Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 75 , Issue 8
Showing 1-29 articles out of 29 articles from the selected issue
  • Nobuhiro Ohta
    Type: scientific monograph
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1637-1655
    Published: 2002
    Released: August 15, 2002
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    Electric field effects on photochemical dynamics have been examined with particular regard to photoinduced electron transfer (PIET) and excimer formation, based on the measurements of the field effects on emission spectra and emission decays. In various pairs of electron donor and acceptor and in their linked compounds, the following processes are shown to be significantly influenced by an electric field in a polymer film: the initial step of PIET, back-electron transfer which produces an fluorescent state, charge recombination, and dissociation of radical–ion pairs generated by PIET. With an oriented molecular system where vectorial interlayer PIET occurs, PIET is shown to be controlled by an electric field; the rate is depressed or enhanced by an electric field, depending on the field direction relative to the direction of the electron transfer. Electric field effects on excimer formation processes suggest that not only the level shift but also the change in orbital overlap between different chromophores play an significant role in electric field effects on photochemical dynamics.
  • Munetaka Akita, Shiro Hikichi
    Type: scientific monograph
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1657-1679
    Published: 2002
    Released: August 15, 2002
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    Our recent research on transition metal complexes containing hydrotris(pyrazolyl)borato ligands (TpR), which ranges from bioinorganic chemistry of dioxygen complexes to organometallic systems, is reviewed. The TpR ligand turns out to be versatile in a wide variety of inorganic studies, because the coordination properties (both steric and electronic) can be finely tuned in a systematic manner by choosing appropriate substituents on the pyrazolyl rings to serve the purpose of the study (e.g. stabilization, activation, functionalization). For first row transition metal complexes, TpR serves as a tetrahedral enforcer to form a coordinatively unsaturated tetrahedral species, which is interconverted with five- and six-coordinate structures via coordination/dissociation of donor(s). In addition to the traditional view of TpR as a ligand system isoelectronic with cyclopentadienyls (η5-C5R5), the TpR ligand is now recognized as a unique ancillary ligand suitable for bioinorganic studies, because the tripodal ligand can mimic the coordination environment created by three imidazolyl groups from histidine residues, which is frequently found in the active sites of metalloenzymes. Through extension of the metal in TpRM-O2 adducts to those not related to biological systems we have unveiled the following new aspects of the chemistry of transition metal dioxygen complexes: (1) formation of higher valent bis(μ-oxo) species, TpRM(μ-O)2MTpR (M = Co, Ni), via O–O cleavage of TpRM(μ-η2 : η2-O2)MTpR intermediates and their relevance to the active intermediate of methane monooxygenase, (2) formation and full characterization of a variety of peroxo, hydroperoxo (Pd, Rh) and alkylperoxo species (Mn, Co, Ni, Pd), (3) structural evidence for conversion of molecular oxygen into hydroperoxide via protonation of the η2-peroxo intermediate (Rh), and (4) formation of an active species which undergoes oxidative C–C cleavage reaction (Ru). The property of the TpR ligand as a tetrahedral enforcer is best demonstrated in organometallic systems. The hydrocarbyl complexes, TpRM-R′ (M= Fe, Co), are stable with respect to thermal decomposition processes involving β-hydrogen elimination despite their highly coordinatively unsaturated electronic structure [Fe(14e), Co(15e)], when they are kept under inert atmosphere. The stability has been ascribed to a high spin configuration caused by the tetrahedral geometry. All frontier orbitals are occupied by unpaired electrons or electron pairs and no vacant frontier orbital is left for interaction with the electron pairs of a donor. Dinuclear xenophilic complexes, TpRM–M′Ln, with a polar metal–metal bond which bridges a Werner complex type hard open-shell metal center and a coordinatively saturated metal carbonyl fragment are also synthesized and fully characterized.
