bluuebunny/crossref_metadata_2025 huggingface dataset:
Exciton Transport Mechanism in 1,4-Dibromonaphthalene (DBN)-1-Bromo-4-chloronaphthalene (BCN) Mixed Crystal at 77 K
Authors: Dutta Ashim K , Talapatra Gautam B , Misra Tridibendra N
Published: July 2006

The exciton transport in the presence of both orientational and substitutional disorders is investigated at 77 K. The systems of study include different compositions of 1,4-dibromonaphthalene (DBN) and 1-bromo-4-chloronaphthalene (BCN). In DBN, crystal phosphorescence emission is in conformity with quasi-one-dimensional exciton motion. Fluorescence emission from an impurity and phosphorescence emissions from the triplet state of DBN and from an impurity site present in the DBN crystal have been observed. However the fluorescence emission from the first excited singlet state of DBN is absent. In BCN-doped DBN crystal, the emission corresponding to first triplet of DBN disappears. With the increase of BCN concentration, fluorescence intensity of impurity S1IMP decreases, while the impurity phosphorescence emission intensity increases. The role of the deep trap present in DBN and the effect of orientational disorder due to BCN on the energy transfer processes have been discussed. The experimental results are explained quite satisfactorily in terms of the percolation model, which suggests a two-dimensional exciton transport topology in the mixed crystal.
Crystal Structures of Chiral Mesogenic 4-[(S)-2-Methylbutyl]phenyl and 4-[(S)-1-Methylheptyloxy]phenyl 4′-Octylbiphenyl-4-carboxylates
Authors: Ito Kyoko , Hori Kayako
Published: July 2006

Single crystal X-ray analysis has been carried out for the title compounds with different chiral groups, which result in different phase sequences: crystal (cryst.)-smectic G(SG)-SJ*-SF*-SI*-SC*-SA-cholesteric (chol.)-isotropic (iso.) for the 2-methylbutyl compound (1) and cryst.-SB-SA-iso. for the 1-methylheptyloxy compound (2). Each crystal has a smectic-like layer structure, in which the molecular tilt angle is 25° in 1 and 15° in 2. Biphenyl moieties are almost coplanar and normal chains have all-trans conformations in both crystals. However, long chains of the chiral groups of 2 have twisted conformations and are arranged between layers. Relationships between the crystal structures and the mesophase behavior are discussed in terms of conjugation of the polar groups and overlapping of biphenyl moieties for the related compounds.
Density and Volumic Properties of N,N-Dimethylformamide + 2-Methoxyethanol + 1,2-Dimethoxyethane Liquid Ternary Mixtures
Authors: Corradini Fulvio , Marchetti Andrea , Tagliazucchi Mara , Tassi Lorenzo
Published: July 2006

Densities (ρ) at various temperatures ranging from −10 up to +80 °C have been measured for N,N-dimethylformamide + 2-methoxyethanol + 1,2-dimethoxyethane ternary solvent system, employing 66 mixtures covering the whole miscibility field. Polynomial equations describing the dependence on temperature, ρ = ρ(t/°C), and molar composition, ρ = ρ(X1,X2), have been checked. Furthermore, the excess molar volumes (VE), derived from ρ values, can provide useful suggestions about the formation of solvent–cosolvent complexes. Excess molar volumes have been interpreted on the basis of specific interactions between unlike molecules, taking into account geometric effects and steric hindrances. The VE quantities have been isothermally fitted by an empirical relation of the type VE = VE(X1,X2,X3) formally derived from the well known Redlich–Kister equation. As a rule, for all the here tested relationships, the calculated values agree very well with the experimental ones, indicating that all the equations can be safely employed for predictive calculations in correspondence of the experimental data gaps.
Charge Transport at Polypyrrole Film Electrodes: Effect of the Electrolyte Concentration
Authors: Komura Teruhisa , Usui Takahiro , Takahasi Kousin
Published: July 2006

From measurements of the a.c. response of polypyrrole film electrodes in KNO3 solution, we found that solvent swelling of the polymer greatly influences the kinetic behaviors of the polymer film electrodes. Electric migration in bulk film was due to background electrolyte ions which permeated through the film. Inside the film in contact with a supporting electrolyte solution, the mobility of the electrons may be much smaller than that of ions. The charge-transfer resistance of a partially oxidized film decreases along with increasing concentration of the electrolyte solution, because of a resultant increase in the activity of polarons. Such an increased activity of polarons also brings about a smaller Warburg coefficient, and thus a smaller limiting diffusion resistance (RL). The pseudocapacitance appearing at low frequencies increases along with an increase in the concentration of the electrolyte solution, which is opposed to the change in RL. These results corroborate that variations in the charge-transport parameters with the electrolyte concentration can be ascribed to an increase in the polaron activity with increasing ion concentration inside the polymer film.
Coupling of Inter- and Intramolecular Vibrations in the p-Xylene Crystal
Authors: Shimizu Fumio , Yoshikai Kazumasa , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

The temperature effect on the low-frequency Raman bands of the four deuterated p-xylene crystals indicates that the coupling between the intramolecular torsional vibration of the CD3 group and the intermolecular rotational vibrations takes place below about −80 °C.
Gelation of Fully Acylated Cellobiose in Alkane Solution
Authors: Ide Nobuhiro , Fukuda Takeshi , Miyamoto Takeaki
Published: July 2006

Cellobiose octa(decanoate), a discotic columnar mesogen, was found to form in hexadecane solution various molecular assemblies such as a lyotropic liquid crystal of discotic columnar type, multimolecular micelles, and a thermoreversible gel, depending on the concentration and temperature. The gelation, observed even at very low concentrations, say, < 0.01 weight fraction of the mesogenic compound, is believed to proceed by local coagulation of long threadlike micelles into micro-liquid-crystallites, which work as cross-linking points combining the threadlike micelles. This will be a new type of gel that could be termed a “liquid crystalline gel.”
Synthesis and Characterization of Some 2,10-Dichloro-6-alkoxydibenzo[d,g][1,3,6,2]dioxathiaphosphocin 6-Oxides
Authors: Reddy C Devendranath , Reddy B Sankara , Anuradha K , Berlin K D , Naidu S Mani , Krishnaiah M
Published: July 2006

