bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Iodine Content of Atmospheric Aerosols as Determined by the Use of a Fluoropore Filter® for Collection
Authors: Tsukada Hirofumi , Hara Hiroshi , Iwashima Kiyoshi , Yamagata Noboru 
Published: July 2006

Abstract
Atmospheric aerosols were collected onto a Fluoropore filter in order to determine the iodine by means of instrumental neutron activation analysis. The collection filter was found to be the best material among the nine filters examined, for it has the lowest blank values for iodine as well as for other halogens and sodium. The iodine concentrations in Tokyo were found to be 1.7–12.7 ng m−3. Of the soluble iodine, 10% or less was in the form of IO3−.
Chromatographic Study of Optical Resolution. XIV. Optical Resolution of Amine Complex Cations of the Type [Co(N)6]3+ by Reversed-Phase Ion-Pair Chromatography Using Bis(μ-d-tartrato)diantimonate(III) and Arsenic Analog as an Ion-Pairing Reagent
Authors: Izumoto Shinji , Miyoshi Katsuhiko , Yoneda Hayami 
Published: July 2006

Abstract
Reversed-phase ion-pair chromatography (RPIPC) was applied to the optical resolution of amine complex cations of the type [Co(N)6]3+ using either bis(μ-d-tartrato)diantimonate(III) ion, [Sb2(d-tart)2]2− or its arsenic analog, [As2(d-tart)2]2− as an ion-pairing reagent. With either reagent, efficient optical resolution was attained for [Co(en)3]3+, [Co(tn)3]3+, [Co(sen)]3+, [Co(sep)]3+, and [Co(diNOsar)]3+ (en=ethylenediamine, tn=trimethylenediamine, sen=1,1,1-tris[[(2-aminoethyl)amino]methyl]ethane, sep=1,3,6,8,10,13,16,19-octaazabicyclo[6.6.6]icosane, and diNOsar=1,8-dinitro-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane). Dependence of retention volumes and separation factors of these complexes on the concentration and the counterion of the ion-pairing reagents was examined with Na+, Me4N+, and Et4N+ employed as counterions. Experimental results were discussed with reference to those obtained by means of normal-phase ion-exchange chromatography (NPIEC) using the same eluents. It was concluded that [As2(d-tart)2]2− serves as a more effective eluent in both RPIPC and NPIEC than [Sb2(d-tart)2]2−, and that RPIPC is a much more useful tool for the optical resolution of the [Co(N)6]3+-type complex cations than NPIEC.
Infrared Absorption Study of Human Hemoglobin α-Chain (123–136) Fragments in Dichloromethane
Authors: Narita Mitsuaki , Doi Masamitsu , Nakai Takao 
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 peptide fragments of human hemoglobin α-chain (123–136) was performed in dichloromethane. In dichloromethane, the conformational behavior of the peptide fragments was, in essence, dependent on their amino acid sequences, and Boc–Ser(Bzl)–Thr(Bzl)–Val–Leu–OPac through Boc–Ala–Ser(Bzl)–Val–Ser(Bzl)–Thr(Bzl)–Val–Leu–OPac had predominantly unordered structures including some intramolecular hydrogen bonds, while Boc–Ala–Ser(Bzl)–Leu–Asp(OBzl)–Lys(Z)–Phe–Leu–OPac had successive intramolecular hydrogen bonds, probably corresponding to an α-helical structure. On the other hand, in carbon tetrachloride, the conformation of Boc–Val–Ser(Bzl)–Thr(Bzl)–Val–Leu–OPac and Boc–Ser(Bzl)–Val–Ser(Bzl)–Thr(Bzl)–Val–Leu–OPac had a typical β-sheet structure. These results are discussed on the basis of the amino acid sequences of the peptide fragments.
Palladium-Promoted Transformation of β-Amino Ketones to Enaminones
Authors: Murahashi Shun-Ichi , Mitsue Yo , Tsumiyama Tatsuo 
Published: July 2006

