bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorenone Monomer Dianion Studied by 1H and 13C NMR and Charge Density Distribution
Authors: Hirayama Masatoshi , Ohhata Hiroshi 
Published: July 2006

Abstract
The diamagnetic monomer dianion of fluorenone was prepared from 1,2-dimethoxyethane solution of neutral molecule in contact with excess sodium metal at −5 °C for 5 days and its 1H and 13C NMR spectra were measured. The possibility that a pinacolate-type dimer dianion occurs in an equilibrium system was ruled out from reactivity with oxygen, water, deuterium oxide, and reducible aromatics in addition to the analysis of NMR spectra. The charge density distribution of neutral and dianion molecules was estimated by MO calculations. Comparison between experimental and theoretical 13C shifts suggested a strong interaction of sodium ions with carbonyl group. It is presumed that an anormalous diamagnetic ring current in 14π-peripheral structure is responsible for poor correlation between theoretical and observed 1H shifts.
Oxidation of Ketones over Metal Oxide Catalysts. II. Biacetyl Synthesis over Co3O4-Lanthanoid Oxide Catalysts
Authors: Takita Yusaku , Hori Fumiaki , Yamazoe Noboru , Seiyama Tetsuro 
Published: July 2006

Abstract
The effects of the addition (10 atomic%) of lanthanoid oxides into Co3O4 on the oxidation of methyl ethyl ketone (MEK) were studied. The addition of La2O3 brought about marked enhancement of the rate of biacetyl (BA) formation. MEK conversion increased by a factor of 2.8 and the BA selectivity was improved at 450–500K owing to the suppression of deep oxidation. The addition of CeO2 much improved the MEK conversion but BA selectivity decreased to less than 50% and the scission reaction leading to acetaldehyde and acetic acid was enhanced. The addition of Pr6O11 improved MEK conversion but the addition of Nd2O3, Gd2O3, or Er2O3 showed little effect on MEK conversion. The reduction of both scission reaction and deep oxidation and the compensative increase in BA selectivities were observed. An approximately linear relationship was found between the specific rate of BA formation of the catalysts and logarithmic solubitity product constants of hydroxides of tervalent lanthanoid elements added, suggesting that the basicity of the catalysts is one of major factors for BA formation. The maximum efficiency (23.4%) of BA formation was attained at a La content of ca. 10 at.%.
The Structure of the Cyclodextrin Complex. XX. Crystal Structure of Uncomplexed Hydrated γ-Cyclodextrin
Authors: Harata Kazuaki 
Published: July 2006

Abstract
Crystal structure of uncomplexed γ-cyclodextrin, C48H80O40·14.1H2O, was determined by the X-ray method. The crystal is monoclinic and the space group is P21 with cell dimensions; a=16.847(2), b=11.098(2), c=20.271(2) Å, and β=104.97(1)°. The structure was solved by the inspection of a Patterson map and the R-map method combined with the rigid-body least-squares technique and refined by the block-diagonal least-squares method to the R-value of 0.061 for 5099 reflections (sinθ⁄λ≥0.57). γ-Cyclodextrin is in a round shape and somewhat distorted from the regular octagonal symmetry. Intramolecular hydrogen bonds are formed between adjacent glucose residues and maintain the round structure of γ-cyclodextrin. γ-Cyclodextrin molecules are arranged in a cage-type packing, and 7.1 water molecules, occupying 14 sites, are located within the host cavity.
Effects of Some Additives on Proton-Transfer Reaction Studied by Ultrasonic Methods
Authors: Yoshida Yukio , Nishikawa Sadakatsu 
Published: July 2006

