Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
88 巻 , 8 号
選択された号の論文の24件中1~24を表示しています
Accounts for Elements Science
  • Sarah A. Weicker, Douglas W. Stephan
    2015 年 88 巻 8 号 p. 1003-1016
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/15
    ジャーナル フリー
    The advent of frustrated Lewis pair (FLP) chemistry almost a decade ago was based on the reactivity of sterically encumbered combinations of electrophilic boranes and phosphines with hydrogen. Since that time the chemistry has broadened dramatically in terms of reactivity and applications. Nonetheless, the majority of the work has continued to exploit the borane B(C6F5)3. In this review, we describe FLP chemistry that has developed by employing alternatives to this Lewis acid. Lewis acids derived from group 13, 14, and 15 based systems are described, thus demonstrating a growing area in the main group reactivity based on FLPs.
    The advent of frustrated Lewis pair (FLP) chemistry almost a decade ago was based on the reactivity of sterically encumbered combinations of electrophilic boranes and phosphines towards small molecules. In this review, we describe the growth of the Lewis acids used in FLP chemistry beyond electrophilic boranes to include a variety of group 13, 14, and 15 based systems. Fullsize Image
     
Award Accounts
The Chemical Society of Japan Award for Young Chemists for 2012
  • Keigo Kamata
    2015 年 88 巻 8 号 p. 1017-1028
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/25
    ジャーナル フリー
    Chemical industries leave much room for improvement in the areas of environmental conservation and resource utilization efficiency. The development of superior catalytic technologies is one priority area when considering current problems faced by society and the global environment. We have designed a variety of highly functionalized polyoxometalate (POM) catalysts for application to achieve environmentally-friendly chemical processes. The following four topics are described in this account: (i) high functionalization of tungstates, (ii) construction of multimetallic active sites effective for concerto catalysis, (iii) base catalysis with POMs, and (iv) the development of POM-based heterogeneous catalysts.
    We have designed a variety of highly functionalized polyoxometalate (POM) catalysts for application to achieve environmentally-friendly chemical processes. The following four topics are described in this account: (i) high functionalization of tungstates, (ii) construction of multimetallic active sites effective for concerto catalysis, (iii) base catalysis with POMs, and (iv) the development of POM-based heterogeneous catalysts. Fullsize Image
     
BCSJ Award Article
 
  • Teruaki Asada, Hajime Kusaba, Hisahiro Einaga, Yasutake Teraoka
    2015 年 88 巻 8 号 p. 1036-1046
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/08
    ジャーナル 認証あり
    Alumina-supported LaMnO3 (LaMnO3/Al2O3) catalysts with various dispersion and locations were prepared by utilizing the alumina pore structures. LaMnO3 perovskite oxides were selectively deposited in and/or outside the pore of γ-Al2O3 support by controlling the deposition methods. The LaMnO3/Al2O3 catalysts were characterized and their catalytic activities for propane oxidation were investigated. X-ray diffraction, electron diffraction, and catalytic studies confirmed the formation of a perovskite structure on the alumina support. The catalytic activity for propane oxidation strongly depended on the preparation method, and the perovskite catalysts deposited in the inside pore of alumina exhibited higher activity than those deposited on the outside pore of alumina. The surface area of perovskite oxides on support was quantitatively evaluated by temperature-programmed desorption of CO2. The trend for the surface areas of LaMnO3 on γ-Al2O3 estimated by the method was consistent with the trend of the rate for complete propane oxidation normalized by catalyst weight, whereas the rate normalized by the surface area of perovskite oxide was almost independent of the dispersion, crystallite sizes, and deposition methods. The activity of LaMnO3/Al2O3 with the intrapore deposition was almost independent of calcination temperatures ranging from 650 to 1000 °C, in marked contrast with the extrapore deposition catalysts, whose activities greatly decreased with increasing calcination temperatures. For the intrapore deposition catalysts, the highest activities were obtained when the loading level was 20 wt % and decreased with a further increase in the loading level. At high loading levels (40 wt %), extrapore deposition of LaMnO3 on the intrapore deposition catalysts improved their activities for propane oxidation.
