Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 76 , Issue 3
Showing 1-30 articles out of 30 articles from the selected issue
  • Osamu Sato, Shinya Hayami, Yasuaki Einaga, Zhong-Ze Gu
    Type: Accounts
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 443-470
    Published: 2003
    Released: March 15, 2003
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    The electrochemical, photochemical and chemical control of the magnetic properties in molecular compounds is described. The preparation of various thin films of CrCr and FeFe Prussian blue on a conducting electrode allowed us to control the magnetic properties by varying the oxidation state of the component metals. The magnetic properties of CrCr Prussian blue show that the critical temperature and coercive field can be drastically modified by electrochemical treatment. That is, the compound, CrII1.29CrIII0.14[CrIII(CN)6] has ferrimagnetic properties with Tc (critical temperature) = 240 K and Hc (coercive field) = 25 G, while the reduced form, KCrII1.29CrIII0.14[CrII(CN)6], has Tc = 100 K and Hc = 220 G. Similarly, it was found that the critical temperature of FeFe Prussian blue shifts continuously from paramagnetic to magnetic with Tc = 12 K. These changes can be expressed as K4FeII4[FeII(CN)6]3 (paramagnetic) FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.5 K) + 4 K+ + 4e and FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.2 K) + 3Cl − 3e FeIII4[FeIII(CN)6]3(Cl)3 (Tc = 12 K). Furthermore, we have discovered that the FeCo Prussian blue and Co valence tautomeric compounds exhibit photo-reversible magnetization effects. The photoinduced magnetization in FeCo Prussian blue is expressed as Na0.4CoII-HS0.3CoIII-LS[FeII(CN)6] (paramagnetic) Na0.4CoII-HS1.3[FeIII(CN)6] (ferrimagnetic, Tc = 26 K and Hc = 6000 G), where HS and LS denote high-spin and low-spin. An example of the photoinduced valence tautomeric behavior is expressed as [CoIII-LS(3,5-dbsq)(3,5-dbcat)(tmeda)] [CoII-HS(3,5-dbsq)2(tmeda)], where tmeda, 3,5-dbsq and 3,5-dbcat represent N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. Additionally, we succeeded in tuning the phase transition temperature by varying the ligand field of the Co ions in the FeCo Prussian blue. Brief comments are also included regarding the first examples of light-induced excited spin state trapping observed in an FeIII complex, i.e. [FeIII-LS(pap)2]ClO4·H2O [FeIII-HS(pap)2]ClO4·H2O (pap = N-2-pyridylmethylidene-2-hydroxy-phenylaminato) and a photoinduced structural change observed in a CuII complex, [CuII(dieten)2](BF4)2 [dieten = bis(N,N -diethylethylenediamine)].
  • Takayuki Kawashima
    Type: Accounts
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 471-483
    Published: 2003
    Released: March 15, 2003
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    Most titled compounds were synthesized by taking advantage of the Martin ligand. Their structures were determined by X-ray crystallography. Thermolyses of most of the four-membered ring compounds gave the corresponding Wittig-type products, while those of 1,2-oxasiletanides in the presence of proton source afforded the homo-Brook rearrangement products depending on bulkiness of the substituent at the 3-position. Pentacoordinate thiasiliranides were hydrolyzed to give the corresponding thiol, which seems to be formed via the initial cleavage of the Si–C bond followed by further hydrolysis of the corresponding thia-Brook rearrangement product. On the other hand, the most polarized bond of a pentacoordinate selenaphosphirane was found to be the P–Se bond, which was confirmed by its reaction with CF3SO3Me to give the corresponding 1-(methylseleno)alkylphosphonium triflate and by the solvent-dependent NMR study.
  • Koichi Fukase, Atsushi Ueno, Yoshiyuki Fukase, Masato Oikawa, Yasuo Su ...
