bluuebunny/crossref_metadata_2025 huggingface dataset:
Concentration Dependence of the Conversion between the Intermolecular β-Structure and the Disordered State of Poly(S-carboxymethyl-l-cysteine) in Aqueous Solutions
Authors: Maeda Hiroshi , Saito Kaoru , Ikeda Shoichi
Published: July 2006

The effects of polymer concentration on the reversible conversion between the intermolecular β-structure and the disordered state of poly(S-carboxymethyl-l-cysteine) were examined by means of circular dichroism at constant pHs in 20 mM NaClO4 solutions. The data were tentatively analyzed based on an assumed all-or-none model. A value of −1.1 kJ (−250 cal) per mole of residues was obtained for the standard free energy of association. It was suggested that the obtained results depended significantly on the molecular weight distribution of the used samples.
Magnetic-superexchange Interactions of Uranium(IV) Chloride-addition Complexes with Amides. II. Complexes with Lactams
Authors: Miyake Chie , Hinatsu Yukio , Imoto Shosuke
Published: July 2006

The magnetic susceptibilities of five cyclic amide (lactam)-addition complexes of uranium(IV) chloride were measured between room temperature and 2 K. Magnetic-exchange interaction was found only for N-methyl-substituted amide complexes, and a dimer structure was assumed for them on the basis of their chemical properties. Treating interdimer interaction with a molecular-field approximation, the magnetic susceptibilities were calculated to be in good agreement with the experimental results in the temperature region of the maxima in χA. The transmission of antiparallel spin coupling via the π orbitals of the bridging amide ligands is proposed to explain the strong intradim er superexchange interaction for the uranium(IV) chloride–amide complexes with the magneticsusceptibility maximum.
Distribution and Chemical Behavior of 21 Elements in River Water in the Yakushima Island
Authors: Tanizaki Yoshiyuki , Nagatsuka Sumiko
Published: July 2006

The concentrations of 21 elements dissolved in the river water collected from around the Yakushima Island were determined by a neutron activation analysis (NAA). From the analytical results, the distribution and chemical behavior of each element in the water were discussed. The chemical composition of the river water was nearly uniform all around the island, and the concentration of each element determined in this work was extremely close to the geochemical background value of river water, since our experimental area had scarcely any pollution. Among the 21 elements chlorine, sodium, and magnesium were mainly supplied into the river water from the ocean, while the others were chiefly driven from the rocks and their efflorescences in the drainage basin. The enrichment factors for the granitic earth crust (FE-value) were very close to 1 for calcium, strontium, and zinc, while those of selenium, arsenic, tungsten, and antimony were much higher than 1. For the elements such as aluminium, iron, manganese, etc., on the other hand, the FE-values were very low. These differences in the FE-values among the elements correspond to differences in their solubilities in the water.
The Relation between the Proton-induced Quenching Rate Constants and the Charge Densities of Aromatic Compounds
Authors: Shizuka Haruo , Tsutsumi Kinzo
Published: July 2006

A plot of log k′q (the proton-induced quenching rate constants) vs. the charge densities PΣ* (or superdelocalizabilities SΣ*) in the excited state gave a straight line. The linear relation strongly supports the proton-induced quenching mechanism involving electrophilic protonation at the proper carbon atoms in the aromatic ring.
Photolysis of Ozonides in the Gas Phase
Authors: Hatakeyama Shiro , Akimoto Hajime
Published: July 2006

Photolysis of four kinds of simple ozonides (ethene, propene, 2-butene, and isobutene ozonides) in the gas phase were carried out. The contribution of the double-β-scission mechanism was 4–13%. The main reaction path is proposed to be intramolecular hydrogen abstraction followed by radical forming unimolecular decomposition.
Crystal Structures of (1,5-Cyclooctadiene)di-μ-methoxo-dirhodium(I) and Tetrakis(η3-allyl)di-μ-hydroxo-dirhodium(III)
Authors: Tanaka Isao , Jin-no Naoki , Kushida Takanori , Tsutsui Noriyoshi , Ashida Tamaichi , Suzuki Hiroharu , Sakurai Humio , Moro-oka Yoshihiko , Ikawa Tsuneo
Published: July 2006

The crystal structures of (1,5-cyclooctadiene)di-μ-methoxo-dirhodium(I) and tetrakis(η3-allyl)di-μ-hydroxodirhodium(III) were determined by the X-ray method. The former belongs to the triclinic space group P\bar1 with cell dimensions, a=7.347(4), b=6.471(3), c=9.554(6) Å, α=87.06(4), β=82.50(5) and γ=77.98(4)°. The space group of the latter is also P\bar1 but two crystallographically independent molecules exist in a cell with dimensions, a=11.704(7), b=9.793(6), c=7.948(5) Å, α=113.49(5), β=54.59(5), and γ=110.99(5)°. Both structures were determined by the heavy atom method and refined by the block-diagonal least-squares method. The final R values were 0.054 for the former and 0.075 for the latter. The coordination of the rhodium atom in the former compound is square planar, the cyclooctadiene ligand being regarded as a bidentate donor. The latter coordination is, in a formal sense, octahedral.
The Ion-exchange Properties toward Hexaamminecobalt(III) and the Characterization of the Complex Cation Form of α-Zirconium Phosphate
Authors: Hasegawa Yoshitsugu , Kizaki Seiichi , Amekura Hiroshi
Published: July 2006

The ion-exchange properties of α-zirconium phosphate have been investigated for the H+–[Co(NH3)6]3+ system. The ion-exchange process was examined by means of the variation in the pH values of the supernatant. α-Zirconium phosphate loaded with hexaamminecobalt(III) was also characterized by chemical analysis, X-ray diffractometry, infrared spectroscopy, and thermal analysis. In spite of the steric hindrance in the crystal structure of α-zirconium phosphate, the ion exchange proceeded gradually. About 30% of the hydrogen ions in α-zirconium phosphate were replaced by hexaamminecobalt(III). The interlayer distance of the exchanger expanded from 0.76 to 1.12 nm.
The Synthesis of 2,7-Bis(dimethylamino)pyrene and -tetrahydropyrene and the Electrical Conductivities of Their Complexes
Authors: Ueda Naomi , Natsume Bunji , Yanagiuchi Kazumi , Sakata Yoshiteru , Enoki Toshiaki , Saito Gunzi , Inokuchi Hiroo , Misumi Soichi
Published: July 2006

