Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 69 , Issue 6
Showing 1-45 articles out of 45 articles from the selected issue
  • Hiroshi Kudo, Keiichi Yokoyama
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1459-1469
    Published: 1996
    Released: June 22, 2006
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    This article describes the nature of bonding in hyperlithiated molecules with stoichiometries exceeding normal valence expectations. The existence of such hyperlithiated or hypervalent molecules as CLi6, Li3O, Li4O, Li5O, Li3S, Li4S, Li4P, Li2CN, Na2CN, and K2CN has already been experimentally confirmed by means of Knudsen-effusion mass spectrometry in our laboratory. These molecules have nine or more valence electrons, violating, at least formally, the octet rule. However, these molecules are thermodynamically more stable than the corresponding octet molecules. Results of ab initio MO calculations reveal that the extra valence electrons beyond the usual octet are in singly occupied orbitals (SOMO) or highest occupied orbitals (HOMO) in the LinA (A = C, O, P, S) molecules. The SOMO as well as HOMO forms the Li–Li bonds between all pairs of lithium atoms and contribute to stabilization of these molecules. The bonding situation of the M2CN (M = Li, Na, K) species is apparently different from that of LinA. The favored structure has Cs symmetry and is best described as a complex of the CN anion with the M2+ cation. The extra valence electron is in SOMO, which corresponds to the radical cation SOMO and contributions to M–M bonding. The presence of the M2+ unit is a typical example of justifying the term hypervalent.
  • Makoto Fujita, Katsuyuki Ogura
    1996 Volume 69 Issue 6 Pages 1471-1482
    Published: 1996
    Released: June 22, 2006
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    Recent developments in the study of the transition-metal mediated supramolecular self-assembly are reviewed. Focus is on the self-assembly of macrocycles, catenanes, and cages from (en)Pd(NO3)2 (1) and pyridine-based bridging ligands. Coordination of linear 4,4′-bipyridine on the cis coordination site of palladium complex gives a macrocyclic square supramolecule, whereas macrocyclic dinuclear Pd(II) complexes self-assemble from 1 and flexible bridging ligands. Unprecedented formation of catenanes through rapid slippage of two preformed molecular rings can be achieved by exploiting the labile character of a Pd(II)-linked macrocycle: i.e., a macrocycle assembling from 1 and PyCH2C6H4CH2Py exists in rapid equilibrium with its catenated dimer and the equilibrium is strongly pushed toward the catenane (> 99 : 1) in a polar media. The combination of 1 with tridentate ligands gives three-dimensional cagelike hosts. A spherical M3L2 complex organizes from 1 and a flexible tridentate ligand only in the presence of specific guests providing a model for induced fit. On the other hand, a nanometer-sized hollow supramolecule self-assembles from four rigid tridentate ligands held together by six protected Pd complex 1.
  • Kenji Matsuda, Nobuo Nakamura, Katsuya Inoue, Noboru Koga, Hiizu Iwamu ...
    1996 Volume 69 Issue 6 Pages 1483-1494
    Published: 1996
    Released: June 22, 2006
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    ‘Starburst’-type nona- and dodecadiazo compounds were designed and synthesized by using the cyclotrimerization of ethynyl ketones as a key step. Construction of the larger dodecadiazo compounds was facilitated by using a trimethylsilyl protecting group for an acetylenic moiety. The diazo compounds were photolyzed in MTHF solid solution at cryogenic temperatures and analyzed by means of Faraday magnetometry and ESR spectroscopy. From the field dependence of the magnetization, the nonacarbene, the photoproduct of nonadiazo compound, was evidenced to have a nonadecet (S = 9) ground state. This spin multiplicity is the highest value ever reported for purely organic materials. On the other hand, the spin multiplicity was low and antiferromagnetic interaction operated in the photoproduct of the dodecadiazo compound. This result was interpreted not in terms of the intermolecular antiferromagnetic interaction but of the intramolecular cross-linking between the carbene centers. In the ‘Starburst’-type polycarbenes with extended branching, the reactive carbene centers can become mutually too close to each other in space and so appear to recombine readily. This study showed one of the limitations of the extension of the carbene network by way of flexible ‘Starburst’-type structures.
  • Yasuo Kameda, Takahiro Mori, Takashi Nishiyama, Takeshi Usuki, Osamu U ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1495-1504
    Published: 1996
    Released: June 22, 2006
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    Time-of-flight neutron and X-ray diffraction as well as Raman spectroscopic measurements were carried out on an aqueous 15 mol% HCOONa solution in order to investigate the hydration structure of both the formate and sodium ions in the concentrated aqueous solution. The intramolecular bond distances of DCOO (rCD = 1.07 ± 0.01 Å, rCO = 1.272 ± 0.007 Å and rOO = 2.18 ± 0.02 Å) were determined through a least-squares fit of the observed neutron interference term in the high-Q region. The average hydrogen-bond distances between the D2O molecules in the solution (r(O···D) = 1.92 ± 0.02 Å and r(D···D) = 2.42 ± 0.02 Å) were also obtained. The hydration parameters on the formate ion were estimated to be rOformate···H2O = 2.82 ± 0.01 Å and nOformate···H2O = 4.4 ± 0.2 from a least-squares fit of the X-ray intermolecular interference term. A preferred orientation between the formate ion and hydrated water molecules was suggested from the present X-ray data. The hydration number of Na+ in the solution was given to be 4.6 ± 0.2, besides the intermolecular distance (rNa+···H2O = 2.37 ± 0.01 Å). The symmetrical stretching vibrational band of the hydrated sodium ion, Na+(H2O)n, in a 15 mol% HCOONa solution was observed at 225 cm−1 in the present isotropic Raman spectrum.
  • Yoshikata Koga, Peter Westh
    1996 Volume 69 Issue 6 Pages 1505-1508
    Published: 1996
    Released: June 22, 2006
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    The normalized fluctuations were reformulated in a unified manner, keeping the number of molecules in each coarse grain fixed. The normalized fluctuations were evaluated for aqueous 2-butoxyethanol using the existing data of κT, Cp, αp, and Vm. The partial molar fluctuations of 2-butoxyethanol were then calculated. These quantities added some more evidences to the mixing schemes in aqueous 2-butoxyethanol conjectured earlier in this laboratory.