  • Yoshiki Katayama, Nobuaki Soh, Mizuo Maeda
    Type: scientific monograph
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1681-1691
    Published: 2002
    Released: August 15, 2002
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    Current methods for monitoring nitrogen monoxide (NO) and new strategies for designing NO probes are reviewed. The production of endogenous NO must be monitored if we are to understand the physiological and pathological roles of NO. Many methods have been reported for this purpose, including colorimetry, fluorometry, electrochemical methods, and electron paramagnetic resonance (EPR). Among these methods, one of the most promising for practical use is EPR using (dithiocarbamato)iron(II) complex as a spin trap. In the structure–sensitivity relationship, it was found that an electron-donating group on the dithiocarbamato ligand is favorable for enhancing the sensitivity of NO detection due to the stabilization of the Fe(II) complex form. A new concept, “radical-exchange”, is also introduced to solve the issue of low sensitivity in EPR methods. This concept has been used to develop two types of NO probe: spin trap and fluorescent probes. These reagents detect NO to a detection limit of 10 nM–sub-µM. This strategy, using radical exchange in conjunction with EPR, is potentially useful for the design of sensitive probes that can detect NO directly.
  • Naoki Usuki, Masaaki Ohba, Hisashi Okawa
    Type: technical report
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1693-1698
    Published: 2002
    Released: August 15, 2002
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    A cyanide-bridged bimetallic compound, [Ni(1,1-dmen)2]2[Fe(CN)6](BPDS)0.5·4H2O (1) (1,1-dmen = 1,1-dimethylethylenediamine, BPDS2− = biphenyl-4,4′-disulfonate), has been prepared. It has a pseudo 2-D network structure based on a Fe4Ni4 square unit with two Fe–CN–Ni–NC–Fe and two Fe–CN···H2O–Ni–NC–Fe linkages and shows a metamagnetic ordering with TC = 3.3 K. The dehydration of 1 at 150 °C has afforded [Ni(1,1-dmen)2]2[Fe(CN)6](BPDS)0.5 (1a). It has a definite 2-D network structure based on a Fe4Ni4 square unit with four Fe–CN–Ni–NC–Fe linkages and shows essentially a ferromagnetic ordering with TC = 10.7 K under weak applied field (> 250 G). 1a is hygroscopic and adsorbed atmospheric moisture to afford [Ni(1,1-dmen)2]2[Fe(CN)6](BPDS)0.5·2H2O (1b), which has a pseudo 2-D network structure similar to that of 1 and shows a metamagnetic ordering with TC = 4.0 K. 1a and 1b can be interconverted by dehydration at 150 °C and hydration in open air at room temperature, producing a unique molecular magnetic system exhibiting a reversible ferromagnetism/metamagnetism modulation.
  • Rameshwar D. Saini, Suresh Dhanya, Tomi Nath Das
    Type: Others
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1699-1705
    Published: 2002
    Released: August 15, 2002
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    Henry’s law constant (Kh) of CF2Br2 was measured to be 0.058 M atm−1 at room temperature. The steady state as well as laser (248 nm) flash photolysis of CF2Br2 was carried out in aqueous solution. The formation of Br2•− radicals involving two primary photodissociation channels was observed in the flash photolysis. One channel produced CF2Br and Br radicals, and the other led to the formation of Br and H+. The spectrum and reactions of CF2Br were studied in aqueous solution by pulse radiolysis. The CF2Br radical was found to absorb in the 230–270 nm region with a molar absorbance (ε) of 710 M−1 cm−1 at λmax = 245 nm. The rate constants of some of the reactions were measured at 299 K as follows: k (eaq + CF2Br2) = 1.20 ± 0.13 × 1010, 2k (CF2Br + CF2Br) = 1.4 ± 0.4 × 109, k(CF2Br + O2) = 1.9 ± 0.5 × 109 M−1 s−1. The CF2BrO2 radical absorbed in the 245–360 nm region with ε = 593 M−1 cm−1 at λmax = 265 nm. An apparatus used to measure Kh, and a closed-loop flow system used to carry out the flash photolysis/pulse radiolysis of sparingly soluble gases, like CF2Br2, are reported.
