Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 76 , Issue 7
Showing 1-23 articles out of 23 articles from the selected issue
  • Ichimin Shirotani
    Type: Accounts
    Subject area: TP
    2003 Volume 76 Issue 7 Pages 1291-1307
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Various ternary metal phosphides, arsenides, antimonides, silicides and germanides have been prepared at high temperatures and high pressures. These ternary metal compounds can be classified into four groups: [1] metal-rich compounds MM′4X2 and [2] MM′X, [3] non-metal-rich compounds MXX′ and [4] MM′4X12 (M and M′ = metal element; X and X′ = non-metal element). We have studied the electrical and magnetic properties of these materials at low temperatures, and found many new superconductors with the superconducting transition temperature (Tc) of above 10 K. The metal-rich compound ZrRu4P2 with a tetragonal structure showed the superconducting transition at around 11 K, and had an upper critical field (Hc2) of 12.2 tesla (T) at 0 K. Ternary equiatomic compounds ZrRuP and ZrRuSi crystallize in two modifications, a hexagonal Fe2P-type structure [h-ZrRuP(Si)] and an orthorhombic Co2P-type structure [o-ZrRuP(Si)]. Both h-ZrRuP and h-ZrRuSi have rather high Tc values of above 12 K; on the contrary, Tc of o-ZrRuP and o-ZrRuSi is about 4 K. The alloys ZrRu1−xRhxP were prepared at high temperatures and at high pressures. The superconductivity and the crystal structure of the alloys are very sensitive to the content of Rh atoms. The Hc2 values of h-ZrRuP, h-HfRuP, h-ZrRuSi and h-ZrRuAs are 14–16 T at 0 K. The coherence length of these compounds is below 50 Å. ZrRhSi with the Co2P-type structure and ZrRuGe with a TiFeSi-type structure showed the superconductivity at around 10.5 K. Tc’s of MoNiP with the Fe2P-type structure and MoRuP with the Co2P-type structure were over 15 K. Both compounds have the highest Tc among the metal phosphides. Non-metal-rich compound NbPS showed the Tc of 13 K and the high Hc2 of 17 T. This Hc2 value is the highest among the phosphide superconductors. The Debye temperature and the density of states at the Fermi level for NbPS are 330 K and 0.51 states/eV-atom, respectively. Filled skutterudites LnRu4X12 (Ln = La and Pr, X = P, As and Sb) with a cubic structure show interesting superconductivity behavior at low temperatures. LaRu4As12 had the highest Tc of 10.3 K among the skutterudite compounds. PrRu4As12 with the magnetic element Pr transformed to a superconductor at around 2.4 K. Superconducting properties of various ternary metal compounds prepared at high pressure are discussed.
  • Yoshihito Watanabe, Takafumi Ueno
    Type: Accounts
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1309-1322
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    We have prepared several myoglobin (Mb) mutants which are protein models for peroxidase, P450, and catalase. In most cases, the distal site of Mb was modified by site-directed mutagenesis on the basis of mechanisms of peroxidase, P450, and catalase reactions. The most important feature of the Mb mutants is the direct observation of their active intermediates, so called compound I. Under catalytic oxidations of sulfides and styrene by H2O2, up to 97% of enantioselectivity was observed. Introduction of an aromatic substrate, tryptophan, near the heme by the site directed mutagenesis of Mb allowed us to proceed almost stoichiometric aromatic hydroxylation. In addition, compound I of Mb mutants exhibit the catalase activity. These results demonstrate that the compound I of Mb mutants are capable to proceed all of the peroxidase, P450, and catalase reactions.
  • Keiichi Tsukahara, Nao Iida, Yuka Kaida, Hiroshi Takashima, Maya Mizob ...
