bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Crystal Structures of cis- and trans-Dinitrobis(1,4-butanediamine)cobalt(III) Nitrates. Conformation of Seven-Membered Chelate Rings
Authors: Shimoi Mamoru , Fujinawa Yuki , Ogino Hiroshi , Kanamori Kan , Kawai Kiyoyasu 
Published: July 2006

Abstract
The structures of cis- and trans-dinitrobis(1,4-butanediamine)cobalt(III) nitrates were determined by the single-crystal X-ray diffraction method. cis-[Co(NO2)2(tmd)2]NO3 (tmd=H2N(CH2)4NH2) is monoclinic with the space group P21⁄a; the cell constants are a=23.878(4), b=8.403(1), c=16.675(3) Å, β=103.24(1)°; Z=8, and the final R value was 0.051. trans-[Co(NO2)2(tmd)2]NO3·H2O is triclinic with the space group P\bar1; the cell constants are a=9.753(3), b=13.909(4), c=6.327(1) Å, α=102.07(2), β=91.05(2), γ=87.83(3)°; Z=2, and the final R value was 0.058. Both complexes have a slightly distorted octahedral geometry around the cobalt center. The conformations of the seven-membered chelate rings have twist-chair and chair forms for the cis and trans complexes, respectively.
Preparation and Stereochemistry of Cobalt(III) Complexes Containing 1,1,11,11-Tetraphenyl-4,8-diaza-1,11-diphosphaundecane or (3S,9S)-3,9-Dimethyl-1,1,11,11-tetraphenyl-4,8-diaza-1,11-diphosphaundecane,(C6H5)2PCH2CHRNHCH2CH2CH2NHCHRCH2P(C6H5)2 (R=H or CH3)
Authors: Jung Min-Ho , Atoh Masamichi , Kashiwabara Kazuo , Fujita Junnosuke 
Published: July 2006

Abstract
Two new quadridentate phosphine ligands 1,1,11,11-tetraphenyl-4,8-diaza-1,11-diphosphaundecane (pp-232PNNP) and (3S,9S)-3,9-dimethyl-1,1,11,11-tetraphenyl-4,8-diaza-1,11-diphosphaundecane (SS(C)-pp-232PNNP), and several their cobalt(III) complexes were prepared and characterized. The RS(N) isomers of trans-[CoCl2(pp- or SS(C)-pp-232PNNP)]+ were formed by oxidation of cobalt(II) complexes of these ligands in dichloromethane with chlorine, while the RR,SS(N), and RR(N) isomers of the pp-232PNNP and SS(C)-pp-232PNNP complexes, respectively, were derived from the corresponding carbonato complexes and hydrochloric acid. The [Co(O-O)(pp- or SS(C)-pp-232PNNP)]n+ (O–O= CO32−, C2O42−, C5H7O2−) complexes yielded only a cisβ isomer. The stereochemistry of the complexes was discussed on the basis of the absorption, circular dichroism and NMR spectra.
High Performance Micro-Enzyme Sensor Using Platinized Microelectrode
Authors: Ikariyama Yoshihito , Yamauchi Shigeru , Aizawa Masuo , Yukiashi Tomoaki , Ushioda Hiroo 
Published: July 2006

Abstract
A unique micro-enzyme sensor for the determination of glucose has been prepared by incorporating glucose oxidase into the micropores of a platinized microelectrode. The electrode diameter is in the range from 10 μm to 200 μm. The detection limit is 5×10−7 mol L−1 for glucose, and an excellent linearity is obtained in the concentration range from 5×10−7 to 10−2 mol L−1 in the case of micro-enzyme electrode whose diameter is larger than 50 μm. In the case of micro-enzyme electrode whose diameter is 10 μm, the detection limit for glucose is 10−5 mol L−1, and the linearity is observed in the concentration range from 10−5 to 5×10−2 mol L−1. The sensor responds to every glucose sample of different concentration in 3 s or less, and the coefficients of variation for glucose (1 mM) determination were within 2%. The sensor output was stable over 4 weeks. This unique microfabrication approach to micro-enzyme electrodes enables the immobilization of intact enzyme molecules by a simple procedure.
Photochemical Trifluoromethylation of Some Aromatic and Heteroaromatic Compounds with Trifluoromethyl Bromide
Authors: Akiyama Takeo , Kato Kohji , Kajitani Masatsugu , Sakaguchi Yoshio , Nakamura Junko , Hayashi Hisaharu , Sugimori Akira 
Published: July 2006

