bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Crystal and Molecular Structure of Bis(4-methylpyridine)bis(thiocyanato)cadmium(II) in Polymeric Form, [Cd(SCN)2(CH3C5H4N)2]n
Authors: Taniguchi Masahiro , Shimoi Mamoru , Ouchi Akira 
Published: July 2006

Abstract
The crystal and molecular structure of the title complex was determined by a single-crystal X-ray diffraction technique. The crystal is triclinic with a space group P\bar1, a=11.323(4), b=18.383(10), c=9.284(5) Å, α=104.62(4), β=114.26(3), γ=77.71(4)°, Z=4; the final R value obtained was 0.034. All cadmium atoms are lined approximately along the [111] axis and each pair of metal atoms are bridged by two thiocyanate ions (SCN), one of which is S-coordinated and the other is N-coordinated to the same side metal atom. Also bonded with two nitrogen atoms of 4-methylpyridine (pic) ligands, the metal atom is 4N2S-hexa-coordinated and is in an octahedral geometry. The cadmium atoms, where the ligated respective pairs of N(SCN), N(pic), and S(SCN) atoms are all in a trans configuration, and the metal atoms where the ligated respective pairs of N(pic) and S(SCN) are in cis, while the pair of the N(SCN) in trans configuration, appear alternatively in the polymer chain.
ESR Study of Radical Halogen Abstractions. Participation of Electron-Transfer Mechanism in the Radical Halogen Abstractions
Authors: Kuwae Yoko , Kamachi Mikiharu , Hayashi Koichiro , Viehe Heinz G 
Published: July 2006

Abstract
The halogen-abstraction reactions of carbon radicals were investigated as a model of the chain-transfer reaction in the radical polymerization of vinyl compounds. The kinetics of the halogen-abstraction reaction of carbon radicals ((CH3)2\dotCX, X=OC6H5, OCOCH3, SC6H5, C6H5, and CN) from tetrahalomethanes(CBr4, CBrCl3, CCl4) were studied in toluene at 80 °C by the ESR method using 2-(t-butyl)thioacrylonitrile as a spin-trapping reagent. The reactivity of these radicals for each halomethane decreased in the order X: OC6H5&gt;OCOCH3&gt;SC6H5&gt;C6H5&gt;CN The reactivity of tetrahalomethanes for each radical decreased in the order CBr4&gt;CBrCl3&gt;CCl4. Results are explained by taking into account the electron-transfer process from carbon radicals to tetrahalomethanes. Absolute rate constants of the halogen abstraction of (CH3)2\dotCCN and (CH3)2\dotCC6H5 from CBr4 and CBrCl3, and of their additions to 2-(t-butylthio)acrylonitrile were estimated by the spin-trapping method, and they were compared with available data for similar reactions.
Microheterogeniety in Aqueous Mixtures of Hydrophobic Solutes through Viscosity Studies
Authors: Ramanamurti M V , Prabhu P V S S , Bahadur S L 
Published: July 2006

Abstract
Precise viscosity data for aqueous binary mixtures of ethylene glycol (EG), 2-methoxyethanol (ME), and 1,2-dimethoxyethane (DME) at different mole fractions and at various temperatures are presented. EG behaves as a structure breaker showing negative deviation in viscosity–composition curve. Hydrophobic solutes ME and DME showed typical maximum in viscosity–composition curve in water rich region; attributed to the existence of “microheterogeniety” in these mixtures.
Solvent Effect on Lifetime of Triplet Exciplex between Chloranil and Durene
Authors: Kobashi Harumichi , Kondo Tomoyuki , Funabashi Masa-aki 
Published: July 2006

Abstract
The triplet exciplex between chloranil (CA) and durene (DH) shows a decay which is associated with solvent viscosity rather than polarity, in spite of having a full charge-transfer (CT) character.
The Asymmetric Ullmann Coupling Reaction of (S)-2,2′-Bis(1-bromo-2-naphthoyloxy)-1,1′-binaphthyl Revisited. Formation of 24-Membered Optically Pure Cyclic Dimer as Well as 12-Membered Cyclic Monomer
Authors: Miyano Sotaro , Handa Shigeru , Tobita Masayuki , Hashimoto Harukichi 
Published: July 2006

