Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 80 , Issue 2
Showing 1-25 articles out of 25 articles from the selected issue
Vol. 80 Commemorative Accounts
  • Ei-ichi Negishi
    2007 Volume 80 Issue 2 Pages 233-257
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    The Pd- or Ni-catalyzed cross-coupling reactions of organometals containing Zn, Al, Zr, and B as well as related reactions of Mg and several other metals collectively represent the most widely applicable organic skeleton construction method discovered and developed over the past several decades, allowing the synthetic chemists to synthesize practically all types of organic compounds. Some of the seminal and critically important discoveries and early developments in the 1970s as well as their current scope (Tables 2 and 3) are briefly discussed. Some of the notable discoveries and developments include (1) identification of superior properties of Pd relative to Ni, (2) the broad scope of Pd- or Ni-catalyzed cross-coupling with respect to metal counter cations including Zn, Al, Zr, B, and Mg, (3) the hydrometallation–Pd-catalyzed cross-coupling tandem processes for selective syntheses of alkenes, dienes, oligoenes, and oligoenynes, (4) double metal catalysis involving Pd or Ni and added metal compounds containing Zn, In, Li, and others, and (5) realization of high turnover numbers (≥103–105) through the use of chelating phosphines, such as DPEphos and dppf. In these reactions, the metal counter cations in organometals and Pd or Ni are to work successively via transmetallation. The Zr-catalyzed alkyne carboalumination and the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction) have provided efficient and selective routes to methyl-branched (E)-trisubstituted alkenylalanes and 2-substituted chiral alkylalanes, respectively. These reactions provide two additional examples of prototypical transition metal-catalyzed organometallic reactions. Significantly, they can be readily combined with the Pd- or Ni-catalyzed cross-coupling for the synthesis of trisubstituted alkenes embracing a wide variety of natural products, such as terpenoids, carotenoids, and others, as well as various chiral organics including deoxypolypropionates and saturated terpenoids. The Zr-catalyzed alkyne carboalumination has been applied to the synthesis of well over 100 complex natural products (Table 4), while the ZACA reaction has been transformed from a mere scientific novelty to a full-fledged asymmetric synthetic method that is catalytic in both transition metal (Zr) and chiral auxiliaries through a series of breakthroughs (Schemes 12–17).
    The Pd- or Ni-catalyzed cross-coupling of organometals containing Zn, Al, Zr, and B as well as the Zr-catalyzed alkyne carboalumination and the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction) are discussed as three prototypical examples of the transition metal-catalyzed organometallic reactions that have collectively revolutionized organic synthesis. Fullsize Image
Award Accounts
The Chemical Society of Japan Award for 2004
  • Mitsuo Kira, Takeaki Iwamoto, Shintaro Ishida
    2007 Volume 80 Issue 2 Pages 258-275
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS FREE ACCESS
    Structural characteristics, spectroscopic properties, and unique reactions of a helmeted dialkylsilylene, 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl, that was synthesized as the first isolable dialkylsilylene and its application to the synthesis of novel silicon unsaturated compounds are surveyed. The silylene was found to be the least electronically perturbed among known stable silylenes by 29Si NMR and UV–vis spectroscopies. The silylene reacts not only with well-known trapping reagents for transient silylenes, such as alcohols, triethylsilane, and 2,3-dimethylbutadiene, but also with less reactive haloalkanes and halosilanes to give the corresponding adducts. One-electron reduction of the silylene using alkali metals affords the corresponding radical anion as a relatively persistent species at low temperatures in solution. Irradiation of the silylene using visible light generates a singlet excited state with a lifetime of 80.5 ns, which reacts with various aromatic compounds and alkenes to give the corresponding silepins and siliranes in a highly regio- and stereoselective manner. The silylene is utilized for the synthesis of unique silicon unsaturated compounds, such as Si=X doubly bonded compounds (X = S, Se, Te, C=NR, etc.), a trisilaallene, a 1,3-disilagermaallene, and silylene transition-metal complexes.
    A comprehensive study of the structure, spectroscopic properties, and reactions of an isolable divalent silicon compound bearing a helmet-like substituent has disclosed the intrinsic properties of silylene that have never been revealed by studies on transient dialkylsilylenes. Fullsize Image
The Chemical Society of Japan Award for Technical Development for 2004
  • Ei-ichiro Suzuki, Kohki Ishikawa, Yasuhiro Mihara, Nobuhisa Shimba, Ya ...