  • Michiaki Adachi, Kiyotaka Yoshii, Yi Zhuo Han, Kaoru Fujimoto
    1996 Volume 69 Issue 6 Pages 1509-1516
    Published: 1996
    Released: June 22, 2006
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    The promotional effects of metal oxides for a silica-supported cobalt catalyst were investigated by using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Temperature Programmed Reaction (TPR), and Fourier Transform-Infrared Spectroscopy (FT-IR) techniques. The La-modified cobalt catalyst with 3% La loading which was prepared by simultaneous impregnation showed higher catalytic activity while keeping slightly higher selectivity of C2+ hydrocarbons. TPR, FT-IR, and TEM studies revealed that CO is adsorbed on the La-modified cobalt catalyst in a more active state compared to the monometallic cobalt catalyst, which was caused by the agglomeration of cobalt.
  • Keishi Ohara, Noboru Hirota
    1996 Volume 69 Issue 6 Pages 1517-1526
    Published: 1996
    Released: June 22, 2006
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    The Chemically Induced Dynamic Electron Polarization (CIDEP) mechanisms in the hydrogen abstraction reactions of excited azaaromatic compounds; quinoxaline, phenazine, and quinoline are investigated in detail. It is shown that several polarization mechanisms are involved and the observed CIDEP spectra vary strongly depending on various factors such as the concentration, the temperature, the delay time, and the excitation light intensity. The net emissive spin polarization is ascribed mainly to the radical–triplet pair mechanism (RTPM), which is strongly dependent on the concentrations of the radical and triplet molecules. It is shown that the triplet molecules are long-lived and the condition to produce the RTPM polarization is satisfied. The observed time evolutions of the transient EPR signals are qualitatively explained on the basis of the rate equations, which include the RTPM polarization and the relaxation.
  • Keizo Horiuchi, Takanori Fukami
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1527-1532
    Published: 1996
    Released: June 22, 2006
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    The crystal structure of bis-2-picolinium hexachlorostannate (CH3C5H4NH)2SnCl6 was determined at room temperature by a single-crystal X-ray diffraction method. This crystal forms triclinic with space group and Z = 1. The temperature dependence of the 35Cl NQR spectrum was investigated at between 77 K and around 340 K, at which temperatures the signals faded out. Three signals with an equal intensity were observed with no anomaly in their temperature variation over the entire temperature region investigated. DTA measurements were carried out at between 140 and 430 K, and no heat anomaly was observed.
  • Ryuji Hanaishi, Yasunori Ohba, Seigo Yamauchi, Masamoto Iwaizumi
    1996 Volume 69 Issue 6 Pages 1533-1541
    Published: 1996
    Released: June 22, 2006
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    A photoinduced electron transfer reaction in a model system of the photosynthesis was investigated by means of pulsed EPR in one (1D)- and two-dimensions (2D). EPR spectra of a spin correlated radical ion pair(SCRP) and a spin polarized radical anion were observed in the system of tetrakis(4-sulfonatophenyl) porphyrinozinc(II) (ZnTPPS)/duroquinone (DQ)/cetyltrimethylammonium chloride micellar solution. In order to investigate the dynamics and structures of the intermediate species, a non-linear least square fitting (NLLSQ), instead of linear prediction (LP), was examined for analyses of free induction decays (FID’s) in a 1D experiment. FID’s were fairly well reproduced with the NLLSQ method as a sum of the signals of the DQ anion and the SCRP. For the DQ anion, the linewidth gradually decreased indicating movement of the anion across the micelle/water interface.
    For a definitive assignment of the SCRP, a 2D nutation experiment was performed. Different flip angle dependences were observed for the SCRP and the free anion. Under an assumption of an average exchange interaction (J), the 2D spectra of the SCRP were simulated, including an off-resonance effect on the basis of density matrix formalism. Comparison of the calculated and observed spectra indicated that the upper limit of the average |J| was 0.3 MHz (J < 0).
  • Pratik K. Sen, Ankan Sanyal, Kalyan K. Sen Gupta
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1543-1548
    Published: 1996
    Released: June 22, 2006
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    The kinetics of the reaction between hydrogen peroxide and gold(III) in a hydrochloric acid medium has been studied. The reaction is first order with respect to [AuIII] as well as [H2O2]. The reaction rate has an inverse dependence on [H+] and [Cl]. AuCl4, AuCl3(OH2), and AuCl3(OH) are the reactive species of Au(III). A rate expression consistent with the experimental findings has been proposed.
  • Tomoharu Ama, Toshiaki Yonemura, Hiroshi Kawaguchi, Takaji Yasui
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1549-1554
    Published: 1996
    Released: June 22, 2006
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    Two isomers of the dinuclear complex with β-alanyl-L-aspartate (β-ad), glycinate (gly), and ethylenediamine (en), [Co(β-ad)Co(gly)(en)(μ-OH)2]+, were prepared by treating an aqueous solution containing [Co(β-ad)(OH2)2] and [Co(gly)(en)(OH2)2]2+ under basic conditions. The geometrical structures and absolute configurations of these isomers were assigned on the basis of the NMR, UV, and CD spectral data; the assignments were confirmed on the basis of the spectral data of the mononuclear species that were obtained by the acid hydrolysis of the isomers. The faster eluted isomer (eluted with H2O on an SP-Sephadex (K+ form) column) consists of [Co(β-ad)(μ-OH)2] (β-ad coordinates to cobalt(III) as a tetradentate) and Δ-fac(O)-[Co(gly)(en)(μ-OH)2] moieties, and the later consists of [Co(β-ad)(μ-OH)2] and Λ-fac(O)-[Co(gly)(en)(μ-OH)2]. Another di-μ-hydroxo–dicobalt(III) complex containing β-alanyl-L-histidinate (car), [Co2(car)2(μ-OH)2], was also prepared by treating an aqueous solution containing [Co(car)(OH2)2]+ under basic conditions. The dinuclear structures of these complexes are stable for several days in the neutral aqueous solutions.