The syntheses of 2,10-dichloro-6-alkoxydibenzo[d,g][1,3,6,2]dioxathiaphosphocin 6-oxides are described. Their IR, 1H, 13C, and 31P NMR spectral characteristics are reported. Long-range couplings (2JPOC and 3JPOCC) between phosphorus and carbons were observed. An X-ray diffraction analysis of a crystal of 2,10-dichloro-6-ethoxydibenzo[d,g][1,3,6,2]dioxathiaphosphocin 6-oxide indicated a boat-chair conformation to the dioxathiaphosphocin ring with the phosphoryl oxygen in axial and the ethoxy group in equatorial orientations. The molecule possesses a symmetry of the mirror plane passing through the sulfur, phosphorus, phosphoryl oxygen, and ethoxy group.
1,3-Dipolar Cycloaddition Reactions of 2,4,6-Cycloheptatrien-1-imines with Benzonitrile Oxides Leading to 1,2,4-Oxadiazaspiro[4.6]undeca-2,6,8,10-tetraenes
Authors: Ito Kazuaki , Saito Katsuhiro
Published: July 2006

1,3-Dipolar cycloaddition reactions of N-aryl-2,4,6-cycloheptatrien-1-imines with p-substituted benzonitrile oxides afforded [2+3]-type cycloadducts in considerable yields. A study of the substituent effect on the reaction rate revealed that the reactions proceeded through nucleophilic reactions of imines to nitrile oxides. Thermal isomerizations and addition reactions of the adducts showed that the contribution of a valence isomerization between cycloheptatriene and norcaradiene lay to the side of the cycloheptatriene form. A comparison of the UV spectra between the adduct and its derivative, which was reduced by catalytic hydrogenation, implies that the spiroconjugation between cycloheptatriene and a five-membered heterocyclic moiety causes a shift of the equilibrium.
Improved Enzymatic Procedure for a Preparative-Scale Synthesis of Sialic Acid and KDN
Authors: Sugai Takeshi , Kuboki Atsuhito , Hiramatsu Shigeki , Okazaki Hanako , Ohta Hiromichi
Published: July 2006

Sialic acid (N-acetylneuraminic acid) and KDN (3-deoxy-β-d-glycero-d-galacto-2-nonulosonic acid) play important roles in a variety of intercellular events. Extensive studies have been reported on the use of sialic acid aldolase as a catalyst to form the C–C bond between N-acetyl-d-mannosamine derivatives and pyruvic acid to give sialic acid and its analogs. However, the reported protocols have a significant drawback in terms of the tedious separation of the desired product from a large excess of pyruvic acid. We report here on a clean solution to this problem that relies on the utilization of pyruvate decarboxylase for catalyzing the decomposition of pyruvic acid into acetaldehyde and carbon dioxide to facilitate product isolation. Concerning our investigation to enhance the activity of this enzyme, we emphasized two points. One was a sufficient supply of cofactors for pyruvate decarboxylase; the other was an improvement of the enzyme reactor. As a result, the activity became nearly four-times as high as that previously reported. The combination of two enzymatic reactions worked well, affording sialic acid and KDN in 60% yield from N-acetyl-d-mannosamine and d-mannose, respectively. In addition, an efficient method for preparing N-acetyl-d-mannosamine by the epimerization of N-acetyl-d-glucosamine was established. Calcium hydroxide was found to be most effective for base-catalyzed epimerization.
Alkenyl- and Alkynyl-Substituted (p-Phenylene)bisiodonium Ditriflates by Reactions of a (p-Phenylene)bisiodine(III) Reagent with Alkynes and 1-Trimethylsilyl-1-alkynes
Authors: Kitamura Tsugio , Furuki Ryuji , Zheng Lei , Nagata Kensuke , Fukuoka Takahiro , Fujiwara Yuzo , Taniguchi Hiroshi
Published: July 2006

A (p-phenylene)bisiodine(III) reagent prepared from iodosylbenzene and trifluoromethanesulfonic acid or the anhydride showed a high reactivity to alkynes. The reaction of alkynes proceeded with stereoselective addition to the carbon–carbon triple bond to give trans-alkenyl(p-phenylene)bisiodonium ditriflates, whereas the reaction of 1-trimethylsilyl-1-alkynes afforded alkynyl(p-phenylene)bisiodonium ditriflates. These reactions indicate that the (p-phenylene)bisiodine(III) reagent is accessible for a (p-phenylene)bisiodine(III) transfer agent.
Electrochemical Impedance Study and Characteristics of Polyaniline Film Electrodes
Authors: Komura Teruhisa , Sakabayashi Hironobu , Takahashi Koshin
Published: July 2006

The ac response of polyaniline (PA) film electrodes in 0.5 M H2SO4 was investigated at different applied potentials and film thicknesses. The results of impedance analysis on the basis of the Randles equivalent circuit indicated that the electron exchange between metal and redox sites of the polymer controlled the rate of the charge transfer process at the film electrode. The oxidation of the PA film brought about a decrease in charge transfer resistance at lower potentials than the first half-wave potential of PA. The redox capacitance of the polymer indicated the dependence on the potential and film thickness, which was expected from a finite diffusion model. A large capacitance of the order of 3—30 mF cm−2 in the partially oxidized state is explained in terms of the charge saturation effect associated with the finite thickness. Impedance plots at high frequencies (the kHz range) suggested the occurrence of a hydrogen adsorption reaction in the reduced state. The PA film probably swells with the electrolyte. A counter ion to maintain the electroneutrality of the polymer can go into and out of the film with negligible resistance.
Electro-Optical and Hydrodynamic Properties of Synthetic Polyribonucleotides in Solutions as Studied by Electric Birefringence
Authors: Tanigawa Masato , Yamaoka Kiwamu
Published: July 2006