New π-donors containing a pyrene or a tetrahydropyrene ring were synthesized by means of a unique transannular reaction of the corresponding [2.2]metacylcophane derivatives. The CT complexes of these donors with a series of TCNQ derivatives different in electron affinity were prepared, and their electrical conductivities on single crystals were measured. The highest conductivity (0.36 Ω−1 cm−1) was that of the tetrahydropyrene derivative-TCNQ complex. It was reconfirmed that the partial charge-transfer from a donor to an acceptor is very important for high conductivity.
Reaction of the Azomethine Moiety Buried in Bilayer Membranes
Authors: Okahata Yoshio , Ando Reiko , Kunitake Toyoki
Published: July 2006

The reaction with water and amines of the azomethine moiety that is part of single-chain ammonium amphiphiles was examined. These amphiphiles form stable bilayer aggregates when they have the alkyl tail of C7 or C12. The reaction with water of the bilayer-forming amphiphiles ceases at the hydration stage and are 10–2000 times slower than those of the amphiphiles which do not form bilayers and undergo hydrolytic cleavage. The reactivity of the azomethine moiety in bilayers decreases with increasing distance from the membrane surface. The Arrhenius plots for the bilayer-forming amphiphiles show discontinuities at temperatures corresponding to phase transition of the respective bilayer (Tc). The apparent activation energy is larger at temperatures below Tc than at temperatures above Tc. This suggests that water penetration is facilitated in the fluid bilayer. The reaction with amines was affected by their solubility in the bilayer matrix, and poly(ethylenimine) gave a much reduced reaction rate when the azomethine moiety was buried deep in the bilayer matrix.
Conformational Changes of the Poly(α-l-glutamic acid)–Cu(II) Macromolecular Complexes in the pH Range of 4–7. A Light Scattering Study with Emphasis on Aggregation and Helix-coil Transitions
Authors: Masujima Tsutomu
Published: July 2006

The overall conformational changes of the macromolecular complex between poly(α-l-glutamic acid), poly(Glu), and Cu(II) in 0.15 M NaCl were investigated by means of the light scattering method at three mixing ratios of Glu residues to Cu2+, R, (32, 16, and 8) in the pH range of 4–7. The root-mean-square radius of gyration and the weight-averaged molecular weight of poly(Glu) were determined by means of the Zimm plot, and those pH dependences show that the poly(Glu) shrinks in the course of the coil-to-helix transition and that it forms aggregates at pH values lower than 4.7, where helix formation is almost completed. In the presence of Cu2+ ions, the bound Cu(II) accelerates the shrinking of the poly(Glu) conformation and induces the aggregation in a high pH region, where the helix is imperfect. With the aid of theoretical treatments in the text, the aggregation scheme in the helix region was disclosed to be side-by-side, in which a 70–95% length of a helix overlaps one another. All these results and the pH dependence of the radius of gyration per poly(Glu) molecule were discussed in relation to the complex formation between Cu(II) and poly(Glu).
Pressure Effect on Transference Numbers for KCl in Ethanol–Water Mixtures at 25 °C
Authors: Ueno Masakatsu , I Sh\={o}go , Shimizu Kiyoshi
Published: July 2006

Cation transference numbers for 0.02 mol dm−3 KCl in 0-, 5-, 10-, 15-, 20-, and 30-mol% ethanol–water mixtures were determined by the moving boundary method at 25 °C up to 1500 kg cm−2 (1 kg cm−2=0.9807×105 Pa). The cation transference number, t+, initially increases with increasing ethanol content up to 10–15 mol% and then decreases at all the pressures studied. In water and ethanol–water mixtures below 20 mol%, t+ at the definite solvent decreases with increasing pressure. The decreasing rate becomes smaller as the ethanol content increases, and the tendency is reversed finally at 30 mol%. To account for the variation of t+ with solvent composition and pressure, specific interactions between the ions and solvent have been taken into consideration.
The Effect of the Difference in the Oxidation State of the Second Component Added to MoO3 on the Generation of the Acidic Property
Authors: Ai Mamoru
Published: July 2006

The effect of the difference in the oxidation state of the second component added to MoO3 on the generation of acidic sites was studied with regard to Sn2+—Sn4+, Fe2+—Fe3+, Cr3+—Cr6+, and Cu+—Cu2+. It was found that a markedly lager amount of acidic sites is generated by the combination of Sn2+, Fe2+, or Cr3+ with MoO3 than by that of Sn4+, Fe3+, or Cr6+ respectively. As a general feature of metal-oxide combination, it is proposed that the addition of a metal ion in a lower oxidation state to MoO3 brings about a markedly more significant acidity generation than that of a metal ion in a higher oxidation state. An explanation to account for the results was attempted in relation to the reducing function of the second component.
A Conductance Study of 18-Crown-6 and Dibenzo-18-crown-6 Complexes with K+ in Various Solvents
Authors: Takeda Yasuyuki
Published: July 2006

Limiting ionic molar conductivities (λ°) of 18-crown-6 (18C6) and dibenzo-18-crown-6 (DB18C6) complexes with K+ in several protic and aprotic solvents have been determined at 25 °C. The crystal ionic radius of 18C6 complex with K+ is nearly identical with that of tetrabutylammonium ion ((n-C4H9)4N+). For CH3OH, the mobility of the 18C6 complex with K+ is nearly equal to that of (n-C4H9)4N+. However, for H2O, the former is much larger than the latter, but the contrary is true for aprotic solvents. Walden products of 18C6 complexes with K+ for the solvents are nearly equal to each other. For acetonitrile and DMSO, the λ° value of the DB18C6 complex with K+ is smaller than those for the tetrapentylammonium ion ((n-C5H11)4N+) and for the tetraisopentylammonium ion ((i-C5H11)4N+). For nitrobenzene and propylene carbonate, that of the DB18C6 complex with K+ is smaller than those of (n-C5H11)4N+ and (i-C5H11)4N+, respectively. In contrast to the case of the aprotic solvents, the λ° value of the DB18C6 complex with K+ for CH3OH is nearly equal to those of (n-C5H11)4N+ and (i-C5H11)4N+. Walden products of the DB18C6 complexes with K+ for the solvents are nearly equal to each other. From the above data, it appears that a solute which contains a unit of 18C6 in its structure does not enforce a hydrogen-bonded structure for a protic solvent.
Reactions of the Octahedral Bis(α-diketone dioximato)iron(II) Complexes with Carbon Monoxide and Benzyl Isocyanide
Authors: Sasaki Yoshihiro
Published: July 2006