Abstract
The copper-promoted Ullmann reaction of the title diester proceeded with high stereoselectivity to give 24-membered optically pure cyclic dimer of (S,S,S,S)-configuration as well as 12-membered monomeric cycle of (S,S)-configuration. The reaction also gave reduced, open-chain dimer enriched in (S,R,S)-diastereomer over (S,S,S)-counterpart (17% d.e.). Stereochemical course to the cyclic dimer was discussed considering the result that the intermolecular Ullmann coupling of chiral alcohol esters of 1-bromo-2-naphthoic acid poorly induced axial chirality in the joining of the two naphthyl units.
The Determination of a Small Amount of Biological Constituent by the Use of Chemiluminescence. VII. An Attempt of Cyclic Immunoaffinity Chromatography
Authors: Hara Tadashi , Toriyama Motohiro , Ebuchi Takashi , Imaki Masakatsu 
Published: July 2006

Abstract
An immunoaffinity chromatography has been established by combining a chemiluminescence detector developed by the authors with two kinds of immunoaffinity columns connected in series. According to the present method, human serum albumin and ovalbumin in the range of 100 ng to 15 μg in their mixtures could be continuously and selectively determined.
Electrochemistry of the Redox-Active Langmuir–Blodgett Films Coated on Glassy Carbon Electrodes
Authors: Fujihira Masamichi , Araki Toshinari 
Published: July 2006

Abstract
In order to study the electrochemical behavior of a redox species in the Langmuir–Blodgett (LB) film on a glassy carbon (GC) electrode, three kinds of amphiphilic redox compounds, each carrying an anthraquinone, a viologen, and a ferrocene moiety, were confined on the electrode surfaces. Prior to the deposition of the film on the electrode, surface pressure–area isotherms for a number of mixed films of the redox-active amphiphiles and arachidic acid were recorded and the stability of the monolayers was discussed. Finally, the cyclic voltammetric behavior of the LB film-modified electrodes was discussed in terms of the changes in the structure and the nature of the LB film caused by the redox reactions.
Mössbauer and DTA Studies of Superionic Conducting AgCl–Ag2O–B2O3 Glasses
Authors: Nishida Tetsuaki , Ogata Michiko , Takashima Yoshimasa 
Published: July 2006

Abstract
A structural study of silver borate glasses containing 20 or 30 mol% AgCl and 1 mol% Fe2O3 has been performed by means of Mössbauer spectroscopy. The distinct decreases in the Mössbauer parameters observed in the borate glasses with Ag2O contents higher than about 10 mol% suggest that chloride ions are covalently bonded with tetrahedral iron or boron atoms as nonbridging chlorine. On the other hand, chloride ions are considered to be ionically bonded with Ag+ ions at the interstitial sites of the three-dimensional network composed of BO3, BO4, and FeO4 units when the Ag2O content is lower than 10 mol%. Measurements of the glass transition temperatures and the electric conductivity show a good agreement with the Mössbauer results, suggesting that mobile and electric conducting Ag+ ions change their configurational sites from the interstitial sites which are close to Cl− ions to different interstitial sites which are close to the nonbridging chlorine atom.
Calorimetric and Spectrophotometric Studies of Copper(II) Chloro Complexes in Dimethyl Sulfoxide
Authors: Ishiguro Shin-ichi , Suzuki Honoh , Jeliazkova Bojana G , Ohtaki Hitoshi 
Published: July 2006