The electro-optical and hydrodynamic properties of four synthetic polyribonucleic acids were clarified by electric birefringence methods which take the molecular-weight distribution into consideration. Parallel double-stranded helices, poly(adenylic acid)·poly(protonated adenylic acid), I, and poly(cytidylic acid)·poly(protonated cytidylic acid), II, are known to possess an electric permanent dipole moment, because the reversing-pulse electric birefringence (RPEB) signals of these duplexes exhibit dips upon pulse reversal. The RPEB signals of antiparallel double-stranded poly(adenylic acid)·poly(uridylic acid), III, and poly(guanylic acid)·poly(cytidylic acid), IV, show no dip; therefore, these polynucleotides have no permanent dipole moment. By analyzing the relaxation time of the birefringence decay signals, the axial translations of the polynucleotides per base-pair were determined to be 4.0 Å for I, 2.7 Å for III, and 2.4 Å for IV, respectively. By analyzing the dependence of the steady-state birefringence values on the electric-field strength, the magnitudes of the permanent dipole moments per unit length of I and II projected onto the helix axes were found to be ca. 0.4 debye Å−1. The electric properties unraveled by electric birefringence experiments were compared with calculations based on a recent Manning theory. An unsaturable induced dipole moment may result from the polarization of the Debye–Hückel ion-atmosphere, while a saturable induced dipole moment is probably caused by the polarization of counter ions that are condensed on the charged sites of a polyion. The experimental values deviate from calculated values at ionic strengths lower than 0.0001; hence, the Manning theory is not applicable in this region.
Interactions of Cu2+ and VO2+ Ions with Phosphatidylcholine Vesicular Membranes as Studied by the 1H NMR Paramagnetic Relaxation Method
Authors: Tanaka Hisao , Saito Harumi , Kawazura Hiroshi
Published: July 2006

The spin-relaxation effects of the paramagnetic ions Cu2+ and VO2+ on the protons of solvent water and lipids in phosphatidylcholine unilamellar vesicles were first observed in order to elucidate the details of the interactions in the membrane surface region. VO2+ ions gave higher rates of the effective paramagnetic relaxation induced by binding to a membrane while Cu2+ ions had a larger partition coefficient from water to the membrane phase. It is concluded that VO2+ occupies a binding site closer to the N-methyl groups in the polar-head network and less accessible to a cation, which causes stronger motional restriction to a bound cation, compared with the site occupied by Cu2+.
Electrical and Optical Properties of α-(BETS)2I3 and α-(BEDT-STF)2I3
Authors: Inokuchi Makoto , Tajima Hiroyuki , Kobayashi Akiko , Ohta Toshiaki , Kuroda Haruo , Kato Reizo , Naito Toshio , Kobayashi Hayao
Published: July 2006

The electrical and optical properties were studied concerning α-(BETS)2I3 and α-(BEDT-STF)2I3, which are isostructural to α-(BEDT-TTF)2I3. It has been shown that α-(BETS)2I3 and α-(BEDT-STF)2I3 undergo metal-insulator transitions at around 50 and 80 K, respectively, and that their electrical resistivities exhibit temperature dependences resembling that of α-(BEDT-TTF)2I3 under high pressure. The optical reflectance spectra of these salts show a two-dimensional nature of their electronic structures, and analyses of the spectral data show that the transverse inter-molecular interaction increases in the order α–(BEDT–TTF)2I3 < α–(BEDT–STF)2I3 < α–(BETS)2I3.
Binuclear Dioxomolybdenum(VI) Complexes of Flexibly-Bridged Hexadentate Tetraanionic Schiff’s Bases Derived from Methylene- or Dithio-bis(salicylaldehyde) and S-Methyldithiocarbazate or S-Benzyldithiocarbazate
Authors: Maurya Mannar R , Antony Deena C , Gopinathan Sarada , Gopinathan Changaramponnath
Published: July 2006

The flexibly-bridged hexadentate tetraanionic ligands, LH4 [LH4 = Schiff’s bases obtained by the condensation of methylene- or dithio-bis(salicylaldehyde) with S-methyldithiocarbazate and S-benzyldithiocarbazate], react with [MoO2(acac)2] in a 1 : 2 molar ratio in refluxing methanol to give complexes of the type [(MoO2)2L]. These complexes show an intense ν(Mo=O) band at 924—948 cm−1 and a broad but strong band at ca. 850 cm−1 due to weakened ν → Mo interactions. An oligomeric structure, in which each Mo(VI) ion achieves a pseudo-octahedral structure via M2)2L] reacts with monodentate ligands (D) like pyridine, 4-methylpyridine, and dimethylsulfoxide and forms six-coordinated complexes of the type [(MoO2)2L(D)2] which are monomers. Cyclic voltammetry measurements indicate that these MoVIO2 complexes are resistant to MoIVO reduction. → Mo interactions. An oligomeric structure, in which each Mo(VI) ion achieves a pseudo-octahedral structure via MoO → Mo bridging, has been suggested for these complexes. [(MoO → Mo bridging, has been suggested for these complexes. [(MoO
Observation of Nuclear Excitation by Electron Transition (NEET) in 197Au with a Nanosecond Stroboscopic Electron Spectrometer
Authors: Shinohara Atsushi , Saito Tadashi , Otozai Kiyoteru , Fujioka Hiromu , Ura Katsumi
Published: July 2006

Nuclear excitation by electron transition (NEET) was investigated on 197Au. It is expected for 197Au that the deexcitation of the K-shell ionized atoms would be accompanied by the nuclear excitation of the first excited level. Time spectra of 63-keV electrons emerging from a 197Au target after bombardment with 100-keV pulsed electron beam were measured with a specially designed nanosecond stroboscopic electron spectrometer. A decay component with a half-life of 1.9 ns was extracted from the electron time spectrum. The decay was attributed to the internal conversion electrons emitted from the excited 197Au nucleus as a consequence of the NEET process and the NEET probability was deduced to be P = (5.1 ± 3.6) × 10−5. The result was compared with several theoretical estimates.
Syntheses and Structural Characterization of Dinuclear and Trinuclear Iron(II) Complexes of Tridentate Thiolic Ligands with an NNS Donor Set
Authors: Mikuriya Masahiro , Kotera Takanori , Adachi Fumiya , Handa Makoto , Koikawa Masayuki , Okawa Hisashi
Published: July 2006