The reactions of bis(α-diketone dioximato)iron(II) coordinated by two nitrogeneous base molecules (X) with carbon monoxide and benzyl isocyanide were studied kinetically in chloroform; here α-diketone dioxime=2,2′-difurylglyoxime (H2fr) and dimethylglyoxime (H2dg). The reactions proceeded reversibly through a dissociative mechanism. For the reaction Fe(Hfr)2(X)2\oversetk1\undersetk−1\ightleftharpoonsFe(Hfr)2(X)+X, plots of logk1  vs. pKa (Ka : dissociation constant of conjugate acid of base) for pyridines gave a negative correlation. The logk1 values of 4-cyanopyridine and 4-acetylpyridine systems were smaller and that of 2,6-dimethylpyridine system larger than predicted by their pKa values. Imidazole and 1-methylimidazole were more inert than pyridines. For the reaction Fe(Hfr)2(X)+(CO)\oversetk2\undersetk−2\ightleftharpoonsFe(Hfr)2(X)(CO), logk−2  vs. pKa plots for sterically unhindered pyridines showed a linear relationship, but the basicity of pyridine bases did not affect the CO dissociation processes very much. 2-Methylpyridine, 2,4-dimethylpyridine, and 2,6-dimethylpyridine facilitated the dissociation of CO slightly as compared with pyridine. Imidazole and 1-methylimidazole allowed CO to be more inert and piperidine more labile than pyridines. The dissociation of the base was significantly affected by the change of substituents in α-diketone dioxime, and the dissociation of CO was slightly affected by the change of substituents. The reaction behavior was discussed on the basis of the activation parameters and infrared data.
Zeta Potentials of Metal Oxides Coated with Titanate Coupling Agents in Aqueous Solution
Authors: Esumi Kunio , Suzuki Toshio , Meguro Kenjiro
Published: July 2006

The zeta potentials of metal oxide surfaces coated with titanate coupling agents were measured as a function of pH in the suspensions. The treatment by titanium(IV) isopropoxide tris(2-methylheptadecanoate) on the metal oxides, such as iron oxide, titanium dioxide, and silica, provided lower zeta potential values over a wide pH range than those of untreated samples. On the other hand, the treatment of the samples by titanium(IV) tris[2-(2-aminoethylamino)ethoxide] isopropoxide rendered the surfaces more cationic. Further, it was found that the titanate coupling layer was almost removed from the surfaces after one day they were immersed in aqueous solution.
Preparation of Tetraethylammonium Hexamolybdate by the Use of Extraction Method
Authors: Murata Katsuo , Yamamoto Etsuko , Ikeda Shigero
Published: July 2006

It was found that cyclohexanone selectively extracts hexamolybdate from weakly acidic solutions. Tetraethylammonium hexamolybdate was prepared as precipitate in the extracted phase by the addition of alcoholic tetraethylammonium chloride solution. This compound was confirmed to be [(C2H5)4N]2Mo6O19 by elementary analysis and Raman measurements.
197Au-Mössbauer Spectroscopic Studies of Monomeric and Trimeric Gold(I) Azolates
Authors: Katada Motomi , Sato Kumiko , Uchida Yoshio , Iijima Seiichiro , Sano Hirotoshi , Wei H H , Sakai Hiroshi , Maeda Yutaka
Published: July 2006

The identical chemical state of three gold atoms in trimeric gold(I) azolates and the Au(I)–Au(III) mixed-valence state in their iodine adducts, Au3(az)3I2, were confirmed by means of 197Au-Mössbauer spectroscopy.
Preparation of Red Organic Pigment with Phenylated Silica Gel as Core
Authors: Suzuki Mituru , Itô Seisirô , Kuwahara Tosihide
Published: July 2006

The silanols on the surface of silica gel were chlorinated and a phenyl group was introduced onto the silica gel (Remark: Graphics omitted.) by phenylating with phenyllithium. The surface group was derived to a structure similar to Sudan I by nitration, reduction, diazotization, and coupling (with 2-naphthol). The prepared pigment showed approximately the same color as Sudan I, and had very good resistance to water.
The Formation of Vinyl Sulfides by the Cleavage of the Carbon-Sulfur Bond in Dithioacetals with CuCl2
Authors: Oida Tatsuo , Tanimoto Shigeo , Ikehira Hideyuki , Okano Masaya
Published: July 2006

The elimination of arene- and alkanethiol from diaryl and dialkyl dithioacetals, in the presence of copper(I) or copper(II) salt plus tertiary amine, to produce the corresponding aryl and alkyl vinyl sulfides, respectively, has been studied. The employment of a combination of 2 mol equiv. of CuCl2 and 2 mol equiv. of N,N-diisopropylethylamine is most favorable.
Magnetic and Spectral Properties of 3,5-Dichloropyridine Adducts of Dimeric Copper(II) Acetate, Chloroacetate, and Dichloroacetate
Authors: Muto Yoneichiro , Tokii Tadashi , Chijiwa Kiyohiko , Kato Michinobu
Published: July 2006

Three complexes with the empirical formula of Cu(RCOO)2·L, where R=CH3, CH2Cl, or CHCl2 and L=3,5-dichloropyridine, were prepared and studied. These complexes display the antiferromagnetic behavior typical of dimeric copper(II) carboxylates. The singlet-triplet splitting energy (−2J) is 349 cm−1 for the acetate, 340 cm−1 for the monochloroacetate and 312 cm−1 for the dichloroacetate. Comparison of their magnetic and electronic spectral properties with those of the corresponding pyridine adducts indicates that both the −2J and \ ildeνmax(absorption maximum of Band I) values of the respective 3,5-dichloropyridine adducts are higher than those of the pyridine adducts. The influence of the pyridines on both the magnetic and spectral properties was discussed.
Kinetics and Equilibrium Studies on the Anation Reactions in Pentakis(dimethyl sulfoxide)dioxouranium(VI) and Tetrakis(hexamethylphosphoric triamide)dioxouranium(VI) Ions in Nonaqueous Media
Authors: Doine Hideo , Ikeda Yasuhisa , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