Abstract
The photochemical introduction of trifluoromethyl group with CF3Br in aromatic and heteroaromatic rings was investigated for 9 compounds. Naphthalene, anthracene, anisole, N,N-dimethylaniline, ferrocene, benzo[b]thiophene, isoquinoline, and N-methylpyrrole gave trifluoromethylated products in 6.5–100% yields. In one step from uracil, a pharmacologically important 5-trifluoromethyluracil can be synthesized by this method in 11% yield. Based on the mechanistic study carried out for the naphthalene–CF3Br–CH3CN system, the reaction is found to proceed via the electron transfer from an excited singlet state of naphthalene to CF3Br.
Preparation of Mesoverdohemochrome IXα Dimethyl Ester and Mössbauer Spectra of Related Porphyrins
Authors: Saito Setsuo , Sumita Shigeya , Iwai Kumiko , Sano Hirotoshi 
Published: July 2006

Abstract
Mesobiliverdin IXα dimethyl ester (7) was obtained by hydrogenation of protobiliverdin IXα dimethyl ester (8). Zinc 5-oxamesoporphyrin IX dimethyl ester tetrafluoroborate (6) was prepared by the cyclization of 7 with zinc acetate in acetic anhydride followed by a treatment with aqueous sodium tetrafluoroborate. Bis(pyridine) mesoverdohemochrome IXα dimethyl ester (4) was obtained by the cyclization of 7 with both iron(II) sulfate and iron(III) chloride in acetic anhydride containing a small amount of pyridine. Bis(tosylmethyl isocyanide) mesoverdohemochrome IXα dimethyl ester (5) was prepared by the addition of excess tosylmethyl isocyanide (TsCH2NC) to 4. Both 4 and 5 reacted with ammonia to give iron(III) 5-azamesoporphyrin IX dimethyl ester (10). The Mössbauer spectra of bis(pyridine) verdohemochromes (4, 13, and 14) snowed doublet peaks having parameters of δ=0.41–0.43 mm s−1 and ΔEQ=1.24–1.26 mm s−1, indicating that the oxidation states of the central irons of these complexes are iron(II). Bis(TsCH2NC) verdohemochromes (5, 15, and 17) showed single peaks having parameters of δ=0.21–0.28 mm s−1. Unstable intermediate and stable final bis(TsCH2NC) octaethyl verdohemochromes, obtained by the addition of TsCH2NC to 4, were compared with the 1H NMR and Mössbauer spectra.
Crystal and Molecular Structures of Tetraisopropyl 1,1′-(1,8-Naphthylene)bis[1H-1,2,3-triazole-4,5-dicarboxylate] and Diisopropyl 1-(1-Naphthyl)-1H-1,2,3-triazole-4,5-dicarboxylate
Authors: Nagawa Yoshinobu , Goto Midori , Honda Koichi , Nakanishi Hiroshi 
Published: July 2006

Abstract
Molecular structures of the title compounds, which belong to the class of peri-substituted naphthalenes, have been determined by means of X-ray diffraction. Tetraisopropyl 1,1′-(1,8-naphthylene)bis[1H-1,2,3-triazole-4,5-dicarboxylate] (1), monoclinic, space group C2⁄c, a=35.034(3), b=9.717(1), c=18.504(1) Å, β=96.43(1)°, Z=8; Diisopropyl 1-(1-naphthyl)-1H-1,2,3-triazole-4,5-dicarboxylate (2), monoclinic, space group P21⁄n, a=16.246(2), b=10.115(1), c=12.390(1) Å, β=96.67(1)°, Z=4. The dihedral angles between the mean plane of the naphthalene ring and that of the triazole ring are 88° and 85° for 1 and 2, respectively. The naphthalene framework of 1 is much more distorted than that of 2 because of a steric repulsion between the two triazole rings with bulky ester groups of 1.
Arylation of Olefins by Arylazo Aryl Sulfones under Palladium(0) Catalysis
Authors: Kamigata Nobumasa , Satoh Akira , Kondoh Tetsuya , Kameyama Masayuki 
Published: July 2006