Thiolate-bridged complexes of iron(II) with 2-[(2-aminoethyl)amino]ethanethiol (HLa), 2-[(3-aminopropyl)amino]ethanethiol (HLb), and 2-[[2-(2-pyridyl)ethyl]amino]ethanethiol (HLc) — [Fe{Fe(La)2}2](ClO4)2·CH3OH (1), [Fe{Fe(Lb)2}2]Cl2·2CH3OH (2), and [Fe2(Lc)2(NO3)2] (3), respectively — have been synthesized and characterized by elemental analyses, and infrared and electronic spectroscopies as well as magnetic susceptibilities (80—300 K). The crystal structures of all of these complexes have been measured by single-crystal X-ray diffraction. Each of complexes 1 and 2 has a thiolate-bridged trinuclear iron(II) structure showing a linear arrangement of the three iron atoms with a geometry that may be described as Oh-Td-Oh. Complex 3 is a thiolate-bridged dinuclear iron(II) molecule, in which each iron atom is coordinated in a distorted octahedron. The electronic spectroscopic and magnetic properties are discussed in relation to the crystal structures.
Synergic Extraction Equilibrium of Mn(II) with 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione and Neutral Multidentate Ligands, Such as Terpyridine and Tetraphenyldiphosphane Dioxide
Authors: Satake Saeko , Tsukahara Satoshi , Suzuki Nobuo
Published: July 2006

The extraction equilibrium of Mn(II) was clarified in novel synergic extraction systems using 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta) and neutral multidentate ligands, such as 2,2′ : 6′,2″-terpyridine (terpy) and tetraphenyldiphosphane dioxide (tpdpo), into benzene. No oxidation of Mn(II) and large synergic effect were observed both in the Htta–terpy and Htta–tpdpo systems, and quantitative extraction of Mn(II) was done, which was not attained with Htta only. Mn(II) was extracted as Mn(tta)2(terpy) in the Htta–terpy system, where only two nitrogen atoms of terpy would coordinate to Mn. In the Htta–tpdpo system, two species, i.e. Mn(tta)2(tpdpo) and Mn(tta)2(tpdpo)2, formed in the benzene phase, where tpdpo functioned as a unidentate ligand. The adduct formation constants (βs) and the synergic extraction constants (Kex,s) were obtained and compared with those of other related compounds.
Analysis of d–d Transitions in [Cr(CN)(NH3)5]2+ as Inferred from Polarized Optical Spectra and Angular Overlap Model Calculations
Authors: Urushiyama Akio , Itoh Mutsuyoshi , Schönherr Thomas
Published: July 2006

The polarized single-crystal absorption spectra of [Cr(CN)(NH3)5]Cl(ClO4) were measured for interconfigurational quartet (t2g3 → t2g2eg) and intraconfigurational doublet transitions (t2g3 → t2g3). The band splittings of the spin-allowed transitions, 4A2g → 4T2g,4T1g, were derived to 600—1000 cm−1 from a Gaussian band deconvolution of the σ and π spectra. At low temperature (77 K), more than 45 sharp bands could be detected in the intercombination band region of the lowest doublets (2Eg, 2T1g), which were completely assigned to the five possible zero-phonon transitions and corresponding vibronic sidebands. The vibrational frequencies due to the electronic ground state were obtained from the infrared spectrum and by measuring the emission lines under resonant excitation, providing us with a sufficient data base for a normal coordinate treatment of the pentaamminecyano cation. The d-energy level scheme is rationalized using the angular overlap model (AOM). Geometric parameters were obtained from an X-ray analysis of the chloride–perchloride salt, which shows a cation of approximately 4mm (C4v) site symmetry, consistent with a linearly coordinated cyano group. The AOM parameters evaluated for the CN- ligand show strong σ-antibonding (eσ = ca. 7500 cm−1) together with unusually larger π-bonding (eπ = ca. −900 cm−1), which both contribute to the extremely high value of the respective ligand field parameter Dq. The large splitting of the lowest doublet state, 2Eg (Oh), has been shown to originate from a low-symmetry effect in the treatment of interelectronic repulsion. The attributed tetragonal orbital expansion parameter (τ = 0.99) was calculated to be similar to values recently obtained for related pentaammineaniono complexes.
Antioxidant Activities of Aminophenols against Oxidation of Methyl Linoleate in Solution
Authors: Iwatsuki Misato , Komuro Erika , Niki Etsuo
Published: July 2006

The antioxidant activities of 48 kinds of aminophenols, chromanols, indoles, carbazoles, aromatic amines, and related compounds were assessed in the oxidations of methyl linoleate in acetonitrile solution induced by azo radical initiator. Chromanols, aminochroman and p-phenylenediamines exhibited strong antioxidant activity. Indole and carbazole did not act as antioxidant per se, but those having either amino or hydroxy group as substituent at the para position acted as potent antioxidant. Amino-substituted compounds were in general more potent than hydroxy-substituted ones. These results were interpreted by both polar and resonance effect.
Synthesis and Molecular Structure of [4][34](1,2,3,4,5)Ferrocenophane
Authors: Hisatome Masao , Watanabe Jun , Yamakawa Koji , Kozawa Kozo , Uchida Tokiko
Published: July 2006