Abstract
Ultrasonic absorption and velocity were measured in aqueous solutions of propylamine at 25 °C both in the absence and in the presence of 2 g dm−3 PVA(poly(vinyl alcohol)), 5 mol dm−3 urea and 1 mol dm−3 NaCl. No excess absorption was observed in these solutions without propylamine. A single relaxational absorption was observed in the concentration range from 0.0196 to 0.719 mol dm−3 of propylamine both in the presence and absence of the additives. The ultrasonic parameters have been found to be quite dependent on the concentration of propylamine and also on the structure of additives. This relaxational absorption has been attributed to the perturbation of an equilibrium associated with a proton-transfer reaction. The rate constants and the standard volume change of the reaction have been determined from the concentration dependences of the relaxation frequency and the maximum excess absorption per wavelength. As a result, it was discovered that the forward rate in a solution with PVA increased and those with urea and NaCl, on the other hand, decreased; also, the standard volume change associated with the reaction increased in a series of the solutions with urea, no additive, NaCl, and PVA. The data have been interpreted by means of the structural changes of the solvent water.
A Linear Response Polarizability Theory for an Extended Fano–DeVoe Model with Comments on the Joint Use of Both Short- and Long-Range Inter(sub)molecular Interaction Approximations
Authors: Ito Hirotoshi , I’Haya Yasumasa J 
Published: July 2006

Abstract
An approach to extend the Fano–DeVoe model is presented for copolymer systems by making use of the Green’s operator method within the dipole–dipole approximation. We derive a model Hamiltonian for a system by expanding its primitive Hamiltonian in terms of a bare complete basis set consisting of zero-order one-site and two-site excitation states in the first-order perturbation theory. A generalized extension of the Fano–DeVoe theory can be given by the polarizability tensor derived for this model Hamiltonian. As a more refined way, we derive another model Hamiltonian by expanding the primitive Hamiltonian of the system in terms of the corrected complete basis set consisting of the first-order excitation states. With such model Hamiltonians, we can fabricate polarizability theories on the same footing with the exciton wave function approaches based on the usual perturbation theory. Simplified schemes for the latter model Hamiltonians are applied to the copolymer system consisting of such chromophores that have permanent dipole moments in their ground states. Even if the constituent chromophores do not have permanent moments, extension of the Fano–DeVoe model is made by allowing for the total polymer ground state wave function corrected in terms of two-site excitation states. To circumvent the deficiency of the dipole approximation in the region of short separations of submolecules, we show a recipe as to how to make use of the monopole approximation together with the dipole approximation in conformity with the compromized idea of Moffitt.
Preparation and Time-Resolved in Situ Reflection Spectra of Bilayer Electrodes with Polythiophene Outer Layers
Authors: Murao Kenji , Suzuki Kazuhiro 
Published: July 2006

Abstract
Bilayer electrodes, Pt/poly-1/polythiophene [1: tris(4-vinyl-4′-methyl-2,2′-bipyridine)ruthenium(II) perchlorate], where polythiophene is derived from poly(3-methylthiophene) [poly(3-methyl-2,5-thienylene), abbreviated as PMeT] and poly(2,2′-bithiophene) [poly(2,2′-dithienyl-5,5′-ene), abbreviated as PBT], have been prepared. Electropolymerizations of MeT and BT at Pt/poly-1 occur at the platinum electrode surface, followed by phase separation of the polymer components which results in the bilayer structure. Significant imbalance, observed between charge densities involved in the cathodic and anodic waves of the cyclic voltammogram for Pt/poly-1/PBT, is explained as being due to the positive charge leakage from the PBT layer to the platinum substrate through the 2+/3+ redox level of the intervening poly-1 during the potential sweep in the negative direction. This charge leakage is ascribed to the consequence of the closely located oxidation potential of PBT to that of the 2+/3+ of poly-1 (E°′=+0.875 V vs. Ag/Ag+). Time-resolved in situ reflection spectra taken at Pt/poly-1/PMeT immersed in electrolytic solutions give evidence for the mediated redox reactions of PMeT by the poly-1 layer. The spectral changes strongly suggest the transient occurrence of polarons during the doping process.
Vapor Phase Fluorination of Silica Surface with Chlorofluoromethanes and CF4
Authors: Okazaki Susumu , Kurosaki Akito 
Published: July 2006