  • Toshio Nakamura, Chiharu Hayashi, Tetsushi Ogawara
    1996 Volume 69 Issue 6 Pages 1555-1559
    Published: 1996
    Released: June 22, 2006
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    Some experiments are carried out in order to clarify the reason why the electrode prepared by coating a platinum disk with a non-plasticized membrane of polyacrylaminde polymer (PAA) coupled to cobalt phthalocyanine (CoPc) shows such a Nernstian response and a special selectivity for fluoride and cyanide ions in acetonitrile (AN). Special interactions between the ions and CoPc are observed spectrophotometrically. A complexing ability of the CoPc with only fluoride and cyanide ions works to respond in a Nernstian way for the ions at the electrode. Since the electrode shows quite poor response to chloride and bromide ions it can be understood that an ion exchange reaction of the ions in the solution at CoPc does not function to the response of the electrode. Furthermore, the PAA matrix of the membrane is found to produce the electrochemical masking effect on chloride and bromide ions. The PAA–CoPc electrode is confirmed as available for use of determining the solubility product constant of sodium fluoride in AN.
  • Satya Prakash Arya, Meenakshi Mahajan
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1561-1563
    Published: 1996
    Released: June 22, 2006
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    A simple and rapid method is presented for the determination of ascorbic acid. This method is based on the reducing action of ascorbic acid, which proportionately decreases the color intensity of the Cr(VI)–diphenylcarbazide complex. The absorbance of the complex was measured at 540 nm. A linear relationship between the absorbance and concentration of ascorbic acid was found to hold well up to 3.2 μg ml−1. Most of the common ingredients present in pharmaceutical preparations were found to be tolerated. The method has been successfully applied to the determination of vitamin C in the pure state, dosage forms and citrus fruits.
  • Tatsuya Sekine, Kazuhiro Osada, Akiko Hokura
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1565-1571
    Published: 1996
    Released: June 22, 2006
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    An addition of trioctylphosphine oxide (TOPO) enhanced the rate of back extraction of manganese in tris(benzoyltrifluoroacetonato)Mn(III) from carbon tetrachloride containing benzoyltrifluoroacetone (4,4,4-trifluoro-1-phenyl-1,3-butanedione, Hbfa) into acid aqueous solutions due to reduction of manganese(III) in this complex in the organic phase. It was found by spectrometry that manganese(III) in this complex in water- and air-saturated carbon tetrachloride was stable for a long time in the absence of TOPO but its reduction occurred in the presence of TOPO. The rate of reduction was first order with respect to the TOPO concentration and inverse first order with respect to the Hbfa concentration. This was explained as follows: An addition of TOPO to the metal ion in the complex promoted the dissociation of one of the bfa ions in the complex and the leaving bfa ion gave an electron to the manganese(III). On the other hand, a bfa ion from the coexisting Hbfa in the solution should exchange with the bfa in the MnIII(bfa)3 complex but it does not cause reduction of manganese(III) and this was assumed to compete with the addition of TOPO and to cause the inverse first order dependence of the rate of reduction on the Hbfa concentration.
  • Masahiro Mikuriya, Ryoji Nukada, Wataru Tokami, Youichi Hashimoto, Tos ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1573-1578
    Published: 1996
    Released: June 22, 2006
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    Manganese(III) complexes with 2-{N-[2-(4-imidazolyl)ethyl]iminomethyl}phenol (HL1) or 2-{N-[2-(2-pyridyl)ethyl]iminomethyl}phenol (HL2), [MnL12]ClO4·CH3OH (1) and [MnL22]ClO4 (2), have been synthesized and characterized by infrared and electronic spectra, cyclic voltammetry, and temperature dependence of magnetic susceptibilities (80—300 K). The molecular structures of 1 and 2 were determined by single-crystal X-ray structure analysis. The manganese atom adopts an elongated octahedral geometry with two phenolic oxygen atoms, two imine nitrogen atoms, and two imidazolyl or pyridyl nitrogen atoms.
  • Toshio Takayama, Shirabe Ohuchida, Yoshio Koike, Masanobu Watanabe, Da ...
    1996 Volume 69 Issue 6 Pages 1579-1586
    Published: 1996
    Released: June 22, 2006
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    Structural analysis of bis(glycylglycinato)cadmium(II) complexes prepared to adjust the pH to 6 (A) and 9 (C), were studied by X-ray diffraction and high resolution 113Cd and 13C solid state NMR. In order to compare with the structure of A, structural analysis of bis(glycylglycinato)zinc(II) complexes (B) prepared to adjust the pH to 6 was also performed by the same methods. The structure of A was six coordinate; a five-membered chelate ring was formed between the terminal amino-group and the adjacent O (peptide) and the terminal carboxygroups of the dipeptide ligands were involved in Cd binding in the complex. The structure of B was similar to A, indicating that the Cd nucleus was better suited for probing the Zn nucleus-ligand structure. The structure of C was six coordinate; the four terminal carboxygroups (O) and the two terminal aminogroups (N) of the dipeptide ligands were involved in Cd binding in the complex. High-resolution 113Cd and 13C CP/MAS NMR spectra have been measured in order to obtain detailed information about the structures. The 113Cd signal of A showed a low field chemical shift compared with the peak of C. This means that the chelate ring shows decreased shielding. From the 13C spectra of A and C, it was seen that the Cd nucleus of A is bonded to a carbonyl oxygen (peptide) and the terminal carboxyl group of the dipeptide, but that for C is not bonded to a carbonyl oxygen (peptide).