    Type: Headline
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 485-500
    Published: 2003
    Released: March 15, 2003
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    New lipid A analogs having acidic groups β-glycosidically linked at the 1-position were synthesized in order to investigate the structural requirement for immunostimulating and endotoxic activity of lipid A. The β-(phosphonoxy)ethyl (PE) and carboxymethyl (CM) analogs of Escherichia coli type having six acyl groups and those of the biosynthetic precursor type having four acyl groups were synthesized via a divergent synthetic route. The E. coli type β-(phosphonoxy)ethyl analog, which was previously reported to be not endotoxic, showed strong immunostimulating activity comparable to the natural-type α-analog. The acidic functional groups are concluded to be essential but their strict spatial arrangement is not required for expression of the biological activity.
  • Yosuke Shiratori, Yoshiaki Nanba, Minoru Kato, Yoshihiro Taniguchi
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 501-507
    Published: 2003
    Released: March 15, 2003
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    The conformational equilibria of chloroacetone and bromoacetone in various solvents were investigated using temperature and pressure-tuning Raman spectroscopy. Three conformational equilibria of gauche trans, gauche trans′ (trans conformer whose halogen atom forms hydrogen bonds with water), and trans trans′ were observed in water. Thermodynamic quantities between the conformers of both haloacetones in various solvents were evaluated from the temperature and pressure dependence of the Raman intensities of the C–X (X: Cl and Br) stretching modes. The effects of the substitution of halogen atoms were observed in the enthalpy and volume differences between the conformers in water. From the present results together with the previous results for fluoroacetone, a good correlation between the conformational thermodynamics for haloacetones in water and the polarizabilities of the halogen atoms was shown.
  • Makoto Sakai, Tadashi Ueda, Takaya Yamanaka, Masaaki Fujii
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 509-514
    Published: 2003
    Released: March 15, 2003
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    We have constructed a picosecond time-resolved IR dip spectrometer having a frequency resolution of < 20 cm−1 and an instrument response time of 25 ps. In this system, the second harmonic of the idler wave from the OPA pumped at 800 nm and the remaining light from a regenerative amplifier (< 2.5 mJ/pulse) were differentially mixed in a KTA crystal to generate tunable high-power IR light (2750–4000 cm−1; > 60 μJ). The picosecond time-resolved IR dip spectra of phenol–(H2O)1 and carbazole–(H2O)1 are presented to demonstrate the capability of the constructed system. The spectral changes show clear vibrational structures of not only S0, but also S1 in the 2800–3800 cm−1 energy region. The system performance is also discussed.
  • Toshio Oguchi, Kazuo Kazama, Toshiro Fukami, Etsuo Yonemochi, Keiji Ya ...
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 515-521
    Published: 2003
    Released: March 15, 2003
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    Ursodeoxycholic acid (UDCA) formed an inclusion complex with phenanthrene or with anthrone when being ground at an ambient temperature, while grinding at lower temperatures did not provide the complex but rather a mixture of amorphous UDCA and the guest compound crystals. Since heat treatment of the sample ground at low temperature did not provide the complex, it was concluded that the interplay of mechanochemical and thermal factors is responsible for the complexation of UDCA with the guest compound.
  • Gerardo R. Echevarría Gorostidi, M Gabriela Castellanos, Piedad ...
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 523-528
    Published: 2003
    Released: March 15, 2003
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    The overall and individual kinetic constants of formation (k1 and k1i) and hydrolysis (k2, kOH and k2i) of the Schiff’s bases formed between pyridoxal 5′-phosphate (PLP) and 4-aminobutanoic acid (GABA) at 10, 20, 25, 30, and 37 °C, a variable pH and a constant ionic strength of 0.1 M (1 M = 1 mol dm−3) were determined. The formation of a Schiff’s base is an intramolecular acid-catalyzed process. The activation and thermodynamic parameters for the formation and hydrolysis of the Schiff’s bases were also determined. ΔH and ΔS for the individual processes were all found to be negative.
