Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 6
Showing 1-31 articles out of 31 articles from the selected issue
  • Takayoshi Kobayashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1211-1224
    Published: 1997
    Released: June 13, 2006
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    A broad-band femtosecond spectroscopy apparatus has been developed. The spectrum of the probe light pulse extends from 400 nm to 3.0 μm, covering near ultraviolet (NUV), visible (VIS), and near infrared (NIR) ranges. The time resolution is better than 100 fs in the NUV and VIS regions, and better than 200 fs in the NIR region. The minimum detectable absorbance change is 2 × 10−3 for wavelengths between 400 nm and 1.6 μm and 3 × 10−3 between 1.6 μm and 3.0 μm. A tunable light pulse for the pump was also developed using the second-harmonic generation (SHG) and sum-frequency generation (SFG) in the cavity of the optical parametric oscillator. The tuning ranges of SHG and SFG are 529—585 nm and 426—483 nm, respectively. The study of ultrafast geometrical relaxation processes in a substituted poly(phenylacetylene) by the use of the broad spectroscopy apparatus is described as an example at the end.
  • Seiichiro Koda, Hideo Kajihara
    1997 Volume 70 Issue 6 Pages 1225-1238
    Published: 1997
    Released: June 13, 2006
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    The energy levels, potentials and relaxation mechanism of O2 doped in rare gas (Ar, Kr) and N2 solids in the neighborhood of the dissociation limit have been studied by means of absorption and emission spectroscopy. The environmental effects of the solids on the energy level shift are not large, but the cage effect is important in considering the relaxation mechanism following the laser irradiation. The efficient cross-relaxation among nested Herzberg states and specific energy transfer dependent on the energy gap between relevant levels, in particular from A′ state to c state, have been found. Due to the very slow vibrational relaxation, vibrationally excited O2 molecules have been accumulated to a high concentration in the solid. Based on the B–X transition energy values from the vibrationally excited O2 molecules, the B state potential curve has been determined. This shows that the cage effect retards the atomic dissociation in the B state.
  • Kazuko Matsumoto, Yoichi Sano, Masaki Kawano, Hiroyuki Uemura, Jun Mat ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1239-1244
    Published: 1997
    Released: June 13, 2006
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    Reaction of [{Ru(CH3CN)3[P(OMe)3]2}2(μ-S2)](PF6)3 with a mixture of acetylene and O2 gave a novel ruthenium(IV) dimer complex [{Ru(IV)(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2]. The newly formed bridging and terminal ligands PF2O2 and PFO32− are produced from the reaction of PF6 with trace amounts of H2O in the solvent. Although acetylene is not incorporated in the final product, it is necessary to accelerate the reaction. Ruthenium(IV) complexes with S2− ligand are rare and only two examples are previously known. The crystal of [{Ru(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2] is monoclinic, space group P21/n, a = 11.061(5), b = 20.764(4), c = 17.074(3) Å, β = 95.74(2)°, V = 3901(1) Å3, and Z = 4. The bridging PF2O2 ligand coordinates to Ru atoms with the two oxygen atoms, while the terminal PFO32− ligand coordinates to a Ru atom with one of the oxygen atoms. The molecular structure is confirmed by 31P and 19F NMR spectroscopy.
  • Kallol Mukherjee, Dulal Chandra Mukherjee, Satya Priya Moulik
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1245-1253
    Published: 1997
    Released: June 13, 2006
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    The kinetics of the reaction between [Fe(CN)6]3− and I was studied in a W/O microemulsion (Water/AOT/Heptane at different [Water]/[Amphiphile] mole ratios) and in mixed water–organic media (water–formamide, water–ethylene glycol, and water–dioxane). The pseudo-first-order rate constants were observed to radically increase in microemulsion media with a [Water]/[AOT] mole ratio below 6. At a mole ratio of 5.4, the rate constant was found to be about 20-fold greater than that in water. At a constant mole ratio, the rate constant was witnessed to be independent of [AOT]. In all mixed media, the rate decreased with increasing proportion of the nonaqueous solvent. The ionic-strength effect on the reaction did not obey either the modified Brønsted–Bjerrum or Brønsted–Bjerrum–Pitzer relations in the studied nonaqueous media, except for ethylene glycol. This disagreement is very prominent in the studied W/O microemulsion medium at [Water]/[AOT] ω = 9.1. The activation parameters for the pseudo-first-order reaction in all of the studied media suggested distinct difference of the microemulsion from other solvents. A reasonable compensation between ΔH and ΔS i.e., the isokinetic effect, was observed.