Abstract
The reaction of β-amino ketones with bis(acetonitrile)dichloropalladium(II) in the presence of triethylamine gives the corresponding enaminones regioselectively. The cyclic β-amino ketones can be converted into the corresponding exocyclic enaminones. The enaminones thus obtained are versatile synthetic intermediates. The reaction of (E)-enaminones with organocuprates gave the corresponding (E)-α,β-unsaturated ketones.
Nitrone Cycloaddition Route to the 1β-Methylcarbapenem Key Intermediate
Authors: Ito Yoshio , Kimura Yoshikazu , Terashima Shiro 
Published: July 2006

Abstract
The 1β-methylcarbapenem key intermediate, (3S,4S)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-4-[(R)-1-carboxyethyl]-2-azetidinone, was prepared from (S)-methyl 3-hydroxy-2-methylpropionate by employing 1,3-dipolar cycloaddition of the chiral nitrone with benzyl crotonate as a key reaction.
Electrochemical Redox Intercalation of Copper(I) Cation for CuxMo6S8 Superconductor Accompanied with a Reversible Structure Change
Authors: Inoue Tooru , Yamase Toshihiro 
Published: July 2006

Abstract
Ternary compounds (Chevrel phase compounds) of molybdenum CuxMo6S8 were prepared by sintering mixed powders of MoS2, Mo, and CuS and employed as electrodes in aqueous solutions. Electrochemical polarization of the electrodes gives rise to intercalation and deintercalation processes of Cu+, resulting in deformative change in crystal structure of the compounds. The lattice constants of rhombohedral unit cells of the compounds are ar=6.66 Å, αr=96°, and Vr=290 Å3 for the intercalated compound Cu4Mo6S7.8, and ar=6.43 Å, αr=91.2°, and Vr=267 Å3 for the fully deintercalated Mo6S7.8. Both the copper(I) composition and the crystal structure of CuxMo6S7.8 can be controlled by the electric quantity in electrochemical redox treatment. Structure deformation results from change in electronic distribution of crystal, as well as in charge density of a Mo octahedral cluster, due to electrolysis.
A Stopped-Flow Kinetic Study on the Binding of Phenylbutazone to Human Serum Albumin Using Absorption and Circular Dichroism Techniques
Authors: Murakami Kiyofumi , Fujisaki Yasuo , Sano Takayuki 
Published: July 2006

Abstract
The mechanism of the binding of phenylbutazone(4-butyl-1,2-diphenyl-3,5-pyrazolidinedione) to human serum albumin has been investigated by kinetic experiments using both optical absorption and circular dichroism (CD) stopped-flow methods. Three distinct processes were found to exist by the absorption technique; one of these was within the dead time of the apparatus and other two slow processes were at around 10−2 and 1 s, of which the relaxation times were determined. On the other hand, only two processes, which correspond in time range to the first and third processes seen by optical absorption, were found using CD technique. By examining the concentration dependence of the reciprocal relaxation time of each process and by taking account of the binding isotherm, a binding mechanism has been proposed. According to the elucidated reaction scheme, successive binding of two molecules of phenylbutazone is followed by a conformational change which destabilizes one of the bound species. The detailed nature is discussed in the light of the circular dichroism change of each process.
Acyclic C-Nucleoside Analogs of the Type of 5-C-Polyhydroxyalkyl-1,3,4-thiadiazoles
Authors: El Ashry Elsayed S H , Nassr Mahmoud A , El Kilany Yeldez , Mousaad Ahmed 
Published: July 2006

Abstract
The synthesis of some acyclic C-nucleoside analogs possessing thiadiazole rings was achieved by the heterocyclization of the 4-arylthiosemicarbazones of d-galactose, d-glucose, d-mannose, d-arabinose, and lactose, Acetylation of the thiadiazoles afforded the corresponding 2-(N-acetylarylamino)-5-polyacetoxyalkyl-1,3,4-thiadiazoles and periodate oxidation gave the corresponding 5-(arylamino)-1,3,4-thiadiazole-2-carbaldehyde.
Preparation of 2-Nitromethyl-2-cycloalkenol and 2-Nitromethyl-2-cycloalkenone
Authors: Sakakibara Tohru , Manandhar Mangala devi , Ohkita Noriaki , Ishido Yoshiharu 
Published: July 2006