  • Hirokazu Masai, Yuto Suzuki, Takayuki Yanagida, Ko Mibu
    2015 年 88 巻 8 号 p. 1047-1053
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/18
    ジャーナル 認証あり
    The authors report on luminescence of SnO-doped 60ZnO–40B2O3 (SZB) glasses melted in air and Ar atmosphere. In photoluminescence (PL), excitation spectra consist of two excitation bands, and the lower excitation band, emerging at lower energy with increasing amount of SnO, affects the optical absorption edge. The present SZB glasses can exhibit light emission by irradiation of near UV light, which is different from the zinc phosphate glass system. X-ray induced scintillation spectra indicate that concentration of Sn2+ mainly affects the intensity. 119Sn Mössbauer spectra show that a certain amount of Sn2+ centers in the SZB glass was oxidized to Sn4+ even when melted under the inert atmosphere, which is one of the reasons for the low PL quantum efficiencies, approximately 60%. The 119Sn Mössbauer spectra also suggest site dispersion of Sn2+ centers, whose local coordination states affect the optical absorption and luminescent properties.
  • Trevor T. Chiweshe, Walter Purcell, Johan A. Venter
    2015 年 88 巻 8 号 p. 1054-1063
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/16
    ジャーナル 認証あり
    A spectrometric method using inductively coupled plasma optical emission spectrometry (ICP-OES) for the determination of Os and the stability of (NH4)2[OsCl6] standard was developed. Results obtained from this study showed a gradual decrease in Os recovery in the liquid reference material (RM) within 96 h of having prepared the calibration standards. The instability of the Os standard (NH4)2[OsCl6] resulted in the decrease in Os percentage recoveries. The Os calibration plots shifted (gained or lost sensitivity) after every 24 h. This gain or loss in sensitivity also varied, depending on acid or base used. In acidic medium, the gain in sensitivity of the calibration curves increased from HCl < HBr < HF whilst in the basic medium, the calibration plots decreased in sensitivity from NaOH < KOH < NH4OH. The stable Cs2[OsO2(CN)4] compound was synthesized and evaluated for its suitability as osmium standard and it was determined to be a good alternative standard for Os analysis due to its excellent stability in HCl matrix and at room temperature. The optimum storage conditions for both Os standards (NH4)2[OsCl6] and Cs2[OsO2(CN)4] and the liquid RM analyte solutions were in the acidic medium (HCl), in the dark and at ca. 10 °C.
  • Kentaro Okuma, Yukiko Tanabe, Noriyoshi Nagahora, Kosei Shioji
    2015 年 88 巻 8 号 p. 1064-1073
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/28
    ジャーナル 認証あり
    2,3-Benzodiazepines were synthesized by two-step or one-pot reactions from aryne precursors. Reaction of 2-(trimethylsilyl)aryl triflates with β-diketones in the presence of CsF gave ortho-substituted benzophenones. Treatment of benzophenones with hydrazine hydrate resulted in the formation of 2,3-benzodiazepines in moderate yields. Tofisopam, a well known anxiolytic, could be synthesized via C–C bond insertion of 3,4-dimethoxybenzyne with 2-ethyl-1-(3,4-dimethoxyphenyl)butane-1,3-dione, followed by the reaction with hydrazine hydrate in one-pot operation. 2,3-Benzodiazepin-4-ones were also synthesized by the reaction of β-keto esters with triflates in the presence of CsF, followed by the addition of hydrazine hydrate. Substituted isoquinolines were synthesized by the reaction of ortho-substituted benzophenones with ammonium hydroxide.
  • Kotomi Takagi, Yasuhiro Kashima, Satoshi Fujii, Kazuya Koumoto
    2015 年 88 巻 8 号 p. 1074-1082
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/20
    ジャーナル 認証あり
    電子付録
    Horseradish peroxidase (HRP), a well-known oxidase, is frequently used in the diagnostic field as a labeling enzyme, where it amplifies the substrate binding signal of antibodies. Though practical for detecting moderate amounts of substrate, there is strong demand for further development of its sensitivity to detect minuscule quantities of biomarkers. Recently, we found that betaine-type cellular metabolite analogs facilitate enzymatic hydrolysis just by dissolving them into the reaction buffer. In the present study, using the analog (2-(N,N,N-tri-n-butylammonium) acetate) and various colorimetric substrates of HRP, we investigated the activation behavior of HRP. As a result, the analog structure- and concentration-dependently facilitated the various HRP-catalyzed oxidative reactions. Interestingly, the analog facilitated not only the reaction rate but also the chromogenic sensitivity. Kinetic and structural analyses revealed that the increased chromogenic sensitivity is related to the enhancement of the conformational flexibility in the substrate binding site in HRP by addition of the analog, which diminishes the binding affinity between HRP and large substrates. The finding serves to create practical applications of the analogs for increased detection sensitivity of HRP-related clinical agents.