  • Hisao Tanaka, Naoko Kato, Hiroshi Kawazura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1255-1260
    Published: 1997
    Released: June 13, 2006
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    Six palmitic acids labeled at different methylene positions by paramagnetic doxyl moiety were used as guests in order to examine molecular discrimination using γ-cyclodextrin (γ-CD). The DPA inclusion complexes using γ-CD in an aqueous solution were characterized according to stability, conformation, and dynamics at 25 °C, mainly based on ESR spectral analyses and supported by force-field calculations. The stability was equal among all DPA complexes, as represented by the formation constant Ks = 8.0(±0.5) × 102 M−1 (M = mol dm−3), corresponding to the conformation constant when the palmitate chain penetrates a CD cavity and the doxyl ring locates inside the cavity. Both overall molecular motion and chain segmental motion of DPA, represented by the parallel (Rzz) and perpendicular components (Rxx = Ryy) of the rotational diffusion tensor, respectively, were significantly restricted in inclusion state. The magnitude of restriction of segmental motion increased towards the chain terminals from the center, indicating that faster segmental motion was restricted at a higher rate. Thus, a series of DPAs were discriminated by γ-CD in terms of chain segmental motion but not in terms of stability, to present a typical example of dynamic molecular discrimination.
  • Ryotaro Midorikawa, Hiroshi Ohoyama, Kohei Imura, Toshio Kasai
    1997 Volume 70 Issue 6 Pages 1261-1265
    Published: 1997
    Released: June 13, 2006
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    An active control for changing the relative population of the 3P0 fine-state of Ar* in a supersonic beam was investigated in a glow discharge by adding a small amount of foreign gases to pure Ar gas. The Ar* mean velocity was determined to be constant at major positions of the time profile, except for a rise and the decay of the beam for all gas mixtures, and also pure Ar. The relative population of 3P0 decreased with the discharge potential for the addition of ethylene, cyclohexane, and benzene. However, the addition of N2 and CH4 and pure Ar, did not show such a 3P0 decrease. These dissimilar behaviors of the foreign mixed gases could be interpreted based on a difference in the ionization potential of the molecules. A useful application of this population control is discussed.
  • Fujiko Iwasaki, Noriko Manabe, Hideyuki Nishiyama, Kiwamu Takada, Masa ...
    1997 Volume 70 Issue 6 Pages 1267-1275
    Published: 1997
    Released: June 13, 2006
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    X-Ray structure analyses were performed on the 2,3,4,5-tetrahydro-3,4-dimethylene-2,5-bis(4-chlorophenylimino)-1,6,6aλ4-trithia-3,4-diazapentalene (5), 2,5-bis(4-chlorophenylimino)-6aλ4-thia-1,6-diselena-3,4-diazapentalene derivative (6) and 2,5-bis(phenylimino)-1,6-dithia-6aλ4-selena-3,4-diazapentalene derivative (7). The lengths of the S–S bonds (mean value of 2.401 Å) for 5 and those of the Se–S bonds (mean value of 2.501 Å) for 6 and 7 are longer than that of the normal S–S or Se–S single bond (2.08 and 2.21 Å for S–S and Se–S bonds, respectively) by about 15%, which shows the hypervalent character of these S–S or Se–S bonds. In molecule 5, a difference in the two S–S bonds (2.488 and 2.314 Å) is considered to be a reflection of the feature of a weak hypervalent bond, which is very liable with effects of the environment, such as substituents or packing. The same tendency was observed for molecule 6. The crystal structures of 5 and 6, both of which are p-Cl-phenylimino derivatives, are isomorphous with each other. The crystal structure of 7, a phenylimino derivative, is different from those of 5 and 6, and two Se–S bonds of 7 are almost similar. The diffraction intensities of 5 were measured by a Weissenberg-diffractometer with imaging-plates, because only very small crystals were obtained, the intensities of which could not be measured by a conventional four-circle diffractometer with a rotating anode generator.
  • Fujiko Iwasaki, Hideyuki Nishiyama, Masanori Yasui, Motoyuki Kusamiya, ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1277-1287
    Published: 1997
    Released: June 13, 2006
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    2,3,4,5-Tetrahydro-3,4-dimethylene-2,5-bis(4-chlorophenylimino)-6aλ4-thia-1,6-diselena-3,4-diazapentalene (6), which contains a hypervalent sulfur atom, has been found to give novel complexes by treating with [Pt(PPh3)4], [Pd(PPh3)4], and [RhCl(PPh3)3]. X-Ray investigations have revealed that the resultant complexes are novel metal–carbene complexes: {1,1′-(perhydroimidazole-1,3-diyl-κC2)bis[(4-chlorophenylimino)methaneselenolato-κ2SeSe′]}(triphenylphosphine)platinum(II) (8), {1,1′-(perhydroimidazole-1,3-diyl-κC2)bis[(4-chlorophenylimino)methaneselenolato-κ2SeSe′]}(triphenylphosphine)palladium(II) (9), and trans(P,P′)-(chloro){(perhydroimidazole-1,3-diyl-κC2)bis[(4-chrolophenylimino)methaneselenolato-κ2SeSe′]}bis(triphenylphosphine)rhodium(III) (10). The central sulfur atom in 6 was substituted by a metal atom to form metal–selenium bonds in the resultant metallapentalene framework. The structure of complex (11), obtained from thiatetraazapentalene-2,5-diselone with [Pd(PPh3)3], was also determined by an X-ray analysis. This complex was also a metal–carbene complex with a metallapentalene framework: {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(4-chlorophenylimino)methaneselenolato-κ2SeSe′]}(triphenylphosphine)palladium(II) (11). The final R values are 0.038, 0.034, 0.046, and 0.032 for the 4494, 4234, 3919, and 4451 observed reflections for 8, 9, 10, and 11, respectively. The fact that similar metal–carbene complexes with a metallapentalene framework were obtained from both thiadiselenadiazapentalenes and thiatetraazapentalene-2,5-dithione/diselones confirms the previously proposed formation mechanism of these metal–carbene complexes.