  • Kazutoshi Kobayashi, Masafumi Shimizu, Teruyuki Nagamune, Hiroyuki Sas ...
    Type: Others
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1707-1713
    Published: 2002
    Released: August 15, 2002
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    Association and dissociation reactions of cytochrome b562 on solid surfaces were investigated by means of surface plasmon resonance spectroscopy. Propionates of side chains in the heme molecule were modified with sulfur moiety as an anchor part to be adsorbed on the gold substrate. This modified heme was firstly reconstituted with apo-protein in solution. This reconstituted holo-protein was then adsorbed on either bare gold substrate or pre-modified gold substrate. Native cytochrome b562 was also adsorbed to the same substrates for the control experiment. The reconstituted cytochrome b562 was successfully adsorbed on the pre-treated gold substrate without denaturation in structure, probably with homogeneous anisotropic orientation. Guanidine hydrochloride in the buffer of pH 5.0 was applied to remove the apo-protein from the surface, with the thiolated heme derivative remaining on the surfaces. Apo-protein was again introduced to the same surface for the reconstitution of holo-cyt.b562. The success of the association and dissociation reactions between apo-protein and tethered heme molecules on the surfaces was confirmed by the optical thickness changes.
  • Yu-Hui Cheng, Ying Fang, Xin Zhao, Lei Liu, Qing-Xiang Guo
    Type: Others
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1715-1722
    Published: 2002
    Released: August 15, 2002
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    The P–X (X = H, F, and Cl) bond dissociation energies (BDEs) for a number of para- and meta-substituted aromatic phosphines were calculated using R(O)MP2/6-311++g(d, 2p)//(U)B3LYP/6-31g(d) method. The results showed the importance of the radical effect as well as the ground effect on the BDEs. For X = H case, because the substituent affected the neutral phosphine to the same extent as it affected the radical, substituent effects on the P–H BDE were small (ρ+ = 0.28 kJ/mol). In comparison, for X = F or Cl case, because the substituent affected the neutral phosphine much more strongly than it affected the radical, substituent effects on the P–F (ρ+ = −3.25 kJ/mol) or P–Cl (ρ+ = −1.31 kJ/mol) BDEs were significant. Therefore, the substituent effects on BDEs of the Z–X bonds in compounds of the general formula 4-YC6H4Z–X varied when X changed, which meant that a recent proposal (J. Am. Chem. Soc., 123, 5518 (2001)) was unfortunately not supported.
  • Ivan Gutman, Dusica Vidovic, Haruo Hosoya
    Type: Others
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1723-1727
    Published: 2002
    Released: August 15, 2002
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    The topological index Z (put forward by one of the present authors, Bull. Chem. Soc. Jpn., 44, 2332 (1971)) has proved to be a structure-descriptor suitable for modeling physico-chemical properties of both saturated and conjugated unsaturated organic compounds. A linear relation between log Z and the Hückel molecular orbital total π-electron energy Eπ was established a long time ago (Theor. Chim. Acta 38, 37 (1975)), but was restricted to π-electron species without non-bonding molecular orbitals (n0 = 0, where n0 is the number of zero eigenvalues of the molecular graph). Recently a novel structure-descriptor ES was put forward, the “eigenvalue sum” equal to Eπ/2, but applicable to saturated hydrocarbons. In this case n0 need not be zero. We demonstrate that, for each group of alkane isomers with a fixed value of n0, there is a linear relation between ES and log Z.