  • Isseki Yu, Kazuyoshi Ueda, Haruo Nakayama
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 529-539
    Published: 2003
    Released: March 15, 2003
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    Molecular dynamics simulations of cellulose triacetate (CTA) were performed with explicit DMSO molecules in order to investigate the solvent structuring of DMSO around the CTA polymer. A hexamer unit of CTA was used as a model instead of polymer CTA. The molecular dynamics trajectory was started from a minimum conformation, which was found from an analysis of the adiabatic potential-energy surface obtained for glycosidic dihedral angles of φ and ψ. It showed that most of the time the trajectory stayed in their initial conformation in DMSO solvent. A distance analysis between the acetyl methyl residues of CTA showed that they are in good accordance with the NMR-NOESY data obtained by Tezuka.1 In order to elucidate the solvation structure of DMSO around the solute molecules, the site-specified radial distribution function, the orientation and the time courses of the DMSO movement were analyzed precisely. The results showed that some DMSO molecules strongly interact with CTA at specific sites, such as acetyl methyl residues and H1 ring protons. Moreover, it was found that those DMSO molecules frequently interact to CTA, not with one site, but with two or more sites simultaneously. These DMSO molecules would play an important role in the conformation of CTA in this solvent.
  • Yulin Lam, Ngai Ling Ma, Hsing Hua Huang, Li Wang
    Type: Short Articles
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 541-542
    Published: 2003
    Released: March 15, 2003
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    The dipole moments of 1,2-dichlorotetranitroethane in carbon tetrachloride and benzene show that the compound favors the gauche conformer in solution-state. Experimentally derived values of the energy difference between the gauche and trans conformers and their population quotient are compared with values estimated by ab initio calculations. The agreement between experiment and theory is found to be excellent.
  • Norihiro Kato, Yasuzo Sakai, Atsushi Kanazawa
    Type: Short Articles
    Subject area: TP
    2003 Volume 76 Issue 3 Pages 543-544
    Published: 2003
    Released: March 15, 2003
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    A linear correlation between the enthalpy of activation (ΔH) and the entropy of activation (ΔS) was observed for the deswelling process of porous poly(N-isopropylacrylamide/methacrylic acid) gels. The free energy of activation (ΔG) was nearly constant at +84 ± 2 kJ mol−1 irrespective of the methacrylic acid content and pH of the solutions.
  • Farzaneh Shemirani, Shiva Dehghan Abkenar, Mohammad Reza Jamali
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 3 Pages 545-548
    Published: 2003
    Released: March 15, 2003
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    In the present study, an effective method was used for the preconcentration and determination of uranium(VI) by solid-phase extraction (SPE). For this purpose, a microcolumn of alumina modified with sodium dodecyl sulfate (SDS) and 1-(2-pyridylazo)-2-naphthol (PAN) was prepared for the preconcentration of trace uranyl(VI) from water samples. The uranium(VI) was completely eluted with 6.0 mol dm−3 HCl and determined by a spectrophotometric method with Arsenazo III. The SPE conditions were optimized by evaluating the effective factors such as pH, flow rate and masking agent. By the proposed method a preconcentration factor more than 150 was achieved. The average recovery of uranium(VI) was 99.8%. The relative standard deviation was 2.6% for ten replicate determinations of uranyl(VI) ion in a solution with a concentration of 50 ng cm−3. Some concomitant ions such as Cd2+, Ni2+, MoO42−, Cu2+, Th4+ and Ce3+, which interfere in the determination process of uranium(VI), were masked with EDTA in the aqueous phase during the extraction process. The proposed method was successfully used for the determination of uranium in natural water.
  • Osamu Asada, Keisuke Umakoshi, Kiyoshi Tsuge, Shingo Yabuuchi, Yoichi ...
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 3 Pages 549-555
    Published: 2003
    Released: March 15, 2003
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    The reaction of K2[PtCl4] with pyrimidine-2-thiol (pymSH) was reinvestigated. Among the possible four isomers, the major product was the cis isomer of [PtIII2Cl2(pymS)4] (1). The Pt(II) complex cis-[Pt2(pymS)4] (2) was prepared by the addition of NaOCH3 in the reaction mixture. The substitution of the axial Cl ligands of 1 with Br afforded the bromo complex [Pt2Br2(pymS)4] (3). While the reactions of K2[PtCl4] with 4-methylpyrimidine-2-thiol hydrochloride (4-mpymSH·HCl) in the presence of NaHCO3 gave a mixture of [Pt2Cl2(4-mpymS)4] (4) and trans-[Pt(4-mpymS)2] (5), the reaction with 4,6-dimethylpyrimidine-2-thiol (4,6-dmpymSH) gave only trans-[Pt(4,6-dmpymS)2] (7). The preference of bis-chelate mononuclear complexes for these ligands may be explained by considering steric hindrance between the ligands in the dimer. The oxidation of 5 by Ce(IV) afforded trans-dichloro Pt(IV) complex, [PtCl2(4-mpymS)2] (6). The crystal structures of 1, 3, 6 and 7 were determined. The redox properties of 1 and 3 are also discussed.