    Type: Headline
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1323-1328
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Horse heart cytochrome c (cytc) modified with an N,N,N′,N″,N″-diethylenetriaminepentaacetatocobaltate(III) ion, [cytcIII{CoIII(dtpa)}], was prepared and characterized. The major component of singly modified [cytcIII{CoIII(dtpa)}] contains a [CoIII(dtpa)] ion at Lys13, of which the ε-amino group is linked with a carboxylate ion of dtpa. A one-electron reduced protein, [cytcII{CoIII(dtpa)}], was prepared by reduction with a methylviologen-radical cation, which was produced in situ by a photoreduction using a tris(2,2′-bipyridine)ruthenium(II) ion in the presence of disodium dihydrogen ethylenediaminetetraacetate at 25 °C, pH 7.5 (0.010 mol dm−3 tris(hydroxymethyl)aminomethane–HCl buffer), and an ionic strength of 0.50 mol dm−3 (NaCl). The reaction of [cytcII{CoIII(dtpa)}] to form [cytcIII{CoII(dtpa)}] was very slow, and was followed by conventional spectrophotometry. The reaction was of first order in the protein and the first-order rate constant ((3.1 ± 0.5) × 10−4 s−1) was independent of the concentration of the protein, indicating that the intramolecular electron-transfer (ET) process is predominant. The reaction mechanism is discussed on a through-bond or through-space pathway. The slow intramolecular ET rate might arise not only from the long distance, but also from the large reorganization energy for the Co(III)/Co(II) couple.
  • Yuri Yamada, Yosuke Kataoka
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 7 Pages 1329-1339
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    We estimated the free energy of homogeneous nucleation in supersaturated Lennard-Jones vapor phase by using Monte Carlo simulations. The nucleation free energy of an N-particle cluster is obtained as the difference between the free energies of the cluster phase and the monomer phase in an N-particle system. In the previous papers, we estimated the Helmholtz free energy of the nucleation by MC calculations under a fixed volume per particle, V/N = 43.2 σ3, and the equation of state of the nucleation energy as a function of cluster size and temperature. In this study, we carried out some additional MC calculations under different volumes per particle and took into consideration the pressure to estimate the Gibbs free energy of the nucleation. Then we established the equations of state of the Helmholtz and Gibbs free energies of nucleation as a function of cluster size, temperature, and volume or pressure.
  • Ken-ichi Yamanaka, Mamoru Fujitsuka, Osamu Ito, Toshihide Aoshima, Tak ...
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 7 Pages 1341-1349
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Photoinduced electron-transfer processes between C60/C70 and tetrathienylethylenes (TTE’s) in benzonitrile have been studied by measuring the transient absorption spectra in the Vis/NIR regions using nanosecond laser photolysis. The absorption bands of the radical anions of C60/C70 (C60•−/C70•−) and radical cations of TTE’s (TTE’s•+) were observed with the decay of the triplet states of C60/C70 (3C60*/3C70*), indicating that electron transfer takes place via 3C60*/3C70*. In addition, formation of the dication of TTE (TTE2+) was confirmed by its characteristic absorption band at 680 nm. The TTE2+ is formed by the stepwise collision of TTE with 3C60*/3C70*. By the substitutions with the MeS groups at the thienyl rings of TTE, the efficiencies and rates of the electron-transfer processes became higher than those of TTE with the PhS groups. For dendrimer TTE’s, the photoinduced electron-transfer processes also took place via 3C60*/3C70*, although the efficiencies and rates were decreased with an increase in the dendrimer generation. After forward electron transfer, the back electron transfer processes were observed between separately solvated C60•−/C70•− and TTE’s•+ even for the dendrimer TTE’s, which suggest that outer-sphere back electron-transfer took place in the backward processes.
  • Norihito Kobayashi, Toshio Naito, Tamotsu Inabe
    Type: Article
    Subject area: TP
    2003 Volume 76 Issue 7 Pages 1351-1362
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Single crystals of mellitate anion ([C6(COO)6H6−n]n) salts with 3-aminopyridinium, [3-NH2C5H4NH+]3[C6(COO)6H33−] (1), 4-methylpyridinium, [4-CH3C5H4NH+]2[CH3C5H4N]2[C6(COO)6H42−] (2), [4-CH3C5H4NH+]2[C6(COO)6H42−]·2CH3OH (3), pyridinium, [C5H5NH+]2[C6(COO)6H42−]·2H2O (4), 3-methylpyridinium, [3-CH3C5H4NH+]2[C6(COO)6H42−] (5), [3-CH3C5H4NH+]5[C6(COO)6H33−][C6(COO)6H42−]·CH3OH (6), and isoquinolinium, [C9H7NH+]2[C6(COO)6H42−]·CH3OH (7), [C9H7NH+]2[C9H7NH0.50.5+][C6(COO)6H3.52.5−]·CH3OH (8) have been structurally characterized. In these crystals, strong hydrogen-bonds between the mellitate anions are formed. Various arrangements that depend on the deprotonation number, n, have been found. All hydrogen-bonds found between the anions are combinations of a carboxy and a carboxylato group. The “triangular hydrogen-bond” unit between the anions, in which three anions are connected by the three hydrogen-bonds to form a triangle, in the salt with n = 3, induces the two dimensional (2-D) sheet self-organizing structure in this crystal. “Dual hydrogen-bond” units between the anions, in which two pairs of the hydrogen-bonds connect the neighboring anions, have been found in the salts with n = 2 or 2.5. The repetition of the co-planer “dual hydrogen-bond” induces the anion one-dimensional (1-D) belt structure, while the combination of the standing and co-planer “dual hydrogen-bond” units induces the 2-D grid structure. These 2-D grids are further linked by hydrogen-bonds to form a channel. In all the salts (n = 3, 2, 2.5), the counter cation molecules are arranged in the space defined by the anion network.