Abstract
The palladium(0)-catalyzed reaction of arylazo aryl sulfones with olefins in benzene at 80°C gave aryl-substituted olefins in good yield. Diarylpalladium(II) species was proposed as an intermediate in this reaction.
The Photocatalytic Activity of a Platinized Titanium Dioxide Catalyst Supported over Silica
Authors: Domen Kazunari , Sakata Yoshihisa , Kudo Akihiko , Maruya Ken-ichi , Onishi Takaharu 
Published: July 2006

Abstract
The effect of the amount of TiO2 loading on the photocatalytic activity of H2 evolution from aqueous methanol solution over a platinized TiO2/SiO2 catalyst was studied. UV diffuse reflectance spectra of TiO2/SiO2 showed the blue shift of absorption edge for the catalyst of lower amount of TiO2 loading, which suggested the higher dispersion of TiO2 on SiO2. The activity decreased monotonously with the decrease of the amount of TiO2 loading over SiO2, i.e. with the increase of the dispersion.
Chromium(VI) or Ruthenium(II) Complex Catalysis in Oxidation of Alcohols to Aldehydes and Ketones by Means of Bis(trimethylsilyl) Peroxide
Authors: Kanemoto Shigekazu , Matsubara Seijiro , Takai Kazuhiko , Oshima Koichiro , Utimoto Kiitiro , Nozaki Hitosi 
Published: July 2006

Abstract
Bis(trimethylsilyl) peroxide (BTSP) serves as an effective oxidant of alcohols in the presence of chromium(VI) or ruthenium(II) complexes as catalysts in dichloromethane. Selective oxidation of primary alcohols in preference to secondary ones using RuCl2(PPh3)3 as a catalyst is also described.
Quenching of Excited Singlet and Triplet States of Some Polyfused Arenes by Dihalobenzenes
Authors: Mallik G K , Pal T K , Ganguly T , Banerjee S B 
Published: July 2006

Abstract
External heavy atom effect on the emission spectra of naphthalene, phenanthrene, and chrysene by perturbers dihalobenzenes are investigated to estimate different nonradiative rate constants associated with the depletion of the singlet and the triplet states of the fluorescers. The bimolecular fluorescence quenching rate constant kq has been evaluated at 300 K by applying Stern–Volmer relation. The dihalobenzene quenchers have triplet states lying below the singlet states of the fluorescers and the overall quenching rate kq is composed of two rate constants, namely, the intramolecular intersystem crossing rate kqISC and the singlet–triplet energy transfer rate constant kqST. The relative magnitudes of the two rate constants kqISC and kqST have been examined in the light of the energy conditions controlling the associated processes. At 77 K, the phosphorescence decay curve of the fluorescers in the presence of dihalobenzenes is biexponential and the triplet decay of the perturbed fraction of the fluorescers is exponential. It is concluded that at the low temperature, heavy atom interaction in the systems studied mainly proceeds through CT mechanism. Speculative suggestion has been made to account for enhancement of phosphorescence emission of polyfused arenes in EtOH solution.
Stereochemistry of the Reactions of Trimethylgermyl Anions with 4-t-Butylcyclohexyl Derivatives
Authors: Mochida Kunio , Kugita Tsuyoshi 
Published: July 2006

Abstract
The stereochemistry of trimethylgermyllithium, -sodium, and -potassium with cis- and trans-4-t-butylcyclohexyl bromides and trimethylstannanes was investigated by 1H NMR spectroscopy. With the 4-t-butylcyclohexyl derivatives trimethylgermyl anions gave mixtures of cis- and trans-4-t-butylcyclohexyltrimethylgermanes. These results confirmed that free-radical pathways are important in such reactions.
Facile Reaction of Te-Aryl Benzenecarbotelluroates, ArCOTeAr′, with Methyl Iodide and Halogens
Authors: Singh Harkesh B , Sudha Narasimhan 
Published: July 2006

Abstract
Reaction of Te-aryl benzenecarbotelluroates of the type ArCOTeAr′ (Ar=phenyl p-tolyl, p-bromophenyl; Ar′=phenyl, p-methoxyphenyl) with methyl iodide was found to give symmetrical telluronium salts, [Ar′Te(CH3)2]+I− in good yields. The reactivity of one of these benzene carbotelluroates towards halogens was also examined.
The Vapor-Phase Preparation of V–P–O Catalysts Effective for Butane Oxidation to Maleic Anhydride
Authors: Takita Yusaku , Hashiguchi Takao , Matsunosako Hitoshi 
Published: July 2006