  • Kin Chin, Kazuo Eda, Takashi Suzuki, Noriyuki Sotani
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 3 Pages 557-560
    Published: 2003
    Released: March 15, 2003
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    The hydrothermal heating of H0.28MoO3 in a KCl solution at 431 K led to the formation of a single phase of K0.28MoO3. Hydrated molybdenum bronze was formed as a mid-product during conversion from hydrogen molybdenum bronze to blue bronze. The formation enthalpy of K0.28MoO3 was determined by solution calorimetry to be ΔfH° (K0.28MoO3, s) = −840.2 kJ mol−1 at 298.15 K. The enthalpies of the transformation reaction from hydrogen bronze to hydrated bronze and of the formation reaction of blue K0.28MoO3 from hydrated bronze were calculated to be +33 kJ mol−1 and −48 kJ mol−1 at 298.15 K, respectively. The calculated enthalpies of the reactions were concordant with the suggested reaction mechanism for a transformation from hydrogen molybdenum bronze to potassium bronze.
  • Keiichi Tsukahara, Rie Ueda
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 3 Pages 561-566
    Published: 2003
    Released: March 15, 2003
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    New chiral quinolinium derivatives, 1-[(S)- or (R)-(1-phenylethyl)carbamoylmethyl]-6-methoxyquinolinium hexafluorophosphate ([PMQ]PF6, 2) and 1-[(S)- or (R)-(1-phenylethyl)carbamoylmethyl]quinolinium hexafluorophosphate ([PQ]PF6, 3), were synthesized and characterized. A cyclic voltammetry in MeCN shows an irreversible redox behavior at −0.88 V and −0.85 V vs SCE (saturated calomel electrode) for 2 and 3, respectively. Fluorescence from the quinolinium moiety of 2 and 3 was observed at 455 nm and 440 nm, respectively. The fluorescence lifetime of 2 was longer than that of 3: τf = 30 ns (2) and 20 ns (3) in MeCN and τf = 26 ns (2) and 16 ns (3) in H2O). The excited triplet state of zinc-substituted myoglobin (3(ZnMb)*) was quenched by chiral [PMQ]+ and [PQ]+ ions; thereafter, the back electron-transfer (ET) reaction from a quinoline radical (PMQ or PQ) to a zinc myoglobin radical cation was detected. The stereoselectivity was observed for both ET quenching and back ET reactions; the (S)-isomers preferentially quench 3(ZnMb)* (kq(S)/kq(R) = 1.3 and 1.4 at 25 °C for [PMQ]+ and [PQ]+, respectively); in contrast, the (R)-isomers react faster than the (S)-isomers in the back ET reaction (kb(R)/kb(S) = 1.3 and 1.4 for PMQ and PQ, respectively). From a comparison of the rate constants with those for the previously reported systems we suggest that both the quenching and back reactions are controlled by ET, but not by conformational gating.
  • Fuminori Akiyama
    Type: Short Articles
    Subject area: AI
    2003 Volume 76 Issue 3 Pages 567-568
    Published: 2003
    Released: March 15, 2003
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    The degradation processes of 2,2′,5,5′-tetrachlorobiphenyl (4Cl-B) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (6Cl-B) with potassium carbonate in supercritical water at 500 °C were studied. Hydrocarbons containing methane as major component were formed in the yield of around 15%. The main reaction product is considered to be inorganic salts, which do not show any NMR spectra and are easily decomposed by dilute acid.