  • Norihiro Kato, Fujio Takahashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1289-1295
    Published: 1997
    Released: June 13, 2006
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    The deswelling rate of a thermally-sensitive gel consisting of poly(N-isopropylacrylamide) crosslinked by 4% N,N′-methylenebisacrylamide (MBA) was accelerated at above the lower critical solution temperature (LCST) by the treatment of a freeze-dry and hydration process (freeze-dry treatment); it was roughly 102 times faster than the gel without a freeze-dry treatment. The values of the apparent activation energy (Ea’s) for the conventional gel crosslinked by 2 and 4% MBA was roughly 140 kJ mol−1 each, and those for freeze-dry treated gel crosslinked by 2, 4, and 10% MBA were 24, 25, and 12 kJ mol−1, respectively. An SEM photomicrograph showed that the freeze-dry treatment made the gel porous. The freeze-dry treated gel exhibited a weaker shrinking force, and showed easy expansion compared with the conventional gel. An expansion of the diffusion area of water and a decrease of the thickness of the surface layer for a macroporous gel could be the reason for the increase in the deswelling rate.
  • Ewa D. Raczynska, Robert W. Taft
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1297-1305
    Published: 1997
    Released: June 13, 2006
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    Proton affinities for seven polyfunctional nitrogen bases (N1,N1-dimethyl-N2-azinylformamidines) containing one amidine moiety and one, two or three nitrogen atoms in ortho-, meta-, and/or para-positions of the heterocyclic six-membered group have been predicted by semiempirical AM1 method. The preferred site(s) of protonation and exceptionally high gas-phase basicity of N1,N1-dimethyl-N2-azinylformamidines containing 2-azinyl group antiperiplanar to the functional carbon atom in the amidine moiety have been discussed. The effects of one group on the basicity of the other one have been compared with those found for the corresponding model amidines and azines.
  • Makoto Isihara
    1997 Volume 70 Issue 6 Pages 1307-1310
    Published: 1997
    Released: June 13, 2006
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    This paper analyzes superdelocalizabilities (SDs) of even-membered linear chains in a simple noncomputational way. Two basic relationships connecting SDs to bond orders are prepared in general form and applied to linear chains to provide a plain analytic expression to SDs. Behaviors of SDs in long linear chains are examined by using this analytic expression. Simple estimation formulas are derived for SDs near the end and in the middle of a long linear chain and the distinctive reactivity of end sites is fully verified. Comparisons with behaviors of frontier electron densities and frontier SDs manifest that these approximate indices cannot substitute for SDs in long linear chains.
  • Atsushi Satsuma, Yenni Westi, Yuichi Kamiya, Tadashi Hattori, Yuichi M ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1311-1317
    Published: 1997
    Released: June 13, 2006
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    The temperature-programmed desorption of pyridine (Py-TPD) was performed for measuring the acid strength and acid amount of binary oxide catalysts. First, the optimum measurement conditions were determined by comparing the TPD spectra with the infrared spectra of adsorbed pyridine measured under the same conditions in order to minimize the shift in the desorption temperature and contribution of physically absorbed and/or weakly held pyridine. The following conditions were found to be optimum: purging at 423 K for 2 h, W/F (W, sample weight; F, flow rate of the carrier) of 100 mg/150 cm 3 min −1, and a heating rate of 5 K min−1. This method was applied then to a series of binary mixed oxide catalysts. The amount of desorbed pyridine was 15—24% of the full coverage of pyridine on the catalyst surface with few exceptions. The highest acid strength, determined from the Py-TPD spectra, was well-correlated to that determined from a color change of Hammett indicators. The potential of the Py-TPD for determining the acid strength and the acid amount on binary oxide catalysts is discussed.