  • Ken-ichi Yamashita, Akihiro Nakamura, Md. Awlad Hossain, Kazunori Hira ...
    2015 年 88 巻 8 号 p. 1083-1085
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/08
    ジャーナル 認証あり
    電子付録
    An intramolecular oxidative C–C bond formation reaction of a 1,2-bis(pyren-2-yl)benzene derivative gave benzodinaphthopentaphene, a new polycyclic aromatic hydrocarbon. Its expanded π-system induced a bathochromic shift in the absorption spectrum and amphoteric multi redox processes in electrochemistry. Furthermore, the [5]helicene moiety of the molecule induced helical chirality.
  • Takashi Shirahata, Shuhei Kohno, Keisuke Furuta, Yusuke Oka, Yohji Mis ...
    2015 年 88 巻 8 号 p. 1086-1092
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/23
    ジャーナル 認証あり
    電子付録
    In this study, we synthesized 2-(4-chloro-5-methyl-1,3-dithiol-2-ylidene)-5-(4,5-dimethyl-1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene (ClMe3-TTP). Results show that the cation radical salts of ClMe3-TTP with PF6 and AsF6 anions show high conductivities (101 S cm−1) at room temperature and semiconducting behavior with low activation energy (24–27 meV). A crystal structure analysis of the PF6 and AsF6 salts reveals a 3:1 donor–anion ratio of these salts. The ClMe3-TTP molecules form one-dimensional columns along the a axis, and tape-structures, connected by the side-by-side S···S interactions, also form along the a axis. The calculated intracolumn and intratape overlap integrals are relatively large; however, the overlap integrals between the one-dimensional columns and the tapes are approximately 1/2–1/5 the value of the intracolumn and intratape overlap integrals. The band calculations suggest that they have one-dimensional electronic structures, indicating that they would comprise a Mott insulator.
  • Shin-ichi Matsuoka, Masanori Nakazawa, Masato Suzuki
    2015 年 88 巻 8 号 p. 1093-1099
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/23
    ジャーナル 認証あり
    電子付録
    The tail-to-tail dimerization of vinyl compounds catalyzed by an N-heterocyclic carbene was found to show a very broad substrate scope and tolerance to various functional groups. The optimization of the dimerizations of 2-vinylpyridine and n-butyl acrylate, as low and high electrophilicity model substrates, indicates that high reaction temperatures around 150 °C are required for both substrates. In addition to methacrylates and methacrylonitrile, the applicable substrates range from an activated styrene and vinyl pyridines to highly reactive acrylonitrile, dimethyl acrylamide, and various functionalized acrylates. The alcohol additives significantly increase the catalytic turnover number to 18 for the dimerization of acrylates. Deuterium labeling experiments indicate that the alcohols promote the intermolecular proton transfers.
  • Hisato Matsumoto, Yoshinobu Nishimura, Tatsuo Arai
    2015 年 88 巻 8 号 p. 1100-1104
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/30
    ジャーナル 認証あり
    電子付録
    We examined intermolecular hydrogen-bonding interactions of pyrene derivatives bearing a urea unit, referred to as 1PUP (one pyrenyl group) and 1DPU (two pyrenyl groups). 1DPU showed a new emission band around 530 nm along with a locally excited emission (LE) attributed to the pyrene moiety, even at 10−7 M, in contrast to 1PUP, which only had an LE, indicating that the symmetrical configuration allowed stable stacking of 1DPU. Time-resolved emission spectroscopy revealed that the intensity of the new band increased relative to that of the LE with the concentration of 1DPU. Furthermore, addition of tetrabutylammonium acetate (TBAAc) resulted in the disappearance of the new band, due to the formation of hydrogen bonds with 1DPU. These results indicate that the new band may originate from intermolecular hydrogen-bonding interactions between 1DPU molecules through the urea unit, even at very low concentrations, and can be attributed to an excimer emission. This implies that hydrogen bond formation by the urea units of 1DPU favors a conformation that results in the formation of the excimer in the absence of anions, and the strength of the hydrogen-bonding interaction between 1DPU molecules is weaker than the interaction between a 1DPU molecule and an anion.