Abstract
Almost pure α-VOPO4·2H2O powder was obtained by a vapor-phase reaction between POCl3, VOCl3, and water at about 763K in the presence of oxygen. Although α-VOPO4·2H2O changed into α- and β-VOPO4 in the calcination in N2, it was transformed into (VO)2P2O7 and a small amount of β-VOPO4 by in situ activation at 733 K at the heating rate of 10 K min−1 in a C4H10–O2–N2 stream, the resulting catalysts effected the selective oxidation of butane to maleic anhydride comparable to pure (VO)2P2O7.
Oxidation of Benzylic and Allylic Alcohols with Cobalt(III) Acetate in Acetic Acid in the Presence and Absence of Sodium Bromide
Authors: Hirano Masao , Morimoto Takashi , Itoh Keiko 
Published: July 2006

Abstract
Benzyl alcohol and its o-, m-, and p-substituted derivatives afforded fairly good yields of the corresponding benzaldehydes through a reaction with a Co(III)–NaBr system. With allylic alcohols, this system failed in a selective formation of unsaturated carbonyl compounds. In the latter cases, the products were effectively obtained by using a higher concentration of cobalt(III) acetate in the absence of NaBr.
Emission Spectrum of Acetylene by Controlled Electron Impact
Authors: Yoshidome Toshifumi , Taniguchi Masaharu , Nakashima Keiji , Kawazumi Hirofumi , Ogawa Teiichiro 
Published: July 2006

Abstract
Emission spectra of C2H2 and C2D2 excited by collisions with electrons of 7–20 eV show a broad and diffuse band in the 240–400 nm region and this band was assigned to the S1(lower vibrational levels)–S0 transition of acetylene on the basis of its .wavelength, excitation function (threshold: 5.5 eV) and lifetime (323±30 ns). Their emission cross sections are on the order of 10−19 cm2. Among intense fragment emissions at higher electron energies, band of C2H has also been observed and its lifetime is 3.9±0.8 μs.
Addition of N-(Hydroxymethyl)phthalimide to Methacrylates by Carbon–Carbon Bond Formation
Authors: Kurita Keisuke , Itoh Hiroshi , Chikamori Shunji , Mabuchi Tomoyuki 
Published: July 2006

Abstract
N-(Hydroxymethyl)phthalimide undergoes addition to the carbon–carbon bond of methacrylates effectively in sulfuric acid, resulting in the formation of a new carbon–carbon bond.
The Synthesis of Se-Alkyl Alkaneselenoates via (1-Iodo-1-alkenyl)dialkylboranes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira 
Published: July 2006

Abstract
Se-Alkyl alkaneselenoates were formed in moderate to good yields by successive reactions of (1-iodo-1-alkenyl)bis(1,2-dimethylpropyl)boranes with alkylselenomagnesium bromides and alkaline hydrogen peroxide.
Synthesis and Chemiluminescence of 5-[(2-Pyridyl)-, (2-Pyrazinyl)-, and (Substituted 2-pyrazinyl)amino]-1,2,4-trioxanes
Authors: Nakamura Hideshi , Goto Toshio 
Published: July 2006

Abstract
From pyridyl- and pyradinylamines and isobutylaldehyde were prepared the corresponding 5-arylamino-1,2,4-trioxanes, whose chemiluminescence was studied by comparing with those of Cypridina luciferin analogs.
Catalytic Upgrading of SRC from Pyrolytic Coal Liquefaction and Hydrocracking of Polycyclic Aromatic Hydrocarbons
Authors: Song Chunshan , Hanaoka Kouji , Ono Tomohiro , Nomura Masakatsu 
Published: July 2006