A review of synthetic and structural studies of ferrocenophanes has led to the presumption that the intramolecular substitution of ferrocenophanepropionic acid gives a bridged product when “the distance” between the two carbons to be bridged is greater than 3.20 Å. According to this prediction, the bridging reaction of [4][32](1,2,4)ferrocenophane-5-propionic acid (“the distance”: ca. 3.5 Å) was carried out, and the expected bridged compound (13) was afforded. Subsequently, the construction of fourth and fifth bridges in [4][32](1,3,4)ferrocenophane (16) was attempted by applying the working hypothesis in order to obtain perbridged [4][34](1,2,3,4,5)ferrocenophane (5). Both bridging reactions occurred as expected, and the synthesis of 5 was achieved. The absorption spectrum of 5 showed d–d* absorption at an unusually short wavelength (λmax = 345 nm; ferrocene, 443 nm), which is the shortest value in ferrocene derivatives to our knowledge. The structure of 5 was determined by an X-ray diffraction method. Compound 5 crystallizes in a tetragonal system, space group 2d with unit-cell parameters of a = 14.574(4), c = 18.208(4) Å and Z = 8; its R value converged to 0.051 for 1315 reflections. The observed distance between the iron atom and the least-squares aromatic ring of 1.55(9) Å is the smallest among those of all observed multibridged ferrocenophanes. The conformation of the ferrocene moiety is exactly eclipsed, and the dihedral angle of the two rings is small (1.9°).
Stereoselective Allylation of 2-Formyl Amides or 3-Oxo Amides
Authors: Taniguchi Masahiko , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Stereoselective allylation of 2-formyl amides or 3-oxo amides has been studied. Treatment of 2-formyl-N,N-dimethylpropanamide (1a) with allylzinc bromide gave 3-hydroxy-2,N,N-trimethyl-5-pentenamide as a stereoisomeric mixture (2a : 3a = 63 : 37). Meantime, the reaction of 1a with allyltrimethylsilane in the presence of Lewis acid such as EtAlCl2 or BF3·OEt2 afforded threo-adduct 2a exclusively. Whereas treatment of 2-benzoyl-N,N-dimethylpropanamide (PhCOCH(Me)CONMe2) with allylzinc bromide provided erythro-3-hydroxy-2-methyl-3-phenyl-5-hexenamide with high stereoselectivity, allylation with allylsilane in the presence of a catalytic amount of n-Bu4NF afforded stereoisomeric threo hydroxy amide exclusively.
Synthesis and Properties of Cationic Organopalladium Complexes. Remarkable Rate Enhancement in Olefin Insertion into the Palladium–Aryl Bond by the Generation of a Cationic Palladium Complex from trans-[PdBr(Ph)(PMe3)2]
Authors: Kawataka Futoshi , Shimizu Isao , Yamamoto Akio
Published: July 2006

By removing the bromide ligand in trans-[PdBr(Ph)(PMe3)2] (1) by AgBF4 in the presence and absence of pyridine, pyridine-coordinated and solvent-coordinated cationic complexes, trans-[PdPh(py)(PMe3)2]BF4 (2) and trans-[PdPh(solvent)(PMe3)2]BF4 (3), have been obtained. These cationic phenylpalladium complexes show much greater reactivities than do the parent neutral complex 1 toward olefins to give phenylated olefins by insertion followed by β-hydrogen elimination processes. Kinetic studies concerning the insertion of methyl acrylate into the phenyl-palladium bond have indicated that the reactions are first order in the phenylpalladium complexes and that addition of pyridine to a system containing 2 and methyl acrylate inhibits the insertion reaction of the olefin. The results suggest that the generation of a cationic arylpalladium complex with a vacant site is important for the olefins to be inserted.
Effects of the Solvent Dynamics and Vibrational Motions in Electron Transfer
Authors: Yoshihara Keitaro , Tominaga Keisuke , Nagasawa Yutaka
Published: July 2006

Recent theoretical and experimental progress concerning electron transfer (ET) in solution is reviewed by focusing on the mechanism of ET, which occurs much faster than solvation dynamics. Theories of ET in solution are briefly reviewed with particular emphasis placed on the relation to solvent dynamics. Experimental methods to investigate solvent polarization relaxation are described. Ultrafast intramolecular ET, which is found in back ET from the photo-induced charge-transfer state to the ground state, is described concerning highly polar betaines and mixed-valence compounds. Ultrafast intermolecular ET has been observed for the systems of various dyes in electron-donating solvents. A non-exponential process with a significant temperature dependence was observed in aniline. A faster ET with a single exponential decay as fast as 1013 s−1 was observed with no temperature dependence in a system of oxazine 1 in N,N-dimethylaniline. The ET rate constants of excited coumarins in electron-donating solvents drastically depend on the substituent groups of the coumarin. Relatively small Stokes shifts in steady-state fluorescence spectra of ultrafast reacting molecules in solution are evidence of a “chemical timing” effect; namely, the reaction occurs in a non-equilibrium configuration of the solvent. These experimental observations are explained in terms of the extended Sumi–Marcus theory, in which the effect of solvation dynamics and low- and high-frequency vibrational modes are taken into account.
Asymmetric Hydrosilylation of 1-Alkenes Catalyzed by Palladium–MOP
Authors: Uozumi Yasuhiro , Kitayama Kenji , Hayashi Tamio , Yanagi Kazunori , Fukuyo Emiko
Published: July 2006

Asymmetric hydrosilylation of simple terminal alkenes (RCH=CH2) with trichlorosilane at 40 °C in the presence of 1 × 10−3 or 1 × 10−4 molar amounts of palladium catalyst prepared in situ from [PdCl(η3-C3H5)]2 and (S)-2-diphenylphosphino-2′-methoxy-1,1′-binaphthyl ((S)-MeO-MOP) proceeded with unusual regioselectivity and with high enantioselectivity to give high yields of 2-(trichlorosilyl)alkanes together with a minor amount of 1-(trichlorosilyl)alkanes. Optically active alcohols, RCH(OH)CH3, were obtained by oxidation of the carbon–silicon bond. Regioselectivities for forming 2-silylalkanes over 1-silylalkanes and enantiomeric purities of alcohols are as follows: R = n-C4H9: 89/11, 94% ee (R). R = n-C6H13: 93/7 95% ee (R). R = n-C10H21: 94/6, 95% ee (R). R = PhCH2CH2: 81/19, 97% ee (S). R = PhCH2CH2CH2: 80/20, 92% ee (R). R = cyclo-C6H11: 66/34, 96% ee (R). A similar hydrosilylation of 1-alkenes, 4-pentenyl benzoate and 1,5-heptadiene gave corresponding 2-alkanols of 90% ee and 87% ee, respectively, the ester carbonyl and the internal double bond remaining intact.
Hydrocracking of Acenaphthene over a Sulfided Ni–Mo/Al2O3 Catalyst
Authors: Miki Yasuo , Sugimoto Yoshikazu
Published: July 2006