  • Satoshi Nakazato, Tatsuo Arai
    2015 年 88 巻 8 号 p. 1105-1107
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/30
    ジャーナル 認証あり
    電子付録
    The fluorescence maximum of the fourth generation of stilbene-cored dendrimer (trans-G4) was affected by solvent polarity. These results indicated that the core of even higher generation dendrimer was not isolated from solvent molecules and the environment of the dendrimer core is constructed by both surrounding dendron groups and penetrated solvent molecules.
  • Mandira Pradhananga Adhikari, Rina Adhikari, Rekha Goswami Shrestha, R ...
    2015 年 88 巻 8 号 p. 1108-1115
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/04/27
    ジャーナル 認証あり
    電子付録
    Nanoporous activated carbons (AC) have been prepared from low-cost agro-waste corncob powder by phosphoric acid activation and investigated for their electrochemical supercapacitor and sensing properties. Surface areas and pore volumes are found in the range of 690–1288 m2 g−1 and 0.49–1.64 cm3 g−1, respectively and could be controlled by adjusting the weight ratio of corncob and phosphorous. The corncob-derived AC showed excellent electrochemical performance giving a maximum specific capacitance ca. 340.8 F g−1 at a scan rate of 5 mV s−1. At relatively a high scan rate of 100 mV s−1 the specific capacitance of 133.7 F g−1 was obtained. About 96% capacitance retention rate was achieved even after 1000 cycles demonstrating potential usages of the materials in high-performance supercapacitor electrodes. Furthermore, our AC showed excellent solvent vapor sensing performance with high selectivity for ammonia.
  • Satoshi Kamiguchi, Ryu Kajio, Hitomi Yamada, Hidetaka Yuge, Kazu Okumu ...
    2015 年 88 巻 8 号 p. 1116-1122
    発行日: 2015/08/15
    公開日: 2015/08/15
    ジャーナル 認証あり
    Solid-state molybdenum halide clusters with an octahedral metal framework MoX2 (or [Mo6X8]X2X4/2) (X = Cl, Br, I) are applied to catalysis. When these clusters are thermally activated in a hydrogen stream above 300 °C, they exhibit catalytic activity for the dehydrogenative C-methylation of piperidine with methanol, to yield 3-methylpyridine. At 400 °C, the selectivity is as high as 74%. This catalytic behavior is different from that of the molecular clusters [(M6Cl12)Cl2(H2O)4]·4H2O (M = Nb, Ta) and (H3O)2[(M6Cl8)Cl6]·6H2O (M = Mo, W), which exhibit Brønsted acidity after thermal activation; piperidine is N-methylated to yield N-methylpiperidine selectively. Elemental analysis and thermogravimetric analysis demonstrate that the solid-state clusters partially eliminate halogen ligands during the activation. Infrared analysis of adsorbed pyridine on the activated clusters shows the presence of a Lewis acid site. This coordinatively unsaturated site of the molybdenum is catalytically active for dehydrogenative C-methylation. The formation of an η3-1-azaallyl species on the molybdenum facilitates the methylation at the 3-position of piperidine, followed by dehydrogenation to yield 3-methylpyridine.
  • Hiroshi Ikeda, Naoko Ikuta, Daisuke Nakata, Yoshiyuki Ishida, Keiji Te ...
    2015 年 88 巻 8 号 p. 1123-1127
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/12
    ジャーナル 認証あり
    The structures of inclusion complexes of (R)-α-lipoic acid with α-, β-, and γ-cyclodextrin (CD) were constructed using restraints derived from ROESY spectra and MMFF94 molecular mechanics calculations. (R)-α-lipoic acid and α-CD generate a single stable inclusion complex, in which the 1,2-dithiolane ring of the (R)-α-lipoic acid is oriented toward the secondary hydroxy side of the α-CD. NMR data suggests that β-CD produces two kinds of inclusion complexes with α-lipoic acid. Finally, γ-CD yields 1:1 and 1:2 host/guest complexes with (R)-α-lipoic acid. The estimated structure of the 1:1 γ-CD inclusion complex has the 1,2-dithiolane ring oriented toward the primary hydroxy side of the γ-CD.