  • Takeyasu Tasaka, Hiroaki Okamoto, Yuki Morita, Koichi Abe, Kazuo Kasat ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 569-574
    Published: 2003
    Released: March 15, 2003
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    The layer structure and phasetransition behavior of smectic A phases for 4-(4-alkoxyphenoxycarbonyl)phenyl 5-X-furan-2-carboxylates (X = CN, NO2) were examined by a small-angle X-ray diffraction method. The higher homologs of both compounds exhibit two kinds of smectic A (Sm A) phases and experience the Sm A-Sm A transition. One Sm A phase exhibited at a higher temperature region having a layer spacing of 1.5–1.9 times the calculated molecular length; and the layer spacing gradually increases with decreasing temperature. The other Sm A phase exhibited at a lower temperature region having a layer spacing of twice the calculated molecular length; also, the layer spacing is almost independent of the temperature. The Sm A–Sm A transition behavior is discussed.
  • Toshihiro Najiwara, Ji-ichiro Hashimoto, Katsunori Segawa, Hirochika S ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 575-585
    Published: 2003
    Released: March 15, 2003
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    1-Naphthoyloxyl and 2-naphthoyloxyl radicals were generated from photocleavage of dinaphthoyl peroxides and 1-(naphthoyloxy)-2-pyridones in acetonitrile. The difference in product distribution between the precursors is ascribed to the contribution of the two-bond cleavage in the peroxide decomposition in the singlet state. A series of methoxynaphthoyloxyl radicals were also generated from the corresponding (methoxynaphthoyloxy)pyridones and their behavior was compared with that of unsubstituted naphthoyloxyl radicals. The introduction of a methoxy group in the naphthalene ring stabilizes the naphthoyloxyl radicals to prevent their decarboxylation completely and reduces remarkably their reactivities in the addition to olefins and hydrogen-atom abstraction. The structure of the naphthoyloxyl radicals was discussed on the basis of their absorption spectra and MO calculations.
  • Miyoko Kamigauchi, Mayumi Yoshida, Yuko Noda, Jujiro Nishijo, Yasuko I ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 587-593
    Published: 2003
    Released: March 15, 2003
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    A possible relation between the stereostructure of (−)-(13aS)-tetrahydroberberine (1) and its enzymatic/chemical N-methylation, an important biosynthetic reaction to isoquinoline alkaloids in plants, was examined by CD spectroscopic, X-ray crystallographic, and energy calculation methods. The CD measurements indicated that 1 has two conformers (cis and trans) concerning the ring junction of the quinolizidine skeleton, and exist with a cis/trans ratio of about 1/4 in a diethyl ether : 2-methylbutane : ethanol (5 : 5 : 2) mixture. The dimensional/conformational difference between these cis and trans conformers was clarified by the X-ray crystal-structure analyses of two stereoisomers of N-methylated 1 (3 and 4). By using these structural parameters, the progress of N-methylation was simulated by energy profile calculations, suggesting that the cis and trans conformers are the major substrate for the enzymatic and chemical N-methylation reactions, respectively. Taking these results and the simulation of N-methylation of 1 by S-adenosyl-L-methionine at the binding pocket of N-methyltransferase into consideration, different pathways for chemical and enzymatic N-methylations of 1 have been proposed.
  • Toshiyuki Moriuchi, Xiuliang Shen, Kaori Saito, Seiji Bandoh, Toshikaz ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 595-599
    Published: 2003
    Released: March 15, 2003
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    A π-conjugated quinonediimine ligand possessing two terminal redox-active ferrocenyl groups, N,N′-bis{(4′-ferrocenylcarboxamide)phenyl}-1,4-benzoquinonediimine (Lox), was synthesized. The quinonediimine ligand Lox was reduced to Lred composed of the phenylenediamine moiety on treatment with hydrazine hydrate. The reaction of Lox with the palladium(II) complex 1 bearing the N,N′-bis(2-phenylethyl)-2,6-pyridinedicarboxamide ligand afforded the multimetallic complex 2. Variable temperature 1H NMR studies of 2 indicated the existence of syn and anti isomers, in which the anti isomer is enthalpically more favorable than the syn isomer in CD2Cl2 by 0.9 kcal mol−1, but entropically less favorable by 2.6 cal mol−1 K−1 from the van’t Hoff plot. The redox function of the quinonediimine moiety is modulated by complexation with 1. The complex 2 showed three separate redox waves, which are assignable to the successive one-electron reduction of the quinonediimine moiety and oxidation of the two terminal ferrocenyl groups. Chemical reduction of 2 in CH2Cl2 with [Co(Cp)2] resulted in the appearance of ESR signals with weak 105Pd coupling centered around g = 2.004. The unpaired electron appears to locate mostly on the quinonediimine moiety with some delocalization onto the palladium center.