Abstract
Complex formation equilibria between copper(II) and chloride ions have been studied by calorimetric and spectrophotometric titrations in dimethyl sulfoxide (DMSO) containing 0.2 mol dm−3 (C2H5)4NClO4 or 1 mol dm−3 LiClO4 as a constant ionic medium at 25 °C. Both calorimetric and spectrophotometric data obtained were well explained in terms of formation of [CuCln](2−n)+ (n=1–4) in each solution, and their formation constants, enthalpies and entropies were determined. It was found that the complexation at each step was appreciably suppressed in the LiClO4 DMSO solution compared to that in the (C2H5)4NClO4 one, which was ascribed to the extensive formation of LiCl ion-pairs in the former solution. As well as in N,N-dimethylformamide (DMF), positive values of stepwise ΔHn° and ΔSn° (n=1–3) and negative ΔH4° values were observed in DMSO. However, the ΔSn° (n=1, 2, and 4) values in DMSO were appreciably smaller than the corresponding ones in DMF. The result was interpreted in terms of stronger intermolecular interactions in the bulk DMSO than those in DMF. The entropies of transfer of [CuCln](2−n)+ (n=0–4) from DMF to DMSO were significantly positive. This result also suggested that DMSO is a highly associated solvent. Electronic spectra of individual copper(II) chloro complexes were extracted from the spectra measured by varying molar ratios of chloride to copper(II) ions in solution. In contrast to the electronic spectra of Cu2+, [CuCl]+ and [CuCl2], the spectra of [CuCl3]− and [CuCl4]2− in DMSO were not appreciably different from those in DMF, indicating that solvation of these complexes are rather weak in both solvents.
Design of the Synthetic Route for Peptides and Proteins Based on the Solubility Prediction Method. I. Synthesis and Solubility Properties of Human Proinsulin C-Peptide Fragments
Authors: Narita Mitsuaki , Ogura Toshihiko , Sato Kazuhiro , Honda Shinya 
Published: July 2006

Abstract
The usefulness of the solubility prediction method is demonstrated using relatively small peptide fragments of human proinsulin C-peptide. The propriety of the solubility prediction method for peptides having polar side chains is also examined in the following respects: (1) Peptide intermediates smaller than a heptapeptide have high solubility regardless of their &lt;Pc&gt; values; (2) the &lt;Pc&gt; values of peptide intermediates are useful for judging solubility of peptide intermediates equal to or larger than an octapeptide level; (3) the Pro residue in a central position of a peptide chain is effective for increasing peptide solubility; and (4) there is critical chain length for peptide insolubility caused by a β-sheet aggregation. A strategy suitable for the design of the synthetic route for human proinsulin C-peptide is subsequently discussed on the basis of the solubility prediction of peptide intermediates.
Infrared Absorption Study of Human Proinsulin C-Peptide Fragments in Dichloromethane
Authors: Narita Mitsuaki , Ogura Toshihiko , Sato Kazuhiro , Honda Shinya 
Published: July 2006

Abstract
In connection with the relationship between the conformation and solubility of peptide intermediates having polar side chains, IR spectroscopic conformational analysis of human proinsulin C-peptide fragments was performed in dichloromethane. The polar amino acid residues involved in the peptide fragments are Glu(OBzl), Asp(OBzl), Gin, and Ser(Bzl). Especially, the N–H stretching absorption spectra have been explored over a wide range of concentration. Based on the concentration dependence of the N–H stretching bands, it has been shown that the characteristic N–H stretching band around 3330 cm−1 is due to the intramolecular hydrogen bond. Intermolecular hydrogen bonding also occurs to a small extent in these peptides, giving rise to a slight concentration dependence of the N–H stretching bands. Conformational behaviors of oligopeptides having protected polar side chains of the Glu(OBzl) and Asp(OBzl) residues are just the same as those of the corresponding homooligo(Leu)s, indicating that the protected polar side chains do not disturb conformational behaviors of the oligopeptides. Conformational analysis of the peptide in dichloromethane, which contains the Pro residue and has a high potential for the formation of an α-helical structure, distinctly suggests that the Pro residue near the N-terminal in the peptide has the great ability to promote successive intramolecular hydrogen bonds, probably corresponding to the α-helical structure of the peptide.
A Diels–Alder Cycloaddition and Electrocyclization Sequence as a New [6.5] Annelation Method to Benzene Ring
Authors: Wada Eiji , Kanemasa Shuji , Tsuge Otohiko 
Published: July 2006