  • Tomiyuki Arakawa, Nobuaki Watanabe, Yuki Haijima, Ayaka Matsumura, Ich ...
    2015 年 88 巻 8 号 p. 1128-1134
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/12
    ジャーナル 認証あり
    Ti-Ni-O nanocomposites were prepared by electrodeposition using Ti nanoparticles of 100 nm in diameter, and subsequent annealing at 600 °C in a vacuum of 1 × 10−4 Pa for one hour. Scanning electron microscopy revealed that clusters of 2 to 15 µm were observed on the surface of Ti-Ni-O nanocomposites. The number of clusters increased with increasing the concentration of Ti nanoparticles in electrodeposition baths. Glow discharge-optical emission spectroscopy showed that Ti concentration in Ti-Ni-O nanocomposites increased with increasing Ti nanoparticles in baths, and the Ti concentration was saturated for Ti nanoparticles of more than 20 g dm−3. Ti atoms of approximately 18 wt % were distributed in Ti-Ni-O nanocomposites. Furthermore, although a Ni(200) peak from Ni electrodeposits was increased by annealing, the increase in Ni(200) peak from Ti-Ni-O nanocomposites was suppressed. X-ray photoelectron spectroscopy analysis indicated that the dominant structure was changed from Ni oxides, Ni(OH)2 and Ni to TiO2 on the surface of Ti-Ni-O nanocomposites by annealing. In fact, Ti-Ni-O nanocomposites in methylene blue reduced the absorbance with wavelength of 664 nm after UV irradiation with the wavelength of 350 nm. It is possible that proposed reactive nanocomposites formation offers a novel TiO2 coated Ti-Ni-O system.
  • Yosuke Imanaka, Hideki Hashimoto, Takanori Nishioka
    2015 年 88 巻 8 号 p. 1135-1143
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/13
    ジャーナル 認証あり
    電子付録
    Exploration of catalysts for organic reactions in water, which is a nontoxic and nonexplosive liquid, has been studied to achieve environmentally friendly chemical processes. For such a purpose, we utilized click chemistry to incorporate sugar units into transition-metal complexes affording water-soluble complexes. In this study, a series of palladium complexes with C–C–N pincer ligands, each of which consisted of two N-heterocyclic carbenes (NHCs) and a triazole moiety with a D-glucopyranosyl unit were synthesized. These complexes possess various N-substituents, namely, methyl, isopropyl, benzyl, or D-glucopyranosyl units on the terminal NHC moieties. The diastereoselectivity in the formation of the complexes and their catalytic ability toward the Suzuki–Miyaura cross-coupling reactions in water exhibited clear N-substituent effects. The tridentate ligand with an acetylated D-glucopyranosyl unit on the terminal NHC moiety led to high diastereoselectivity in the formation of its complex, while each of the other ligands with achiral substituents on the terminal NHC units afforded both of the diastereomers with low selectivity. Catalytic reactions using the complexes were examined for the Suzuki–Miyaura cross-coupling reactions of phenylboronic acid and 4′-bromoacetophenone in water. The complex possessing an isopropyl group on the terminal NHC moiety exhibited excellent catalytic activity with TON (800000), which is comparable to the best value reported for a similar reaction.
  • Yuji Hashimoto, Nobuto Yoshinari, Naoto Kuwamura, Takumi Konno
    2015 年 88 巻 8 号 p. 1144-1146
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/14
    ジャーナル 認証あり
    電子付録
    A thiolato-bridged AuI2CoIII trinuclear complex, [Co{Au(PPh3)(D-pen)}2]+ ([2]+), was synthesized by the reaction of a newly prepared gold(I) complex containing triphenylphospine and D-penicillamine (D-H2pen), [Au(PPh3)(D-Hpen)] ([H1]), with Co2+ in air. The structure and properties of [2]+ are reported in comparison with those of the corresponding polynuclear complexes having diphosphine or triphosphine ligands.
  • Masashi Hatanaka
    2015 年 88 巻 8 号 p. 1147-1149
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/18
    ジャーナル 認証あり
    Unusual imino preference in 4n azaheterocycles is theoretically analyzed. It is attributed to less topological charge stability of the amino forms due to antisymmetric nonbonding molecular orbitals. The theory is applicable for designing stable imino species. The same analysis is also applicable for hydroxyl/oxo tautomerism, and results in very stable lactams.