  • Nurun Nahar, Masaaki Tabata, Kentaro Kaneko
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1587-1592
    Published: 1996
    Released: June 22, 2006
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    Kinetic and equilibrium studies on the complexation of mercury(II) ion with N-p-nitrobenzyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin, (NO2Bz(Htpps)4−; HP4−) were carried out. The equilibrium constant, defined as KHgP = [HgP3−][H+][Hg2+]−1[HP4−]−1, was determined spectrophotometrically in the pH range 2—3 and at temperatures of between 15 and 35 °C. The value of KHgP was found to be 106.28 ± 0.04; and ΔH° and ΔS° values were 4.5 ± 0.7 kJ mol−1 and 134 ± 2 J mol−1 K−1, respectively at 25 °C. The kinetic studies were carried out under a pseudo-first order condition in an aqueous medium at 10—35 °C, I = 0.1(NaNO3), [HP4−] = 3 × 10−6, [Hg(II)] = 4.74 × 10−5 to 2.84 × 10−4, [acetate buffer] = 5 × 10−3 to 1 × 10−1 mol dm−3, and pH 4.2 to 5.6. The observed rate constant of the reaction was dependent of the total concentrations of mercury(II) and acetate buffer, but independent of the pH and ionic strength. The overall reaction was first order with respect to the total [Hg(II)] and [HP4−]. The rate expression of the reaction is d[HgP3−]/dt = (k1[Hg(OH)2] + k2[Hg(oac)2])[H2P3−]. The k1 and k2 values were found to be (1.26 ± 0.19) × 106 and (1.87 ± 0.01) × 106 mol−1 dm3 s−1 (25.0 °C), and the activation enthalpies and entropyies were ΔH = 24.8 ± 3.8 kJ mol−1and ΔS = −46 ± 13 J mol−1 K−1 for the k1, and ΔH = 45.0 ± 2.1 kJ mol−1, ΔS = 25.4 ± 7.4 J mol−1 K−1 for the k2. The kinetic data revealed that dihydroxomercury(II) directly reacts with the protonated porphyrin with a small activation enthalpy and a negative activation entropy.
  • Dai Ooyama, Noriharu Nagao, Hiroshi Kuroda, Utako Satoh, F. Scott Howe ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1593-1598
    Published: 1996
    Released: June 22, 2006
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    [Ru(N,O-hia)(bpy)2]+ (I) and [Ru(N,O-hia)(bpy)(py)2]+ (II) (hia: CH3COC(NO)COCH3) were prepared by the reactions of cis-[Ru(NO)(OH2)(bpy)2]3+ and cis-[Ru(NO)(OH)(bpy)(py)2]2+ with acetylacetone(Hacac) respectively. An X-ray structure analysis shows that the products have the identical nitroso ligand. Electrochemical behaviors of the complexes differ dramatically: I underwent an ECEC reaction, which could be illustrated as involving a structural rearrangement of the Ru-hia bonding, but II did not show such behavior and a typical reversible one-electron redox nature was found.
  • Shin-ichi Nakagawa, Satoru Murata, Masakatsu Nomura, Tetsuo Sakai
    1996 Volume 69 Issue 6 Pages 1599-1603
    Published: 1996
    Released: June 22, 2006
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    A detailed investigation of the hydrogenation reaction of biphenyl with MmNi3.5Co0.7Al0.8H4.2 [Mm: mixture of La, Ce, Pr, and Nd (30 : 52 : 5 : 13 wt ratio)] to give either cyclohexylbenzene or bicyclohexyl was performed. Time profiles of the amounts of hydrogen evolved from the alloy and that introduced into biphenyl during the reaction were measured; it was suggested that the hydrogen absorbed by the alloy could predominantly react with the substrate, and the hydrogen released into the gas phase played only a minor role in the reaction. The deuteration of biphenyl with the deuterated alloy, MmNi3.5Co0.7Al0.8D3.5, was also examined; a GC-MS analysis of the reaction mixture indicated that a H–D exchange between the hydrogen in the substrate and the deuterium in the alloy took place as a parallel reaction to hydrogenation of the aromatic rings, and, as a result, the product cyclohexylbenzene appeared to contain 3-9 deuterium atoms.
  • Yayoi Yokoyama, Keiichiro Ogawa, Takeshi Iwai, Kazuko Shimazaki, Yasuh ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1605-1612
    Published: 1996
    Released: June 22, 2006
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    The conformations of the E-forms of photochromic furylfulgides with a methyl substituent (1E) and an isopropyl substituent (2E) were investigated by X-ray crystallographic analyses, NMR measurements, and molecular orbital (MO) calculations in relation to the large quantum yield of the coloring reaction of 2E upon the irradiation of UV light. The conformations of 1E and 2E obtained by X-ray crystallographic analyses are the photocyclization-possible ones (Eα), in which the distances of the bond-forming carbon atoms of 1E and 2E are essentially the same. NOESY of 1H NMR measurements of 1E and 2E showed that they take both the Eα and cyclization-impossible Eβ conformations in solution. Although MO calculations of 2E proved that the population of 2Eα is dominant when the entropy contributions of the rotation of substituents are considered, the large difference in the quantum yields was not fully elucidated. The difference may have come from a difference in the nature of the excited states of 1E and 2E, which is evidenced by the large difference in the molar absorption coefficient (1E: 6700, 2E: 4250 mol−1 dm3 cm−1 in toluene).
    The thermodynamic parameters of the enantiotopomerization process of 2E were determined by variable-temperature 1H NMR measurements. The mechanism of enantiotopomerization was specified by MO calculations.
  • Nami Choi, Satoshi Morino, Shin-ichiro Sugi, Wataru Ando
    1996 Volume 69 Issue 6 Pages 1613-1620
    Published: 1996
    Released: June 22, 2006
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    Lithium dimesitylgermanedithiolate reacted with titanocene or zirconocene dichloride to give 2,2-dimesityl-1,3-dithia-2-germa-4-titanacycle (3a) and its zirconocene analogue (3b), which afforded a stable 2,3,4,5-tetrathiagermolane (4) in treatment with S2Cl2. The reaction of 3b with Ph2GeCl2 gave unsymmetric 1,3,2,4-dithiadigermetane (5). The bis(η5-cyclopentadienyl) derivative of cis-2,3-di-t-butyl-2,3-diphenyl-1,4-dithia-2,3-disila-5-titanacyclopentane (7a) obtained from lithium 1,2-di-t-butyl-1,2-diphenyldisilane-1,2-dithiolate reacted with electrophilic reagents (SCl2, S2Cl2, Se2Cl2, R2GeCl2) to give the corresponding heterocycles.
  • Chunmin Li, Yunhong Go, Zihua Mao, Kazuo Koyano, Yasushi Kai, Nobuko K ...