  • Jun-ichi Aihara, Sumio Oe
    Type: Short Articles
    Subject area: TP
    2003 Volume 76 Issue 7 Pages 1363-1364
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Even for the simplest polycyclic aromatic hydrocarbons, such as naphthalene and azulene, the nucleus-independent chemical shift (NICS) calculated at a ring center does not always represent local aromaticity. NICS reflects currents induced in many cyclic paths in a π-system.
  • Tsuyoshi Kitano, Yoshiki Sohrin, Yasuo Hata, Hiroki Wada, Takeyoshi Ho ...
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1365-1373
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    The separation of first-series transition metal and Cd2+ ions has been studied by solvent extraction using methyl substituted poly(pyrazolyl)borates. These ligands did not extract all of the studied metal ions at a lower pH compared to the parent ligands, and the selectivity was high for Cu(II) and low for Fe(II), although the extracted species were A2M complexes as well (A: poly(pyrazolyl)borate, M2+: metal ion) for all the four ligands. An examination of the structures of the nine complexes determined the present and related ones, which were previously determined elsewhere, revealed that 3-methyl groups of the pyrazolyl rings are arrayed around a metal ion, and that the distances between the methyl groups are smaller than the sum of van der Waals radii of the methyl groups. This suggests that the interligand contact of 3-methyl groups decreases the stability of the complexes. Since the geometry in the copper complexes with these ligands is square bipyramid, the increase in steric energy caused by the interligand contact seems to be smaller than that for those complexes having similar ionic radii. Moreover, the spin state of the iron complexes with these ligands is high-spin due to interligand contact. Thus, while the interligand contact causes a general decrease in the stability of all the complexes, the effect is smallest for Cu(II) and largest for Fe(II), resulting in a unique selectivity.
  • Masami Nakada, Takafumi Kitazawa, Takashi Saito, Junhu Wang, Masuo Tak ...
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1375-1378
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A new type of neptunyl(VI) hydroxide α-NpO2(OH)2 I which is topologically similar to α-UO2(OH)2 has been synthesized from the thermal decomposition of the orthorhombic type NpO2(OH)2·H2O II. The powder X-ray diffraction patterns and 237Np Mössbauer spectra have shown that properties of α-NpO2(OH)2 I are different from those of the reported β-NpO2(OH)2 III, which is similar to β-UO2(OH)2.
  • Yoki Yulizar, Hitoshi Watarai
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1379-1386
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Complex formation of nickel(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (HL) and the aggregation of the monomer complex at the heptane-water interface have been kinetically studied by using centrifugal liquid membrane (CLM) spectrophotometry. The interfacial aggregation of ligand in NiL2 complex was observed as the growth of a remarkably intense and narrow absorption band (J-band) at 588 nm, showing a bathochromic shift from the absorption maximum of the monomer complex (569 nm), accompanied by a decrease of the absorbance of the free ligand at 452 nm. The formation of aggregate was initiated when the interfacial concentration of the monomer complex attained the critical aggregation concentration (cac) of 2.4 × 10−10 mol cm−2. The initial formation rate of the interfacial aggregate was proportional to concentrations of both free Ni(II) and free ligand after the attainment of cac. The observed rate constant for the aggregation, 4.1 × 101 M−1 s−1, was smaller than the formation rate constant of NiL2 complex at the interface. A long period observation of the profile of absorbance change showed an oscillation of the interfacial aggregate concentration until all of the ligand was consumed, suggesting a subsequent flocculation of the aggregate in the rotating cell.