  • Masahide Yasuda, Takuya Nakai, Yasumasa Kawahito, Tsutomu Shiragami
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 601-605
    Published: 2003
    Released: March 15, 2003
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    The tetra-O-acetylriboflavin (Fl)-photosensitized dehydrogenation of benzyl alcohols 1 proceeded more efficiently in aqueous solutions in the presence of sodium dodecyl sulfate (H2O/SDS) than acetonitrile solutions. The fluorescence quenching of Fl with 1 occurred efficiently in H2O/SDS. The apparent rate constants (kQ) for the fluorescence quenching were determined by Stern–Volmer plots. The plots of kQ vs the free-energy changes for the electron transfer from 1 to the excited singlet of Fl showed the Rehm–Weller-type correlation. However, plots for H2O/SDS were deviated from a curve calculated by the Rehm–Weller equation, although plots for MeCN were fitted to the calculated curve. The deviation in H2O/SDS is attributable to the incorporation of Fl and 1 into the hydrophobic domain of the SDS micelle, where the condensation, less-polar medium, and exteior negative charge operate favorably for efficient electron transfer.
  • Masaki Matsui, Masayuki Suzuki, Masahiro Hayashi, Kazumasa Funabiki, Y ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 607-612
    Published: 2003
    Released: March 15, 2003
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    A series of mono- and bisazo dyes were synthesized to obtain soluble, thermally stable, and enhanced second-order nonlinear optical chromophores (NLOphores). To prepare good sol-gel films, the most important factor was the solubility of NLOphores. Those azo NLOphores showing sufficient solubility were further classified into three groups: non-nitro-containing, nitro-containing, and fluorine-containing derivatives. Though non-nitro-containing NLOphores showed high solubility, their second-order nonlinearity was low. Nitro-containing NLOphores showed a rather high Td and a medium nonlinearity. Fluorine-containing NLOphores, especially perfluoroalkylsulfonyl derivatives, showed high nonlinearity and a rather low Td.
  • Yutaka Ono, Yoshiaki Sugihara, Akihiko Ishii, Juzo Nakayama
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 613-617
    Published: 2003
    Released: March 15, 2003
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    2,5,5-Trimethyl-3-hexyn-2-ol was successively treated with NaH and SCl2 in Et2O to provide 3-t-butyl-4-chloro-5,5-dimethyl-5H-1,2-oxathiole (1b), a class of α,β-unsaturated sulfenic acid ester, in 74% yield. Several S-unoxidized 5H-1,2-oxathioles were synthesized in similar ways. Analysis by cyclic voltammetry uncovered that the oxidation potentials of 1b, 3-(1-adamantyl)-4-chloro-5,5-dimethyl-5H-1,2-oxathiole (1c), and 4-chloro-5,5-dimethyl-3-phenyl-5H-1,2-oxathiole (1d) are +0.69, +0.68, and +0.78 V, respectively, and are lower than those of sulfides (thioanisole, +0.97 and dimethyl sulfide, +1.09 V), and also lower than that of an acyclic sulfenate ester (ethyl benzenesulfenate, +0.90 V). Thermolysis of 1c in boiling toluene furnished 2-(1-adamantyl)-3-chloro-4-methylthiophene in 81% yield.