Abstract
The Diels–Alder reactions of 1-aryl-2-methylene-3-buten-1-ols, readily available from chloroprene and aryl ketones, with olefinic dienophiles and subsequent electrocyclic reactions of the cycloadducts offer a new method of [6.5] annelation to benzene ring. By this way, tetrahydrofluorene skeletons bearing functional groups can be prepared. Stereochemical aspect of this sequence is also discussed.
Novel Regioselective Iodination of Estradiol 17β-Acetate
Authors: Horiuchi C Akira , Haga Akinori , Satoh J Yasuo 
Published: July 2006

Abstract
Direct iodination of estradiol 17β-acetate (3) using iodine–copper(II) acetate in acetic acid afforded the 2-iodo derivative regioselectively in high yield. The iodination of 3 using several methods was discussed. On the other hand, the reaction of 3 with iodine–copper(II) bromide gave the 4-bromo derivative (7), not the 2-iodo compound. The reaction of 3-methoxy-17β-acetoxy-1,3,5(10)-estratriene (4) with iodine–copper(II) chloride–iron(III) chloride in acetic acid gave the 2- (10) and 4-iodo (11) derivative.
[2+4] and [6+4] Type Cycloaddition Reactions of 1-Ethoxycarbonyl-1H-azepine and 1-Ethoxycarbonyl-1H-1,2-diazepine with 3,4,5,6-Tetrachloro-1,2-benzoquinone
Authors: Saito Katsuhiro , Mukai Toshio , Iida Shigenori 
Published: July 2006

Abstract
The reaction of 1-ethoxycarbonyl-1H-azepine with 3,4,5,6-tetrachloro-1,2-benzoquinone at room temperature gave a [6+4]-type cycloadduct as the major product and two kinds of [2+4]-type cycloadducts. In this reaction the diketone moiety of the benzoquinone derivative was used as the 4π component to form ether linkages. The [6+4]-type cycloadduct became rearranged to one of the [2+4]-type cycloadducts by heating at 90 °C. The same reaction, but using 1-ethoxycarbonyl-1H-1,2-diazepine, afforded two kinds of [2+4]-type cycloadducts. An electronic attraction between the oxygen atoms of the benzoquinone derivative and the carbons in the 2 and 7-positions of the azepine derivative is considered to be one of the driving force of the [6+4]-type cycloaddition reaction. The [2+4]-type cycloadducts are regarded to be formed via inverse electron demand Diels–Alder reactions.
Structures of Agelasines, Diterpenes Having a 9-Methyladeninium Chromophore Isolated from the Okinawan Marine Sponge Agelas nakamurai Hoshino
Authors: Wu Houming , Nakamura Hideshi , Kobayashi Jun’ichi , Kobayashi Masaki , Ohizumi Yasushi , Hirata Yoshimasa 
Published: July 2006

Abstract
Novel diterpenes, agelasine-A, -B, -C, -D, -E, and -F were isolated from the Okinawan marine sponge Agelas nakamurai Hoshino and their structures were established to be monocyclic and bicyclic diterpenes having a 9-methyladeninium unit by spectral analyses and chemical transformations.
Insertion of Sulfur Trioxide into the N–Si Bond of Anilinotrimethylsilane. An Improved Method for the Preparation of Free Phenylamidosulfuric Acid
Authors: Kanetani Fujio , Okada Eiji , Negoro Kenji 
Published: July 2006

Abstract
The reaction between anilinotrimethylsilane (1) and a variety of sulfonating agents [SO3, ClSO3H, trimethylsilyl chlorosulfate (5), dioxane–sulfur trioxide complex, ethyl chlorosulfate (10)] has been studied. With SO3, 5, or a dioxane–sulfur trioxide complex a sulfur trioxide molecule was inserted selectively into the N–Si bond of 1 to yield trimethylsilyl phenylamidosulfate (2), which on treatment with acetic acid, trifluoroacetic acid, or methanol gave free phenylamidosulfuric acid (3). The reaction of 1 with ClSO3H afforded 3 directly, but the product was contaminated with slight amounts of anilinium hydrogensulfate and anilinium chloride. The reaction of 1 with 10 yielded a mixture containing dianilinium (4-sulfonatophenylamido)sulfate, 4-aminobenzenesulfonic acid, and ethyl phenylamidosulfate as major products (after desilylation). The reaction of 1 with 5 has been found to provide an improved method for preparing 3.
Synthetic Versatility of N-(Silylmethyl)imines: Water-Induced Generation of N-Protonated Azomethine Ylides of Nonstabilized Type and Fluoride-Induced Generation of 2-Azaallyl Anions
Authors: Tsuge Otohiko , Kanemasa Shuji , Hatada Akira , Matsuda Koyo 
Published: July 2006