  • Tetsushi Ohmura, Wasuke Mori, Mari Hasegawa, Tohru Takei, Toshiya Iked ...
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1387-1395
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A new series of microporous materials containing infinite chains of a mononuclear metal (Cu(II), Zn(II), Ni(II))-pyridine unit bridged by dicarboxylates (copper(II) terephthalate-pyridine 1a, copper(II) terephthalate-4-phenylpyridine 1b, zinc(II) fumarate-pyridine 2a, zinc(II) terephthalate-pyridine 2b, nickel(II) fumarate-pyridine 3a, and nickel(II) terephthalate-pyridine 3b) have been prepared. These complexes, which have a regular one-dimensional structure, occlude large amounts of gases. The maximum amount of N2 gas is 0.7–10.7 mole per mole of metal(II) salt, indicating the presence of a large number of micropores. A porous structure, which is formed by stacking and self-assembly of the linear metal(II) dicarboxylates, was determined by X-ray crystallography. We have elucidated the paramagnetic properties of 1a, 1b, 3a, and 3b by magnetic measurement (SQUID), whereas 2a and 2b were found to be diamagnetic. The magnetic susceptibilities of 1a and 1b obey the Curie-Weiss law over the range of 70–300 K (θ = −1.4 K and θ = +5.5 K, respectively); the obtained Weiss constants (θ) indicate the existence of small antiferromagnetic interactions (1a) and ferromagnetic interactions (1b). The different magnetic behaviors between 1a and 1b demonstrate that hydrogen bonding between the carboxylate groups and coordinated water molecules plays an important role in determining the bridge geometries and super-exchange interaction between the Cu(II) ions through the Cu–O–C–O–H–O–Cu pathways. In contrast to those of the copper(II) complexes, the magnetic susceptibilities of 3a and 3b obey the Curie law.
  • Yoshiro Honma
    Type: Article
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1397-1402
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A simple speciation of chromium oxidation states based only on the difference in reaction rates of Cr(III) and of Cr(VI) has been developed. This speciation, which was carried out in an ammonium 1-pyrrolidinecarbodithioate (APCD)/diisobutyl ketone (DIBK) extraction system, required no sample splitting. At the first extraction, Cr(VI) was extracted into a DIBK phase, and Cr(III) remaining in the sample was extracted secondly after replacement of the phase by fresh DIBK. Inert Cr(III) was extracted directly without the oxidation process. The concentration of chromium in the extract was measured by AAS. In the first extraction, 0.4–0.5% of Cr(III) was extracted and 0.2% of Cr(VI) was carried over to the second extraction. Using artificial seawater, the detection limit (3σ) and the relative standard deviation (n = 5, at 100 μg/L) were 10 μg/L and ca. 4% (concentration factor = 2). Interferences of heavy metal ions were examined; 5-fold cation group (Mn2+, Fe3+, Ni2+, Cu2+ and Zn2+) and 1-fold anion group (VO3, Mo7O246− and WO42−) exhibited negative errors of 5 and 10% in Cr(III) determination respectively. Validity of the method was checked with the standard reference material JAC-0032 (river water); total chromium was determined as 11.0 μg/L (certified value is 10.1 ± 0.2 μg/L).
  • Yan Wang, Xing-Mei Ouyang, Yi-Zhi Li, Wei-Yin Sun
    Type: Short Articles
    Subject area: AI
    2003 Volume 76 Issue 7 Pages 1403-1404
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A novel coordination polymer, [Zn(NCS)2(L)2]·2H2O, with strong blue fluorescent emission was prepared by an assembly reaction of 1,2-bis(3-pyridylmethyleneamino)ethane (L) with Zn(ClO4)2 and NaSCN. A crystallographic analysis indicates that the structure of the complex contains (4,4) two-dimensional layers, which interlock each other in parallel to form a three-dimensional framework.