Abstract
Catalytic upgrading of SRC (solvent refined coal) derived from short contact time pyrolytic liquefaction of Wandoan subbituminous coal was carried out. The upgrading with unsulfided and sulfided nickel–molybdenum catalysts produced about 77 wt% and 85 wt% of oil plus light distillates from the SRC, respectively. The reactions occurring during the upgrading process were assessed by referring to the hydrocraking of related polycyclic aromatic hydrocarbons.
Classification of DNA Sequences by Hayashi’s Quantification (III) Method. Sequences Involving 5′-Splice Signals in Pre-mRNA of Higher Eukaryotes’ Genes
Authors: Iida Yôichi 
Published: July 2006

Abstract
Concerning the signals which direct the excision of introns from mRNA precursors in higher eukaryotes’ genes, a consensus sequence, \oversetCAAG/GT\oversetAGAGT, has been proposed with a 5′-splice site, but actual 5′-splice site sequences differ from it to a greater or lesser degree. In the present paper, we took a set of 1751 sequences, which are composed of 9-nucleotide sequences including 5′-splice signals and of other sequences including no such signals. Hayashi’s quantification analysis (Class III) was applied to such a system. Assuming no external criterion for 5′-splice signals, we examined how the 1751 sequences show responses to the positions and species of nucleotides. The optimum classification led to a fair separation of the 5′-splice signal sequences from sequences including no such signals. The results were compared with those derived previously by the use of the quantification (Class II) method.
Environmental Intensity Increments of the S1(nπ*)←S0 Absorption Spectra of Benzil in Fluid Solutions
Authors: Miyata Kaori , Koyanagi Motohiko 
Published: July 2006

Abstract
A remarkable solvent effect on intensity of molecular electronic transitions has been found in near UV absorption spectra of benzil. Great intensity enhancement is observed in alcohols and in chloromethanes as well as in nitriles. Parameters which are required to explain the origin of those environmental intensity enhancement are neither solvent refractive indexes nor polarities. A some rotationally flexible freedom around the –OC–CO– axis of benzil in the solvent seems important. Week complex formation between the solute and the solvent molecule is likely to play an important role. Similar solvent effects are found for absorption spectra of benzophenone and dicyclohexyl ketone, but with more complexity regarding their spectral shifts in contrast to the case of benzil.
Vibrational Analysis of Tangled Spectra. II. Role of Phonon Side Band Structure in the T←S Spectra of Acetophenones
Authors: Nakashima Kenichi , Futami Hiroshi , Koyanagi Motohiko 
Published: July 2006

Abstract
T1,2←S0 phosphorescence excitation spectra of acetophenone, acetophenone-methyl-d3, and acetophenone-phenyl-d5 have been observed in the crystals at 4.2 K. Vibration analysis for the observed tangled spectra becomes possible only by the help of calculations which allow untangling of the tangled spectra. The calculations involve interstate mixings, by vibronic and environmental interactions, among 36 crude adiabatic Born-Oppenheimer vibronic functions of 3ππ* and 3nπ* states. A new aspect of the present work is introduction of a role of intermolecular phonon side bands into the calculations; this clearly showing that the observed spectra are reproduced much better than unless otherwise.
Study of the Effect of Structural Factors on Magnetism of Di-μ-alkoxodicopper(II) Complexes by Ab Initio MO Calculations
Authors: Handa Makoto , Koga Nobuaki , Kida Sigeo 
Published: July 2006

Abstract
The effect of variation of structural factors on the spin-exchange interaction between copper(II) centers in dialkoxo-bridged dinuclear copper complexes were studied by the ab initio MO method with UHF formalism. The calculations were performed on di-μ-methoxotetraamminedicopper(II). The J-values were obtained as functions of Cu–O–Cu angle, dihedral angle between two coordination planes, planarity of bonds on the bridging oxygens, tetrahedral distortion of coordination planes, and the tilt of O–C bond from the O–O axis. The results demonstrated that the Cu–O–Cu angle most effectively affect the J-value but the other factors are less effective.
Oxygen-17 NMR Study of the Uranyl Ion. V. Kinetics and Mechanisms of Formation and Decomposition Reactions of Di-μ-hydroxo-bis[uranyl(VI)] Ion in Aqueous Nitrate Solutions
Authors: Jung Woo-Sik , Harada Masayuki , Tomiyasu Hiroshi , Fukutomi Hiroshi 
Published: July 2006

