bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular and Crystal Structure of Azobenzene-Containing Amphiphile, C6AzoC10N+Br−
Authors: Xu Guiqing , Okuyama Kenji , Shimomura Masatsugu 
Published: July 2006

Abstract
A totally synthetic azobenzene-containing amphiphile C32H52N3O3Br (C6AzoC10N+Br−) was crystallized from its solution in trichloromethane and ethanol. The crystal is triclinic with space group P\bar1; Z=2; a=24.317(5), b=8.632(1), and c=8.043(2) Å; and α=91.41(2), β=80.62(2), and γ=99.01(1)°. The structure was solved by the direct method and refined by the full-matrix least-squares method: R=0.038 for 4305 observed reflections (2θ&lt;120°, Cu Kα, λ=1.5418 Å). Two molecules in a unit cell are related by a center of symmetry and pack tail-to-tail in a bilayer structure. The plane of the azobenzene chromophore is almost perpendicular to the layer surface and is overlapped with that of the azobenzene chromophore along its long axis with a separation of 3.55 Å. Different from other homologous compounds, this molecule bends almost 90° at the neck of the hydrophilic head group.
The Design of Amino Hydroxamic Metal Chelates and Their Activity in Biological Systems. Formation Constants between 2-Amino-4-methylpentanehydroxamic Acid with Proton, Copper(II), and Iron(III) in Aqueous Solution
Authors: Leporati Enrico , Nardi Gianluca 
Published: July 2006

Abstract
The complex-formation equilibria and relative stability constants of species present in aqueous solution of copper(II) and iron(III) with “l-leucinehydroxamic acid” (2-amino-4-methylpentanehydroxamic acid, ahmpe) have been determined by using potentiometric and spectrophotometric titrations in 0.5 mol dm−3 KCl solution at 25°C. Their acid-base reaction stoicheiometries have been evaluated and the protonation constants calculated from potentiometric data with the aid of the GAUSS Z and SUPERQUAD programs. The complex formation constants have been determined by using SQUAD (absorbance data), SUPERQUAD and STBLTY (potentiometric data) programs. The ligand is bound to the metal ions through the coordination of the N atoms of the α-amino group and the deprotonated –NHO− group in copper(II)–ahmpe system. For iron(III)–ahmpe system the coordination is referred to oxygen atoms of carboxylate and hydroxamate moieties. The UV-visible studies provide important evidence for the formation of several complex species depending on the pH. The experimental curves [ε=f(λ)], deduced from refinement of absorbance data with the program SQUAD, have been split up into precisely positioned absorption bands by Gaussian analysis using a nonlinear least-squares computer program NLIN. So the solution electronic spectra have been also employed to estimate the coordination sphere and have let us to suppose a weak tetragonal coordination [CuL2(H2O)2] and octahedral for Fe3+ complexes. The determination of formation constants and the coordination pattern proposed have a great interest in terms of metal chelate structures and their important role in biological systems.
Oxidation of Sulfite and Thiosulfate by the Cobalt(III) Complex of Dipicolinate in Aqueous Medium
Authors: Ali Mahammad , Saha Swapan K , Banerjee Pradyot 
Published: July 2006

Abstract
The oxidation of sulfite and thiosulfate by Co(dipic)2− (where H2dipic=2,6-pyridinedicarboxylic acid) was studied in aqueous medium. The reactions were carried out by varying reagent concentrations, pH, and ionic strength. For thiosulfate oxidation, the rate is zero order in complex and second order in thiosulfate. The reaction rates were found to increase with the acidity and the general rate law is expressed as kobs={k′0+k′1[H+]}[S2O32−]2 where k′0 and k′1 denote the acid independent and dependent paths respectively. The values of rate parameters are k′0=(2.87±0.20)×10−8 mol dm−3 s−1 and k′1=(0.57±0.02) mol−2 dm6 s−1 at 30°C. A plausible mechanism is suggested by considering the formation of an intermediate active species in the rate-determining step. The sulfite oxidation was, however, first order both in complex and reagent. An inverse dependence on [H+] was obtained for this reaction indicating a higher reactivity of the anionic species in solution. The general rate law is given by kobs=2(k1[SO2·H2O]+k2[HSO3−]+k3[SO32−]) and the evaluated second-order rate constants are: k1=(5.60±0.04)×10−5 mol−1 dm3 s−1, k2=(3.02±1.21)×10−3 mol−1 dm3 s−1 and k3=(4.91±0.05)×10−2 mol−1 dm3 s−1 at 60°C. The reactivity order SO32−&gt;HSO3−&gt;SO2·H2O has been explained successfully by considering the two isomeric structures for these species in solution. An overall rate law has been derived to interpret these results over the whole range of pH. The theoretical pH rate profile calculated from the different rate parameters shows an excellent agreement with the experimental one suggesting the validity of the proposed mechanism.
Gamma Radiolysis of Flavin Mononucleotide and Flavin-Adenine Dinucleotide in Aqueous Solution
Authors: Saha Abhijit , Mandal Parikshit Chandra , Bhattacharyya Sudhindra Nath 
Published: July 2006