  • Yuki Tanaka, Masaharu Tsuji
    Type: Others
    Subject area: TP
    2002 Volume 75 Issue 8 Pages 1729-1737
    Published: 2002
    Released: August 15, 2002
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    Chemical ionization of n-alkyl alcohols (n-CxH2x+1–OH = M; x=8–18) by the CH5+, C2H5+, and C3H5+ ions has been studied under a reactant-ion selective mode of an ion-trap type of GC/MS. In all reactions, [M – H]+, alkyl CyH2y+1+ (y = 3−x), and alkenyl CyH2y−1+ (y = 4−x) ions were observed. On the basis of observed initial distributions and calculated thermochemical data, it was concluded that the major reactions for the formation of CyH2y+1+ were proton transfer to a hydroxy group in the CH5+ reactions, proton transfer and/or hydroxide-ion abstraction in the C2H5+ reactions, and CzH2zOH-ion (z < x) abstraction in the C3H5+ reactions, while the major reactions for the formation of CyH2y−1+ ions were proton transfer to alkyl chain in the CH5+ reactions, hydride-ion abstraction in the C2H5+ reactions, and alkanide-ion abstraction in the C3H5+ reactions.
  • Satoru Nakashima, Naoki Ichikawa, Tsutomu Okuda
    Type: Others
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1739-1746
    Published: 2002
    Released: August 15, 2002
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    57Fe Mössbauer spectroscopy was applied to determine the difference, if any, in the interactions between host and guest molecules among the (R)-, (S)- and racemic isomers for (2-methylbutyl)-, (2-phenylpropyl)- and (2-phenylbutyl)ferrocene-deoxycholic acid (DCA) clathrates. The (S) isomer is included into DCA, while the (R) isomer is not in the case of (2-phenylpropyl)ferrocene. There is no significant difference in the temperature dependences of the 57Fe Mössbauer spectra between the (S) and racemic isomers-DCA for (2-phenylpropyl)ferrocene. For 2-methylbutyl and 2-phenylbutyl derivatives, all isomers form DCA clathrates. 57Fe Mössbauer spectroscopy revealed a difference in the molecular motion of guest molecules in the DCA lattice among them. For the 2-phenylbutyl derivative, the (S) isomer-DCA clathrate has one solvated molecule per guest molecule, a racemic isomer-DCA 0.7 solvated molecule, while the (R) isomer includes no solvated molecule. There was a difference in the powder X-ray diffraction patterns among them. An interesting phase transition was observed in (S)- and racemic (2-phenylbutyl)ferrocenes-DCA, which was accompanied by a desolvation, and then a change of crystal structure to that of (R) isomer-DCA heated up to the same temperature. Such a phase transition was not observed in (R) isomer-DCA. 57Fe Mössbauer spectroscopy revealed that (R) isomer-DCA changes in lattice vibration around 160 K, while (S) isomer-DCA does not.
  • Toshiyuki Nakashima, Ikuko Nishida, Terufumi Fujiwara
    Type: Others
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1747-1753
    Published: 2002
    Released: August 15, 2002
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    Acid dissociation of (5,10,15,20-tetraphenylporphyrinato)zinc(II), Zn(tpp) dispersed in reversed micellar media of cetyltrimethylammonium chloride (CTAC) in chloroform/water and chloroform–cyclohexane/water has been investigated using a stopped-flow spectrophotometer. When Zn(tpp) is mixed with the reversed micellar solution containing a concentrated acid, spectral data reveal that its dissociation, following immediate formation of the chloro-coordinated complex Zn(tpp)Cl in the interfacial phase of the reverse micelle, occurs rapidly to produce the diacid salt of 5,10,15,20-tetraphenylporphyrin, H4(tpp)2+(Cl)2. The dissociation rate increases with an increase of acid concentration in the reversed micellar aqueous pool. At higher acid concentrations (> 3 mol dm−3 in the pool), the rate constant and the fraction of Zn(tpp)Cl formed increase in the order: HNO3 < HCl ≤ H2SO4 < HBr < HClO4, and decrease with an increase in volume fraction of cyclohexane in the reversed micellar bulk solvent. These observations may be explained by assuming selective distribution of the Cl ion to the interfacial surfactant and bulk organic phases, which is affected by affinities of the acid anions for the surfactant head group and by the Cl solvation.