Abstract
oxidation of 1-nitromethylcycloalkenes with m-chloroperbenzoic acid afforded the corresponding 2-nitromethyl-2-cycloalkenols, which were further converted into 2-nitromethyl-2-cycloalkenones.
Ordering of Cations in Ba(Mg1⁄3Nb2⁄3)O3 and Ba(Zn1⁄3Nb2⁄3)O3
Authors: Yoshioka Hideki 
Published: July 2006

Abstract
The ordering of B-site cations in Ba(Mg1⁄3Nb2⁄3)O3 (BMN) and Ba(Zn1⁄3Nb2⁄3)O3 (BZN) was studied from superlattice reflections in X-ray diffraction patterns. The degree of ordering in BMN increases with increasing sintering temperature. While in BZN an ordered structure was observed up to 1673 K, and an order-disorder phase transition was found below 1773 K.
Solid-Phase Thermal Reactions of Chromium(III) and Copper(II) Complexes Containing Pentadentate Ethylenediaminetetraacetate and 1,2-Propanediaminetetraacetate Ions
Authors: De Goutam , Suzuki Masatatsu , Uehara Akira 
Published: July 2006

Abstract
Thermal reactions of the solid complexes [Cr{Hedta or (RS)-Hpdta}(H2O)] and [Cu{H2edta or (RS)-H2pdta(H2O)] were investigated under quasi-isothermal and -isobaric conditions (Q-conditions) and under open dynamic conditions (D-conditions), where Hedta and H2edta, and Hpdta and H2pdta denote mono- and diprotonated ethylenediaminetetraacetate and 1,2-propanediaminetetraacetate ions, respectively.
Syntheses of New Multi-Sulfur 1,2-Dithiolene Complexes. Ni- and Pd-Complexes of 1,4-Dithiin-2,3-dithiolate
Authors: Nakamura Tadashi , Nogami Takashi , Shirota Yasuhiko 
Published: July 2006

Abstract
The title dithiolene complexes possessing eight sulfur atoms were synthesized. They are expected to give highly conductive organic salts. The improved synthesis of 4,5-(vinylenedithio)-1,3-dithiole-2-thione is also reported.
Ruthenium Complex-Catalyzed N-Heterocyclization. Syntheses of N-Substituted Pyrroles and Pyrrolidines from 1,4-Diols and Primary Amines
Authors: Tsuji Yasushi , Yokoyama Yasuharu , Huh Keun-Tae , Watanabe Yoshihisa 
Published: July 2006

Abstract
2-Butyne-1,4-diol reacts with aliphatic amines in the presence of a catalytic amount of [RuCl2(PPh3)3] at 150 °C to give N-alkylpyrroles in good yields. 1,4-Butanediol reacts with aromatic or aliphatic amines to give N-substituted pyrrolidines in excellent yields; [RuCl2(PPh3)3] and [RuCl3·nH2O–3PBu3] are the best catalysts for aromatic and aliphatic amines, respectively. The reaction of 2-butene-1,4-diol with alkyl amines gives a 1:1 mixture of N-substituted pyrroles and pyrrolidines in high yield.
Preparation and Some Properties of Acyltin Compounds
Authors: Kosugi Masanori , Naka Hiroyuki , Sano Hiroshi , Migita Toshihiko 
Published: July 2006

Abstract
According to Quintard’s method, acyltin compounds were prepared by the reaction of tributylstannylmagnesium chloride with an excess of aldehyde, and their physical data were described. These compounds were sensitive to oxygen air to give the corresponding tributyltin carboxylates. Free radical chain mechanism was suggested.
Synthesis of α-Methylene-γ-butyrolactones via Addition of Tin Hydride to Enynes Induced by Triethylborane
Authors: Nozaki Kyoko , Oshima Koichiro , Utimoto Kiitiro 
Published: July 2006

Abstract
Et3B induced addition of Ph3SnH to suitably constituted enynes provides (triphenylstannylmethylene) oxolanes stereoselectively in one pot. Destannylation followed by oxidation affords α-methylene-γ-butyrolactones in fair yields.
An NMR Study of Phenyl- and Diphenylphosphine Alkali Metal Salts
Authors: Yokoyama Yukihiro , Takahashi Kensuke 
Published: July 2006