  • Juzo Nakayama, Tomohiro Furuya, Akihiko Ishii, Akira Sakamoto, Takashi ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 619-625
    Published: 2003
    Released: March 15, 2003
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    Bromine added to the 1-oxide, 1,1-dioxide, and sulfoximide derivatives of 3,4-di-t-butylthiophene exclusively in a 1,4-cis-addition mode. Thus, bromine added to 3,4-di-t-butylthiophene 1-oxide at room temperature in CH2Cl2 to give the 1,4-cis-adducts exclusively. The adducts are composed of two compounds in the ratio 57 : 43, where the major one is the anti-adduct respective to the S=O bond and the minor one is the syn-adduct. Addition of bromine to 3,4-di-t-butylthiophene 1,1-dioxide gave the 1,4-cis-adduct as the sole product. Addition of bromine to the N-tosyl substituted sulfoximide derivative of 3,4-di-t-butylthiophene afforded the single 1,4-cis-adduct in which two bromine atoms are anti to the N-tosyl group. Bromine added to the N-unsubstituted sulfoximide derivative of 3,4-di-t-butylthiophene to produce the 1,4-cis-addition products exclusively, which are a 67 : 33 mixture of the anti- and syn-adducts to the S=O bond.
  • Emi Yamamoto, Kanji Kubo, Akira Mori
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 627-634
    Published: 2003
    Released: March 15, 2003
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    Azamacrocycles 13, having one to three tropon-2-yl groups, were found to display unique absorption spectral changes in the presence of guest cations. Aza-15-crown-5 1, 1,7-diaza-12-crown-4 2a, 1,7-diaza-15-crown-5 2b, 1,10-diaza-18-crown-6 2c, and 1,5,9-triazacyclododecane 3 derivatives showed Ba2+, Zn2+, Ca2+, Ba2+, and Zn2+ selectivities, respectively. The crystal structures of free hosts 2a and 2c, the calcium thiocyanate complexes of 1 and 2c, the barium thiocyanate complex of 1, and the zinc thiocyanate complex of 2a were elucidated by X-ray analysis. The 2a·zinc and 2c·calcium thiocyanate complexes consist of an ion pair with a zinc tetrathiocyanate anion and a 2a·zinc cation and with a calcium hexathiocyanate anion and a 2c·H2O·calcium cation, respectively. The aminotropone moiety of 2a and 2c forms a conjugated 10-electron system. Complexation gave rise to deconjugation between the tropone ring and the nonbonding electron pair of the nitrogen atom to cause absorption spectral changes.
  • Toshiki Nishino, Yutaka Nishiyama, Noboru Sonoda
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 635-641
    Published: 2003
    Released: March 15, 2003
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    Benzylic and allylic alcohols were deoxygenatively dimerized by a treatment with lanthanum metal and chlorotrimethylsilane in the presence of a catalytic amount of iodine, giving the corresponding coupling products, alkanes, in moderate-to-good yields. This dimerization reaction was dramatically accelerated by the addition of a catalytic amount of copper(I) iodide. Similarly, ethers and esters were deoxygenatively dimerized by La/Me3SiCl/cat.I2/cat.CuI system in the presence of a catalytic amount of H2O.
  • Nobuaki Endoh, Yasuchika Yonezawa, Chung-gi Shin
    Type: Short Articles
    Subject area: OB
    2003 Volume 76 Issue 3 Pages 643-644
    Published: 2003
    Released: March 15, 2003
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    Stoichiometric asymmetric reduction of the ketone group of a 2-acetyl-3,6-disubstituted pyridine derivative with an oxazaborolidine and N-ethyl-N-isopropyl aniline-borane complex gave the corresponding (S)-lactone derivative 5 in 96% ee almost quantitatively. Hydrogenolytic cleavage of 5 gave the expected (S)-2-(1-hydroxyethyl)pyridine derivative.