  • Makoto Handa, Yasuhiro Muraki, Masahiro Mikuriya, Hiroshi Azuma, Kunin ...
    Type: Introduction
    Subject area: AI
    2002 Volume 75 Issue 8 Pages 1755-1756
    Published: 2002
    Released: August 15, 2002
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    Polymer complexes of rhodium(II) trifluoroacetamidate dimers bridged by bidentate ligands [{Rh2(HNOCCF3)4(L)}n], L = pyrazine (pyz), 4,4′-bipyridine (4,4′-bpy), and 1,4-diazabicyclo[2.2.2]octane (dabco), have been prepared and characterized.
  • Yoshito Andou, Kazuki Ishikawa, Kensuke Shima, Tsutomu Shiragami, Masa ...
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1757-1760
    Published: 2002
    Released: August 15, 2002
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    The O-alkylation of dihydroxo(tetraarylporphyrinato)phosphorus(V) complexes with several kinds of alkyl bromide in MeCN in the presence of K2CO3 and 18-crown-6 ether produced dialkoxo(tetraarylporphyrinato)phosphorus(V) complexes in-moderate-good yields. Similar O-alkylation was applied to dihydroxo(tetraarylporphyrinato)antimony(V) complexes. The O-alkylation proceeded by the occurrence of an SN2 attack of the alkoxide anion of the complexes at the carbon substituted with halides.
  • Habib Firouzabadi, Arezu Jamalian, Babak Karimi
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1761-1764
    Published: 2002
    Released: August 15, 2002
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    Tungsten(VI) chloride (WCl6) or molybdenum(V) chloride (MoCl5) in the presence of zinc powder in CH3CN provides an efficient and facile procedure for the deprotection of oximes to their corresponding aldehydes and ketones in high yields.
  • Yohji Nakatsuji, Masahiro Muraoka, Hiroyuki Kajiya, Wanbin Zhang, Tosh ...
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1765-1770
    Published: 2002
    Released: August 15, 2002
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    Three kinds of positional isomers of the C-pivot type of double-armed 15-crown-5 ethers (cis and trans isomers for each positional isomer) bearing two 8-quinolyloxy moieties as part of the electron-donating sidearms were prepared, and their complexation properties were evaluated by measuring the stability constant in THF, the extractability, and passive transport velocity. Cis isomers were found to be much better host compounds toward alkali metal cations than trans isomers possibly because of the potential cooperative coordination of two electron-donating sidearms. All trans isomers showed almost the same stability constants toward Na+ and K+. On the other hand, in the case of cis isomers, the difference in the position of the two sidearms on the crown ring was found to remarkably affect the complexation properties toward alkali metal cations.
  • Annabelle Renard, Jean Lhomme, Mitsuharu Kotera
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1771-1775
    Published: 2002
    Released: August 15, 2002
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    A concise, two-step preparation of dimethyl 3-hydroxy-4-hydroxymethylcyclopentane-1,1-dicarboxylate, an optically pure precursor of spiro carbocyclic nucleosides is described.
  • Osamu Takahashi, Kenji Yasunaga, Yoshinobu Gondoh, Yuji Kohno, Ko Sait ...