  • Naru Tanaka, Atsushi Okazawa, Akira Sugahara, Norimichi Kojima
    2015 年 88 巻 8 号 p. 1150-1155
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/18
    ジャーナル 認証あり
    電子付録
    To develop an organic–inorganic hybrid photomagnet, we performed the intercalation of sulfonate-substituted spiropyran anions into layered cobalt hydroxides, obtaining the photoresponsive compound, Co(OH)1.84(nSPSO3)0.16·0.8H2O (CoLHSP; nSPSO3: 1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-5′-sulfonate). After UV irradiation (313 nm), the optical and magnetic properties of CoLHSP clearly changed. A new band emerged in the absorption spectrum at 564 nm, corresponding to the π–π* transition in the open form of nSPSO3. Moreover, the photoisomerization of nSPSO3 induced a new ferrimagnetic phase transition at 10 K in the temperature dependence of DC and AC magnetic susceptibilities in addition to the ferrimagnetic phase transition at 15 K for the unirradiated sample. Analyzing the magnetic measurements before and after UV irradiation, we estimated the phototransformation ratio of the magnetic phase in CoLHSP at approximately 40%.
  • Rajamuthy Vikneswaran, Naser Eltaher Eltayeb, Subramaniam Ramesh, Rosi ...
    2015 年 88 巻 8 号 p. 1156-1158
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/25
    ジャーナル 認証あり
    A new mononuclear zinc complex of N-phenyl-substituted thiophene thiosemicarbazone ligand [Zn(Httsc-N-Ph)2] was synthesized and characterized, and investigated as nuclease mimic. As compared to carboplatin, a much greater activity against HeLa cells is exhibited by [Zn(Httsc-N-Ph)2] which binds to DNA through an intercalation mechanism.
  • Mohamed Lamine Aouissi, Abdelaziz Ghrib
    2015 年 88 巻 8 号 p. 1159-1163
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/28
    ジャーナル 認証あり
    In the present study, the solid solutions with a chemical composition of Ce0.8Y0.2−xLaxO2 (x = 0, 0.1, 0.2) were synthesized via two routes, by hydrothermal method using NaOH as precipitating agent at 230 °C for 15 h and by the sol–gel process using citric acid as chelating agent. Compounds have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA) techniques for appropriate characterization of the distinct thermal events occurring during synthesis. All the compounds crystallize in cubic fluorite structure. The ceria lattice expands depending on the ionic radii of the dopant cations, as indicated by X-ray diffraction study. The sol–gel oxide Ce0.8Y0.1La0.1O2 exhibits a good thermal stability compared with hydrothermal oxide. The microstructure of oxides synthesized by sol–gel showed porosity which increased with the lanthanum La3+ contents and on the other side the hydrothermal method gives single crystal oxides.
  • Masashi Kaneko, Satoru Nakashima
    2015 年 88 巻 8 号 p. 1164-1170
    発行日: 2015/08/15
    公開日: 2015/08/15
    [早期公開] 公開日: 2015/05/27
    ジャーナル 認証あり
    Fe(II) spin-crossover (SCO) phenomenon for fifteen sets of coordination polymers possessing a trans-[Fe(NCS)2(pyridine)4] unit is investigated by means of density functional calculations. Constrained geometry optimization is applied to Fe(NCS)2(pyridine)4 models by fixing the dihedral angle between Fe-NCS axis and pyridine plane. Zero-point corrected energy difference between HS and LS, ΔE0HL, by TPSSh single point calculation reproduces successfully the experimental SCO-on and SCO-off behaviors for most compounds. In order to investigate the origin of whether SCO behavior occurs or not, we perform Mulliken’s overlap population analysis to wavefunction in valence region. Overlap population between d-orbital of Fe atom and all atomic orbitals of six N atoms enables us to assign the kind of d-orbital type molecular orbitals. Calculating ligand field splitting (Δo) obtained by population analysis, we find good correlation between Δo of LS and ΔE0HL indicating that the bonding of LS state depends on the switching behavior of SCO-on/off. Furthermore, combining the ligand field theory with quantum chemical calculation, we obtain the Δo value of the crossing point where ΔE0HL is zero as ca. 4.61 eV.
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