  • Yukako Ohashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1319-1324
    Published: 1997
    Released: June 13, 2006
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    [N,N′-o-Phenylenebis(salicylideneaminato)]cobalt(II), [Co(saloph)], forms two solvated complexes in the dmf solution; that is [Co(saloph)]·dmf at higher temperature and [Co(saloph)]·2dmf at lower temperature. The transient absorptions of the two species were measured in the present work with irradiation of the 532 nm- and 355 nm-light. For [Co(saloph)]·2dmf, the intensity change of the transient absorption induced by the 532 nm-excitation was ca. 5 times larger than that induced by the 355 nm-excitation, although the spectra was the same. By contrast, for the transient absorption of [Co(saloph)]·dmf, no dependence on the excitation wavelength was found with respect to the spectra, the absorption intensity or the decay rates. A quantum calculation of the electronic excited states was carried out by ZINDO model. Taking into consideration the calculated results, the observed differences between the excitation-wavelength dependence of the transient absorptions are discussed.
  • Ibrahim Mohamed El-Naggar, Essam Saleh Zakaria, Hisham Fouad Aly
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1325-1329
    Published: 1997
    Released: June 13, 2006
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    Self-diffusion coefficients () for Cs+, Sr2+, and Co2+ ions in cerium(IV) antimonate and tin(IV) antimonate have been investigated under conditions of particle diffusion and the limited batch technique for these ions in solutions of different acidity. The effect of heat treatment on the rate of isotopic exchange reactions on both materials was also studied. Values for the diffusion coefficients, activation energy, and entropy of activation have been evaluated. The data obtained have been compared with those reported for other organic and inorganic exchangers, which give some information regarding the mechanism of ion exchange on the surface of the ion exchange materials.
  • Mala Nath, Rakesh Yadav
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1331-1337
    Published: 1997
    Released: June 13, 2006
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    Some new di- and triphenyltin(IV) complexes of the general formulae Ph2SnL and Ph3SnL′, where H2L/HL′ = Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde (H2L) and benzaldehyde (HL′) with glycine (H2L-1/HL′-1), DL-α-alanine (H2L-2/HL′-2), L-methionine (H2L-3/HL′-3), DL-valine (H2L-4/HL′-4), D-phenylalanine (H2L-5/HL′-5), 2-aminobutyric acid (H2L-6/HL′-6), and L-leucine (H2L-7/HL′-7), have been synthesized and characterized by elemental analyses, molar conductance, electronic, infrared and far-infrared, multinuclear magnetic resonance (1H, 13C, and 117Sn), and 119Sn Mössbauer studies. Thermal decomposition of a few complexes using TG, DTG, and DTA techniques indicates the formation of SnO2 as a residue. The complexes have also been tested in vitro against bacteria [Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus Penicillin resistance (2500 units)] and fungi [Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii, Trichophyton mentagrophytes, and Aspergillus fumigatus]. All of the complexes show remarkable activity.
  • Fumio Hamada, Shingo Minato, Tetsuo Osa, Akihiko Ueno
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1339-1346
    Published: 1997
    Released: June 13, 2006
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    Flexible hosts, 6A,6B-; 6A,6C-; 6A,6D-; and 6A,6E-bis(2-naphthylsulfonyl)-γ-cyclodextrins (γ-1, γ-2, γ-3, and γ-4, respectively) were used as fluorescent sensors with which a variety of organic compounds were detected by naphthalene excimer and monomer emissions. In a 10 vol% ethylene glycol aqueous solution, γ-1 exhibits almost pure monomer fluorescence while γ-2, γ-3, and γ-4 exhibit both monomer and excimer emissions. The intensities of the emissions changed upon addition of guest species, particularly in the case of γ-2 and γ-3, and the guest-induced intensity variations were used as sensitivity factors of the sensors. When (−)-borneol (5), cyclohexanol (6), cyclododecanol (7), and 1-adamantanecarboxylic acid (8) were added to each host solution, γ-2, γ-3, and γ-4 increased the excimer emission intensity but decreased the monomer one, the absolute intensity variations being 6 < 58 < 7. When geraniol (9), nerol (10), and (−)-menthol (11) were added, the hosts decreased intensities in both monomer and excimer emissions for 9 and 10 while their emission variations for 11 were similar to those of 5. For steroids such as cholic acid (12), deoxycholic acid (13), chenodeoxycholic acid (14), and ursodeoxycholic acid (15), γ-4 showed depression in the excimer emission and enhancement in the monomer one while γ-2 and γ-3 showed complicated features in which the excimer emission was enhanced with the order of 15 < 14 < 1312 but the monomer one was depressed or enhanced depending on the hosts. All these data demonstrate that the hosts can be used as sensors for molecular recognition.