The anation reactions in [UO2(dmso)5]2+ (dmso=dimethyl sulfoxide) and [UO2(hmpa)4]2+ (hmpa=hexamethylphosphoric triamide) ions by SCN− and N3−have been studied by the stopped-flow method in DMSO and acetonitrile. For the anation reactions of [UO2(dmso)5]2+ in DMSO as a medium, the pseudo-first order rate constant(kobsd) is expressed by kobsd={k−1+(k1+k−1)×Kos[X]}/(1+Kos[X]), where X=SCN− and [UO2(dmso)5]2+ for the anation reactions by SCN− and N3−, respectively. The values of k1, k−1, and Kos at 25 °C are 2.06×102 s−1, 62 s−1, 35 M−1 (M=mol dm−3), and 7.60×102 s−1, 0.0 s−1, and 41 M−1 for the SCN− and N3− anation reactions in [UO2(dmso)5]2+, respectively. For the anation reaction in [UO2(hmpa)4]2+ by SCN−, the pseudo-first order rate constant was found to be proportional to the concentrations of [UO2(hmpa)4]2+ and free HMPA: kobsd=kf[UO2(hmpa)42+]+kb[HMPA]free. The values of kf and kb at 25 °C are 9.70×103 M−1 s−1 and 9.05×102 M−1 s−1, respectively. The equilibrium constants for the titled reactions were also measured at 25 °C: K=85 M−1for the anation reaction of [UO2(dmso)5]2+ by SCN− in DMSO and K’=42.7 for the SCN− anation reaction in [UO2(hmpa)4]2+ in acetonitrile. The kinetic results suggest that the anation reactions in uranyl complexes proceed through an associative or an associative interchange mechanism.
Pyridoxal Methochloride Catalysis of the β-Elimination Reaction of Methyl 3-Chloroalaninate in Water
Authors: Kondo Hiroki , Morita Kanzi , Kitamikado Tatsuya , Sunamoto Junzo
Published: July 2006

The β-elimination reaction of methyl 3-chloroalaninate has been investigated in the absence and presence of pyridoxal methochloride (2) or pyridoxal (3). Apparently, compound 2 was about twice as effective as 3 in the catalytic reaction that proceeds via a Schiff base of substrate and 2 or 3. The pH-rate profiles for the catalytic reaction with 2 and 3 were analyzed in terms of ionization of the various Schiff base species present in solution. It was found that the reactivity of the Schiff base decreases as the ionization of the molecule progresses. The reaction mechanism and its relevance to the catalysis of pyridoxal phosphate–dependent enzymes are discussed.
Kinetics of the Racemization and Dissociation of Tris(1,10-phenanthroline)iron(II). The Aggregate Formation of the Complex Cation with 1-Alkanesulfonate Anions through Hydrophobic Interaction
Authors: Tachiyashiki Satoshi , Yamatera Hideo
Published: July 2006

The kinetics of the racemization and dissociation of [Fe(phen)3]2+ were investigated in the presence of a series of 1-alkanesulfonate ions (n-CnH2n+1SO3−, n=2,4,6,…,14). The racemization rate increased, while the dissociation rate decreased, gradually as a function of the alkanesulfonate concentration at low concentrations of each alkanesulfonate. With alkanesulfonates of n≥8, the second phase of rate changes, i.e., steep increases in both rates, were observed at higher concentrations. The gradual initial changes in the rates were explained in terms of the formation of the 1:1 aggregate of the complex cation with the alkanesulfonate ion caused by hydrophobic interaction. The formation constant (mol−1 dm3) increased almost exponentially from 4 (n=4) to 770 (n=14) with the increase in the alkyl-chain length, the energy of the hydrophobic interaction of the complex cation and the alkanesulfonate anion being 0.9 kJ mol−1 per methylene group of the latter. The second phase of the rate changes were explained in terms of the formation of the 1:m aggregate of the complex cation with the alkanesulfonate ions. The rate behavior of the hydrophobic aggregates is discussed in connection with the reaction mechanisms of the racemization and dissociation of [Fe(phen)3]2+.
Solvent Effects on the Intensity of the nπ* Absorption Spectra of 1-Phenylethylenetrithiocarbonate and p-Benzoquinones
Authors: Jinnouchi Yasufumi , Kohno Motohisa , Kuboyama Akira
Published: July 2006

The nπ* absorption intensities of 1-phenylethylene trithiocarbonate (1), p-benzoquinone (2), and 2,5-di-t-butyl-p-benzoquinone (3) in nonpolar solvents are compared with the theoretical ones calculated by the use of Abe’s formula, in which the Onsager-cavity field is used. For 3, the theoretical intensities are well correlated with the observed ones, whereas for the others there are discrepancies, especially for 1. These discrepancies are attributed to strong dispersion-force interactions with the solvents.
Application of Liquid Crystals for Gas-Liquid Chromatography
Authors: Sakagami Sakumitsu , Nakamizo Minoru
Published: July 2006

A liquid crystalline homologous series of N-[4-(4-alkoxybenzoyloxy)benzylidene]-4-cyanoanilines was applied as a stationary liquid phase for the gas-liquid chromatographic separation of various positional isomers. It is shown that the nematic phase has higher selectivity for several positional isomers compared with the other mesomorphic phases.
Studies of Bitter Peptides from Casein Hydrolyzate. VIII. Bitter Taste of Cyclic Analog of BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val)
Authors: Miyake Ichizo , Kouge Katsushige , Kanehisa Hidenori , Okai Hideo
Published: July 2006

In order to elucidate the structure-taste relationship of bitter peptide BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val), cyclo-BPIa was synthesized. The result of both taste and CD examinations suggested that the bitterness of BPIa is caused by its spatial structure, which is analogous to that of cyclo-BPIa.
The Complexation of Zinc Tetraphenylporphyrintrisulfonate by Viologen and Its Role in Photoredox Processes
Authors: Okura Ichiro , Kusunoki Shin , Aono Shigetoshi
Published: July 2006