Abstract
Flavin-adenine dinucleotide (FAD) and flavin mononucleotide (FMN) were irradiated with 60Co γ-ray and G-values for their decomposition under aerated, argon and nitrous oxide saturated conditions at pH 6.5 were determined by spectrophotometric, fluorescence and HPLC measurements. Among the water-borne radicals the hydroxyl radical (OH) was found to be responsible for causing permanent changes in FAD and FMN. The striking similarity between the difference spectra of irradiated FAD and FMN in N2O saturated conditions shows that the OH radicals attack at the isoalloxazine moiety. A plausible mechanism for the reaction of the OH radicals with the isoalloxazine moiety has been discussed. The rate constant for the reaction of isoalloxazine moiety of FAD with OH radicals was determined to be 4.7×109 dm3mol−1 s−1 by competition kinetic studies using glucose as the reference solute. From the kinetic consideration and G-values it is evident that ca. 50% of the OH radicals attack at the AMP (adenosine monophosphate) portion of FAD apart from isoalloxazine moiety. The attack at the AMP portion of FAD is supported by the observed phosphate release in the irradiated FAD solution. Effect of Fe3+ ion on the radiolysis of FAD and FMN was also studied.
Conductivity of Manganese(II) Sulfate in Aqueous Solution at Various Temperatures
Authors: Kubota Eiji , Takizawa Satoru , Kashiwagi Wataru , Yokoi Masatoki 
Published: July 2006

Abstract
The molar conductivity of manganese(II) sulfate, MnSC4, in aqueous solution was measured in a temperature range of 10–45°C. The acquired data were analyzed by the Quint-Viallard equation, and the resulting ion association constant, KA, was used in the Bjerrum equation to determine the contact ion size, RB. The limiting ionic molar conductivity λ0 (1/2 Mn2+) for the manganese ion at 15, 25, 35, and 45°C are 40.8, 53.1, 65.2, and 79.8 S cm2 mol−1, respectively. The resulting thermodynamic properties for the ion association reaction are: ΔG°298=−13.5 kJ mol−1, ΔH°=7.91 kJ mol−1, and ΔS°298=74.1 JK−1 mol−1.
Circular Dichroism Spectrum of Ci-trans(O)-[Co(C(S)-edma-d1)2]+ Containing Chiral Methylene Formed by Stereospecific Deuteration
Authors: Ama Tomoharu , Yasui Takaji , Hidaka Jinsai 
Published: July 2006

Abstract
C i-trans(O)-[Co(C(S)-edma-d1)2]+ was prepared by way of the stereospecific deuteration of the facially coordinated edma (ethylenediamine-N-acetate) in (−)543CD-C2-trans(O)-[Co(edma)2]+. The vicinal CD spectrum due to the C(S)-edma-d1 in the Ci-trans(O) complex was investigated in connection with the D→H exchange in the ligands, suggesting a two-step mechanism.
Diastereoselective Synthesis of 2,3-anti-5-Benzyloxy-2,4-dimethyl-1,3-pentanediols via Cyclic Hydroboration
Authors: Yokoyama Yasushi , Terada Yuji , Kawashima Hideyuki 
Published: July 2006