Abstract
The 1H, 13C, and 31P NMR spectra were observed for the title salts in several solvents. The formation of the salts by the deprotonation of the neutral precursors causes significant changes in their NMR parameters. First, the delocalization of the excess charges into the phenyl ring of the salts was confirmed from the 1H and 13C chemical-shift data. Second, the parameters concerned with the center of the anions are dependent on the circumstances of the center atom, phosphorus, such as the hybridization. The results are discussed in terms of the effects of the counter cations and the solvents. Third, a strong polar solvent, HMPA, exerts significant effects on the chemical shifts and the one-bond 13C–31P coupling constants. These parameter changes are explained in terms of an equilibrium between two kinds of ion-pairs (contact ion-pairs and solvent-separated ion-pairs). The parameters obtained in this solvent, HMPA, correspond to those of the solvent-separated ion-pairs or the free anions.
Synthesis of Dichlorocyclobuta[b]benzofuran-2a-carboxylic Derivatives and 3-(Trichloroethenyl)coumarin through Cross Photocycloadduct of Coumarin and Tetrachloroethylene
Authors: Nonoyama Shinji , Yonezawa Noriyuki , Saigo Kazuhiko , Hasegawa Masaki , Iitaka Yoichi 
Published: July 2006

Abstract
Photoirradiation of coumarin and tetrachloroethylene with a high-pressure mercury lamp through Pyrex filter in the presence of benzene and benzophenone gave cross cycloadduct (3) in a moderate yield. By treatment with bases or nucleophiles at room temperature, 3 underwent ring-contraction reaction through lactone-opening, cyclobutene formation, and intramolecular SN2′ displacement to yield dichlorocyclobuta[b]benzofurancarboxylic derivatives exclusively. By use of a non-nucleophilic base, 3-(trichloroethenyl)coumarin was alternatively obtained through [2+2] cycloreversion of cyclobutene intermediate in a good yield.
New Discogenic Compounds: N,N′-Dialkanoyl-2,3,5,6-tetrakis(alkanoyloxy)-1,4-benzenediamines
Authors: Kobayashi Yukio , Matsunaga Yoshio 
Published: July 2006

Abstract
A series of N,N′-dialkanoyl-2,3,5,6-tetrakis(alkanoyloxy)-1,4-benzenediamines has been prepared and found to be mesogenic over a wide temperature range. The transformation into an isotropic liquid at a temperature between 189 and 209 °C is followed by thermal decomposition. The X-ray diffraction pattern of unoriented specimens in the mesophase consists of two sharp inner peaks and a broad outer one assignable to 100, 110, and 001 reflections respectively, indicating that the phase is hexagonal columnar.
Stereochemistry of a Porphyrin Atropisomer. The Molecular and Crystal Structure of Six-Coordinate [5α,10β-bis(o-nicotinamidophenyl)-15,20-diphenylporphinato]zinc(II)
Authors: Scheidt W Robert , Eigenbrot C W , Ogiso Motoyasu , Hatano Keiichiro 
Published: July 2006

Abstract
The synthesis and molecular structure of the title complex was investigated as part of our work into the chemical significance of atropisomerism in porphyrin compounds. The complex crystallizes in the triclinic system, space group P\bar1, a=11.707 (2) Å, b=12.744 (5) Å, c=9.521 (2) Å, α=102.60 (3)°, β=101.31 (2)°, and γ=100.29 (2)°, Z=1. A total of 3737 reflections (average of two forms) were considered observed and used in the solution and refinement of the structure. The structure was refined to a final R=0.081. The molecule, with a crystallographically imposed inversion center, has disordered nicotinamide side chains. This disorder leads to some ambiguity in defining the relative substitution pattern of the phenyl rings. Independent of the assumptions used to define the disorder, the nicotinamide side chains are found to coordinate the zinc ions of adjacent molecules to form a polymeric, linear chain containing six-coordinate zinc ions. The average equatorial Zn–N bond distance is 2.052 (3) Å and the unique axial bond distance is 2.432 (5) Å.
Surface Properties and Catalytic Activities of Niobic Acid Treated with Diluted Phosphoric Acid
Authors: Kurosaki Akito , Okuyama Tetsuhiro , Okazaki Susumu 
Published: July 2006