  • Toshiyuki Abe, Noriaki Kawai, Akio Tajiri, Masao Kaneko
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 3 Pages 645-650
    Published: 2003
    Released: March 15, 2003
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    The synthesis of iron(III) ruthenocyanide (Ruthenium Purple, RP) in a Nafion (Nf) membrane was carried out. The visible-light absorption spectrum of the resulting RP exhibited an inter-valent charge-transfer band around 550–570 nm similar to that of neat RP, evidently showing that RP is formed in a polymer matrix. The voltammetric characteristics of the RP confined in the Nf matrix (Nf[RP]) were investigated compared with the neat RP. When Nf[RP] was used as an electrocatalyst to reduce H+, efficient H2 formation was found to originate from its molecular catalysis. In order to investigate the dominant factor that affects the overall kinetics in H+ reduction catalysis, the dependencies of both the catalytic activity (represented by the turnover number (TN) of a RP unit) and the diffusion coefficient of electron (Dapp) were studied as a function of the RP concentration in the matrix. The Dapp value decreased with increasing the concentration. The dependence of TN on the concentration was similar to that of Dapp, indicating that the overall kinetics is dominated by electron transport by RP.
  • Katsutoshi Tanaka, Atsushi Shimizu, Masami Fujimori, Souhei Kodama, Sh ...
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 3 Pages 651-657
    Published: 2003
    Released: March 15, 2003
    JOURNALS RESTRICTED ACCESS
    Dinitrogen oxide (nitrous oxide, N2O), a non-CO2 greenhouse gas, is produced as a by-product in the oxidation of cyclohexanone and cyclohexanol with nitric acid in adipic acid production plants. A Cu/Al2O3 catalyst has been used to decompose N2O to nitrogen and oxygen. We investigated the rate of deactivation of Cu/Al2O3 to establish an industrial abatement process for N2O. When Cu/Al2O3 catalyst containing 3 wt% of Cu was used, the apparent activation energy for the N2O decomposition reaction was estimated to be 167 kJ mol−1 at 746–853 K and 113 kJ mol−1 at 853–953 K. The former activation energy has been ascribed to an inhibition effect of oxygen. The rate constants of the N2O decomposition reaction have decreased with time. The decrease in the reaction-rates was analyzed by applying a first-order equation with respect to the rate constants. Simulation of the catalyst deactivation process has revealed that the Cu/Al2O3 catalyst is effective for at least for two years under the condition that 15 m3 of the catalyst is used for an adipic acid plant with a production capacity of 120 kt per year. Thus, we have concluded that the catalyst is suitable for use in industrial processes.
  • Susira Perera, Rohan Senadeera, Kirthi Tennakone, Seigo Ito, Takayuki ...
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 3 Pages 659-662
    Published: 2003
    Released: March 15, 2003
    JOURNALS RESTRICTED ACCESS
    Solid-state dye-sensitized photo cells were fabricated with nanocrystalline SnO2 covered with a thin layer of MgO as the anode and the hole conductor CuI as the cathode. While the cell fabricated with SnO2/Ruthenium bipyridyl dye/CuI delivered almost no photocurrent with very low photovoltage, the cell SnO2 (MgO)/Ruthenium bipyridyl dye/CuI delivered a short circuit photocurrent of ∼2.5 mA cm−2 with an open circuit voltage of ∼500 mV. Enhancement in the photocurrent and the voltages was found when the percentage of MgO to SnO2 was around 4 wt%. This is due to the formation of a thin energy barrier, which suppresses the recombination of photoelectrons.
  • Atsuhiro Fujimori, Tohru Araki, Hiroo Nakahara, Eisuke Ito, Masahiko H ...
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 3 Pages 663-672
    Published: 2003
    Released: March 15, 2003
    JOURNALS RESTRICTED ACCESS
    The molecular orientation in multilayer films of fluorinated comb polymers with various side-chain lengths can be characterized by near-edge X-ray absorption fine structures (NEXAFS) spectroscopy at the C K- and F K-edges. The spectra are found to change significantly with respect to the incidence angles of the soft X-rays and the number of layers in organized molecular films as well as chemical modifications such as fluorocarbon side-chain lengths, the atoms at the ω-position of the fluorocarbon side-chains, and α-methyl substituents. Analysis of these changes of the NEXAFS spectra provides useful information about the average molecular orientation in the X- and Z-types of mono- and multilayer films of the fluorinated comb polymers on solids.
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