Abstract
The treatment of (2E,4S)- and (2Z,4S)-1-benzyloxy-5-ethenyloxy-2,4-dimethyl-2-pentene with borane both with and without a catalytic amount of Rh(Ph3P)3Cl gave 2,3-anti-3,4-anti-(2R,3R,4S)- and 2,3-anti-3,4-syn-(2R,3R,4R)-5-benzyloxy-2,4-dimethyl-1,3-pentanediols, respectively, with fair to good diastereoselectivity.
Halogenation Using Quaternary Ammonium Polyhalides. XXXI Halogenation of Thiophene Derivatives with Benzyltrimethylammonium Polyhalides
Authors: Okamoto Tsuyoshi , Kakinami Takaaki , Fujimoto Hiroshi , Kajigaeshi Shoji 
Published: July 2006

Abstract
The reactions of thiophene derivatives with benzyltrimethylammonium tetrachloroiodate, benzyltrimethylammonium tribromide, and benzyltrimethylammonium dichloroiodate in acetic acid or in acetic acid–zinc chloride under mild conditions gave chloro-, bromo-, and iodo-substituted thiophene derivatives, respectively, in satisfactory yields.
A New Calix[6]arene-Based Uranophile with Phosphonate Groups as Ligands
Authors: Nagasaki Takeshi , Arimura Takashi , Shinkai Seiji 
Published: July 2006

Abstract
A new calix[6]arene-based uranophile which has six phosphonomethyl groups on the upper rim was synthesized. This compound forms a 1 : 1 complex with uranyl ion (UO22+). The stability constant was estimated to be 1017.5 M−1, which is satisfactorily comparable with those for calix[6]arene-based uranophiles bearing OH or COOH groups on the lower rim.
The Formation of Two New Ring-Enlargement Products in the Lead Tetraacetate Oxidation of l-2(10)-Pinene
Authors: Matsubara Yoshiharu , Youzhu Yuan , Zhi Cheng , Takekuma Shin-ichi , Yamamoto Hiroshi 
Published: July 2006

Abstract
The oxidation of l-2(10)-pinene with lead tetraacetate in glacial acetic acid at 60°C afforded, besides fifteen known other products, (1S,6S)-7,7-dimethylbicyclo [4.1.1]octan-3-one (2) and (1S,6S)-2-one isomer (3), whose structures were established on the basis of their spectroscopic data. A possible reaction pathway for the formation of these new compounds 2 and 3 involving novel ring-enlargement is described.
Oxidative Cleavage of Chalcones by Electrochemically Generated Superoxide Ion (O2\divdot)
Authors: Singh Manorama , Singh Krishna Nand , Misra Ram Achal 
Published: July 2006

Abstract
Various chalcones were efficiently cleaved to carboxylic acid(s), in considerably high yield by the reaction with electrochemically generated superoxide ion (O2\divdot) at mercury cathode and molecular oxygen.
Mixed Adsorbed Film and Micelles of Sodium Taurocholate and Sodium Taurodeoxycholate
Authors: Wada Atsunori , Matubayasi Norihiro , Motomura Kinsi 
Published: July 2006

Abstract
The surface tension of an aqueous mixture of sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC) in the presence of 0.1 mol kg−1 sodium chloride was measured as a function of the total concentration and composition of the bile salts at 25°C. The result, processed by a thermodynamic treatment based on excess thermodynamic quantities, showed that NaTC and NaTDC are freely miscible in an adsorbed film, while mixing in a limited composition region of the micelle.
Thermal Decomposition of Ammonium Amidotriphosphate (NH4)4P3O9NH2·H2O
Authors: Takenaka Atsushi , Ooe Junichi , Motooka Itaru , Nariai Hiroyuki 
Published: July 2006

Abstract
Ammonium amidotriphosphate (NH4)4P3O9NH2·H2O was heated at 5 K min−1 up to 100, 145, 180, and 240 °C in four different atmospheres: in a stream of dry air, humid air, ammonia, and dry hydrogen chloride. The products were analyzed by HPLC-FIA, X-ray diffractometry, and IR spectrophotometry. A new phase of ammonium cyclo-triphosphate was observed at lower temperatures, except for in the ammonia atmosphere. Oligophosphates (chain length=4–12) were more abundant in samples heated to 145 and 180°C in hydrogen chloride. The cyclo-tri- and oligophosphates were most probably formed via a zwitterion form. When heated to 240°C, the samples were changed to ammonium polyphosphates. Elemental analyses for the sample heated to 240°C in dry air showed that the ammonium polyphosphates formed contained some phosphorus-nitrogen bonds. Isothermal experiments at 180°C in dry air indicated that the new phase of ammonium cyclo-triphosphate was converted completely to ammonium polyphosphates.
Association of Cycloalkanes with Cyclodextrins in Aqueous Medium
Authors: Osajima Tomonori , Deguchi Toshio , Sanemasa Isao 
Published: July 2006