    1996 Volume 69 Issue 6 Pages 1621-1627
    Published: 1996
    Released: June 22, 2006
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    In order to search for a new kind of antileukemic drug, we synthesized four indirubin derivatives, including indirubin monooxime (IM), indirubin monooxime O-methyl ether (IMME), N1-methylindirubin monooxime O-methyl ether (MIMME), and indirubin monooxime O-ethyl ether (IMEE). Their antileukemic activities in vivo and in vitro were tested; some of these compounds showed good activities. Their molecular and crystal structures were determined by an X-ray diffraction method. The results revealed that all four indirubin derivatives are planar, and have a tendency to form a big π-system. The molecular structures also showed that oximation of indirubin resulted in only a slight change in the antileukemic activity. On the other hand, the amido moiety in the compounds may play an important role in the activity of the indirubin monooxime derivatives. This conclusion was supported by the calculation results of the electrostatic-potential (esp) derived charge distribution of the indirubin derivatives, which were obtained using an ab initio molecular orbital of the basis set (3-21G), taking the electronic correlation into account at the MP2 level.
  • Kyoko Nozaki, Naomasa Sato, Hidemasa Takaya
    1996 Volume 69 Issue 6 Pages 1629-1637
    Published: 1996
    Released: June 22, 2006
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    (Z)-1,3-Diaryl-3-cyano-2-propen-1-ones ((Z)-1) are prepared from arenecarbonyl cyanide and terminal arylacetylene in the presence of Pd(OAc)2–PPh3 (1 mol amt. to Pd)–0.5dppb (1,4-bis(diphenylphosphino)butane) (0.5 mol amt. to Pd). The reaction proceeded via the formation of acetylenic ketone 3, followed by the palladium-catalyzed addition of HCN, and isomerization of the resulting (E)-1 to (Z)-1. Oxidative addition of arenecarbonyl cyanide to zero-valent palladium metal has been observed by admixture of 4-MeOC6H4COCN to Pd2(dba)3 · CHCl3–PPh3–0.5dppb oxide (dppb oxide = Ph2P(O)(CH2)4P(O)Ph2). The resulting Pd(4-MeOC6H4CO)(CN)(PPh3)(ligand) afforded (Z)-1c by reaction with phenylacetylene. Thus, the role of two kinds of phosphine, PPh3 and dppb, suggests that the former acts as a ligand and the latter works as a reductant of Pd(II). The product (Z)-1 can be photoisomerized to (E)-1 under room light in CDCl3. The product (Z)-1 was obtained by a four-component coupling reaction of 4-iodotoluene, phenylacetylene, KCN, and carbon monoxide. A new synthesis of tetrasubstituted furans is also mentioned.
  • Roseane Fett, Inês Maria Costa Brighente, Rosendo Augusto Yunes
    1996 Volume 69 Issue 6 Pages 1639-1643
    Published: 1996
    Released: June 22, 2006
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    The effect of calcium ions on the reaction of acetoin with hydroxylamine was studied. This reaction proceeds by a two-step mechanism: the attack of hydroxylamine on the carbonyl compound to give a tetrahedral addition intermediate, and the dehydration of this intermediate to form the oxime. The presence of calcium ions decreases the value of the equilibrium constant of the tetrahedral addition intermediate formation, but increases the overall rate constant of the reaction when dehydration is the rate-determining step. Evidence suggests that the effect of calcium ions is through the formation of a complex with the hydroxyl groups of the tetrahedral addition intermediate, facilitating the dehydration step of the reaction.
  • Tetsuya Ueno, Haruhiko Toda, Masafumi Yasunami, Masaaki Yoshifuji
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1645-1656
    Published: 1996
    Released: June 22, 2006
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    1-Fluoro- and 1,3-difluoroazulenes were synthesized for the first time by the electrophilic fluorination of azulenes with N-fluoro reagents. Selective preparation of 1-fluoroazulenes were performed by the fluorination of methyl azulene-1-carboxylates, followed by demethoxycarbonylation in 100% H3PO4. 2-Substituted azulenes were fluorinated in higher yields. In the 1H NMR of 1-fluoroazulene, long-range JFH values were not observed at H-2 and H-8, in contrast to those for 1-fluoronaphthalene. The 1-fluorine atom causes significant bathochromic shifts in the visible absorption of azulene, due to the so-called +Iπ effect.
  • Itaru Hamachi, Tomoaki Matsugi, Shigeaki Tanaka, Seiji Shinkai
    1996 Volume 69 Issue 6 Pages 1657-1661
    Published: 1996
    Released: June 22, 2006
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    A synthetic heme bearing ruthenium bis(terpyridine) through a covalent bond was successfully prepared. Ruthenium bis(terpyridine) pendant myoglobin, which was synthesized by a conventional cofactor reconstitution method, was efficiently activated through a photoinduced electron-transfer reaction from the ruthenium complex to the heme center. No reaction occurred in the corresponding intermolecular reaction system.
  • Tadahiro Kato, Tsutomu Watanabe, Toshifumi Hirukawa, Norihiro Tomita, ...
    1996 Volume 69 Issue 6 Pages 1663-1666
    Published: 1996
    Released: June 22, 2006
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    In order to explore the oxidation mode of lipoxygenase (LOX) obtained from infected rice plants, typical unsaturated fatty acids (38) were treated with LOX and oxygen. It was observed that ω-10 and ω-6 positions of unsaturated fatty acids were oxidized predominantly in the cases of exotic ω-6 (4 and 5) and ω-3 (7 and 8) series, respectively. In the case of endogenous fatty acids (3 and 6), oxidation at ω-6 position predominated. All the allylic alcohols obtained by reduction of the oxidation products with NaBH4 possess S-configuration.
  • Yoichi Taguchi, Tohru Tsuchiya, Akihiro Oishi, Isao Shibuya
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1667-1672
    Published: 1996
    Released: June 22, 2006
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    The [2 + 2]cycloaddition of phenyl isocyanate to 2,3-dihydrofuran was appreciably accelerated by compression to produce a β-lactam ring; its apparent activation volume was estimated to be −28 ml mol−1. Similar β-lactams were obtained under high pressure in the reaction of phenyl isocyanate with various vinyl ethers. Although the [2 + 2]cycloaddition of alkyl isocyanates to 2,3-dihydrofuran was also accelerated under high pressure to give β-lactams with good yields; the reactions of alkyl isocyanates with ethyl vinyl ether were slow, even at high pressure.