    2007 Volume 80 Issue 2 Pages 276-286
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS FREE ACCESS
    The existence of a flexible region for substrate recognition by an enzyme was first discovered through a structure comparison study among ribonuclease T1–related molecules, including intact molecules, intact molecules complexed with 2′-guanylic acid (GMP), and carboxymethylated molecules complexed with 2′-GMP. Next, it was demonstrated that transglutaminase activity could be enhanced by identifying the flexible residues that affect the active site using nuclear magnetic resonance. Finally, such an approach was used to increase the production of 5′-inosinic acid (5′-IMP) and 5′-GMP. The enzyme is a nonspecific acid phosphatase with pyrophosphate-nucleoside phosphotransferase activity that is C-5′ position-selective. The crystal structure of G74D/I153T with a reduced KM is virtually identical to that of the wild type, and neither of the side chains that were introduced Asp74 and Thr153, directly interact with the nucleoside, although both residues are situated near a potential nucleoside binding site. In addition, the two regions around residues 70 and 140 have the most flexible conformational rearrangement upon phosphate analogue binding. On the basis of three-dimensional (3D) structural information, some practical, high-performance enzymes for 5′-nucleotides production were discovered, and new varieties of microorganisms were developed.
    To enhance the PPi-inosine phosphotransferase reaction and to reduce the phosphatase reaction, site-directed mutagenesis was carried out on the basis of the stereostructure of a nonspecific acid phosphatase and random mutagenesis results, and some highly improved mutants were produced. Fullsize Image
Accounts
  • Masako Kato
    2007 Volume 80 Issue 2 Pages 287-294
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS FREE ACCESS
    Square-planar platinum(II) complexes often exhibit intense color and luminescence when they are stacked via self-assembly or bridging by ligands. The origin of the color and luminescence are the metal–metal electronic interactions, and thus, remarkable changes in color (i.e., chromism) are expected by controlling the Pt···Pt interactions. The molecular arrangement of the assembled complex systems is sensitive to environmental factors such as temperature, pressure, solvent, and vapor. This account focuses on the sensing functionalities of luminescent platinum(II) complexes with 2,2′-bipyridine or its derivatives toward their environment. Especially, luminescence changes that are induced by the vapor molecules will be examined from the viewpoint of chemical sensing. The vapochromic behavior and structural aspects of the mononuclear and dinuclear platinum(II) complexes are discussed.
    The molecular arrangement of the assembled platinum(II) complexes is sensitive to temperature, solvent, and vapor. The chromic behavior of the luminescence and structural aspects of mononuclear and dinuclear platinum(II) complexes containing 2,2′-bipyridine and its derivatives are reviewed. Fullsize Image
BCSJ Award Article
  • Zhong-min Ou, Hiroshi Yao, Keisaku Kimura
    2007 Volume 80 Issue 2 Pages 295-302
    Published: January 15, 2007
    Released: February 13, 2007
    JOURNALS FREE ACCESS
    Ion-based organic dye nanoparticles ranging from tens to hundreds of nanometers have been prepared in aqueous solution. The synthetic approach is based on “ion-association” (hydrophobic ion-pair formation) in water between the dye cation pseudoisocyanine (PIC) and the anion tetraphenylborate (TPB) or tetrakis(4-fluorophenyl)borate (TFPB) ion. Size tuning of spherical and amorphous PIC nanoparticles was accomplished by varying the molar ratio (ρ) of the loaded anion to the dye cation. Electrophoretic characterization revealed that the increase in surface adsorption of anions onto PIC particles brings about an increase in the negative surface charge density, causing a reduction in the surface tension and the mean size of nanoparticles. We found that the optical absorption properties of the PIC nanoparticles exhibited (i) matrix dependence, that is, the 0–0 band position of the PIC chromophore within similar-sized nanoparticles was dependent on the type of counter anions used, and (ii) size dependence, i.e., the 0–0 band position of the PIC chromophore was dependent on the mean nanoparticle diameter when the particles were prepared using the same counter anion.
    We report the synthesis of ion-based organic dye nanoparticles in aqueous solution. The approach is based on “ion-association” in water between the pseudoisocyanine (PIC) dye cation and the tetraphenylborate or tetrakis(4-fluorophenyl)borate anion. Size tuning of spherical PIC nanoparticles was accomplished by varying the molar ratio of the loaded anion to the dye cation. Fullsize Image
 
  • Mohammad Hossein Fatemi, Mohammad Reza Hadjmohammadi, Kamyar Kamel, Po ...