Abstract
The rates of formation and decomposition reactions of di-μ-hydroxo-bis[uranyl(VI)] ion, (UO2)2(OH)22+, have been measured in aqueous nitrate solutions (ionic strength=0.5 M; M= mol dm−3) by 17O NMR spectroscopy. In weakly acidic solutions the reactions obey the rate law:
d[(UO2)2(OH)22+]⁄dt=k2[UO22+][UO2OH+]−k−2Ka[H+][(UO2)2(OH)22+]⁄2,
where Ka=[(UO2)2OH3+]/[H+][(UO2)2(OH)22+]. A mechanism involving a single-bridged binuclear intermediate, (UO2)2OH3+, is proposed. Rate constants (M−1 s−1) at 25 °C and activation parameters ΔH\eweq (kJ mol−1) and ΔS\eweq (J K−1 mol−1) for the formation and decomposition are as follows: 1.52×105, 18.9±1.5, and −82.4±5.0 for k2 and 2.10×105, 23.6±1.3, and −64.0±4.2 for k−2Ka. The rate of the decomposition reaction is compared with that in several related systems.
Role of the Interface in Solvent Extraction Processes
Authors: Freiser Henry 
Published: July 2006

Abstract
This paper reviews 25 years’ investigation of kinetics of metal chelate extraction systems under high speed stirring conditions. Values of chelate formation rate constants for both analytical and hydrometallurgical extractants derived from such measurements using the assumption that the rate-determining step(s) occur in bulk aqueous phase, have been shown to be in reasonable agreement with expectations. Nevertheless, the introduction of the microporous Teflon phase separator in extraction kinetics resulted in clear evidence of reaction pathways involving the interface, as well as the bulk aqueous phase, even for simple chelating extractants.
A Convenient Synthesis of 1α-Hydroxyvitamin D2
Authors: Tachibana Yoji 
Published: July 2006

Abstract
The enol acetylation of ergosta-1,4,6,22-tetraen-3-one (4) by treatment with isopropenyl acetate under acidic condition gave 3-acetoxy-1,3,5,7,22-ergostapentaene (5). The reduction of 5 with calcium borohydride afforded ergosta-1,5,7,22-tetraen-3β-ol (6). The t-butyldimethylsilyl ether derivatives (8) of the Diels–Alder cyclo adduct (7) derived from 6 and 4-phenyl-3H-1,2,4-triazole-3,5-dione was oxidized with m-CPBA to the diepoxide adduct (9). The 1α,2α-epoxide of the diepoxy alcohol (10) obtained after the removal of the silyl group of 9 was selectively reduced with LiAlH4 to yield the 22,23-epoxy-1α,3β-diol (11) and 11 was subsequently converted to the corresponding diacetate (12). The deoxygenation of the 22,23-epoxide of 12 with a combination of sodium iodide and trifluoroacetic anhydride gave the 1α-acetoxyergosteryl acetate (13). Irradiation of 13 with a high-pressure mercury lamp followed by thermal isomerization, saponification, purification on silica gel and crystallization gave 1α-hydroxyvitamin D2 (1) as colorless crystals.
Synthesis of Gramicidin S Analogues Consisting of Fourteen Amino Acid Residues
Authors: Tamaki Makoto , Takimoto Michiaki , Muramatsu Ichiro 
Published: July 2006

Abstract
Four cyclotetradecapeptides related to gramicidin S, cyclo(–Val–Orn–Leu–Leu–d-Phe–Pro–Leu–)2 (14-peptide-1), cyclo(–Val–Orn–Leu–d-Leu–d-Phe–Pro–Leu–)2 (14-peptide-2), cyclo(–Val–Orn–Leu–Leu–d-Phe–Pro–d-Leu–)2 (14-peptide-3), cyclo(–Val–Orn–Leu–d-Leu–d-Phe–Pro–d-Leu–)2 (14-peptide-4), were prepared in order to investigate the contribution of the ring size and the amino acid sequences around the Pro residue to the antibiotic activity and conformation. The CD spectra of these synthetic peptides in ethanol solutions were different from each other, indicating that they possess various conformations in ethanol solutions. 14-Peptides-1, -2, and -3 showed 1/4–1/8 of the antibiotic activity of gramicidin S against the gram-positive microorganisms tested, whereas 14-peptide-4 showed no activity. A clear relationship between CD spectra and the antibiotic activity of these synthetic peptides could not be found.