  • Hajime Irikawa, Satoru Kanke, Kousuke Mito, Yasuhiro Kobayashi, Tomoko ...
    1996 Volume 69 Issue 6 Pages 1673-1677
    Published: 1996
    Released: June 22, 2006
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    Green trichotomine derivatives bearing alkyl groups on C1 and C1′ were prepared. In their absorption spectra, the λmax shifted to longer wavelengths as the 1,1′-substituents became bulkier, and the bathochromism indicated twisting of the central C2=C2′ double bond. A 1,1′ -dimethyltrichotomine derivative underwent autooxidation to give orange-red 1,11b-dihydroxylated and 1,11b-seco-dicarbonyl compounds, in which twisting of the central C2=C2′ double bond might be relieved by the decreasing steric interactions between the substituents on C1 and the C3′ carbonyl groups.
  • Atsuyoshi Ohno, Akihiro Tsutsumi, Norimasa Yamazaki, Mutsuo Okamura, Y ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1679-1685
    Published: 1996
    Released: June 22, 2006
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    6,7-Dihydro-1,6,11-trimethyl-5-oxo-5H-benzo[c]pyrido[2,3-e]azepin-1-ium iodide (11-Me-MMPA+I) was synthesized, and it was confirmed that the axial chirality in the salt is stable at room temperature. Upon the reduction of 11-Me-MMPA+ with a pair of diastereomeric dihydropyridine derivatives, the reacting face is always that in which the carbonyl dipole in the cation is included (i.e., syn selectivity), regardless the configuration of the reducing agent. A steric hindrance, in a classical sense, and other factors contribute to the stereochemistry of the reaction only in a minor part. Plausible intermolecular arrangements at the transition state of the reaction are discussed in order to understand the mechanism of this nonsteric stereochemistry.
  • Yoshihito Inai, Shyu Kurashima, Yoshio Okado, Tadamichi Hirabayashi, K ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1687-1694
    Published: 1996
    Released: June 22, 2006
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    In order to investigate the effect of bulky β-substituents on the conformational preference in α, βZ)-β-phenyldehydroalanine, (Z)-β-(1-naphthyl)dehydroalanine, or (Z)-β-(1-pyrenyl)dehydroalanine residue were synthesized: Boc–Ala–ΔZAA–Val–OMe (Boc, t-butoxycarbonyl; Ala, L-alanine; ΔZAA, (Z)-β-aryldehydroalanine; Val, L-valine; OMe, methoxy). Their conformations in solution were investigated using 1H NMR spectroscopy. The solvent accessibility of the NH resonances and the nuclear Overhauser effect (NOE) indicated that the three peptides in CDCl3 form a type II β-turn conformation supported by hydrogen bonding between CO (Boc) and NH (Val). From a conformational energy calculation, the three kinds of ΔZAA residues were also shown to favor a type II β-turn conformation. In each β-turn, the orientation of the aryl plane was found to be non planar relative to the Cα=Cβ–Cγ plane, suggesting that a steric interaction between the β-aryl group and the peptide backbone leads to the internal rotation angles preferred for the β-turn backbone.
  • Masato Kitamura, Masaki Tsukamoto, Hidemasa Takaya, Ryoji Noyori
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1695-1700
    Published: 1996
    Released: June 22, 2006
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    The title enamide compounds can exist in either a sickle or U conformation with respect to the C=C–N–C=O conjugated moiety, where the sickle form is greatly favored. The sickle rotamers are chiral in nature in both solution and crystalline states, as proved by 1H NMR and a single-crystal X-ray analyses. The molecular distortion from the standard structure occurs in such a way as to retain the amide planarity, indicating a higher significance of the orbital interaction compared to the overlapping. The pathway and interconversion rate between the rotational stereoisomers are highly dependent on the nature of the 1-alkylidene and N-acyl groups. The energy barrier for the stereomutation of (Z)-2-(p-bromobenzoyl)-1-(3,4-dimethoxyphenylmethylene)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline has been determined by a lineshape analysis of the 1H NMR spectra.
  • Hiroaki Sawai, Kenji Yamamoto
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1701-1704
    Published: 1996
    Released: June 22, 2006
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    The lanthanide ion-catalyzed oligomerization of adenosine 5′-(1-imidazolylphosphate) was performed to yield short-chained oligoriboadenylates. The effect of lanthanide ions on the synthesis of oligoriboadenylates increased nearly in the order of the atomic number: None < Nd3+ La3+ Ce3+ Pr3+ Sm3+ Eu3+ Gd3+ < Tb3+ < Dy3+ Ho3+ < Er3+ < Yb3+ < Lu3+. The total yield of the oligoriboadenylates was 49% when Lu3+ was used as a catalyst. The linkage in the resulting oligoribadenylate was mainly 2′–5′.
  • Sunil K. Ghosh, Rekha Verma, Usha Ghosh, Vasant R. Mamdapur
    1996 Volume 69 Issue 6 Pages 1705-1711
    Published: 1996
    Released: June 22, 2006
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    A one-pot self regulated approach for the synthesis of amides/peptides based on two reduction–oxidation (redox) reactions has been described. The primary and secondary amides/peptides are made by using azidotrimethylsilane and alkyl azides/α-azido acid derivatives respectively as the direct source of amine components. Benzeneselenol, generated in the reaction medium during carboxyl activation, has been found to be an effective reducing agent for the conversion of azides to primary amines. The methodology has been applied to the synthesis of methionine enkephalin.