Abstract
For a surface modification, fluorinations of silica samples including a quartz fiber and a commercial glass fiber, were carried out at around 500 °C in a conventional flow reactor. The surface compositions before and after the fluorination were determined by XPS analyses. Among chlorofluoromethanes and CF4, CCl3F was the most effective for fluorination. Surface OH groups were completely removed or replaced by the fluorination. Adsorptions of water vapor, hexane, hexafluoropropene, and octafluorocyclobutane showed that the silica surface became more hydro- and lipophobic after the fluorination. On the contrary, the chlorofluoro-methanetreated surface exhibited a higher affinity to the perfluorocarbons compared to the untreated surface.
A New Detection Method of Electromigrating Ions through a Cation-Exchange Membrane
Authors: Kawaguchi Akihiro , Magaino Shin-ichi , Suzuki Takashi , Takeuchi Yasushi 
Published: July 2006

Abstract
An isotachophoretic analysis and electromigration of ions through a cation-exchange membrane have been investigated. K, Li, Na, and Cu ions were migrated at a constant current. The potential difference between fibrous ion exchanger and cathode reservoir was measured during migration of ion zone. The relative ionic mobility of K+, Na+, Li+, and Cu2+ calculated by potential difference was 1, 0.667, 0.420, and 0.218, respectively. The concentration of mobile cations in unit volume of the membrane was calculated by the amount of migration and the migration time of each ion. The concentration of mobile Li+ in the Li zone was about 10% lower than that of mobile K+ in the K zone. This difference in concentration is similar to the result by the usual isotachophoresis using a capillary tube. The migration time of each ion zone through detection part was proportional to the amount of migration. K+ and Li+ in the concentration range from 0.6×10−3 to 0.2 mol dm−3 were quantitatively determined by the migration time with reproducible errors less than ±5 %.
Properties of Alkali-Free Lead Phosphate Glasses as an Ion-Selective Electrode and Their Application to a Potentiometric Detector for Ion Chromatography
Authors: Nomura Tsuyoshi , Nakagawa Genkichi 
Published: July 2006

Abstract
The properties of alkali-free lead phosphate glasses containing silver oxide as an anion selective electrode were examined, and their application to a potentiometric detector for an ion chromatographic technique were developed. The series of these glasses are characterized by their low softening temperature and are only responsive to anionic substances. The featureless potential response of almost anions tested becomes a rather useful property as a detector for an ion chromatographic analysis of anions. The response characteristics and selectivity coefficients revealed that the glass composition of 10Ag2O : 55P2O5 : 25PbO : 10Al2O3 is the most suitable electrode materisl for anion chromatography. With this glass electrode, nonsuppressed anion chromatographic parameters were studied, including a comparison of an eluent composition, the flow rate and the retention time. This detector could be used in a high pH eluent without any interference of the large blank value. In paticular, the detector was highly sensitive to iodide ions. This may be due to the interaction of iodide ions with silver ions which are involved in membrane materials.
Preparation, Stereochemistry, and CD Spectra of Cobalt(III) Complexes with 1,3-Propanedithiolate and 1,3-Propanedisulfinate. Crystal Structure and Absolute Configuration of (−)460CD-(1,3-Propanedisulfinato)(3,6-diazaoctane-1,8-diamine)cobalt(III) Perchlorate Monohydrate
Authors: Okamoto Ken-ichi , Umehara Hideki , Hidaka Jinsai 
Published: July 2006

Abstract
The cis-α isomers of the 3,6-diazaoctane-1,8-diamine (trien) cobalt(III) complexes with 1,3-propanedithiolate (pdt) and 1,3-propanedisulfinate (pdsi) were selectively prepared and optically resolved. Of these isomers, the crystal structure and the absolute configuration of (−)460CD-[Co(pdsi)(trien)]ClO4·H2O have been determined by X-ray diffraction method. The complex cation takes a Δ-cis-α configuration. The 1,3-propanedisulfinate coordinates to cobalt atom through two sulfur atoms and its chelate ring takes a skew boat form with the λ conformation. The CD spectral behaviors in the d–d transition and the sulfur-to-metal (Co(σ*)←S(σ)) charge-transfer band regions are discussed in relation to the absolute configurations of the cobalt(III) complexes with sulfinate type sulfur donor atoms and the corresponding thiolate ones.
Mössbauer and DTA Studies on the Structure of Semiconducting Sodium Vanadate Glasses
Authors: Nishida Tetsuaki , Ogata Michiko , Takashima Yoshimasa 
Published: July 2006