Abstract
The complex formation of α-, β-, and γ-cyclodextrins (CyDs, hosts) with five cycloalkanes (guests), cyclo(pentane, hexane, heptane, octane, and decane), has been studied in aqueous media at 25°C by making use of the volatilization rate of guest molecules from the aqueous into gas phase. In the excess of the host, α-CyD forms both 1 : 1 and 2 : 1 (host: guest) complexes, while β- and γ-CyDs form 1 : 1 complexes with an exception that β-CyD forms a 2 : 1 complex with cylodecane. The 2 : 1 complex formation constants of α-CyD with cyclo(hexane, heptane, octane, and decane), particularly with cyclooctane, are extremely large compared with their 1 : 1 formation constants. The host–guest spatial fitting models are proposed.
A New Reduction of Some Carboxylic Esters with Sodium Borohydride and Zinc Chloride in the Presence of a Tertiary Amine
Authors: Yamakawa Tomio , Masaki Mitsuo , Nohira Hiroyuki 
Published: July 2006

Abstract
In the presence of a tertiary amine, sodium borohydride (NaBH4) combined with zinc chloride (ZnCl2) showed powerful reducing properties and carboxylic esters were smoothly reduced to their corresponding alcohols which were not obtained by reduction with NaBH4 and ZnCl2 alone. Tetrahydrofuran (THF) was an efficient solvent, and the effective molar ratio of the reducing agents, NaBH4 : ZnCl2 : tertiary amine, was 2 : 1 : 1. In particular, aminobenzoates such as anthranilic esters, were reduced to aminobenzyl alcohols with high yields without the addition of a tertiary amine. Further, it was also found that this combination reduced nitro, cyano, and amido groups to their corresponding amino groups.
Flash Photolytic Generation of a Dithio Carbocation from 1,3-Dithiolane Derivatives and Its Reaction with Nucleophiles
Authors: Okuyama Tadashi , Haga Naoki , Takane Shin-ya , Ueno Kenji , Fueno Takayuki 
Published: July 2006

Abstract
2-Phenyl-1,3-dithiolanylium ion is generated as a transient intermediate by flash photolysis of aqueous ethanol and acetonitrile solutions of 2-methoxy and other dithiolane derivatives with a xenon lamp. Decay of the absorption (342 nm) of the cation generated from the 2-methoxy derivative follows pseudo-first-order kinetics. Rate constants were measured for the reaction of the cation with various nucleophiles. Decay curves for the cations generated from 2-arylthio and 2-sulfonyl derivatives are steep and show second-order kinetic character owing to the recombination of the cation with the counter anions (thiolate and sulfinate).
Photochemistry of 2H-Azirine—Formation of Nitrile Ylide Evidenced by Laser Flash Photolysis and Pulse Radiolysis—
Authors: Naito Ikuo , Morihara Hideaki , Ishida Akito , Takamuku Setsuo , Isomura Kazuaki , Taniguchi Hiroshi 
Published: July 2006

Abstract
Laser flash photolysis of 3-(4-biphenylyl)-2H-azirine (AZ) was carried out in cyclohexane for the direct detection of a nitrile ylide (NY). Two kinds of transient species, triplet AZ (T1) and NY, have been measured. Decay rates of these species were determined to be 6.7×105 s−1 (T1) and 8×10 s−1 (NY). The rate constants for the reactions of NY toward acetone and acrylonitrile were determined to be 2.5×103 dm3 mol−1 s−1 and 2.3×106 dm3 mol−1 s−1, respectively. These results were supported by the results of pulse radiolysis of AZ in benzene and stational irradiations of AZ.
The Synthesis of Hyptol and Its C-15 Epimer from (+)-Dehydroabietic Acid
Authors: Matsumoto Takashi , Terao Hiromitsu , Wada Makoto , Imai Sachihiko 
Published: July 2006