    2007 Volume 80 Issue 2 Pages 303-306
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Half-wave potentials (E1/2) are an important electrochemical property of organic compounds, which depends on both solute and solvent. In this work, a quantitative structure–property relationship (QSPR) study was carried out to predict the reduction E1/2 behavior of 15 substituted nitrobenzenes in five solvents, including acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, methanol, and tetrahydrofuran. For selection of the most relevant descriptors, a stepwise multiple linear regression (MLR) technique was used. Five descriptors that appeared in the MLR model were: minimum charges of the oxygen atom in the nitro group, Guttmann acceptor number of the solvent, dipole moment of solute, dipole moment of the solvent, and Hammet substitution constant (σ). The leave-one out cross validation method was used to evaluate the credibility of the model. Statistical parameters derived from this test are: R2 = 0.960, Q2 = 0.959, and SPREES = 0.046. These indicate the suitability of the constructed model.
  • Ahmed Abd El-gawad Hasanein, Samir Abd El-aziz Senior
    2007 Volume 80 Issue 2 Pages 307-315
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Optimum molecular geometries of 2-aminopyrimidine and 2-amino-4,6-dichloropyrimidine have been calculated by using MP2 and B3LYP methods with different extended basis sets. Dimer interactions for these two pyrimidine derivatives have been also investigated. Full geometry optimization at MP2 and B3LYP levels has been performed for the dimers. BSSE correction was made using the counterpoise method, and the H-bond energies have been calculated.
  • Kayako Hori, Minako Maeda, Atsusi Nidaira, Hitoshi Kawaji, Tooru Atake
    2007 Volume 80 Issue 2 Pages 316-320
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Thermodynamic studies have been made on the title compound in order to elucidate the successive phase transitions between low-temperature (L), intermediate-temperature (M), and high-temperature (H) crystalline phases, which were previously found by X-ray diffraction studies. Using homemade adiabatic calorimeters in the temperature range of 13–360 K, the transition temperatures of the LM and MH phase transitions were determined as 173.5 and 174.2 K, respectively, and the total entropy change due to the two phase transitions was 7 to 11 J K−1 mol−1, depending on the assumed baseline. Melting from H phase to the isotropic liquid phase was at 341.18 K with an entropy change of 103 J K−1 mol−1, while that from the super-cooled Sm A phase to the isotropic liquid phase was at 325.3 K with an entropy change of 11.5 J K−1 mol−1. Thermodynamic functions H(T)–H(0), S(T)–S(0), and (G(T)–G(0))/T were obtained for the first time for a perfluoroalkyl chain compound, except for unsubstituted perfluoroalkanes, and they are 122.4 kJ mol−1, 851.0 J K−1 mol−1, and 440.5 J K−1 mol−1, respectively, at 295.15 K. The nature of the phase transitions is discussed in terms of an order–disorder type of mechanism.
  • Takehiko Satoh, Takemasa Tsuji, Hiroko Matsuda, Susumu Sudoh
    2007 Volume 80 Issue 2 Pages 321-323
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    The carbonyl stretching vibrations of the title compounds were studied using DFT calculations at the B3LYP/6-311G** level and the IR spectra in terms of the intramolecular hydrogen bond (H-bond). Two types of H-bond systems were examined: type I in which the H-atom of the OH group points towards to neighboring carbonyl oxygen atom, and type II in which the H-atom points away. The results of the DFT calculations show that the IR spectra of 2-hydroxy-1,4-naphthoquinone (1), 3-chloro-2-hydroxy-1,4-naphthoquinone (2), 3-bromo-2-hydroxy-1,4-naphthoquinone (3), and 2-hydroxy-3-iodo-1,4-naphthoquinone (4) in CCl4, are well explained by the assumption of the two types of H-bond systems.
  • Kan Kanamori, Koji Kusajima, Hiroyuki Yachi, Honoh Suzuki, Yoshitaro M ...
    2007 Volume 80 Issue 2 Pages 324-328
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    New vanadium(III) and -(IV) complexes with N-(2-hydroxyphenyl)-N-(2-pyridylmethyl)amine (H2hppma) have been prepared, and their structures have been determined by X-ray crystallography. As for the vanadium(III) complex, the vanadium(III) center has a center of symmetry and adopts an ordinary octahedral structure, in which the H2hppma ligand coordinates as a monoanion (Hhppma) in a facial fashion. The vanadium(IV) complex with H2hppma has been determined to be an unusual non-oxo or bare vanadium(IV) complex. In this complex, the H2hppma ligand coordinates as a dianion (hppma) in a meridional fashion. Both complexes are fairly unstable in an aerobic solution and decompose to an oxovanadium(IV) complex.
