration. It was concluded that the linewidth variation is due to the reduction of dipole–dipole interactions between the unpaired electrons of the oxygen molecules and radicals of PPy (polarons), while the spin concentration variation is due to the disappearance of the oxygen molecules. Below 0.2 Torr (region II), the conductivity increased, deviating from the Langmuir relationship, while the ESR spectra almost remained constant. These findings were discussed, considering that the interaction positions of the adsorption were radical sites (polarons) in connection with the conductive process and that only a small number of the oxygen molecules adsorbed in this region II.
  • Hideki Nishimori, Masahiro Tatsumisago, Tsutomu Minami
    1996 Volume 69 Issue 3 Pages 815-818
    Published: 1996
    Released: June 20, 2006
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    Monodispersed silica particles, which ranged from 0.14 to 0.42 μm in diameter, were prepared by the sol–gel method. These particles were first separated from original sols, and dried, heat-treated, and then re-dispersed in a mixture of ethanol, water, and triethoxy(methyl)silane. Thick silica films without micro-cracks were formed by electrophoretic deposition of the particles on a stainless steel sheet in the re-dispersed sols. The weight of the silica films deposited was increased with increasing particle size at a given applied voltage. On the other hand, density of the films was increased with decreasing particle size. When the particle size was 0.32 μm in diameter, crack-free films of ca. 20 μm in thickness were prepared after heat treatment at 800 °C for 1 h.
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