Abstract
Distinct decreases in the quadrupole splitting of the tetrahedral Fe3+ ions and the Tg suggest a gradual change from the layer structure composed of the VO5 tetragonal pyramids to the chain structure composed of the VO4 tetrahedra. It is also concluded that nonbridging oxygen atoms are present in the VO4 tetrahedra.
Hydroxylation of Acetoxy-p-menthenes in the Cultured Cells of Nicotiana tabacum. Epoxidation of the Carbon–Carbon Double Bond
Authors: Hirata Toshifumi , Izumi Shunsuke , Ekida Teiji , Suga Takayuki 
Published: July 2006

Abstract
The process of the formation of glycols in the biotransformation of 1-acetoxy-p-menth-4(8)-ene and 8-acetoxy-p-menth-1-ene in the cultured cells of Nicotiana tabacum was examined. The formation of the glycols was found to result from epoxidation of the C–C double bond, followed by hydrolysis of the resulting epoxides.
Photochemical Reactions of Ethoxycarbonyl-Substituted Quinolines
Authors: Ono Isao , Hata Norisuke 
Published: July 2006

Abstract
The photochemical reactions of the quinoline derivatives substituted by an ethoxycarbonyl group at the 2-, 3-, and 4-positions of a quinoline nucleus have been investigated in several alcohols and cyclohexane. Irradiation of ethyl 4-quinolinecarboxylate (1) yielded ethyl 2-hydroxyalkyl-4-quinolinecarboxylates (4a–c) in alcohols and ethyl 2-cyclohexyl-4-quinolinecarboxylate (4d) in cyclohexane in a good yield, respectively. The photochemical reactions of ethyl 3-quinolinecarboxylate (2) showed remarkable solvent dependency. Irradiation in methanol and cyclohexane afforded a solvent-additive product, ethyl 4-hydroxymethyl-1,4-dihydro-3-quinolinecarboxylate (5a) and ethyl 4-cyclohexyl-1,4-dihydro-3-quinolinecarboxylate (5b), while such photoaddition of the solvent did not proceed in ethanol and 2-propanol but instead ethyl 1,4-dihydro-3-quinolinecarboxylate (6) and dimeric compounds were formed, both of which were unstable and finally reverted to 2 at room temperature in air. In the case of ethyl 2-quinolinecarboxylate two types of the products, ethyl 4-hydroxyalkyl-1,4-dihydro-2-quinolinecarboxylate (7) and ethyl 1,4-dihydro-2-quinolinecarboxylate (8) were obtained in ethanol and 2-propanol but the yields of those products were poor. On the basis of triplet quenching experiments, the photochemical reactions of those ethyl quinolinecarboxylates are suggested to occur through hydrogen abstraction from the solvents by the ring nitrogen in the S1 state.
Studies on Hydrogenation by Nickel Complexes. 5. The Selective Hydrogenation of 1,4-Cyclohexadienes to Cyclohexenes Catalyzed by a Nickel Complex
Authors: Sakai Mutsuji , Hirano Nobuo , Harada Fumiya , Sakakibara Yasumasa , Uchino Norito 
Published: July 2006

Abstract
1,4-Cyclohexadiene was hydrogenated selectively to cyclohexene with a nickel catalyst generated from bis(acetylacetonato)nickel(II), triethyldialuminium trichloride, and triphenylphosphine at 40 °C under an atmospheric pressure of hydrogen. The hydrogenation of eleven kinds of alkyl-substituted 1,4-cyclohexadienes gave the corresponding cyclohexenes in good yields by the nickel catalyst. The structural factors of the alkyl substituent on the diolefin are shown to affect the hydrogenation rate. The homogeneous nickel catalyst system, in which a nickel hydride complex NiH(PPh3)(AlCl4) is supposed to be an active species, was effective for the selective hydrogenation of the diolefin to the olefin. A plausible pathway involving π-allylnickel complexes for the hydrogenation is proposed.
Unequivalent Chemical Environment of Diene Groups in 1- and 2-Acyl Chains of Polymerizable Lipids Analyzed by Radical Polymerization
Authors: Ohno Hiroyuki , Takeoka Shinji , Tsuchida Eishun 
Published: July 2006