  • Takuya Hasegawa, Yasuharu Fukumoto, Jotaro Ishise, Ryota Hattori, Yanb ...
    2007 Volume 80 Issue 2 Pages 329-334
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    An octadecylsilyl silica (ODS) column coated with phosphatidylcholine (PC) was prepared by using a dynamic coating method, and its separation characteristics were evaluated for direct sample injection analysis of biological fluids. First, fundamental separation behaviors of various kinds of large and small molecules/ions were examined by HPLC using the PC-coated ODS column with UV absorption detection, for which pure water was used as a mobile phase. In the experiments, proteins (large molecules) were rapidly eluted in the range of 2.07 min (dead time)–3.20 min, while small molecules, such as inorganic anions, amino acids, organic acids, and organic drugs, were eluted after 3.50 min. The fact that proteins and small molecules/ions were separated on the PC-coated ODS column suggested that the present column can be used for direct sample injection analysis of biological fluid samples, such as urine and blood serum. Thus, the PC-coated ODS column was used in the analysis of arsenic species in urine and in the analysis of nicotinamide, theophylline, tryptophan, and caffeine in a model blood serum solution without any sample pretreatment.
  • Atsushi Wada, Masayuki Watanabe, Yoshinori Yamanoi, Takuya Nankawa, Ko ...
    2007 Volume 80 Issue 2 Pages 335-345
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Lanthanide complexes with linear and cyclic octadentate oligopyridine-amine ligands were synthesized, and their molecular structures were determined by single-crystal X-ray crystallography. All of the complexes had a distorted capped square antiprism (CSAP) geometry, and the coordination environments of lanthanide complexes were more distorted for the complexes with the linear ligand than those with the cyclic ligand. The Eu3+ and Tb3+ complexes showed intense luminescence due to energy transfer from the ligand to the metal center (antenna effect). The Eu3+ complexes with the linear ligand showed more intense emissions, which were attributed to the 5D07F2 transition, than the complex with the cyclic ligand in acetonitrile, which can be attributed to the distortion in the coordination environments. In contrast, the coordination of water molecules to Eu3+ and Tb3+ ions was strongly prevented because the metal ions were surrounded by the cyclic ligand, resulting in intense luminescence in water. These results indicate that the coordination environments of lanthanide complexes, and thus the luminescence properties, can be controlled by tuning the geometrical structures of polydentate ligands.
  • Takaomi Suzuki, Eiichi Iguchi, Katsuya Teshima, Shuji Oishi
    2007 Volume 80 Issue 2 Pages 346-348
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Contact angles of water and formamide droplets on a ruby crystal grown from MoO3 flux were determined. The specific surface free energies of the () and (0001) faces, calculated using the Fowkes approximation, were 48 ± 1 and 65 ± 1 mN m−1, respectively. The length of the normal lines from the center of the crystal to () and (0001) faces were 1.06 and 1.45 mm, respectively. The relationship between the specific surface free energy and the morphology of the crystal satisfies Wulff’s relationship.
  • Hiroyuki Kurata, Seiji Muro, Tetsuya Enomoto, Takeshi Kawase, Masaji O ...
    2007 Volume 80 Issue 2 Pages 349-357
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Tetra(2-furyl, 2-thienyl, and 2-selenienyl)butatrienes and their derivatives have been prepared by dimerization of ate-type complexes derived from the corresponding 1,1-dichloro-2,2-diarylethenes using appropriate copper complexes in moderate to high yields. These new butatrienes are relatively stable crystalline substances with intense absorption bands at long wavelengths. The electronic properties of the substituents at the 5-position of aryl groups remarkably influence the wavelength of the longest absorption and the π-electron distribution of butatriene moiety. Their redox potentials, measured by cyclic voltammetry, have higher amphoteric redox properties than those of tetraphenylbutatriene. The crystal structures of tetrakis(5-trimethylsilyl)-substituted derivatives show the following two features: (1) the thiophene and selenole derivatives have pseudo-D2 structures, while the furan derivative has a C2 symmetric structure probably due to the counterbalance between the energy of conjugation and the nonbonded chalcogen–chalcogen interaction; (2) the central double bonds of these butatrienes are considerably short.