  • Tsuguo Ishihara, Katsuhisa Tanaka, Kazuyuki Hirao, Naohiro Soga
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1347-1351
    Published: 1997
    Released: June 13, 2006
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    A transparent LiAl5O8 : Co2+ film was prepared by the sol–gel method using LiNO3, Al(i-OC3H7)3, and Co(NO3)2·6H2O. The microstructure and optical properties of the film were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical absorption, and fluorescence measurements. The XRD analysis indicated that a (110)-oriented LiAl5O8 film is formed when the gel film is heat-treated at 773 K. The XRD patterns of LiAl5O8 films heat-treated above 1173 K manifest diffraction lines assigned to reflections from the (110), (220), and (440) planes. In contrast, only the diffraction lines corresponding to the (220) and (440) planes were observed in a LiAl5O8 film heat-treated below 1073 K. These results suggest that LiAl5O8 films heat-treated below 1073 K and above 1173 K possess disordered and ordered structures, respectively. The LiAl5O8 : Co2+ films obtained by a heat treatment below 1173 K, which contain crystallites of less than 10 nm, are optically transparent. The optical absorption spectra at room temperature indicate that the absorption band due to the 4A24T1(P) transition of Co2+ ions in tetrahedral sites showed three peaks (540, 580, and 625 nm). The fluorescence spectra of the films obtained by a heat treatment above 1173 K manifest a sharp line at around 658 nm with vibronic sidebands in the long-wavelength region. The emission bands are ascribed to transition from 4T1(P) to 4A2 of Co2+ ions in tetrahedral sites in the ordered phase.
  • Masaaki Tabata, Hiroaki Ishimi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1353-1359
    Published: 1997
    Released: June 13, 2006
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    The incorporation reaction of zinc(II) and cadmium(II) into 21-(4-nitrobenzyl)-5,10,15,20-tetrakis(4-sulfonatophenyl)-23H-porphyrin (NO2Bz(Htpps)4−; HP4−) and the dissociation reaction of the metalloporphyrins ([MP]3−) have been studied spectrophotometrically at I = 0.1 mol dm−3 (NaNO3). The formation rate of the metalloporphyrins is expressed by the following equation: d[MP3−]/dt = kfM[M2+][HP4−]+kfMOH[MOH+][HP4−]-kdMP[MP3−][H+]. The rate constants and the activation parameters of the reaction were found to be kfZn = (4.86 ± 0.06) × 102 mol−1 dm3 s−1 (25 °C), ΔH = 62.1 ± 1.6 kJ mol−1, and ΔS = 14.8 ± 5.3 J mol−1 K−1; kfZnOH = (6.39 ± 0.14) × 103 mol−1 dm3 s−1 (25 °C), ΔH = 22.8 ± 0.9 kJ mol−1, and ΔS = −90.2 ± 3.1 J mol−1 K−1; kdZnP = 122.3 ± 2.3 mol−1 dm3 s−1 (25 °C), ΔH = 19.8 ± 2.2kJ mol−1, and ΔS = −139 ± 18 J mol−1 K−1 for zinc(II) and kfCd = (1.17 ± 0.02) × 105 mol−1 dm3 s−1 (25 °C), ΔH = 42.5 ± 1.3 kJ mol−1, and ΔS = −5.3 ± 4.2 J mol−1 K−1; kdCdP = (2.51 ± 0.04) × 107 mol−1 dm3 s−1 (25 °C), ΔH = 14.6 ± 0.5 kJ mol−1, and ΔS = −54.3 ± 1.7 J mol−1 K−1 for cadmium(II).
    Nitrobenzyl group lowers the basicity of porphyrin. The effect of the lowered basicity appeared strongly in the following order for the formation rate and equilibrium constants of the metalloporphyrins: Cd2+ < Zn2+ < [ZnOH]+. A hydrogen-bond formation between [ZnOH]+ and the pyrrole proton in NO2Bz(Htpps)4− is proposed for the reaction based on the larger rate constant than the water-exchange rate constant enhanced by the hydroxide ion bound to zinc(II), the small activation enthalpy, the negative activation entropy, and the dependence of porphyrin basicity.
  • Mutsuo Kodama
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1361-1367
    Published: 1997
    Released: June 13, 2006
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    Formation equilibria of ternary copper(I)-macrocyclic triamine ([11]aneN3, [12]aneN3, iso[12]aneN3, and [12]aneN3S) complexes with monodentate π-ligand (SCN, CH3CN, or imidazole) were studied by the polarographic method. The copper(I)-macrocyclic triamine complexes in solutions containing an excess monodentate π-ligand were found to produce a polarogram consisting of two separate reduction steps of equal height. The chemical equilibria for the formation of the 1 : 1 : 1 ratio copper(I) mixed ligand complexes including macrocyclic triamine and π-ligand were determined by studying the effects of solution pH and concentrations of macrocyclic triamine and π-ligand on the half-wave potential of the 2nd reduction step, which appears at more negative potentials. The eleven-membered macrocyclic triamine, [11]aneN3, forms the most thermodynamically stable copper(I) mixed ligand complex, [CuIL(A)]1−b. The formation constants for 1 : 1 : 1 ratio copper(II), macrocyclic triamine, and monodentate π-ligand were determined potentiometrically by studying the effects of SCN, CH3CN, or imidazole concentration on the formation equilibrium of copper(II)-macrocyclic triamine complexes.