The formation of the cation radicals of viologen dyes was established when an aqueous solution containing zinc tetraphenylporphyrintrisulfonate (Zn–TPPS3), viologen dye, and 2-mercaptoethanol was irradiated by visible light. The reduction of viologen has been studied kinetically; its reduction rate may be expressed as follows:

v=\fracd[V+]dt=\left(\frack3[Zn−TPPS3]01+K1[V2+]+K2[V+]\ight)\left(\frack4[V2+]k−3+k4[V2+]\ight)\left(\frack6[RSH]k5[V+]+k6[RSH]\ight),

where [V2+], [V+], and [RSH] are the concentrations of the oxidized form and the reduced form of viologen, and 2-mercaptoethanol respectively. On the basis of the rate expression, a reaction mechanism containing the complexation of Zn–TPPS3 by viologen was proposed. On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by the irradiation of visible light.
Kinetics and Equilibrium Studies of the Formation of a Cobalt(II) Complex with N-(8-Quinolyl)aminoacetic Acid
Authors: Hara Yasuo , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko
Published: July 2006

Stopped-flow kinetic and equilibrium studies have been made of the formation of a cobalt(II) complex with N-(8-quinolyl)aminoacetic acid in 0.10 mol dm−3 aqueous sodium chloride containing 12 vol% ethanol at 25 °C. Octahedral mono- and bis-ligand complexes were formed via the two pathways of the reactions of deprotonated and monoprotonated ligand species with the aquacobalt(II) ion. The coordination mechanism is discussed.
Kinetic Studies of the Hydrolysis of Diketene Catalyzed by the Chloropalladium(II) Complex
Authors: Okeya Seichi , Kawaguchi Shinichi
Published: July 2006

When diketene and sodium tetrachloropalladate(II) are mixed in aqueous solution, color of the solution changes promptly from dark red to yellow. During this fast primary reaction about one equivalent of diketene is consumed and acetoacetic acid (H2A) is retained as a trihapto ligand in [PdCl2(HA)]− (2). The succeeding steady hydrolysis of diketene (S) proceeds as a pseudo first-order reaction, obeying the rate law: –d[S]/dt=kobsd[S]=(k0+kcat)[S], kcat=kobsd–k0=(k1+k2/[H+])[PdII]/[Cl−], where k1=2.0×10−5 s−1 and k2=2.96×10−6 mol dm−3 s−1 at 0 °C and μ=1.0 mol dm−3 (HClO4 and NaClO4). A mechanism which postulates complex 2 as the effective catalyst is proposed to explain the observed two-term rate equation.
Equilibrium Solubilities of Iodine Vapor in Water
Authors: Sanemasa Isao , Kobayashi Toyohisa , Piao Cheng Yun , Deguchi Toshio
Published: July 2006

Equilibrium solubilities of iodine vapor in water were measured by introducing iodine vapor, in equilibrium with solid iodine, into water and by circulating it in a closed system, and Henry’s law constants were determined. Equilibrium distributions of iodine vapor between a gas phase and an aqueous phase were also measured by another method, and partition coefficients were determined. The solubilities of iodine vapor in water estimated from both the Henry’s law constants and the partition coefficients are compared with those of solid iodine reported in the literature. Thermodynamic parameters for the hydration of iodine vapor are evaluated experimentally.
Aggregate Morphology and Hydrogenation Reactivity of Functionalized Bilayer Membrane Composed of Peptide Lipid Having NADH Activity
Authors: Murakami Yukito , Kikuchi Jun-ichi , Nishida Koji , Nakano Akio
Published: July 2006

A peptide lipid bearing the 1,4-dihydronicotinamide moiety, N,N-dihexadecyl-Nα-[1-(6-trimethylammoniohexyl)-1,4-dihydro-3-pyridylcarbonyl]-l-alaninamide bromide [N+C6(NAH)Ala2C16], and its dehydrogenated form, N,N-dihexadecyl-Nα-[1-(6-trimethylammoniohexyl)pyridinium-3-ylcarbonyl]-l-alaninamide chloride bromide [N+C6(NA+)Ala2C16], were prepared. Both lipids formed bilayer membranes when they were dispersed in aqueous media, and the 1,4-dihydronicotinamide and nicotinamide moieties of the respective lipid molecules were placed in the so-called hydrogen-belt domain upon membrane formation. In an aqueous dispersion of the latter dicationic lipid, relatively small multilayered vesicles were predominantly formed while the related monocationic lipids bearing the same double alkyl chain composed much larger vesicles and/or lamellae. Formation of the charge-transfer (CT) complex of the nicotinamide moiety of N+C6(NA+)Ala2C16 with 3-indolylacetic acid was much enhanced in the membrane through tight electrostatic interaction. The bilayer membrane composed of N+C6(NAH)Ala2C16 acted as a potential reductant toward anionic substrates in aqueous media. The high reactivity is gained primarily by the effective incorporation of the substrates into the hydrogen-belt domain through electrostatic, hydrogen bonding, and CT interactions and partly by the proximity effect which becomes valid between the 1,4-dihydronicotinamide moiety and the bound substrate molecule.
Chemical Synthesis of Fully Active and Heat-stable Fragments of Heat-stable Enterotoxin of Enterotoxigenic Escherichia coli Strain 18D
Authors: Yoshimura Shoko , Takao Toshifumi , Ikemura Haruo , Aimoto Saburo , Shimonishi Yasutsugu , Hara Saburo , Takeda Tae , Takeda Yoshifumi , Miwatani Toshio
Published: July 2006