Abstract
N-(Silylmethyl)imines generate N-protonated azomethine ylides of nonstabilized type when treated with water in HMPA, which undergo stereospecific and regioselective cycloadditions with electron-poor olefins affording N-unsubstituted pyrrolidines. On the other hand, fluoride-induced desilylation of the imines leads to 2-azaallyl anions which are found to be synthetic equivalents of aminomethyl anion in the Michael additions with electron-poor olefins and nucleophilic additions with carbonyl compounds.
Photocatalytic Isomerization of Butenes over TiO2. Photo-Formed Active Species and Characteristics of Reaction
Authors: Anpo Masakazu , Yabuta Masaaki , Kodama Sukeya , Kubokawa Yutaka 
Published: July 2006

Abstract
It has been found that UV irradiation of powdered TiO2 catalysts in the presence of butene molecules leads to both cis-trans and double bond shift isomerization reactions with high efficiency. In the photocatalytic isomerization the reactivity of 2-butene is much higher than that of 1-butene, being in contrast to the feature in the thermal isomerization. The addition of O2 or NO molecules leads to the complete inhibition of photocatalytic isomerization of butenes. The effect of adsorbed water on the photocatalytic isomerization has been investigated. From these results together with the ESR measurements under UV irradiation of TiO2 at 77 K in the presence of butene as well as O2 or NO, the following conclusion emerges: The interaction of the photo-formed O− species or [Ti3+–O−] pairs results in opening of the C=C bond of butene, i.e. formation of a radical species, which acts as the intermediate in the photocatalytic isomerization. The O− as well as surface OH− species participates in the hydrogen shift, i.e. the double bond shift isomerization. Thus, the reaction mechanism which has been proposed for the photocatalytic isomerization of butene over ZnO has been confirmed over TiO2.
Syntheses and Properties of Copper(II) Triperchlorates with N,N′,N″,N'″-Tetrakis(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane and an Anion
Authors: Kida Sigeo , Murase Ichiro , Harada Chizu , Daizeng Liao , Mikuriya Masahiro 
Published: July 2006

Abstract
Copper complexes of the title ligand (taec) of the general formula Cu2(taec)X(ClO4)3 (X=F, Cl, Br, I, HCOO, CH3COO, NO2) were prepared and characterized. The formation constants for [Cu2(taec)]4++X−=[Cu2(taec)X]3+(X=F, Cl, Br, I) were determined spectrophotometrically in aqueous solution. The stabilities of the halogen-copper bonds were greatly enhanced relative to those of ordinary halogenocopper complexes, the order of the formation constants being Cl&gt;Br&gt;I&gt;F. This result can be explained as that the anion is trapped in a cavity formed by two copper ions and the methylene chains of taec molecule, thereby the stability of the bound anion is enhanced and the fitness of the size of anion to the cavity is the most important factor for the formation constant.
Nonsteroidal Antiinflammatory Drugs. V. The Crystal and Molecular Structure of (±)-(2S*)-2-[4-((1S*,2R*)-2-hydroxycydopentylmethyl)phenyl]propionic Acid
Authors: Hata Tadashi , Sato Sadao , Tamura Chihiro 
Published: July 2006

Abstract
The crystal structure of the title compound was determined by X-ray diffraction techniques and was refined to a final R index of 0.094 for 1249 reflections. The cyclopentane ring takes a half-chair conformation in which the two substituents are attached at equatorial positions. The molecules form centrosymmetric tetramers by the two hydrogen bonds through the carboxyl and hydroxyl groups.
An 1H NMR Study on the Motion of Guanidinium Cations in Some Crystals Formed with Tetrahedral or Octahedral Complex Anions Having Halide Ions as Ligands
Authors: Furukawa Yoshihiro , Nakamura Daiyu 
Published: July 2006