  • Kazunori Kawasaki, Kazuhisa Sakakibara
    2007 Volume 80 Issue 2 Pages 358-364
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Thermal paper, which is comprised of sulfonylurea molecule R1SO2NH–CO–NH–R2 (color developer) and the leuco-dye, can develop strong black color, and the developed color is durable. This is because sulfonylurea functional group has sufficient hydrogen bond donor ability to stabilize a π-delocalized carbocation generated from the leuco-dye due to heat-induced lactone ring opening. Thus, the color-developing complex (CDC) that appears can be stabilized by hydrogen-bond formation between two N–H bonds of the sulfonylurea and the carboxylate anion from the leuco-dye. The hydrogen bond donor ability of the color developer can be evaluated in terms of the α2H parameter proposed by Abraham. 1H NMR chemical shift values of the N–H protons in the sulfonylurea and HPLC retention times of the sulfonylurea on a silica column show a good correlation with the α2H parameter values. The essential factors necessary for the sulfonylurea to give rise to high color developing by forming a stable hydrogen-bond complex are also discussed on the basis of the structure and the electronic properties of the sulfonylureas.
  • Takuro Hamazaki, Kenji Matsuda, Seiya Kobatake, Masahiro Irie
    2007 Volume 80 Issue 2 Pages 365-370
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Single crystals of the closed-ring isomer of the diarylethene derivative 1,2-bis(2-methyl-6-styryl-1-benzothiophen-3-yl)perfluorocyclopentene underwent a ring-opening reaction with high conversion while keeping their crystalline shape and transparency. Polar plots of the absorption anisotropy revealed that the closed-ring isomer in the crystal maintained an ordered alignment even at high conversion, and the transparency of the single crystal remained intact during photoreaction. X-ray crystal structural analysis showed that the length of the b axis of the unit cell increases as the photoreaction proceeds. The photostimulated crystal-lattice change is attributed to the rotational movement of the thiophene rings of the molecule during the photochemical ring-opening reaction.
  • Naoto Hayashi, Takashi Nishihara, Takuya Matsukihira, Hiroki Nakashima ...
    2007 Volume 80 Issue 2 Pages 371-386
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Orientational isomers of the octaethylporphyrin–dihexylbithiophene (OEP–DHBTh) derivatives connected with a diacetylene linkage were synthesized, with various electron-withdrawing substituents X attached at the ends. The effects of DHBTh orientation and X substituent on the properties of OEP–DHBTh–X (X = H, Br, CN, CHO, and NO2) were studied and compared with those of related OEP derivatives.
  • Katsuyuki Nakashima, Naoki Kikuchi, Daisuke Shirayama, Takuo Miki, Kaz ...
    2007 Volume 80 Issue 2 Pages 387-394
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    (+)-Goniodiol, a potent and selective cytotoxin, and (−)-6-epi-goniodiol, as well as their enantiomers, have been synthesized starting from cinnamyl alcohol. The key steps of the synthesis were Sharpless asymmetric epoxidation and cyclization of an acrylate derivative using ring-closing metathesis reaction. The cytotoxicity of both enantiomers of goniodiol and 6-epi-goniodiol against HL-60 cells was examined.
  • Toshiyuki Shigetomi, Kosei Shioji, Kentaro Okuma, Yoshinobu Yokomori
    2007 Volume 80 Issue 2 Pages 395-399
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    The synthesis of selenoketone–platinum complexes 3a3c was achieved by reacting selenoketones 4 with (η2-ethylene)bis(triphenylphosphine)platinum(0) (1). 1,1,3,3-Tetramethylindan-2-selone–platinum complex 3b was determined by X-ray crystallographic analysis to be an η2-selenoketone–platinum complex. Interestingly, only one isomer of selenofenchone–platinum complex 3c was formed by this reaction.
  • Yoshiro Furuya, Kazuaki Ishihara, Hisashi Yamamoto
    2007 Volume 80 Issue 2 Pages 400-406
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    The dehydration reaction of primary amides is one of the most fundamental methods for the synthesis of nitriles, and the development of environmentally benign catalytic reaction processes is needed. We surveyed a variety of metal catalysts and found that perrhenic acid was extremely effective for the dehydration of not only primary amides but also aldoximes. Typically, 1 mol % of perrhenic acid gave the corresponding nitriles from amides or aldoximes under azeotropic reflux conditions with the removal of water in toluene or mesitylene. In addition, perrhenic acid is an extremely efficient catalyst for the Beckmann fragmentation of α-substituted ketoximes to functionalized nitriles. This new catalytic system can be applied to the gram-scale synthesis of nitriles without further modifications.