Two shorter peptides of a heat-stable enterotoxin (STp), which is produced by enterotoxigenic Escherichia coli strain 18D, were prepared by two different procedures; i) chemical synthesis and ii) Edman-degradation of STp. These peptides (designated as STp(4–18) and STp(5–18)) corresponded to 15 and 14 amino acid residues in the sequence of STp without three and four residues, respectively, of the N-terminus. Peptides STp(4–18) and STp(5–18) prepared by chemical synthesis had the same biological and physicochemical properties as the peptides obtained by the Edman method. Furthermore, they showed almost the same toxicity as native and synthetic STp, and their toxicity was neutralized by anti-native STp antisera. Synthetic STp(4–18) had similar heat-stability to STp, but synthetic STp(5–18) was much more heat-stable. These findings suggest that the sequence from the Cys residue near the N-terminus to the C-terminal residue is extremely important for the unique characters of toxicity and heat-stability of the toxin.
Vibrational Energy Levels and Infrared Absorption Intensities of Carbon Monoxide
Authors: Miyazaki Tomoo , Matsuura Azuma , Takeuchi Hisao
Published: July 2006

The vibrational energy levels and infrared absorption intensities of carbon monoxide have been calculated with due consideration for the mechanical and electrical anharmonicities of vibration by the use of ab initio molecular orbital calculation in which the C-I treatment and polarization functions were introduced.
The Number of Water Molecules Bound to Insulin
Authors: Nagashima Nobuya , Suzuki Ei-ichiro , Tsuboi Masamichi
Published: July 2006

On cooling an aqueous solution of zinc pig-insulin to −40 °C, 108 water molecules per insulin molecule have been found (by NMR) unfrozen. This number is nearly equal to what was found crystallographically of the water molecules located within 4.7 Å of the protein molecule.
The Formation of Metastable Potassium Trivanadate from Melts
Authors: Kera Yoshiya
Published: July 2006

Potassium vanadates, which were prepared from melts by rapid quenching and slow cooling over the composition range of K2O-contents of C=(K)/(V)=0–0.50, were examined by means of IR spectrometry and X-ray powder diffraction. In the composition range of C≤0.17, mixtures of V2O5, K2V18O45, and K2V8O21 were produced by the slow cooling. At the composition of C=0.33, however, an unknown compound and K2V8O21 were the main products upon rapid quenching from melts, while at C=0.50 the main products were K3V5O14 and an additional unknown compound. The unknown compound was confirmed to be metastable and was formed as a single compound only by a rapid quenching from melts of K2O and V2O5 especially at C=0.37. The X-ray diffractions for the compound were characterized as d=8.2 (very strong), 4.05, and 3.27 Å, and the V=O stretching frequencies, as 995, 968, and 955 cm−1. By comparing these characteristic data with those of lithium trivanadate and sodium trivanadate (γ-phase), it was suggested that the unknown compound was isomorphous with trivanadate (M1+xV3O8).
Characterization of Cobalt(III) Complex with 2-Aminoethaneseleninate. Spontaneous Resolution and Crystal Structure of (−)500CD-(2-Aminoethaneseleninato)bis(ethylenediamine)cobalt(III) Nitrate
Authors: Okamoto Ken-ichi , Konno Takumi , Nomoto Masayo , Einaga Hisahiko , Hidaka Jinsai
Published: July 2006

The crystal structure and the absolute configuration of the spontaneously resolved title complex cation, (−)500CD-[Co(aesei)(en)2]2+, has been determined by X-ray diffraction. The red crystalline needle was monoclinic, space group P21, a=9.572(4), b=10.410(3), c=8.838(5) Å, β=115.35(3)°, Z=2, and the final R value was 0.035 for 2358 independent reflections with |F0|>3σ(|F0|). The crystal used showed a negative CD value at 500 nm and had Δ configuration. The 2-aminoethaneseleninate is bound to the cobalt atom by the nitrogen and oxygen atoms, and the asymmetric selenium atom takes an S configuration. The value of the protonation constant (pKa) was determined to be 1.91±0.05, on the basis of the major absorption spectral change at 304 nm of the title complex by spectrophotometric titration (μ=1.0 mol dm−3 (NaClO4) and 25 °C). The electronic absorption and CD spectral behavior were compared with those of the related sulfinato complexes, in which the S-bonded sulfinato complex, (+)500CD-[Co(S(O)2CH2CH2NH2)(en)2]2+, was resolved in this work.
Bromination of 2,6-Dimethyl-4-methoxybenzyl Alcohol Derivatives
Authors: Nakatani Munehiro , Takahashi Kimi , Watanabe Sumie , Shintoku Atsuko , Hase Tsunao
Published: July 2006

The reaction of 2,6-dimethyl-4-methoxybenzyl alcohols, ethyl ethers, and acetates, possessing electrondonating and -withdrawing groups at the benzylic position, with bromine water was studied at different temperatures. The reaction was strongly affected by the electronegativity of a benzyl substituent to afford bromination products of aromatic nuclei and 2,4-dibromo-3,5-dimethylmethoxybenzene along with 2,4,6-tribromo derivatives formed by the cleavage of C–C bond.
Studies of the Hydrous Tin(IV) Oxide Ion-exchanger. II. Some Properties as a Cation-exchanger
Authors: Inoue Yasushi , Yamazaki Hiromichi
Published: July 2006

In order to elucidate the fundamental properties of hydrous tin(IV) oxide as a cation-exchanger, the stoichiometry of cation exchange and its acid-base property were studied by means of the uptake curves for alkali-metal ions. The results are summarized as follows: 1) The equivalent exchange between the hydrogen ion and either alkali-metal or alkaline-earth-metal ions holds, irrespective of the ionic strength of the solution and the extent of exchange. 2) The water content in the exchanger depends on the ionic composition. 3) This material is an amphoteric ion-exchanger, with at least two kinds of weakly dissociable ion-exchange sites, and the conditional dissociation constant depends on the ionic composition of the exchanger. The stability to various reagents was also examined.
The Effects of Salts on the Solubilities of Benzene, Toluene, Ethylbenzene, and Propylbenzene in Water
Authors: Sanemasa Isao , Arakawa Seiji , Araki Masatake , Deguchi Toshio
Published: July 2006

Salt effects on the solubilities of benzene, toluene, ethylbenzene, and propylbenzene were studied by making use of the solute vapor. The salting coefficients were determined at 25 °C, and the results were compared with the literature values and with those estimated by means of theoretical equations. The McDevit-Long equation did not give satisfactory predictions until the equation was multiplied by a factor of 0.4. The scaled particle theory gave a favorable agreement with the observations in most cases if suitable pair-potential parameters of solutes were used in the calculations.
Physicochemical Speciation of Trace Elements in River Water by Size Fractionation
Authors: Tanizaki Yoshiyuki , Yamazaki Masao , Nagatsuka Sumiko
Published: July 2006