  • Kenji Nomiya, Chika Nozaki, Kohji Miyazawa, Yasushi Shimizu, Toshio Ta ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1369-1377
    Published: 1997
    Released: June 13, 2006
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    The water-soluble form of the Dawson-type trisubstituted tungstoheteropolyanion, B-α-P2W15Nb3O629−, was synthesized as its nona alkali-metal salts of Li, K, and Cs. Analytically pure compounds, obtained as homogeneous colorless solids, had nonahydrate for the nonalithium (Li9) salt, tetrahydrate for the nonasodium (Na9) salt, trihydrate for the nonapotassium (K9) salt and trihydrate for the nonacaesium (Cs9) salt, respectively, after each was dried overnight at room temperature under 10−3—10−4 Torr. TG/DTA analyses show that they can be made with 25 water for the Li9 salt, 23 water for the Na9 salt, 9 water for the K9 salt, and 8 water for the Cs9 salt under atmospheric conditions. A compositional characterization was accomplished by complete elemental analyses and TG/DTA, and structural characterization was achieved by a combination of FT-IR and variable-temperature solid-state 31P NMR and by both 31P and 183W NMR measurements at room temperature in D2O and DMSO-d6 solutions. The amount of hydrated waters, solubility in solvents and ease of crystallization were significantly influenced by the alkali-metal countercations. These cation-dependent properties are useful for selecting polyoxoanion precursor favorable to the crystallization of P2W15Nb3O629−-supported organometallic complexes. The effects of the cations (Li, K, Na, and Cs) on the P2W15Nb3O629− were observed as different hydrated structures of the polyoxoanion and its cation-dependent thermal stability in the solid state by a combination of TG/DTA and FT-IR measurements, and also as a spectral change of the downfiled 31P signal due to interactions of the polyoxoanion with the countercations and/or with hydrated waters by variable-temperature (VT) solid-state GHD/MAS 31P NMR spectroscopy.
  • Shigehiro Kagaya, Joichi Ueda
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1379-1383
    Published: 1997
    Released: June 13, 2006
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    Gallium(III) phosphate coprecipitates quantitatively 0.1—2.0 μg of lead(II) from 100—500 cm3 of a sample solution at pH 2.5—6.0. The coprecipitated lead(II) can be sensitively determined by electrothermal atomization atomic absorption spectrometry without any influence of gallium(III) phosphate. The calibration curve is linear from 4 to 80 ng cm−3 for lead(II). The detection limit (signal/noise = 2) is 0.095 ng cm−3 of lead(II) in 500 cm3 of the initial sample solution. Thirty-four diverse ions tested did not interfere seriously with the determination of lead(II). This method was successfully applied to the determination of lead(II) in tap and river water.
  • Tatsuya Sekine, Ichiro Ninomiya, Masayuki Tebakari, Junji Noro
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1385-1392
    Published: 1997
    Released: June 13, 2006
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    The solvent extraction of divalent metal ions, manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) in aqueous 0.1 mol dm−3 sodium nitrate solutions with 2-hydroxy-4-(1-methylethyl)-2,4,6-cycloheptatrien-1-one (4-isopropyltropolone; Hipt) into chloroform was studied in the absence and presence of trioctylphosphine oxide (TOPO). When the concentration of metal ions (M2+) was 1 × 10−5 to 1 × 10−4 mol dm−3 in the initial aqueous solutions, the extracted species of the metal ions in the absence of TOPO were only the mononuclear complex, M(ipt)2, with copper(II); these species were both the mononuclear complex, M(ipt)2, and the mononuclear self-adduct complex, M(ipt)2·Hipt, with zinc(II); they were both the mononuclear complex, M(ipt)2, and the dinuclear complex, M2(ipt)4, with cobalt(II) and cadmium(II); and they were predominantly the dinuclear complex, M2(ipt)4, with nickel(II) and manganese(II). It was also found that the extraction of manganese(II), cobalt(II), nickel(II), zinc(II), and cadmiun(II) was enhanced when TOPO was added into the organic phase. This was explained in terms of the formation of mononuclear adduct complex, M(ipt)2TOPO, from M(ipt)2, M(ipt)2·Hipt, and/or M2(ipt)4. The extraction constants for those species were determined. The extractability and the tendency to form dinuclear complexes are discussed.
  • Kimiko Kobayashi, Takayuki Kato, Masafumi Unno, Shinji Masuda
    1997 Volume 70 Issue 6 Pages 1393-1401
    Published: 1997
    Released: June 13, 2006
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    Optically active silanes were synthesized by a novel asymmetric synthesis which involved the diastereoselective ring-opening reaction of 1,3-dioxa-2-silacycloheptanes bearing a C2 chiral auxiliary with Grignard reagents, followed by a lithium aluminum hydride (LiAlH4) reduction. (R)-Ethylmethylphenylsilane and (R)-methylphenylpropylsilane were derived in 93%ee and 98%ee, respectively. The preparation of the other optical silanes is also described. The maximum rotations of some of them have been determined by 1H NMR and/or capillary GC methods. A mechanism for a diastereoselective ring-opening reaction is proposed based on the stereochemical results.