  • Ivan Damljanovic, Mirjana Vukicevic, Rastko D. Vukicevic
    2007 Volume 80 Issue 2 Pages 407-409
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    A-ring bromination of estrogens has been achieved by constant current electrolysis of the solutions of these substrates and Et4NBr in appropriate solvents. Thus, electrolysis consuming 2 F mol−1 charge gave mixtures of 2- and 4-estrogens (1:1.1–2.5; up to 97%), whereas 4 F mol−1 charge experiments yielded 2,4-dibromoestrogens as the sole products.
  • Yeonhwan Jeong, Kazuya Uezu, Masataka Kobayashi, Shinichi Sakurai, Hir ...
    2007 Volume 80 Issue 2 Pages 410-417
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    When we mixed two transparent aqueous solutions of tetrasodium N,N-bis(carboxylatomethyl) glutamate (GLDA) and sodium oleate (OleNa), a white gel phase was formed when the total solute concentrations were higher than about 2.8 wt %, indicating that complexation between GLDA and OleNa caused the gelation. The appearance of the gel was completely opaque, the gel displayed thixotropy, and the gel state changed to the sol state upon heating. Optical microscopy showed that the gel consisted of very long fibers with diameters ranging from nanometers to micrometers. Transmission electron microscopy showed that the long fibers were made from many bundled, straight fibrils with a width of 200–1000 nm. The fibril consisted of lamellae parallel to the axial direction of the fibril. X-ray scattering confirmed the lamellar structure with a spacing of 4.5 nm, and the spacing was independent of the concentration and the molar ratio of GLDA and OleNa. The area of the lamellar first peak reached a maximum at the molar ratio of GLDA:OleNa = 4:1, i.e., this ratio is the stoichiometry of the GLDA/OleNa complex. This stoichiometric number was confirmed by high-performance liquid chromatography.
  • Makoto Kimura, Toshihiko Kurata, Yasuhiko Sawaki, Yasumasa Toba, Toshi ...
    2007 Volume 80 Issue 2 Pages 418-422
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Using 9,9-dialkyl-functionalized fluorenes as monomers, novel fluorene-based oligomers were prepared in order to improve the thermal stability of a typical hole-transport material (HTM), N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD), in organic light emitting diodes (OLEDs). 2,7-Bis(diphenylamino)fluorene was utilized as a TPD unit throughout the present synthetic work. 9,9-Bis(2-methylallyl)fluorene and its TPD congener underwent a new cyclopolymerization reaction affording six-membered oligomers under acid catalysis with p-toluenesulfonic acid. Intermolecular Suzuki coupling of a 9,9-bis(p-bromobenzyl)fluorene analogue with the corresponding bis-boronate afforded a new oligomer containing the TPD substructure. These oligomers (3 and 6) for use as HTMs have high glass-transition temperatures (Tg’s) (147 and 167 °C, respectively); the values are much higher than the Tg for TPD (63 °C). These materials are soluble in organic solvents to allow easy processing for preparing layered devices, though their electroluminescent performances were lower than that of the single molecule TPD.
  • Yungi Lee, Tomoaki Watanabe, Tsuyoshi Takata, Michikazu Hara, Masahiro ...
    2007 Volume 80 Issue 2 Pages 423-428
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    A fine powder of sodium tantalum(V) trioxide as single-phase perovskite NaTaO3 has been successfully prepared by hydrothermal synthesis through the reaction of a sodium hydroxide solution and ditantalum pentaoxide powder at low temperature (373–473 K). The NaTaO3 powder has high photocatalytic activity for both H2 evolution (8.0 mmol h−1) and O2 evolution (4.1 mmol h−1), which is attributed to the high surface area, small particle size and high crystallinity of the powder catalyst.
  • Yunle Gu, Mingtao Zheng, Zilin Xu, Yingliang Liu
    2007 Volume 80 Issue 2 Pages 429-431
    Published: February 15, 2007
    Released: February 13, 2007
    JOURNALS RESTRICTED ACCESS
    Hexagonal boron nitride was synthesized from MB6 (M = Ca and La) in liquid sodium amide at 600 °C. The as-synthesized boron nitride powders were composed of sub-micrometer-sized triangles and hexagons.
feedback
Top