  • Masaki Matsui, Takahiro Higeta, Masahiro Kimura, Kazumasa Funabiki, Ke ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1405-1408
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A lactam-type enantiomeric fluorescent labeling reagent was prepared from Rhodamine B. This reagent showed its absorption and emission maxima at λ 557 and 580 nm in an acetonitrile–acetic acid (9:1) mixed solution, respectively. Racemic Flurbiprofens reacted with this reagent to produce diastereomeric esters, which were separated by non-chiral high-performance liquid chromatography (HPLC).
  • Motoko Hirooka, Asako Yoshimura, Izumi Saito, Fumio Ikawa, Yoko Uemoto ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1409-1421
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    O-α-D-Rhamnopyranosyl-(1→3)-O-α-D-rhamnopyranosyl-(1→2)-D-rhamnopyranose, a repeating trisaccharide of the O-specific polysaccharides (OPSs) of Pseudomonades, and O-α-D-tyvelopyranosyl-(1→3)-O-α-D-mannopyranosyl-(1→4)-L-rhamnopyranose, a trisaccharide composing the OPSs of Salmonella typhi, were synthesized by in-situ activating glycosylation reactions using hemiacetal sugar derivatives. Allyl 2,4-di-O-benzyl-α-D-rhamnopyranoside was prepared via the direct ditritylation of allyl α-D-mannopyranoside. 3-O-Acetyl-2,4-di-O-benzyl-D-rhamnopyranose was used as a precursor for the moiety of D-tyvelose (3,6-dideoxy-D-arabino-hexose, 3,6-dideoxy-D-mannopyranose, 3-deoxy-D-rhamnose) of the salmonella trisaccharide.
  • Toshiyuki Ohe, Sakae Uemura
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1423-1431
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A variety of aryltin compounds and sodium tetraarylborates can be employed for Michael-type hydroarylation reactions of nitroalkenes to afford β-arylnitroalkanes in moderate to good yields in the presence of either LiCl, MgCl2, or CaCl2 and a catalytic amount of palladium(II) salt (0.05 molar amount) in acetic acid. Results show that 50–70% of aryl groups out of all in these aryl compounds can be transferred to the products in this hydroarylation. The addition of a catalytic amount (0.05–0.10 molar amount) of a Lewis acid chloride, BiCl3 or SbCl3, much improves the product yield in some cases.
  • Jun-ichi Matsuo, Asahi Kawana, Hiroyuki Yamanaka, Hiroaki Kamiyama
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1433-1440
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Two polymer-supported sulfinimidoyl chlorides, i.e., 4-(N-tert-butylchlorosulfinimidoyl)phenoxymethylpolystyrene (3) and 4-(N-tert-butylchlorosulfinimidoyl)polystyrene (10), were prepared from chloromethylpolystyrene and polystyrene, respectively. Stoichiometric or catalytic oxidation of various primary and secondary alcohols using these polymer-supported sulfinimidoyl chlorides proceeded smoothly, and the corresponding aldehydes and ketones were conveniently prepared in good-to-high yields by simple work-up procedures. The polymer-supported oxidant 10 was recycled repeatedly by chlorination of a used polymer 11 with N-chlorosuccinimide (NCS) after stoichiometric oxidation.
  • Takashi Sakai, Kyoko Hayashi, Fumika Yano, Mie Takami, Megumi Ino, Tos ...
    Type: Article
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1441-1446
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    For the enhancement of enantioselectivity and acceleration of the reaction rate in the lipase-catalyzed resolution of primary alcohols, the use of a very low reaction temperature (−30 °C) and an immobilized lipase on organic bridges-coated porous ceramic support was found to be highly effective. Furthermore, the structure of the organic bridges greatly influenced the temperature effect between ln E and 1/T as well as the reaction rate. Among the organic bridges examined in the resolution of (±)-2-hydroxymethyl-1,4-benzodioxane, the 6-(2-methylpropanoyloxy)hexylsilanetrioxyl bridge was the best choice for both the E value and the reaction rate at −30 °C.
  • Mitsuhiro Okimoto, Yuji Nagata, Yukio Takahashi
    Type: Short Articles
    Subject area: OB
    2003 Volume 76 Issue 7 Pages 1447-1448
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Several aldehyde and ketone phenylhydrazones were converted into the corresponding methoxy(phenylazo)alkane derivatives by electrochemical oxidation in MeOH.