Abstract
1,2-Di-O-(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine is polymerized by radical initiators. An azobisisobutyronitrile (AIBN) and an azobis(2-amidinopropane) dihydrochloride (AAPD) are incorporated into hydrophobic membrane region of the lipid liposomes and an aqueous medium, respectively by sonication. The use of either AIBN or AAPD gives polymerization conversion of about 50% at 60 °C. This is not improved by the elongation of polymerization period at 60 °C or the increase of the amount of these radical initiators. The lyophilized lipids thus polymerized by either AIBN or AAPD are soluble in methanol suggesting the formation of linear polymers. Simultaneous polymerization by both AIBN and AAPD provides almost complete polymerization. AIBN and AAPD have been suggested to initiate radical polymerization of diene groups in 1- and 2-acyl chains, respectively. Potassium peroxodisulfate, another water-soluble radical initiator, yields polymerized liposomes with polymerization conversion of more than 80%. This corresponds to the polymerization of diene groups of not only 2- but also 1-acyl chains due to the hydroxyl radicals which are generated by the radial transfer in an aqueous medium. These different initiation reactions are attributed mainly to the unequivalent chemical environment of diene groups in 1- and 2-acyl chains.
Nucleotide Sequences of DNA and Their Structural Analysis. Categorical Discrimination of 5′-Splice Site Sequences in mRNA Precursors
Authors: Iida Yôichi 
Published: July 2006

Abstract
The signals which direct excision of introns from mRNA precursors in higher eukaryotes’ genes are not well-understood. Although a consensus sequence, (Remark: Graphics omitted.), has been proposed with the 5′-splice site, actual 5′-splice site sequences differ from it to a greater or lesser degree. In the present paper, structural analysis of 5′-splice site sequences was done by using quantification theory (class II). Nucleotide sequences were transformed into categorical data, and categorical discriminant analysis was carried out between 5′-splice site sequences and sequences other than 5′-splice site. Relative importance of each position of nucleotide sequence was then estimated by calculating partial correlation coefficient on each position.
Interaction of Divalent Metal Acids with Pentyl Alcohol and Isopentyl Acetate
Authors: Beg Mirza Aijaz , Kidwai Mohd Shakil 
Published: July 2006

Abstract
Extraction of monobasic divalent metal bromo acids in pentyl alcohol–benzene and isopentyl acetate–benzene mixtures was studied at room temperature (25 °C). Three molecules of pentyl alcohol ae well as of isopentyl acetate were associated with each metal acid molecule of cobalt and copper in the organic phase. Zinc, cadmium, and mercury acids take up two molecules of pentyl alcohol and one molecule of isopentyl acetate. Metal acids studied here mostly exist as monomer in the organic phase. In pentyl alcohol, however, copper acid is monomeric only at lower concentrations (4×10−5 to 2×10−4M) and dimeric at higher concentrations (3.3×10−4 to 1.4×10−3M).
Coordination Chemistry of New Sulfur-Containing Ligands: Transition Metal Complexes of N-Ethoxycarbonyl-1-pyrrolecarbothioamide
Authors: Chauhan Veena , Dikshit Sheo Kant 
Published: July 2006

Abstract
Reaction of N-ethoxycarbonyl-1-pyrrolecarbothioamide (Hept) with a variety of transition metal ions leads to the formation of [MnII(ept)2] (M=Ni, Cu, Pd, Pt), [MII(ept)2(py)] (M=Co, Ni), [RhICl(Hept)PPh3)]2, and [MIIICl(ept)2(H2O)] (M=Ru, Rh). Reaction of Hept with Ag(I), Cu(II), Pb(II), Hg(II), and Cd(II) under refluxing conditions yields the corresponding sulfides and an oxygenated form of the ligand (Hept), which was characterized as (Remark: Graphics omitted.). All metal complexes have been characterized on the basis of analytical, IR and electronic spectral, and magnetic measurement studies.
α,β-Epoxy Sulfoxides as Useful Intermediates in Organic Synthesis. IX. A Novel Synthesis of Alkyl Vinyl Ketones and Divinyl Ketones from Carbonyl Compounds and 1-Chloro-3-phenylthiopropyl Phenyl Sulfoxide as a Three-Carbon Homologating Agent
Authors: Satoh Tsuyoshi , Kumagawa Takumi , Sugimoto Atsushi , Yamakawa Koji 
Published: July 2006