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1777-1783
    Published: 2002
    Released: August 15, 2002
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    Ab initio MO calculations were carried out for the conformation of 2-phenylpropionaldehyde 1 and related ketones CH3CH(C6H5)–CO–R (R = CH3 2, C2H5 3, i-C3H7 4, and t-C4H9 5) at the MP2/6-311G(d,p)//MP2/6-31G(d) level. The conformation whereby the alkyl group R is synclinal to the phenyl group (rotamer a, C6H5–C–CO–R torsion angle φ 64–93°) has been found to be the most stable. The second most favorable one has been shown to have R flanked by the benzylic methyl group and C6H5 (rotamer b: φ 282–297°). The difference in the enthalpy between a and b has been calculated to be 1.58, 2.16, 2.19, 2.08, and 4.89 kcal mol−1, respectively, for 1, 2, 3, 4, and 5. The C6H5/R antiperiplanar conformation (rotamer c) has been shown to be the least stable for 1 (φ 171°) and is not at an energy minimum for 25. In rotamers a and b, short interatomic distances have been shown between one of the alkyl hydrogens and the phenyl group. In rotamer a, a short distance has been calculated between one of the hydrogens of the benzylic methyl group and the carbonyl oxygen. The ab initio results are compatible with those obtained by NMR measurements. Contributions of the CH/π and CH/O interactions to the conformational equilibria have been invoked to accommodate the above results. Instability of rotamer c may be due to the unfavorable electrostatic interaction of the C=O dipole vs the quadrupole of the phenyl group. Conformational energies of methyl formate 6, N-methylformamide 7, and propionaldehyde 8 were also calculated to examine the effect of the CH/O interaction in carbonyl compounds. The results are consistent with the notion that the CH/O interaction is important in stabilizing the CH3/O eclipsed conformation.
  • Matsujiro Akakura, Nobuaki Koga
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1785-1793
    Published: 2002
    Released: August 15, 2002
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    The five equilibrium structures of dimethyl maleate were theoretically determined using the RHF and B3LYP methods. In all of the structures, one of the O=C–O planes is nearly perpendicular to, and the other is coplanar with, the C–C=C–C plane. It is well known that maleic acid diester has peculiar reactivity compared with other conjugated esters, which can be ascribed to the characteristics of the conformations. Calculations of complexes of dimethyl maleate and Lewis acids were performed, and the binding energies for the complexes were analyzed by decomposing them into the deformation energy and the interaction energy. For a comparison, the conformational properties of methyl acrylate and its Lewis acid complexes were also investigated.
  • Kazuo Takimiya, Ken-ichi Kato, Yoshio Aso, Fumio Ogura, Tetsuo Otsubo
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1795-1805
    Published: 2002
    Released: August 15, 2002
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    Two isomeric naphthodithiophenes (syn-NDT and anti-NDT), isoelectronic with pyrene, as well as their dimethyl, bis(methylthio), and di(2-thienyl) derivatives have been successfully synthesized as novel peri-fused heteroaromatics. Among them, the parent syn-NDT and the di(2-thienyl) derivative of anti-NDT were examined by X-ray crystallographic analyses, revealing that the molecular structures comprise fairly planar, but considerably strained skeletal rings, and their crystal structures are characterized by a herringbone arrangement of uniform stacking columns. The UV/vis spectra of these heteroaromatics show considerable red-shifts of the π–π* transitions as compared to that of pyrene, making them chromogens ranging from yellow to purple. Cyclic voltammetry indicates that they have much stronger electron donating abilities than pyrene. Consequently, all of them, except for the methyl derivatives, can form highly conductive molecular complexes with iodine and DDQ. In addition, the electrochemical oxidation of the parent naphthodithiophenes and the di(2-thienyl) derivatives leads to the formation of conductive polymers, which show low HOMO–LUMO bandgaps upon undoping. In particular, both polymers of syn-NDT and anti-NDT have very low bandgaps of ca. 0.8 eV (77 kJ mol−1).
  • Michiharu Mitani, Hideo Sakata, Hisayuki Tabei
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1807-1814
    Published: 2002
    Released: August 15, 2002
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    The reactions of ketene silyl acetals and silyl enol ethers in a CCl4 solution containing no promoter under ambient temperature, reflux, or photo-irradiation conditions afforded products via the addition of a trichloromethyl group to those silyl substrates. Polyhalides other than CCl4 were subjected to photoreactions in a hexane solution, resulting in the formation of carbonyl derivatives based on the addition of polyhalogenated alkyl groups.