Abstract
In order to elucidate the absolute configuration of C-15 in natural hyptol, methyl (15S)-12,16-dihydroxy-8,11,13-abietatrien-18-oate and its (15R)-epimer were transformed into (15S)-12,16-epoxy-11,14-dihydroxy-8,11,13-abietatrien-7-one (1a) and its (15R)-epimer (1b), respectively. The synthetic 1a w as identical to natural hyptol. Thus, the stereochemistry of C-15 in the natural compound was conclusively assigned as S-configuration.
H-Aggregate of a Long-Chain Crystal Violet Dye in Langmuir–Blodgett Films
Authors: Miyata Akio , Unuma Yutaka , Higashigaki Yoshiyuki 
Published: July 2006

Abstract
The molecular orientation and aggregate formation in Crystal Violet (CV) dye monomolecular layers have been investigated by means of polarized reflection and absorption spectral measurements at an incident angle of 60°. A relatively sharp absorption band at 2.04 eV and a broad band around 2.23 eV assignable to the J-dimer and the H-dimer, respectively, were observed in the optical measurement geometry with polarized light either parallel(p) or perpendicular(s) to the incident plane. A sharp band at 2.61 eV, assigned to the H-aggregate (tetramer), was detected by p-polarized spectral measurement, but not s-polarized measurement. The J- and H-dimers have horizontal transition moments and the H-aggregate has a vertical transition moment. The H-aggregate peak shifted from 2.53 eV (10 mN m−1) to 2.61 eV (40 mN m−1) with increasing surface pressure. This is due to an increase in the slip angle between the transition dipole moments and their center-to-center lines because the chromophoric planes become to be gradually oriented normal to the water surface. The behavior of these aggregates is interpreted in terms of the extended dipole model.
High-Resolution Solid-State Cross-Polarization Magic-Angle Spinning 13C NMR of Metal-Free Phthalocyanines
Authors: Enokida Toshio , Hirohashi Ryo , Morohashi Nobuo 
Published: July 2006

Abstract
The high-resolution solid-state cross-polarization magic-angle spinning 13C NMR spectra of α, β, τ and X-form metal-free phthalocyanines (H2pc) were investigated. Chemical shifts differed according to crystal forms. As a result of the temperature dependence of chemical shifts, we could observe the change in the spectra because of the inner protons.
Co-Intercalation of Tetrahydrofuran and Propylene Carbonate with Alkali Metals in β-ZrNCl Layer Structured Crystal
Authors: Ohashi Masao , Uyeoka Koji , Yamanaka Shoji , Hattori Makoto 
Published: July 2006

Abstract
Alkali metal intercalation compounds of β-ZrNCl were prepared by both chemical and electrochemical processes in tetrahydrofuran (THF) and propylene carbonate (PC), used as solvents. Among the six combinations of alkali metals (Li, Na, and K) with THF and PC, only the Na–THF system did not form a co-intercalation phase. In the other systems, the solvent molecules co-intercalated with alkali metals in mono- and double layer arrangements between the chloride layers of β-ZrNCl, the structures of which were estimated from one-dimensional electron distribution maps along the direction normal to the basal plane. The electrochemical characteristics of β-ZrNCl, used as the cathode of a lithium battery, were greatly influenced by the electrolyte solvent used. The co-intercalation mechanisms are discussed in terms of the energetics of the solvation of alkali metal ions with polar molecules and an expansion of the β-ZrNCl interlayers.
Redox Properties for Pentacoordinated Manganese(III) Complexes with Bis(salicylideneamino)alkanes
Authors: Nakamura Masaaki , Miyanaka Yuri , Ohmura Yasuhiro , Sekine Satoko , Huang Hu , Kai Fumiaki 
Published: July 2006