  • Jingmei Xu, Siu Choon Ng, Hardy Sze On Chan
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 7 Pages 1449-1458
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Alkylthio(SR)-functionalized polymers poly(3-alkylthio-2,5-thiophenediyl-1,4-phenylene-alt-4-alkylthio-2,5-thiophenediyl-1,4-phenylene) (P1, alkyl = butyl, octyl and dodecyl) and poly[4,4′-bis(alkylthio)-2,2′-bithiophene-5,5′-diyl-alt-1,4-phenylene] (P2, alkyl = butyl, octyl and dodecyl) have been synthesized by Grignard coupling and FeCl3 oxidation methods, respectively. Spectral measurements indicate that they are highly fluorescent, with quantum yields comparable to those of their alkyl(R)-functionalized analogues, poly(3-alkyl-2,5-thiophenediyl-1,4-phenylene-alt-4-alkyl-2,5-thiophenediyl-1,4-phenylene) (P1′, alkyl = butyl, octyl and dodecyl) and poly(4,4′-dialkyl-2,2′-bithiophene-5,5′-diyl-alt-1,4-phenylene) (P2′, alkyl = butyl, octyl and dodecyl). P1 and P2 are thermally less stable than P1′ and P2′, because of the alkylthio group instead of an alkyl group. Modulated differential scanning calorimetry (MDSC) studies reveal a plasticizing effect exerted by the long side chains on the glass transitions (Tg) of the polymers. The P2 series of polymers exhibit a much higher Tg than the P1 series, ascribable to a greater resistance to segmental rotation in the former structure. A cyclic voltammetric study of polymers indicates that they are n-dopable. When doped by I2 or FeCl3, high doping levels of the polymers can be deduced from the weight change, XPS and elemental analysis, but conductivities are not high.
  • Naoki Nakamura, Yutaka Amao
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 7 Pages 1459-1462
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    A new optical CO2 sensor based on luminescence intensity changes of europium(III) complex, tris(thenoyltrifluoroacetonato)europium(III) dihydrate complex ([Eu(tta)3]) due to the absorption change of pH-indicator dye (thymol blue) with CO2 was developed and its CO2 sensing properties were investigated. The observed luminescence intensity (I) from [Eu(tta)3] at 613 nm increased with increasing the CO2 concentration. The ratio I0/I100, where I0 and I100 represent the detected luminescence intensities from a layer exposed to 100% nitrogen and 100% CO2, respectively, that we takes the sensitivity of the sensor is estimated to be 16.0. The response times of the sensing film were 4.0 s for switching from nitrogen to CO2, and 36 s for switching from CO2 to nitrogen. The signal changes were fully reversible and no hysterisis was observed during the measurements.
  • Chun Yi Liu, Ken-ichi Aika
    Type: Article
    Subject area: AM
    2003 Volume 76 Issue 7 Pages 1463-1468
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    The behavior of ammonia adsorption was studied on various types of surface-treated active carbon (HNO3-AC, H2SO4-AC, HCl-AC, NaOH-AC, CuO-AC, and H2-AC) under 0–75 kPa and 323–473 K. Amount of ammonia adsorption on active carbon was increased by the surface oxidation through acid treatment or metal nitrate decomposition. It was decreased by the hydrogen treatment at 1173 K. The equilibrium amount of ammonia adsorption was found to relate with the amount of surface organic oxygen. Ammonia adsorption was analyzed through the isotherm and classified into three types: (1) strong adsorption relating to surface organic oxygen content and being independent of pressure, (2) weak adsorption relating to surface organic oxygen content and depending upon the pressure, (3) van der Waals adsorption. The model well represented the data, and the average relative error was 10%. When the samples are assumed to be used for ammonia separation with temperature swing adsorption method (323–473 K, 40 kPa), H2SO4-treated active carbon was found to have the highest ammonia separation capacity (2.58 mmol g−1).
  • Yunle Gu, Luyang Chen, Yitai Qian, Wanqun Zhang
    Type: Short Articles
    Subject area: AM
    2003 Volume 76 Issue 7 Pages 1469-1470
    Published: 2003
    Released: July 15, 2003
    JOURNALS RESTRICTED ACCESS
    Nanocrystalline boron phosphide (BP) powders 10 to 40 nm in size have been synthesized via a sodium co-reduction of PCl3 and BBr3 in benzene at 300 °C. X-ray diffraction data show a cubic pattern with lattice constant a = 4.539 Å.
feedback
Top