Eight kinds of Millipore filters with different pore sizes (8–0.025 μm) were used for the filtration of two water samples taken from the Tama River. The filtrates were analyzed for 31 elements using a neutron activation analysis. Most alkali and alkaline earth elements were distributed in the smallest size fraction (<0.025 μm). The same fractionation pattern was also recognized for As, Se, Mo, Sb, and W, which tend to form oxoanions. But the major transition elements were concentrated in the larger size fractions (>0.45 μm). For the river water sample with higher concentration of total organic carbon, however, most of such elements were found in the smallest size fraction. The solubilities of rare earth elements bacame higher with increasing their ionic potentials.
A Basic Study of the Amino Acid Residue in Protein. The Role of Hydrocarbon Groups in Enantiomer-differentiating Acylation
Authors: Hiraki Yuji , Tai Akira
Published: July 2006

The enantiomer-differentiating acylation (kinetic resolution) of 1-phenylalkylamines and their derivatives was carried out with (S)-2-phenylbutyric anhydride and its derivatives in aqueous and nonaqueous media. On the basis of the distributions of the two diastereomeric products, the molecular interactions between hydrocarbon residues responsible for the structural recognition of the reacting molecules were studied. In nonpolar media, the (R,S)-isomer was predominantly formed over the (S,S)-isomer. Moreover, the differentiation was mainly controlled by the size of the alkyl substituents of the substrates. In aqueous media, though, the (S,S)-isomer was predominantly formed. By a comparative study of the cyclohexyl analogs of the substrates and the reagents, it was shown that alkyl-phenyl and/or phenyl-phenyl interactions were important in the recognition process. A partitioning process of the substrate into the reagent phase was not effective in the differentiation of the enantiomer by the reaction in suspensions of optically active reagents in highly aqueous media.
Kinetics of the Ligand Exchange Reaction between Tetrakis(acetylacetonato)thorium(IV) and Free Acetylacetone in CD3CN and CDCl3
Authors: Fujiwara Naoshi , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

Kinetics of the ligand exchange reaction between tetrakis(acetylacetonato)thorium(IV) and free acetylacetone in CD3CN and CDCl3 was studied by 1H NMR. The rate law was written as rate =k[Th(acac)4][Hacac]enol, where k=(1.0±0.1)×102 s−1 mol−1 kg at 0 °C in CD3CN and (1.7±0.1)×102 s−1 mol−1 kg at −16 °C in CDCl3. The rates were retarded by addition of bases and the retardation effect well correlated with the donor number of the bases. Under the conditions studied, the activation entropies gave large negative values. A ligand exchange mechanism passing through a nine-coordinate intermediate is proposed to interpret the kinetic law.
Electrophilic Substitution Reactions on Methine Carbon of the Unsymmetrical Tetradentate Schiff Base and its Complexes with Nickel(II) and Copper(II)
Authors: Kasuga Kuninobu , Nagahara Takeo , Masuda Teruaki , Kiyota Shunji , Yamamoto Yasuo
Published: July 2006

A number of unsymmetrical tetradentate Schiff base complexes of nickel(II) and copper(II) having only one methine carbon in the ligand were synthesized and characterized by means of UV and 1H NMR spectra. The kinetic studies of the electrophilic substitution reactions on the methine carbon with N-halogenosuccinimide gave no support to an aromatic character of the chelate ring, being consistent with the results of 1H NMR studies for the nickel(II) complexes.
Cyclic Carbonates Obtained by Reactions of Alkali Metal Carbonates with Epihalohydrins
Authors: Rokicki Gabriel , Kuran Witold
Published: July 2006

A study has been carried out on the reaction of alkali metal carbonates with epihalohydrins in the presence of cation complexing agents e.g. crown ethers. 3-Glycidyloxypropylene carbonate was found to be formed as the main product of the reaction of epichlorohydrin with potassium carbonate promoted by 18-crown-6. The effect of various epihalohydrins and alkali metal carbonates on the reaction course was examined. It was found that the reaction of potassium hydrogencarbonate with epichlorohydrin gives 4-hydroxymethyl-1,3-dioxolan-2-one. When the reaction of epihalohydrins with potassium carbonates was carried out in the atmosphere of carbon dioxide the products contained linear carbonate linkage apart from cyclic one. From these results, a plausible mechanism was proposed for the reaction of alkali metal carbonates with epihalohydrins in the presence of crown ethers.
A Short Synthesis of Dihydrojasmone, cis- and trans-Jasmones
Authors: Ogura Fumio , Otsubo Tetsuo , Sakamoto Tetsuo , Yamaguchi Hachiro
Published: July 2006

The titled jasmones were synthesized from N,N′-dimethyl-2-oxo-1,3-propanedisulfonanilide, a new three carbon building block for organic preparation.
Conformations of 3-Alkoxycarbonyl-1-tetralols and 2-Ethoxycarbonyl-4-chromanols
Authors: Hanaya Kaoru , Muramatsu Takashi , Onodera Shinji , Ikegami Yusaku , Hirota Minoru
Published: July 2006

The 1- or 4-hydroxyl group in cis isomers of 3-alkoxycarbonyl-1-tetralols and 2-ethoxycarbonyl-4-thiochromanols are predominantly quasi-equatorial and those of the trans isomers quasi-axial. cis-2-Ethoxycarbonyl-4-chromanol prefers the quasi-axial OH conformation.
The Crystal Structure of a New Thiosilicate of Thallium, TlInSiS4
Authors: Nakamura Yuji , Aruga Atsushi , Nakai Izumi , Nagashima Kozo
Published: July 2006