Abstract
The oxidation potentials of Mn(III/IV) for pentacoordinated chloromanganese(III) complexes with bis(salicylideneamino)alkanes shifted cathodically in the presence of excess chloride ions in their solution. The formation of dichloromanganese(IV) complexes with Schiff bases was spectrophotometrically detected by addition of chloride and hydrogen ions to acetonitrile solutions of the corresponding chloromanganese(III) complexes under aerobic conditions.
Apparent Molal Volumes of Urea and Its Derivatives in Aqueous Alkali Chloride Solutions
Authors: Ogawa Toshio , Mizutani Kiyoshi , Ando Yukimi , Yasuda Motoo 
Published: July 2006

Abstract
The apparent molal volumes (φv) at 25°C have been measured for the following urea derivatives in aqueous alkali chloride solutions (from density measurements) using a digital densimeter: urea, methylurea, ethylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1-diethylurea, and 1,3-diethylurea. The limiting values (φv°) were obtained by a linear extrapolation using the least-squares method. A notable feature of the transfer volumes found in this study was that hydrophobic urea derivatives, such as dimethylureas and diethylureas, had negative values for transfer from water to lithium chloride solutions. For the remainder, however, all transfer volumes were positive.
Structural Study of Triazole Antifungals. II. Crystal and Molecular Structures of the Two Diastereoisomers (4R*,5R*)- and (4S*,5R*)-5-(2,4-Difluorophenyl)-4-methyl-5-[(1H-1,2,4-triazol-1-yl)methyl]-3-[4-(trifluoromethyl)benzoyl]oxazolidine
Authors: Hata Tadashi , Furukawa Youji , Konosu Toshiyuki , Oida Sadao 
Published: July 2006

Abstract
The title compounds were designed and synthesized as potential inhibitors of cytochrome P-450 14α-demethylase. The antifungal activity of (4R*,5R*)-isomer is markedly higher than that of (4S*,5R*)-isomer. The crystal structures of the two diastereoisomers were determined by X-ray diffraction technique. The final R indices of (4R*,5R*)- and (4S*,5R*)-isomers were 0.063 and 0.070 for 2840 and 2365 reflections, respectively. The different configuration at the 4-position in the oxazolidine ring causes the differences in the ring conformation and in some torsion angles. The three-dimensional structures of the two diastereoisomers are consequently different. Among the diastereoisomers and enantiomers, the (4R,5R)-enantiomer is superimposable on lanosterol, which is a substrate of cytochrome P-450 14α-demethylase, suggesting that the 4β-methyl group plays an important role in the antifungal activity.
Fragmentation of Energy-Selected Fluorobenzene Ion
Authors: Nishimura Toshihide , Meisels Gerry G , Niwa Yoshio 
Published: July 2006

Abstract
Dissociation of the fluorobenzene ion has been studied using threshold photoelectron–photoion coincidence (TPEPICO) mass spectrometry. The detailed breakdown curves were measured over internal energies from 0 to 9 eV. Asymmetric flight time distributions due to metastable dissociation were observed for the formations of C6H5+ and C4H3F+, and their absolute decay rate constants were derived from their flight time distributions. The information-theoretical approach has been employed for the analysis of kinetic energy release distribution (KERD). The results of surprisal analysis demonstrated that experimental KERDs are in good agreement with the predictions based on the statistical theory of mass spectra (QET). The heat of formation of C4H3F·+ has been estimated to be 222±2 kcal mol−1.
Chemical Analysis of Thortveitite from Oro, Mineyama-cho, Naka-gun, Kyoto Prefecture, Japan
Authors: Moriyasu Kazuhisa , Nishikawa Yasuharu 
Published: July 2006

Abstract
The geochemically interesting rare mineral, thortveitite, from Oro, Kyoto Prefecture was studied. Major constituents, scandium, yttrium, and lanthanoids, niobium, tantalum, aluminum, titanium, iron, calcium, and manganese were determined. The chemical analysis of the mineral assemblage gave Sc2O3 18.20, Y2O3 0.72, Σ Ln2O3 1.70, FeO 0.97, MnO 0.54, Nb2O5 trace, Ta2O5 9.96, Al2O3 3.02, CaO 1.72, TiO2 0.83, SiO2 58.31, and H2O 4.20; total 100.17%. This sample contained tantalite 11.47, anorthite 8.37, rutile 0.83, and quartz 37.91% in addition to thortveitite 37.40%. Scandium-tantalum substitution is suggested to occur similarly to yttrium-niobium substitution in earth acid minerals.