Abstract
The temperature dependences of 1H NMR spin-lattice relaxation times were determined at 20 MHz for [C(NH2)3]2ZnX4 (X=Cl, Br), [C(NH2)3]2MCl6 (M=Sn, Te, Pt), and [C(NH2)3]2PtBr6. Above room temperature, the D3h cation undergoes reorientational motion by 120° about the cationic C3 axis. For [C(NH2)3]2TeCl6 crystals, two phase transitions were located at 312 and 373 K.
Vacuum Sublimation Behavior of Iron(III), Cobalt(II), Nickel(II), Copper(II), and Palladium(II) Chelates with Tetradentate N,N′-Disalicylideneethylenediamine and N,N′-Bis(1-methyl-3-oxobutylidene)ethylenediamine
Authors: Honjo Takaharu , Nukui Kazuhiko 
Published: July 2006

Abstract
A vacuum sublimation apparatus with a continuous temperature gradient (25–200°C) along the tube (50–0cm) at 2×10−2 Torr (1 Torr=133.322 Pa) was used. N,N′-disalicylidenmhylenediamine, N,N′-bis(1-methyl-3-oxobutylidene)ethylenediamine and its metal chelates (FeIII, CoII, NiII, CuII, and PdII) were sublimed without thermal decomposition, while the chelates of FeIII, CoII, NiII, CuII, and PdII with N,N′-disalicylideneethylenediamine were thermally stable, but did not sublime completely.
Preparation and Characterization of Nickel(II) Complexes with Diethyl N,N′-Ethylenebis(2-hydroxyimino-3-iminobutanoate) and Its Analogue
Authors: Kim Soo Han , Okamoto Ken-ichi , Einaga Hisahiko , Hidaka Jinsai 
Published: July 2006

Abstract
The reaction of nickel(II) chloride hexahydrate and ethyl α-(hydroxyimino)acetoacetate with ethylenediamine or (R)-propylenediamine gives [diethyl N,N′-ethyIenebis(2-hydroxyimino-3-iminobutanoato)]nickel(II) or {diethyl N,N′-[(R)-1-methylethylene]bis(2-hydroxyimino-3-iminobutanoato)}nickel(II). The nickel(II) complexes with Schiff base ligands were characterized by their electronic absorption, 13CNMR, infrared, and CD spectra.
Optical Resolution of Asymmetric Selenoxides by High-Performance Liquid Chromatography Using Optically Active Column
Authors: Shimizu Toshio , Kobayashi Michio 
Published: July 2006

Abstract
The optical resolution of asymmetric diaryl selenoxides and the determination of the enantiomeric excess of the partially active selenoxides were found to be possible by HPLC using an optically active column.
Racemic Structures and Optical Resolution by Preferential Crystallization of Organic Ammonium Salts of (±)-Mandelic Acid
Authors: Shiraiwa Tadashi , Nakamura Mitsuhiro , Nobeoka Masanobu , Kurokawa Hidemoto 
Published: July 2006

Abstract
According to a thermodynamic analysis the 4-methylpiperidinium salt of (±)-mandelic acid is a conglomerate around room temperature, though the salt forms a racemic compound in the vicinity of the melting point. A successive preferential crystallization in ethanol at 10°C yields both the (+)- and (−)-salts with optical purities of over 95%.
The Point of Zero Charge and the Isoelectric Point of γ-Fe2O3 and α-Fe2O3
Authors: Watanabe Haruo , Seto Jun’etsu 
Published: July 2006

Abstract
The difference of the point of zero charge (PZC) and isoelectric point (IEP) values for γ- and α-Fe2O3 were measured and are quantitatively explained by the difference in crystal structure. Great care was taken to assure the purity of the samples and that measurements were taken under identical conditions. The PZC and the IEP for the “unhydrated” samples, were the same for each crystal structure, with the values for γ-Fe2O3 being more acidic, by 1.1 or 1.2 pH units, than for α-Fe2O3. This difference can be quantitatively explained by Parks’ equation, in terms of the difference in the coordinations of the Fe3+ ions in the two crystal structures.