  • Mizue Fujio, Hiroshi Morimoto, Hyun-Joong Kim, Yuho Tsuno
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1403-1411
    Published: 1997
    Released: June 13, 2006
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    The solvolysis rates of 1-(substituted phenyl)-1-phenyl-2,2,2-trifluoroethyl and 1,1-bis(substituted phenyl)-2,2,2-trifluoroethyl tosylates or bromides were conductimetrically measured at 25.0 °C in 80% aqueous ethanol. The substituent effects on these solvolyses were analyzed on the basis of the Yukawa–Tsuno equation. The former monosubstituted diphenyl system did not show a single linear Yukawa–Tsuno correlation; a bilinear correlation was observed with ρ = −4.33 and r = 1.26 for substituents more deactivating than p-methyl, and ρ = −6.08 and r = 1.45 for the substituent range more reactive than 3,4-dimethyl. The bilinear correlation was explicable in terms of the changing coplanarity of the respective benzene rings.
    On the other hand, the symmetrically disubstituted diphenyl substrates gave an excellent linear Yukawa–Tsuno correlation for the whole substituent range with a ρ value of −8.3/2 and an r value of 1.19. The substituent effect correlation leads to the conclusion that the two aryl rings in this symmetrical system remain in the equivalent propeller-shape conformation with respect to deviations from coplanarity with the carbenium ion center in the transition state.
  • Masanori Wada, Wen-hao Wei, Katsuhiko Kirishima, Satoko Natsume, Tatsu ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1413-1420
    Published: 1997
    Released: June 13, 2006
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    By reactions of diethyl p-phthalate with 2,6-dimethoxyphenyllithium, ΦLi, a tri-substituted compound, p-HOCΦ2C6H4C(O)Φ (1), or tetra-substituted 1,4-benzenedimethanol, p-HOCΦ2C6H4CΦ2OH (2a), were obtained. Compound 1 further reacted with aryllithium, ArLi, to give the 1,4-benzenedimethanols, p-HOCΦ2C6H4CArΦOH (Ar = 4-MeC6H42b, 4-MeOC6H42c). When 2a was treated with acid in dimethyl sulfoxide, 3-(2,6-dimethoxybenzoyl)-3-(2,6-dimethoxyphenyl)-6-[bis(2,6-dimethoxyphenyl)methylene]-1,4-cyclohexadiene, (4a) was obtained in quantitative yield under a variety of conditions. The reaction is understood to involve an initial formation of carbenium ion, [p-Φ2C+–C6H4CΦ2OH] (3a), of which the positive charge must be partly shared with the other end of the p-phenylene ring, where one of the neighboring Φ-groups migrates. Reactions in acetone resulted to give 4a or dark-violet crystals of (2′,6′-dimethoxy-4-biphenylyl)bis(2,6-dimethoxyphenyl)carbenium perchlorate, [(4-ΦC6H4)CΦ2]ClO4, depending on the reaction conditions. Reactions in methanol, ethanol, or in hot 2-propanol resulted to give the reduced compound, (4-ΦC6H4)Φ2CH. The 1,4-benzenedimethanols, 2b and 2c, also reacted with perchloric acid in dimethyl sulfoxide to form the 3-methylene-1,4-cyclohexadiene derivatives, (Ar = 4-MeC6H44b, 4-MeOC6H44c), respectively. Evidence is given by the 1H NMR spectrum, which shows the formation of intermediate carbenium ions 3ac.
  • Takeshi Hanamoto, Yuichi Sugimoto, Yong Zhi Jin, Junji Inanaga
    1997 Volume 70 Issue 6 Pages 1421-1426
    Published: 1997
    Released: June 13, 2006
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    Scandium(III) perfluorooctanesulfonate [scandium(III) perflate, Sc(OPf)3] was prepared from either scandium(III) chloride or oxide and perfluorooctanesulfonic acid. The perflate thus obtained acts as a novel Lewis acid catalyst for the intermolecular hetero Diels–Alder reaction of aldehydes with non-activated dienes under mild conditions. The characteristic features of the catalyst include (i) low hygroscopicity, (ii) ease of handling, and (iii) robustness for the recycling use.