  • Masahiro Yamanaka, Seiji Mori, Eiichi Nakamura
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1815-1818
    Published: 2002
    Released: August 15, 2002
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    There is a frequently used organocuprate species that was introduced by Lipshutz and possesses a molecular structure written as CuLi2R2(CN). This species was previously called “higher order cuprate”, but is now considered to exist as an equilibrating mixture of various isomers of R2CuLi·LiCN and R(CN)CuLi·LiR, among which R2Cu·Li2CN+ is known to be dominant in solution. The present studies on the kinetic reactivity of these species in the addition reaction to acetylene suggest that the minor species R(CN)CuLi·LiR may be more reactive than the major species, thereby making it equally possible that addition reaction products may arise through both the major and the minor reactive species. The reason for the high reactivity of the minor species has been ascribed to the anisotropic and multi-coordination capability of the cyanide ligand to metals; such capability is not available for a halide or alkyl anion ligand.
  • Yasuki Niwa, Kazuki Takayama, Makoto Shimizu
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1819-1825
    Published: 2002
    Released: August 15, 2002
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    Diethyl 2-[N-(p-methoxyphenyl)imino]malonate underwent amination reactions with alkyl Grignard reagents to give N-aklylation products in good yields. The obtained N-alkylation products were readily converted into N-alkyl-p-anisidines by the oxidative removal of the malonate moiety. The p-methoxyphenyl group was subsequently deprotected to give primary amines.
  • Kimihisa Yamamoto, Masayoshi Higuchi, Toyohiko Nishiumi, Hirokazu Taka ...
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1827-1832
    Published: 2002
    Released: August 15, 2002
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    N,N′-Diphenyl-1,4-benzoquinone diimine (PBI), which is the minimum redox-active unit of polyaniline, was reduced to N,N′-diphenyl-1,4-phenylenediamine (PDA) derivatives through Michael-type additions of some nucleophiles. The addition of thiophenol to PBI proceeded very rapidly. The polyaddition of PBI-endcapped monomers (P-2PBI, B-2PBI, and TB-2PBI) with thiobisbenzenethiol (TB) produced the novel thermostable oligo(thio-1,4-phenylene)s (OTP) having PDA units as a redox-active site (OTP-P-PDA, OTP-B-PDA, and OTP-PDA). This polymerization proceeded at room temperature without catalysts. OTP-P-PDA, one of the oligomers obtained, was found to have a moderate molecular weight (Mw 8400) and to possess good thermostability (Td10% 400 °C). The polymerization based on Michael-type additions was also confirmed by NMR measurements. The oligomers obtained behaved as good electro-responsive materials. The redox process was determined by the slope of the Nernst plot that involved two electrons and two protons per PDA unit.
  • Masato Yoshida, Masanori Ohkoshi, Tsunehiro Muraoka, Haruo Matsuyama, ...
    Type: Others
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1833-1842
    Published: 2002
    Released: August 15, 2002
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    Reactions of perfluoroalkyl iodides with styrene and its derivatives were investigated under radical conditions in the presence of oxygen. The photochemical reaction of styrene with CF3(CF2)5I in the presence of tributyltin hydride or tris(trimethylsilyl)silane under an oxygen atmosphere afforded the corresponding perfluoroalkylated alcohols in moderate yields together with CF3(CF2)5H. However, the photochemical reactions of styrene and its derivatives with CF3(CF2)nI (n = 3, 5) in the presence of hexabutylditin under oxygen produced the perfluoroalkylated alcohols in good yields. Furthermore, the reactions of styrenes with CF3(CF2)nI (n = 3, 5, 9) and Na2S2O4 in the presence of a base under air formed the same alcohols in good yields. The alcohols were found to provide a novel type of α-fluoroalkylated styrenes by acidic dehydration. Perfluoroalkylated α,β-unsaturated ketones were synthesized by oxygenative perfluoroalkylations of α-chlorostyrene and its derivatives using CF3(CF2)nI (n = 3, 5) under radical reaction conditions. The ketones were found to be good synthetic building blocks for perfluoroalkylated heterocycles, such as pyrazoles, dihydrodiazepines, pyrimidines, and isoxazoles.