Abstract
A surface treatment of niobic acid using about l mol dm−3 of phosphoric acid was effective for the enhancement of the surface acidity and the catalytic activity for some acid-catalyzed reactions such as cyclohexanol dehydration and alkylation of benzene with methanol. However, a treatment with phosphoric acid of higher concentration might form a deposit on the surface, which would prevent the penetration of reactants and/or products and, thus, decreased the catalytic activity of niobic acid. The P component added to the niobic acid was hardly removed by steaming at 400 °C, although it could be taken off by soaking in water at room temperature for twelve hours.
Syntheses and Characterization of Dinuclear Iron(II, II) and Iron(II, III) Complexes with a Dinucleating Ligand, 2,6-Bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenolate (1—)
Authors: Suzuki Masatatu , Uehara Akira , Oshio Hiroki , Endo Kazutoyo , Yanaga Makoto , Kida Sigeo , Saito Kazuo 
Published: July 2006

Abstract
Dinuclear iron(II, II) complexes, [Fe2(L-py)(RCOO)2]BF4·nH2O (RCOO : CH3COO (1a) and C6H5COO (2a)), and two types of dinuclear mixed valence iron(II, III) complexes [Fe2(L-py)(RCOO)2](BF4)2·nH2O (RCOO : CH3COO (1b) and C6H5COO (2b)) and [Fe2(L-py)(CH3COO)(OH)](BF4)2·2H2O (3) were prepared, where L-py represents 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methyl-phenolate(1–). Only one of the two iron(II) ions in the iron(II, II) complexes is easily oxidized with molecular oxygen in methanol to form the mixed valence complexes, [Fe2(L-py)(RCOO)2](BF4)2·nH2O, which were characterized by chemical analyses and Mössbauer measurements. Magnetic susceptibility measurements over the temperature range 80–300 K revealed that high-spin iron(II) and iron(III) ions are antiferromagnetically coupled with the spin-exchange coupling constants J=−3–−8cm−1. The complexes exhibited an ESR signal of gav≈1.7 near liquid helium temperature. Such an ESR signal arises from an antiferromagnetically spin-coupled high-spin iron(II, III) dimer. An inter-valence charge-transfer transition was observed in the region 7000–8500 cm−1. The electron delocalization parameter α is estimated to be ca. 0.08, which corresponds to the class II mixed valence type in the classification of Robin and Day. Cyclic voltammogram of the complex 2b in acetonitrile showed two reversible couples at +0.05 and +0.73 V (vs. SCE), which were assigned to the redox reactions of Fe(II, III)/Fe(II, II) and Fe(III, III)/Fe(II, III), respectively. The comproportionation constants of 1b and 2b at 20 °C are 1.6×1012 and 5.0×1011, respectively, implying that the present mixed valence complexes are significantly stabilized.
Inhibition of Dimerization of Copper(II) Carboxylates by Cyclohexane Ring in Extraction of Copper(II) with Cyclohexanecarboxylic Acid
Authors: Yamada Hiromichi , It\={o} Miyuki , Mizuta Masateru 
Published: July 2006

Abstract
The extraction of copper(II) with cyclohexanecarboxylic acid in benzene was carried out at 25 °C and at the aqueous ionic strength of 0.1 mol dm−3 (NaClO4). The partition constant, KD,HA of cyclohexanecarboxylic acid between benzene and water, and the dimerization constant, K2,HA of cyclohexanecarboxylic acid in benzene were determined: logKD,HA=0.90 and logK2,HA=1.54, respectively. The monomeric and dimeric copper(II) cyclohexanecarboxylates were responsible for the extraction:
Cu2++(HA)2,o \ightleftharpoons (CuA2)o+2H+
Cu2++2(HA)2,o \ightleftharpoons (CuA2(HA)2)o+2H+
2Cu2++2(HA)2,o \ightleftharpoons (Cu2A4)o+4H+
2Cu2++3(HA)2,o \ightleftharpoons (Cu2A4(HA)2)o+4H+
with the extraction constants, logKex(10)=−8.34, logKex(12)=−7.33, logKex(20)=−12.47, and logKex(22)=−11.73, respectively. By comparing the overall formation constant of the dimeric copper(II) cyclohexanecarboxylate, Cu2A4(HA)2 in the aqueous phase with that of copper(II) decanoate and lipoate, the cyclohexane ring was found to inhibit the formation of the dimeric copper(II) carboxylate.
Studies on the Interaction of Molybdate Ion and Magnesium Ion Observed in the Raman Spectra of the Mixture Solutions
Authors: Ozeki Toru , Murata Kazuko , Kihara Hiroshi , Hikime Seiichiro 
Published: July 2006