The selectivity of ring opening was investigated for the hydrocracking of acenaphthene under an initial hydrogen pressure of 6 MPa and in the temperature range from 390 to 450 °C. Major products were classified into the following six components: tetrahydroacenaphthylene, hexahydroacenaphthylene, perhydroacenaphthylene, ring opening products (bicyclic compounds and monocyclic compounds), alkylation products (tricyclic compounds of C13 or larger), and dimerization products (biacenaphthene and their hydrogenated compounds). Ring opening of acenaphthene proceeded via two routes: the direct ring opening of acenaphthene and ring opening after hydrogenation to hexahydroacenaphthylene. In the former reaction only 1-ethylnaphthalene was produced, while 1,8-dimethylnaphthalene and its hydrogenated products were not observed. In the latter reaction, on the other hand, two types of ring opening of a C–C bond adjacent to the benzene ring, the opening of a saturated five-membered ring to produce 1-ethyltetralin and the opening of a saturated six-membered ring to produce 1-propylindane, were observed.
Electrochemical Study of the Micellization of Hexadecylpyridinium Bromide in Binary Methanol–Water Mixtures
Authors: Alizadeh Naader , Gharibi Hossein , Shamsipur Mojtaba
Published: July 2006

A membrane electrode selective to hexadecylpyridinum bromide was used to study the micellization of the surfactant in various methanol–water mixtures at 25 °C. There is a linear relationship between log cmc and the weight percent of methanol in solvent mixtures. The degree of counter-ion dissociation at different solvent compositions is reported. The degree of methanol attachment was found to be 2.04. The charged phase-separation model was used to express the mechanism of the mixed micelle formation.
Structures of Bis(phenylthio/seleno)dibenzothio/selenophenes with Short Intramolecular S···S and Se···Se Contacts
Authors: Yasui Masanori , Murata Shin , Iwasaki Fujiko , Furukawa Naomichi
Published: July 2006

The crystal structures of 1-phenylsulfinyl-9-phenylthiodibenzothiophene (1), 1,9-bis(phenylthio)dibenzothiophene (2), 1,9-bis(phenylthio)dibenzoselenophene (3), and 1,9-bis(phenylseleno)dibenzoselenophene (4) have been determined by an X-ray method in order to investigate the existence of a short intramolecular S···S or Se···Se contact. The crystal data are: 1, C24H16OS3, Mw = 416.59, Monoclinic, P21/n, a = 9.980(4), b = 8.843(4), c = 21.933(9) Å, β = 92.20(4)°, V = 1934(1) Å3, Z = 4, R = 0.028, wR = 0.027 for 2899 observed reflections. 2, C24H16S3, Mw = 400.59, Monoclinic, P21/n, a = 17.862(2), b = 8.050(2), c = 13.549(2) Å, β = 95.74(1)°, V = 1938.4(5) Å3, Z = 4, R = 0.053, wR = 0.075 for 3251 refined reflections (R = 0.057 for 3256 observed reflections). 3, C24H16S2Se, Mw = 447.48, Monoclinic, P21/n, a = 17.899(4), b = 8.086(2), c = 13.631(2) Å, β = 96.33(2)°, V = 1960.8(7) Å3, Z = 4, R = 0.046, wR = 0.070 for 2818 refined reflections (R = 0.050 for 2822 observed reflections). 4, C24H16Se3, Mw = 541.27, Monoclinic, P21/n, a = 18.094(2), b = 8.1571(6), c = 13.723(1) Å, β = 96.51(1)°, V = 2012.4(3) Å3, Z = 4, R = 0.066, wR = 0.066 for 3095 refined reflections (R = 0.067 for 3096 observed reflections). The nonbonding distances between two S atoms of phenylthio groups are 3.016(1), 3.012(1), and 2.973(1) Å for 1, 2, and 3, respectively. The distance of Se···Se of 4 is 3.070(1) Å. These distances correspond to 82.0, 81.8, 80.8, and 76.8% of the sum of the van der Waals radii for 1, 2, 3, and 4, respectively. Dibenzothiophene frameworks show severe deformation based on the steric effect of the 1,9-disubstituents. The dihedral angles between the benzene rings and the thiophene/selenophene rings are 6.6—8.5°. Two S/Se atoms of the phenylthio/seleno groups deviate from the thiophene/selenophene ring by about 1 Å on the opposite sides from each other.
High-Resolution Solid-State 13C NMR Studies on Molecular Motions and Solid-State Polymerization of Octatetraynes
Authors: Hayamizu Kikuko , Okada Shuji , Doi Takanori , Kawanami Hajime , Kikuchi Naoto , Matsuda Hiro , Nakanishi Hachiro
Published: July 2006

The effects of monomer alignment on the solid-state polymerizations of five octatetraynes and a butadiyne to produce polydiacetylenes were studied. Structural relaxations of the resulting polymers were found to occur over long time intervals. Solid-state high-resolution 13C NMR spectra were observed for six symmetrical monomers having alkyl chains (C14H29) and side chains containing either urethane or p-toluenesulfonate and the derived polydiacetylenes (PDA’s). The spin-lattice relaxation times (T1) of the PDA’s were also measured. The alignment and mobility of the monomers, which are closely related to the solid-state polymerizability and structure of the resulting polymers, are reflected in the solid-state 13C NMR spectra of the monomers.

The PDA’s with urethane side chains were found to have slow structural relaxation. When the number of spacer methylenes between the acetylenic carbon and the urethane moiety is odd, a planar main-chain structure was assumed. It was found that PDA-4A’s having an odd number of spacer methylenes achieved a more homogeneous structure after long-term relaxation than a PDA-4A with an even number of spacer methylenes.
Electrical Transport Properties of Perchlorate-Doped Oriented Polyacetylene
Authors: Miyamae Takayuki , Mori Takehiko , Seki Kazuhiko , Tanaka Jiro
Published: July 2006

The electrical conductivities of perchlorate-doped highly oriented polyacetylene films were measured from 290 to 1.5 K. The conductivity and its anisotropy were significantly enhanced by stretching. The value of the conductivity was 18000 S cm−1 at 190 K, and remained at 14000 S cm−1, even at 1.5 K. The extraordinary high conductivity at very low temperature showed that the film is really metallic. The temperature dependence of the conductivity could be expressed as the sum of two terms : One is almost a temperature-independent term, which may be due to a very weakly localized free carrier; the other is due to a three-dimensional variable-range hopping mechanism of a more localized carrier. The conduction mechanism is discussed in terms of the polson model of doped polyacetylene.
Properties of Hydrogel Membranes of Poly(vinyl alcohol) and Poly(acrylic acid) under a Pressure Gradient
Authors: Kiyono Ryotaro , Niimi Yoshiharu , Tasaka Masayasu
Published: July 2006