  • Tatsuo Yamamura, Takafumi Ishida, Hiroyuki Ueyama, Hirokazu Hayashida, ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1713-1717
    Published: 1996
    Released: June 22, 2006
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    The antioxidant activities of 9H-xanthene-2,7-diols that are structurally related to tocopherols and 2,2′-alkylidenedi(hydroquinones) were measured by the inhibition of the thermally initiated autoxidation of tetralin at 60 °C using an oxygen-absorption method. The stoichiometric factors were calculated as n = 3.3—5.5 for 9H-xanthene-2,7-diols and 0.5—0.9 for 2,2′-alkylidenedi(hydroquinones) that lack the fused six-membered heterocyclic ring. Comparison of the alkyl substituent on the bridged methylene carbon showed that 9-methyl-9H-xanthene-2,7-diols increased in n value compared with 9-ethyl-9H-xanthene-2,7-diols. For the 9-methyl-9H-xanthene-2,7-diols, alkyl groups ortho to the phenolic hydroxyl group decreased the Rinh value: two methyl groups by 10-fold, one methyl group by 1.9-fold, and one t-butyl group by 1.4-fold, compared to that for the 9-methyl-9H-xanthene-2,7-diol. On the other hand, 2,2′-alkylidenedi(hydroquinones) were poorer antioxidants than the structurally comparable 9H-xanthene-2,7-diols. The low reactivity of 2,2′-alkylidenedi(hydroquinones) compared to those of 9H-xanthene-2,7-diols is attributed to electronic factors. The p-type lone pair on the hydroxyl oxygen can not help stabilizing the phenoxyl formed upon abstraction of the phenolic hydrogen.
  • Yasumasa Fukushima
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1719-1726
    Published: 1996
    Released: June 22, 2006
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    The effect of sodium chloride on the absorption and CD spectra of the β-sheet structure of a zwitterionic poly(Glu–Val–Lys–Val)/22,24-diprotonated 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin system in aqueous solution was studied under various conditions. The monomeric TPPS was aggregated by the addition of the polypeptide and/or NaCl; at least four kinds of TPPS aggregation were observed. Although the aggregated species with an absorption band at around 489 nm formed an S-chiral conformation at [P]/[D] from 1 to 5 below 100 mM NaCl, the S-chirality changed to R-chirality by increasing to 500 mM NaCl or above. These results may indicate that an increase in the ionic strength induces a chiral conformational transition due to the prevention of electrostatic interactions between TPPS and the polypeptide; also the S-and R-chiralities could be caused by the secondary structure of the polypeptide and original property of TPPS, respectively. It is presumed that the electrostatic interactions play an important role in binding TPPS with the polypeptide as a major driving force. However, even 1000 mM NaCl could not completely shield the electrostatic interactions.
  • Tadao Uyehara, Toshihiro Inayama, Toshiaki Furuta, Tadahiro Kato, Yosh ...
    1996 Volume 69 Issue 6 Pages 1727-1735
    Published: 1996
    Released: June 22, 2006
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    Pinacol-type rearrangement of 2-substituted 1-methoxybicyclo[2.2.2]oct-5-en-exo-2-ols (1) by treatment with p-toluenesulfonic acid in boiling benzene gave bicyclo[3.2.1]oct-6-en-2ones (2) and -3en-2-ones (4) in a ratio of ≥ 10 to 1 along with small amounts of dehydration products. Treatment of the endo isomers (3) under the same conditions gave 2, 4, and the dehydration products. The ratios of 2 to 4, in this case were within a certain range and were influenced by the substituent at the C-2 position. The ratio of the relative disappearance rate constant of 1 to that of the corresponding 3 was less than 10. This observation suggests that the unsaturated bridge does not offer remarkable anchimeric assistance in the reaction of 1. A similar acid treatment of the dehydration products gave 2 and 4 and their ratio was somewhat affected by the substituent. A mechanism is proposed for the pinacol-type rearrangement.
  • Katsuo Shinozaki, Kazuhiro Mizuno, Hirohisa Oda, Yukio Masaki
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1737-1745
    Published: 1996
    Released: June 22, 2006
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    Biologically important threo-β-hydroxy-γ-amino acids, (3S,4S)-statine ((3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid) (1) and (3S,4S)-AHPPA (3S,4S)-4-amino-3-hydroxy-5-phenylpentanoic acid) (2), were synthesized starting from D-glucosamine (3) as a chiral pool. Two routes for the transformation of D-glucosamine to key intermediates, which are applicable to the synthesis of threo-β-hydroxy-γ-amino acids, were investigated. The successful route involved C(6)-carbon degradation and elimination of the C(4)-hydroxy group of D-glucosamine in 8 steps and 30% overall yield to furnish (4R,5S)-2-oxo-5-vinyloxazolidine-4-carbaldehyde dimethyl acetal (17), which has been utilized as a versatile intermediate for synthesizing the target compounds.
  • Shigeru Kunugi, Masahito Yokoyama, Yasue Kuroda, Masumi Yoshida, Akira ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1747-1753
    Published: 1996
    Released: June 22, 2006
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    The thermolysin-catalyzed hydrolysis of N-Cbz-tripeptides was studied by means of a fluorescence stopped-flow method using N-dansyl-L-phenylalanine (Dns–Phe) as a displacement probe at lower pH.
    To determine the probe features of Dns–Phe, the equilibrium and kinetics of the binary interaction between Dns–Phe and the enzyme were studied by means of static differential fluorescence and by fluorescence temperature-jump methods in the pH range 4.5—5.6.
    The dissociation constant (Kd) increased along with an increase in pH. Both the decreasing (apparent) binding rate and the increasing (apparent) dissociation rate with increasing pH were attributed to this decline of complex formation at higher pH.
    The pre-steady state process in the substrate hydrolytic reaction was studied with this displacement probe, and the observed rate constant for the four tripeptide substrates had saturation kinetics that indicated the existence of a new intermediate during the sequence of the enzyme reaction. Four tripeptide substrates had comparable k2 values (rate constant of intermediate formation), whereas the KS value of Cbz–Phe–Leu–Ala was about twice that of the others.