Abstract
When alkali metal or alkaline earth metal chloride, (except magnesium chloride) was added to a solution of sodium molybdate, similar Raman spectra were observed. When magnesium chloride was added to the molybdate solution, however, the intensity of the peak (ν1) based on the symmetric stretching vibration of the tetrahedral molybdate decreased and a new peak (νx) appeared at a higher wavenumber than ν1. The wavenumber of the new peak is almost equal to that observed for solid magnesium molybdate. This suggests that the new peak can be ascribed to the molybdates of the distorted octahedral structure, since the molybdate ion exists as an octahedral in the solid state of magnesium molybdate. The tetrahedral and the octahedral molybdates seem to be in equilibrium in the solution.
13C and 1H NMR of Arylnitrones. Substituent Effects of α-Phenyl-N-(p-substituted phenyl)nitrones
Authors: Suda Kohji , Tsujimoto Toshio , Yamauchi Masashige 
Published: July 2006

Abstract
Substituent effects on the chemical shifts of the conjugation sites in α-phenyl-N-arylnitrones (2) have been investigated. Resonance effects predominate at these positions. The electronic effects of the substituents should be treated separately between electron-donating groups and electron-withdrawing ones. A plausible mechanism for the transmission of the substituent effects in 2 has been proposed.
Enzymatic Reactions in Aqueous-Organic Media. II. Effects of Reaction Conditions and Selectivity in the Esterification of Aromatic Amino Acids by α-Chymotrypsin in Alcohols
Authors: Kise Hideo , Shirato Hitoshi , Noritomi Hidetaka 
Published: July 2006

Abstract
N-Acetylated aromatic amino acids were esterified by α-chymotrypsin suspended in alcohols. The reaction rate and the yields of the esters depended primarily on the amount of the aqueous buffer solution in which α-chymotrypsin was dissolved. The reaction rate increased but the equilibrium yield of the esters decreased with increasing concentration of water. High substrate selectivity and stereospecificity were observed for l-aromatic amino acids; and therefore, in this system α-chymotrypsin was considered to be an effective catalyst which maintains its native conformation. When the amount of the substrate was increased, the present reactions gave higher yields of the esters than the reactions in chloroform (two-phase method).
Excimer Formation and Induced-Fit Type of Complexation of β-Cyclodextrin Capped by Two Naphthyl Moieties
Authors: Moriwaki Fumio , Kaneko Hiromi , Ueno Akihiko , Osa Tetsuo , Hamada Fumio , Murai Koichi 
Published: July 2006

Abstract
Host–guest complexation of β-Cyclodextrin bearing two naphthyl moieties (1) has been studied by circular dichroism and fluorescence spectroscopic methods. The circular dichroism spectrum exhibits a positive band around 225 nm while the fluorescence spectrum exhibits a predominant monomer peak with a shoulder of excimer emission. These data suggest that 1 can take two forms, one of two naphthyl moieties being included in the cavity of the predominant form (A) while both naphthyl moieties being located outside of the cavity in another form (B). With increasing concentration of guests, the dichroism intensity diminishes but the excimer intensity increases. This result indicates that 1 moves the included naphthyl moiety outward from the interior of the cavity during guest binding and then the two naphthyl moieties act as hydrophobic caps. The binding of 1 was stronger for cyclohexanol and 1-adamantanecarboxylic acid but weaker for cyclododecanol than that of the corresponding γ-cyclodextrin derivative in correspondence with size-fitting between the guests and hosts.