The dependence of the electric potential difference on time under a pressure gradient across hydrogel membranes, obtained by esterification of poly(vinyl alcohol) and poly(acrylic acid), was measured. At the moment when a pressure difference was applied, a sharp spike of the electric potential difference was observed. The overall variation of the electric potential difference on time consisted of two different processes. One of them, which gradually increased with time, and finally reached a steady-state value, reflects a relaxation of polymer chains dissolved in the liquid phase of the gel membrane under the pressure difference. The other, which showed a sharp inverse spike just after applying the pressure difference, and reached zero immediately, may have been caused by a transformation of the membrane matrix due to a sudden change in pressure before the migration of the water, that is, by compaction of the membrane matrix. When hydrogen molecules of the carboxyl groups in the gel membrane were exchanged with potassium ions, the gel membrane expanded. The relationship between the magnitude of the electric potential difference for each of the forms and the properties of the membranes is discussed.
Synthesis of N-Hydroxy-N-(o-chlorophenyl)-N′-(p-methoxyphenyl)benzamidine Hydrochloride and Its Reactions with Various Metal Ions
Authors: Tiwari Sushil Chandra , Sharma K N , Mohabey Hemlata
Published: July 2006

A new reagent N-hydroxy-N-(o-chlorophenyl)-N′-(p-methoxyphenyl)benzamidine hydrochloride, has been synthesized and is characterized on the basis of mp, elemental analysis, IR and UV spectra. The reactions of the reagent with metal ions suggest that new methods can be developed for gravimetric and extraction spectrophotometric determination of metal ions. The reagent has been successfully used for the extraction-spectrophotometric determination of vanadium(V) in presence of phenol. Many common ions including Co2+, Zn2+, Ag+, Mn2+, etc. do not interfere in the determination. The method has been applied for the determination of vanadium in steel samples.
Preparation and NMR Spectra of Hexacoordinate Metal Complexes of Mono(N-ethylethanediamine) and Mono(N-benzylethanediamine) and Crystal Structure of [Co(NH3)4(N-benzylethanediamine)] (NO3)3·1.5H2O
Authors: Kurosaki Hiromasa , Koga Sayuri , Goto Masafumi
Published: July 2006

Mono N-ethylethanediamine and N-benzylethanediamine complexes of Co(III), Fe(II), and Fe(III) with four cyano or ammine groups were prepared. Their 1H NMR spectra were measured to determine the conformation of N-ethyl and N-benzyl groups. These N-alkyl groups take pseudo-equatorial orientation at the coordinated secondary amine. The most preferred conformation is that the methyl and phenyl groups are anti with respect to the central metal ions. The crystal structure parameters of [Co(NH3)4(N-benzylethanediamine)](NO3)3·1.5H2O were determined: P21, Z = 2, a = 8.639(3), b = 21.240(3), c = 10.897(2) Å, β = 94.11(1)°. The crystallographically independent Co complex cations had opposite absolute configuration around coordinated secondary amine sites and the benzyl groups are anti to the cobalt atom.
Cobalt(III) Complexes with [N6−nXn]-Type Ligands. VIII. Preparation and Properties of Isomers of the (Salicylaldoximato)(triethylenetetramine)cobalt(III) Complexes and Crystal Structure of cis-β1-(RS, SR)-[Co(salal)(trien)]Cl·(CH3COCH3)·2H2O
Authors: Toyota Eiko , Umakoshi Keisuke , Yamamoto Yoshihisa
Published: July 2006

The title complexes of cis-β1-(RR,SS)-, cis-β1-(RS,SR)-, cis-β2-(RR,SS)-, and cis-β2-(RS,SR)-[Co(A)(trien)]Cl·nH2O and cis-β1-(RR,SS)-, cis-β1-(RS,SR)-, and cis-β2-(RR,SS)-[Co(B)(trien)]Cl2 have been obtained from a reaction mixture of cis-α-[CoCl2(trien)]Cl, Ag2O, and salicylaldoxime (Chart 1).

Separations of the A- and B-type complexes, and of the geometrical isomers of cis-β1 and β2, as well as those of the diastereoisomers of (RR,SS) and (RS,SR) were attempted by using Dowex 50W-X2 column chromatography. The B-type complexes were obtaind from the reaction mixture of the corresponding A-type complexes and hydrochloric acid. The structure of cis-β1-(RS,SR)-[Co(A)(trien)]Cl·(CH3COCH3)·2H2O has been confirmed by an X-ray analysis. Crystal data: CoC16H33N5O5Cl, orthorhombic, Pb21a, a = 14.091(2), b = 22.385(3), c = 7.011(2) Å, V = 2211.5(6) Å3, Z = 4, and R = 0.076. A property between A- and B-type complexes has been compared in the IR, NMR spectra, and electric conductivity in aqueous solution; i.e., the CH=N streching vibrations (ca. 1590 cm−1) of A-type complexes have a lower wavenumber than those (ca. 1600 cm−1) of B-type complexes. The chemical shifts (δ = 148—150) of the CH=N carbon signal of A-type complexes are at a higher field than those (δ = 160—162) of B-type complexes in D2O. The chemical shifts (δ = 7.9—8.0) of the CH=N proton signal of A-type complexes are at a higher field than those (δ = 8.2—8.4) of B-type complexes in D2O. The electric conductivities in aqueous solutions of A- and B-type complexes were ca. 120 and ca. 220 S cm2 mol−1, respectively. The absorption spectra of cis-β-(RS,SR)-isomers and the corresponding (RR,SS)-isomers showed two peaks at around 350 and 540 nm and three peaks at around 350, 470, and 540 nm, respectively.
Multielement Determination of Rare Earth Elements by Liquid Chromatography/Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Sawatari Hideyuki , Asano Takaaki , Hu Xincheng , Saizuka Tomoo , Itoh Akihide , Hirose Akio , Haraguchi Hiroki
Published: July 2006