  • Yukie Mori, Yumiko Horikoshi, Koko Maeda
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1755-1761
    Published: 1996
    Released: June 22, 2006
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    X-Ray structure analyses of 1-(9-anthryl)alkyl acetates [AnCH(OAc)R; An = 9-anthryl, R = Me (1a), Et (1b), i-Pr (1c), t-Bu (1d), CF3 (1e)] indicated that these molecules adopted similar conformations in which the bond connecting the chiral carbon and the substituent was oriented almost perpendicular to the anthracene plane. In the crystals of 1b1e two adjacent anthracenes related by an inversion center was stacked with a short interplane distance (3.5—3.6 Å), which was favorable for the formation of the meso head-to-tail dimer. Photolysis of crystals of 1b, 1c, and 1e afforded meso-dimers in almost 100% yield, while 1d was photostable. The quantum yield of dimerization for 1b (0.16) was higher than that in solution. Although the dimerization did not proceed in single crystal-to-single crystal fashion, the observed high selectivity suggested that the reaction took place between the π-stacking pair even when the crystalline lattice of the monomer was destroyed. Irradiation of 1a1e in benzene solution gave meso- and dl-head-to-tail dimers in a ratio of 1 : 1. The quantum yield of dimerization decreased with increase in the size of the substituent.
  • Hidemitsu Uno, Kenji Oka, Hiroyuki Tani, Yoshihiro Kawada, Noboru Ono
    1996 Volume 69 Issue 6 Pages 1763-1767
    Published: 1996
    Released: June 22, 2006
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    1-Phenylsulfanyl-2,2,2-trifluoroethyl isocyanide (2a) readily and selectively trimerized to 4,6-bis(phenylsulfanyl)-1-(1-phenylsulfanyl-2,2,2-trifluoroethyl)-5-(2,2,2-trifluoroethylideneamino)-2-trifluoromethyl-1,2-dihydropyrimidine (5) at room temperature, while other α-phenylsulfanyl isocyanides such as phenyl(phenylsulfanyl)methyl isocyanide (2b) are stable. Heating of 2b resulted in formation of the corresponding nitrile as well as diphenyl disulfide and [bis(phenylsulfanyl)methyl]benzene.
  • Akikazu Kakehi, Suketaka Ito, Yasunobu Hashimoto
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1769-1776
    Published: 1996
    Released: June 22, 2006
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    Various pyridinium (monosubstituted methylide)s were smoothly attacked to the cyano group in ethyl thiocyanatoacetate or ethyl 2-thiocyanatopropionate to afford the corresponding pyridinium (substituted cyanomethylide)s in low-to-moderate yields, while pyridinium (unsubstituted amidate)s reacted with the ester carbonyl group in the same reagents to give pyridinium (thiocyanatoaceto)- or (2-thiocyanatopropiono)amidates in considerable yields. The 1,3-dipolar cycloadditions of some pyridinium (unsymmetrically substituted cyanomethylide)s with dimethyl acetylenedicarboxylate (DMAD) in various solvents afforded only dimethyl 3-cyanoindolizine-1,2-dicarboxylate, except a few examples. On the other hand, the treatment of pyridinium (thiocyanatoaceto)- or (2-thiocyanatopropiono)amidates with a strong base, such as potassium t-butoxide, gave new bicyclic mesoionic compounds, N-[2-(1,3,4-thiadiazolo[3,2-a]pyridinio)]acetamidate derivatives, in moderate yields. The intermediacy of N-[1-(2-thiocyanatopyridinio)]acetamidates in the formation reactions of the latter compounds was also proven by independent syntheses.
  • Takanori Sugiki, Norimitu Tohnai, Yuhua Wang, Takehiko Wada, Yoshiaki ...
    1996 Volume 69 Issue 6 Pages 1777-1786
    Published: 1996
    Released: June 22, 2006
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    Photodimerizations of thymine derivatives having a long alkyl chain on a carbamate bond were investigated by irradiation of UV light at 280 nm in amorphous and crystalline film states. The amorphous films obtained by spin-coating from chloroform solution had higher initial rate constants for photodimerization relative to those of the crystalline films after annealing. X-Ray crystal structure analysis showed that the thymine derivatives had intermolecular hydrogen bonds that led to disadvantageous molecular orientation for the photodimerization. The photodimerization, however, is preferred in the localized layer structures of thymine units and alkyl chain.
  • Chan Woo Lee, Yoshiharu Kimura
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1787-1795
    Published: 1996
    Released: June 22, 2006
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    An A–B–A triblock copoly(ester-ether) comprising poly(L-lactide) (A) and poly(oxyethylene-co-oxypropylene) (B) was prepared by copolymerization of L-lactide and a commercially available telechelic copolyether, Pluronic® (PN), with different molecular weights by the catalysis of tin(II) octanoate. The low molecular weight PN gave the copolymers having a low or medium molecular weight and a unit composition slightly different from the feed ratio. With PN whose molecular weight was around 10000, high molecular weight copolymers were obtained in high yield. For the PN with molecular weight of 8400, the block copolymerization was examined at different feed ratios, in which the molecular weight and the unit composition were successfully controlled by changing the L-lactide/PN ratio in feed. The copolymer containing 10 wt% of this PN was melt-spun into a filament, which was drawn to various draw ratios at 40 and 60 °C. The tensile modulus and strength of the filament increased with the draw ratio increasing at 60 °C, while at 40 °C they reached a plateau above the draw ratio of 5.0. It was found that the copolymer filaments showed an improved flexibility due to the incorporation of the soft PN segments. The in vitro hydrolysis test of the drawn filaments showed that the block copolymer has much higher degradability than the homo poly-L-lactide.
  • Junji Furukawa
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 6 Pages 1797-1803
    Published: 1996
    Released: June 22, 2006
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    Adhesive force fa acts on the adherend surface through pseudo links and is given by a product of wetting force W/l and the fraction of links of about 10−2. W is a wetting energy of about 101—2 cgs-unit and l is a length of a segment of 1 nm in the adhesives polymer and fa is about 106—7 cgs-unit or 1—10 kg cm−2. On peeling a tape of pressure-sensitive adhesives, the adhesives layer is expanded and voids and fibrils are often formed. The shear forces in fibrils are integrated to give the peeing force P. The layer is deformed to give a concaved shape expressed with a catenary curve. In this model, P increases with increasing the relaxation time τ, thickness h, velocity v, and decreasing the peeling angle θ. P is expressed as P = (0.7 fa/sin/θ)/(1/h + 1/τv). For the tensile test in parallel plates, the thickness is expanded uniformly and P = fa(1 + τv/h). For the shear test, the cohesive rupture occurs and P = ηv/h, η being viscosity.
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