Abstract
The α,β-epoxy sulfoxides easily derived from carbonyl compounds and 1-chloro-3-phenylthiopropyl phenyl sulfoxide were treated with sodium benzeneselenolate to give β-phenylthio carbonyl compounds in excellent yields. The phenylthio group was oxidized to the sulfinyl group and was then treated with a base to afford alkyl vinyl ketones in quite good yields. This reaction presents a novel method for the preparation of alkyl vinyl ketones from carbonyl compounds by three-carbon homologation. The treatment of α,β-epoxy sulfoxides mentioned above with benzenethiolate gave α,β′-bis(phenylthio) ketones. The elimination of the both thio groups afforded divinyl ketones.
Protein Engineering of Dihydrofolate Reductase. pH Dependency of Phe-31 Mutants
Authors: Taira Kazunari , Chen Jin-Tann , Fierke Carol A , Benkovic Stephen J 
Published: July 2006

Abstract
Site-specific mutations on dihydrofolate reductase from Escherichia coli at the Phe-31 site have generated (Try-31)-DHFR and (Val-31)-DHFR mutant enzymes. The pH dependence of logV and logV⁄KDHF for these enzymes suggests that protonation is important for both the interaction of dihydrofolate and the maximum velocity of the reaction. More importantly, a “hollow” is observed for the Tyr-31 mutant in a logV⁄K–pH profile, necessitating a modification of the wild-type kinetic scheme. The intrinsic pKa of 5.8, obtained based on the modified more general kinetic scheme, for the Tyr-31 mutant agrees well with that obtained from inhibition studies by 2,4-diamino-6,7-dimethylpteridine.
Electrooxidative Functionalizations of Dehydroabietic Acid
Authors: Uneyama Kenji , Katayama Tatsuo , Torii Sigeru 
Published: July 2006

Abstract
Dehydroabietic acid methyl ester (1) was converted into 7-acetoxydehydroabietic acid methyl ester by direct electrooxidation in acetic acid and 7-oxodehydroabietic acid methyl ester by ruthenium dioxide-mediated oxidation. Non-Kolbe type electrodecarboxylation of 1 resulted in the introduction of a double bond into the ring A of 1.
Synthesis and Characterization of Imidazolate-Bridged Trinuclear (Copper(II)–Manganese(II)–Copper(II)) Complexes
Authors: Matsumoto Naohide , Kanesaka Junko , Ohyoshi Akira , Nakamura Masaaki , Kohata Susumu , Okawa Hisashi 
Published: July 2006

Abstract
Imidazolate-bridged trinuclear(copper(II)–manganese(II)–copper(II)) complexes [CuLMn(tfa)2LCu]2H2O 1 and [CuLMn(hfa)2LCu]3H2O 2 have been prepared and characterized, where tfa=trifluoroacetylacetonate, hfa=hexafluoroacetylacetonate, H2L=unsymmetrical quadridentate Schiff base derived from the condensation reaction of acetylacetone, ethylenediamine, and 4-formylimi dazole with the mole ratio of 1:1:1. The magnetic susceptibility data were represented by a spin-only interaction model(1/2–5/2–1/2) with JMn-Cu value of −13 cm−1 for 1 and −8 cm−1 for 2.
Enantiotropy of 2,4-Diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine
Authors: Kamagata Kazuo , Yoshida Shuuji 
Published: July 2006

Abstract
Measurements using elementary analysis, differential thermal analysis, IR spectroscopy, and X-ray diffractometry have revealed that the title triazine assumes two crystalline forms α and β. The conversion from α to β proceeds rapidly at 230 °C, whereas the reversal takes place slowly at 60 °C and 95% RH.