The rapid determination of rare earth elements (REEs) has been investigated by an on-line system of high performance liquid chromatography/multichannel inductively coupled plasma atomic emission spectrometry. In the present system, all REEs could be detected simultaneously in a single chromatographic measurement without spectral interferences. Utilizing a cation exchange column and 2-hydroxy-2-methylpropanoic acid aqueous solution as the mobile phase, the detection limits of 0.4—30 ng ml−1 for all REEs were obtained. The system was applied to the determination of REEs in geological standard rock samples and rare earth impurities in high purity rare earth oxides. The REEs in standard rocks could be determined by the present HPLC/ICP-AES system without pretreatment after acid digestion, although the detection limits were not sufficient for the analysis of rare earth oxides.
Photoisomerization and Photocyclization Reactions of 1-Styrylanthracene
Authors: Karatsu Takashi , Kitamura Akihide , Zeng Hualing , Arai Tatsuo , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

On triplet sensitization, 1-styrylanthracene (1SA) undergoes adiabatic cis → trans one-way isomerization (3c* → 3t*) similarly to 2-anthrylethylenes. However, upon direct irradiation, cis-1SA in the singlet excited state mostly undergoes cyclization to a dihydrophenanthrene-type product (DHP), 4a,4b-dihydrobenzo[b]chrysene, competing with an inefficient intersystem crossing to 3c* followed by one-way isomerization. The produced DHP, in deaerated benzene, is reverted to cis-1SA by a thermal (Ea = 14.9 kcal mol−1) or a photochemical pathway; however, under an oxygenated atmosphere DHP gives benzo[b]chrysene. A failure in the production of a cyclized product upon the excitation of trans-1SA shows that the isomerization really takes place in a one-way fashion.
Stilbene Dimer Radical Cations in the Radiolyses of Stilbenes and 1,2,3,4-Tetraphenylcyclobutanes
Authors: Tojo Sachiko , Morishima Kazuhiro , Ishida Akito , Majima Tetsuro , Takamuku Setsuo
Published: July 2006

The reaction of the stilbene radical cation formed by pulse radiolysis or γ-radiolyses is explained based on neutralization as well as the formation of a π-type stilbene dimer radical cation (π-St2+•), converting to the σ-type St2+• (σ-St2+•). The r-1,c-2,t-3,t-4-tetraphenylcyclobutane radical cation generated in a rigid matrix at 77 K which converted to σ-St2+• upon warming. Both r-1,c-2,t-3,t-4- and r-1,t-2,c-3,t-4-tetraphenylcyclobutane radical cations underwent photochemical cycloreversion to π-St2+• upon irradiation at wavelengths longer than 390 nm at 77 K, and converted to σ-St2+• upon warming. It is suggested that π-St2+• has overlapping arrangements of π-electrons, while σ-St2+• has radical and cation centers on the 1- and 4-positions of the C4 linkage.
Design, Synthesis, and Characterization of Carbon Nanotube Solubilizers Carrying a Reactive Group
Authors: Narimatsu Kaori , Nishioka Junichi , Murakami Hiroto , Nakashima Naotoshi
Published: July 2006

We describe the design of new carbon nanotube (CNT) solubilizers based on a novel concept, that is, “reactive carbon nanotube solubilizers” that are compounds carrying a reactive moiety for the introduction of the desired functional groups.
Preliminary Study on Cogeneration of Carbon Nanotubes and C2 Hydrocarbon in CH4/H2 Corona Discharge
Authors: Yu Kailu , Ruan Guoling , Ben Yuheng , Zou Jijun
Published: July 2006

La-doped carbon nanotubes and valuable C2 hydrocarbon (C2H2 and C2H4) are simultaneously generated in CH4/H2 corona discharge. The analysis of off gas indicates that the addition of anodic alumina membrane shows no influence on plasma methane conversion reactions.
Synthesis of 1D Nanorutile (α-TiO2) by Interfacially Initiating Redox Reaction at Low Temperature
Authors: Li Xuebing , Liu Yankuan , Li Tanwei , Zhang Zude
Published: July 2006

One-dimensional nanorutile crystals have been synthesized by interfacially initiating redox reaction between titanium trichloride (TiCl3) and benzoyl peroxide (BPO) in a hydrothermal way at a relatively low temperature. It not only produced a large quantity of rutile nanorods but also provided a novel method to synthesize 1D nanomaterials at low temperature.
Dramatic Effects of the Substituents on the Solid-state Fluorescence Properties of Structural Isomers of Novel Benzofuro[2,3-c]oxazolocarbazole-type Fluorophores
Authors: Ooyama Yousuke , Harima Yutaka
Published: July 2006

Structural isomers of novel benzofuro[2,3-c]oxazolocarbazole-type fluorophores have been synthesized and their photophysical properties in solution and in the solid state were investigated; remarkable differences in the absorption and fluorescence spectra were observed between structural isomers in both states, and a drastic solid-state fluorescence enhancement was found to be caused by N-alkylation of fluorophores.
An Improved Volume Measurement for Determining Soil Water Retention Curves
Authors: Péron H , Hueckel T , Laloui L
Published: July 2006

The complete determination of soil water retention curves requires the sample volume to be measured in order to calculate its void ratio and degree of saturation. During drying in the pressure plate apparatus, cracks often appear in the sample altering its deformation and evaporation patterns. Consequently, this causes a significant scatter in the volume measurement when using the volume displacement method. This paper proposes a simple method to avoid cracking, by limiting friction and adhesion boundary effects, to allow for unrestrained shrinkage of the sample. Such modification of the technique decreases the measurement error by a factor of three.
Experimental Measurement of Selected Snowboard Mechanical Properties
Authors: Grewal D , Lund C , Rossetter E
Published: July 2006

Snowboard manufacturers attempt to design boards with mechanical properties that provide desirable ride and handling characteristics, adequate strength, and low manufacturing costs. Snowboards are typically a sandwich composite of several individual layers that vary significantly in geometry and composition. To better understand the influence of core materials and construction on a board's stiffness, ultimate failure load, and stored energy, several commercially available snowboards were tested to failure in three point bending. A series of representative boards were tested with three different core materials: foam, wood, and honeycomb. The results show that stiffness and ultimate failure load are most strongly influenced by the core wrap thickness, while the energy storage is most strongly influenced by the core material and construction method used.