  • Morio Yashiro, Maiko Higuchi, Yusuke Washizu, Makoto Komiyama
    Type: Introduction
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1843-1844
    Published: 2002
    Released: August 15, 2002
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    Hydrolyses of di- and triribonucleotides assisted by alkaline earth metal ions were investigated at pH 7.3 and 50 °C. Mg2+ was the most effective for the phosphodiester hydrolysis, and the rate exibited first-order dependence on the concentration of Mg2+ in a range of 0.1–1.0 mol dm−3.
  • Kaori Saito, Toshikazu Hirao
    Type: Introduction
    Subject area: OB
    2002 Volume 75 Issue 8 Pages 1845-1846
    Published: 2002
    Released: August 15, 2002
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    A p-t-butylcalix[4]arene bearing four redox-active phenylenediamine pendant groups on the lower rim was synthesized and characterized spectroscopically and electrochemically. The interconversion of the oxidation states of the pendant groups was demonstrated both chemically and electrochemically.
  • Xiaomei Wang, Yufang Zhou, Guangyong Zhou, Wanli Jiang, Minhua Jiang
    Type: Others
    Subject area: AM
    2002 Volume 75 Issue 8 Pages 1847-1854
    Published: 2002
    Released: August 15, 2002
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    The luminescence behaviors of a series of symmetrically and asymmetrically substituted stilbene or its analogues on one-photon excitation (OPE) and two-photons excitation (TPE) have been investigated and compared. To understand the influence of intramolecular charge transfer upon the fluorescence properties, steady-state and time-resolved fluorescence spectra on one-photon-/two-photons-excitation, the solvent effect and the linear absorption spectra as well as the relative fluorescence quantum yields were examined. Based on the quantum chemical calculations of the charge density and the twisted intramolecular charge transfer (TICT) model, the luminescence properties have been interpreted. The results obtained have shown that the OPE and the TPE fluorescence behaviors are both strongly influenced by the intramolecular charge transfer process and by the planarity of effective fluorophore under the excited state. On the other hand, for a given dye, its luminescence behaviors on one-photon- and two-photons-excitation are very much alike, which means that the knowledge of two-photon fluorescence properties can be obtained by understanding the one-photon fluorescence behaviors.
  • Ken-ichiro Ota, Shigenori Mitsushima, Naotaka Hattori, Nobuyuki Kamiya
    Type: Others
    Subject area: AM
    2002 Volume 75 Issue 8 Pages 1855-1859
    Published: 2002
    Released: August 15, 2002
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    Liquid sodium is used in new energy conversion systems such as fast breeder reactors and sodium-sulfur batteries. Liquid sodium forms high-temperature molten salts once it is exposed to air by reactions with oxygen or moisture. These molten salts might cause the severe corrosion of metals. In this study, the high-temperature corrosion of iron was studied in the presence of sodium salt using thermogravimetry in an air-simulated atmosphere. The corrosion reaction with coexisting NaOH obeyed a parabolic rate law. On the other hand, severe corrosion occurred with coexisting Na2O2. The corrosion reaction changed from a parabolic rate law to a linear rate law as the amount of melt increased, because the dissolution on the corrosion of the corrosion layer would increase with the amount of melt. Since the oxidation ability of Na2O2 is not as high as that of O2, dissolution of an oxide scale on iron would be the main reason for severe corrosion.
  • Nobuko Tsumori, Qiang Xu
    Type: Introduction
    Subject area: AM
    2002 Volume 75 Issue 8 Pages 1861-1862
    Published: 2002
    Released: August 15, 2002
    JOURNALS RESTRICTED ACCESS
    In strong acids, the reaction of Cu0, CuI or CuII compounds with atmospheric NO at room temperature results in the formation of the copper(II) nitrosyl cation, [CuNO]2+, during which the oxidation of Cu0 to CuII is accompanied by the formation of N2 and N2O, whereas the oxidation of CuI to CuII results in the formation of N2O without a significant amount of N2.
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