  • Chung-gi Shin, Kazushige Arai, Keitaro Hotta, Takeshi Kakusho
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1427-1434
    Published: 1997
    Released: June 13, 2006
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    Enzymatic ester hydrolysis and coupling of various N-protected Δ2-dehydrotripeptide methyl esters (Boc–AA–ΔAA–AA–OMe) (4) by using protease papain in McIlvaine buffer are mainly described. The substrates (4) used were prepared by one-pot coupling of N-carboxy-α-dehydroamino acid anhydride (ΔAA·NCA) with N- and C-component L-α-amino acids (AA). Even in the enzymatic reaction of 4 containing an unusual ΔAA residue, the normal ester hydrolysis took place to give Boc–AA–ΔAA–AA–OH (6) and, in certain cases, the interesting unusual peptide bond cleavage at P2 of 6 occured further to give the unexpected N-(1,2-dioxoalkyl)–AA–OH. Besides examining in detail the differences between the enzymatic actions to the structures of 4, we also studied the mechanisms of the ester and peptide bond hydrolyses. As the results, the reverse enzymatic coupling of 4 with H–AA–ΔVal–OMe was first achieved to give dehydropentapeptide containing two ΔAA residues.
  • Masato Oikawa, Akira Wada, Hiroaki Yoshizaki, Koichi Fukase, Shoichi K ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1435-1440
    Published: 1997
    Released: June 13, 2006
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    A biosynthetic precursor of lipid A has been synthesized by an improved efficient method. Two appropriately modified acyl-substituted glucosamine units were synthesized from D-glucosamine using (R)-3-(benzyloxy)tetradecanoic acid and then coupled by the Lewis acid-promoted glycosidation via the corresponding trichloroacetimidate. Glycosyl phosphorylation and hydrogenolytic deprotection, followed by purification by liquid–liquid partition chromatography, afforded the target compound in 2.9% total yield through 13 steps from N-Troc-D-glucosamine.
  • Wen-Chi Liu, Masato Oikawa, Koichi Fukase, Yasuo Suda, Hendig Winarno, ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1441-1450
    Published: 1997
    Released: June 13, 2006
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    Synthesis of unnatural analogues, that contain (S)-3-hydroxytetradecanoyl moieties in place of the corresponding natural (R)-isomers, of both lipid A and its biosynthetic precursor, designated precursor Ia or lipid IVA, has been achieved through our recently developed procedure. (S)-3-Hydroxytetradecanoic acid was prepared from its racemate through the optical resolution by the use of a lipase and subsequent fractional recrystallization. The (S)-acyl analogue of lipid A exhibited slightly stronger interleukin-6 inducing activity than the corresponding natural lipid A, and the (S)-acyl analogue of the biosynthetic precursor was far more active than the natural precursor in inhibiting the induction of interleukin-6 by lipopolysaccharide.
  • Chieko Uchida, Kaori Wakamatsu, Masanao Oya
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 6 Pages 1451-1458
    Published: 1997
    Released: June 13, 2006
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    The interaction between high molecular-weight synthetic polypeptides containing proline residue and salmon DNA were studied by circular dichroism spectra (CD) in aqueous solution, 1H NMR in D2O solution, and 13C NMR spectra in solid state. The interactions were compared with those of polypeptides containing lysine residue and DNA. The complexes of poly(Pro) and poly(Pro-co-Gly) with DNA were made by lyophilization after dialysis of the mixed solution of the corresponding solutions. These complexes were soluble in water and insoluble in 1 M NaCl, in contrast to the poly(Lys)–DNA complex, which was insoluble in water and soluble in 1 M (mol dm−3) NaCl. The polypeptides containing proline residue (poly(Pro-co-X)) interacted with DNA in the solution, which differed from the interaction of poly(Lys) with DNA. In addition, the interactions of poly(Pro) and poly(Pro-co-Gly) with DNA differed from each other.
  • Shigeru Kunugi, Yuuichi Yanagi, Moto Kitayaki, Naoki Tanaka, Yukiko Ue ...
    1997 Volume 70 Issue 6 Pages 1459-1463
    Published: 1997
    Released: June 13, 2006
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    The effects of high pressure, up to 400 MPa, on the catalytic activity and the fluorescence and CD of carboxypeptidase Y (CPDY) were investigated.
    CPDY showed a pH-dependent Suc–Ala–Ala–Pro–Phe–pNA hydrolysis similar to other neutral substrates. The apparent second-order rate showed a gradual decrease with increasing pressure, which was related to an increase in Km and a decrease in kcat.
    The intrinsic fluorescence of CPDY showed a gradual decrease in the intensity and a red shift in the maximum wavelength with pressure. The transition curve did not follow a simple tow-state transition, but contained at least three states. The first transition occurred at around 100 MPa and the second one occurred at pressures higher than 200 MPa. After incubation at 300 MPa, both the peak intensity and the maximum wavelength did not show complete restoration; the pressure-induced change is substantially irreversible.
    The latter change corresponds to the increased binding of a fluorescent hydrophobic probe molecule (8-anilino-1-naphthalenesulfonic acid) to this protein; however, the CD spectrum showed practically no evidence of irreversible changes in the protein’s secondary structure.
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