The crystal structure of a new synthetic compound with the composition of TlInSiS4 has been determined. The crystal is orthorhombic, and the space group is Pbnm with Z=8. The cell dimensions are a=11.74(1), b=17.038(7), and c=7.285(3) Å. The structure was solved by the Patterson method and refined to a final R-value of 0.074 for all the observed reflections. The structure is characterized by a sheet structure built up from alternating infinite(InS3)n chains and dimeric Si2S6groups. The Si2S6 groups consist of two SiS4 tetrahedra sharing an edge. The thallium atoms are situated between the sheets and are surrounded by nine sulfur atoms at distances between 3.293 and 3.957 Å.
Electron Spin Distributions and g-Value Shifts in the Novel Electron Donors with 1,3-Dithiole Rings
Authors: Terahara Atsushi , Ohya-Nishiguchi Hiroaki , Hirota Noboru , Awaji Hiroshi , Kawase Tokuzo , Yoneda Shigeo , Sugimoto Toyonari , Yoshida Zen-ichi
Published: July 2006

The ESR spectra of the cation radicals of TTF and its related compounds in which two 1,3-dithiole rings are connected by conjugated carbon and cumulene chains are measured. The spin distributions obtained from the hfcc due to the protons and sulfur atoms agree well with the results of the MINDO/3 calculations. The spin densities on the sulfur and central carbon atoms decreases as the central chain length increases. A linear relationship, g=2.00379+0.00108 a(S), between the g-values and the sulfur hfcc is noted and explained in terms of the Stone’s theory. The g-values of the cation radicals with cumulene chains deviate from this relation and a possible cause is suggested.
Molecular Motion and Phase Transitions in 2-Methyl-2-nitropropane as Studied by Proton Magnetic Resonance and Relaxation
Authors: Hasebe Tooru , Nakamura Nobuo , Chihara Hideaki
Published: July 2006

Proton spin-lattice relaxation times (T1 and T1ρ) were measured in solid and liquid phases of 2-methyl-2-nitropropane. In the lowest temperature solid phase (Phase III) a broad, asymmetric minimum in T1 as well as a large reduction in the second moment was observed due to the coupled reorientations of methyl and t-butyl groups. The analyses of the T1 and T1ρ in Phase III gave the activation parameters Ea=14.6±0.2 kJ mol−1 and τ0=(6.45±0.10)×10−14 s for the methyl reorientation and Ea=15.1±0.3 kJ mol−1 and τ0=(1.35±0.10)×10−13 s for t butyl reorientation. In Phase II, the T1 is governed by the t-butyl reorientation with the activation parameters Ea=15.3±0.1 kJ mol−1 and τ0=(5.85±0.10)×10−14 s. In the low temperature region of the highest temperature plastic phase (Phase I) the molecular overall reorientation governs the T1 and the molecular translational self-diffusion becomes the dominant relaxation mechanism near melting point. The T1ρ results were analyzed with the isotropic translational diffusion model and the activation parameters were determined to be Ea=46.5±0.9 kJ mol−1 and τ0=(4.6±1.8)×10−15 s. The mean jump time of the molecule at the melting point, 6×10−7 s, is slightly longer than those in other plastic crystals. The activation energy for the translational diffusion is 9.7±1.5 kJ mol−1 in the liquid phase.
Kinetic and Thermodynamic Characterization of Thermal Pyridine Liberation-Anation Reactions of Bis(2,3-alkanedione dioximato)dipyridinecobalt(III) Iodide in the Solid State
Authors: Kinoshita Setsuko , Wakita Hisanobu , Masuda Isao
Published: July 2006

Thermodynamic and kinetic characterizations were carried out on the thermal, pyridine liberation-anation reactions, [CoIII(R,CH3-dioxH)2(py)2]I \oversetΔ→ [CoIII(R,CH3-dioxH)2(py)I]+py↑.* These occurred endothermally in the solid state of the complexes. The ΔH values of the reactions were determined. A large increment in the entropy was found to be indispensable for the progress of the reactions; it could be brought about by the liberation of gaseous pyridine from the solid system of the complexes. The kinetic analyses revealed that the reaction rates were increased by the substitution of R with the longer-carbon-chain alkyl groups. The activation enthalpies and activation free energies were shown to be decreased by the above substitutions. The CoIII-pyridine bond was observed to be weakened by the electron-donating inductive effect of R to the central cobalt atom and by the steric interference of R toward axial pyridine coordination.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. V. Stepwise Complex Formation of the Nickel(II) Ion with 2,2′-Bipyridine and 1,10-Phenanthroline
Authors: Moriyasu Masataka , Hashimoto Yohei
Published: July 2006

The stepwise complex formation of the nickel(II) ion (M2+) with 2,2′-bipyridine(bpy) and 1,10-phenanthroline(phen) (Mn−12++L\ightleftharpoonsMLn2+ with Kn=[MLn2+]/[MLn−12+][L], where n=1–3), has been investigated by means of high-performance liquid chromatography. Peaks of the labile partially ligand substituted complexes, ML2+ and ML22+, have appeared on chromatograms, along with peaks of the ML32+ and excess free ligands, on reverse phase ion-pair chromatography using sodium dodecyl sulfate in acidic media. Each labile species has been found to be eluted without any noticeable change, such as ligand addition, dissociation, or disproportionation, during chromatography. Thus, the chromatograms obtained have directly indicated the equilibrium concentrations of each species in the solutions prior to chromatography. The stepwise complex formation constants of nickel(II) with bpy or phen have been determined by means of high-performance liquid chromatography.
The Color Reaction of Purine Bases by Ternary-complex Formation with Eosin and Silver(I)
Authors: Fujita Yoshikazu , Mori Itsuo , Kitano Shoko , Kawabe Hiroshi , Kamada Yoshiyuki
Published: July 2006

A color reaction of purine bases utilizing a ternary-complex system among a purine base, a metal ion, and a xanthene dye was studied, and the fundamental conditions for the spectrophotometric determination of purine bases(as adenine) with eosin and silver(I) were established. The absorption maxima of the ternary-complexes lie at 550–560 nm against water. The optimum pH ranges for the color formation of the complexes are pH 4.8–5.4. Beer’s law is obeyed over the range of 1–10 μg/10 cm3 of adenine, and the apparent molar absorptivity is 1.1×105 dm3 mol−1cm−1 at 560 nm. In the determination of adenine, the coexistence of pyrimidine bases, such as uracil and cytosine, and nucleotides containing adenine, such as 5′-adenosine triphosphate(ATP) and β-nicotinamide–adenine dinucleotide(NAD), scarcely interfere.