bluuebunny/crossref_metadata_2025 huggingface dataset:
Conductometric Study of Ion Association between Tris(ethylenediamine)cobalt(III) Ion and Monovalent Anions at Temperatures from 0 to 50 °C
Authors: Yokoyama Haruhiko , Ohta Tomoko , Iida Masayasu
Published: August 2006

The conductivities for aqueous solutions of the chloride, bromide, iodide, nitrate, and perchlorate of the tris(ethylendiamine)cobalt(III) complex, [Co(en3)]3+, were measured with varying temperatures from 0 to 50 °C. The ion-association constants (KA) of the complex ion with the anions had minimum values at temperatures (tmin) characteristic of the salts. The values of tmin increased in the order Cl− < Br− < I− < NO3− < ClO4−. The order in magnitude of KA at 25 °C was ClO4− < NO3− < I− < Cl− < Br−, but was somewhat dependent on the temperature. Both the KA and tmin values for the halides of [Co(en)3]3+ were larger than those of the hexaamminecobalt(III) complex, [Co(NH3)6]3+; the difference in KA was greatest for the iodide. The entropy and enthalpy changes in the ion association of [Co(en)3]3+ with the halide ions were smaller than those of [Co(NH3)6]3+. These results suggested that the hydration of [Co(en)3]3+ was relatively weak and its hydration water molecules in the vicinity of the methylene groups could be more easily substituted by the structure-breaker anions, compared with the water molecules around the amino groups. The KA and tmin values for the nitrate and perchlorate of [Co(en)3]3+ were smaller than those of [Co(NH3)6]3+, and both the entropy and enthalpy changes of ion association for the former salts were more positive. This was attributed to the decrease in the fraction of the contact ion pairs formed by the hydrogen bonding between the polar hydrogen atoms of the complexes and the oxygen atoms of the anions.
Solution Equilibrium and EPR Study of the Dinuclear Copper(II) Complexes of Aminopolycarboxylic Acids with an Alcohol OH Group in the Alkyl Chain Linkage
Authors: Kawata Satoshi , Kosugi Hiroshi , Uda Hisashi , Iwaizumi Masamoto , Yokoi Hiroshi
Published: August 2006

Dinuclear copper(II) complexes of 2-hydroxy-1,3-diaminopropane-, 2-hydroxy-1,4-diaminobutane-, and 3-hydroxy-1,5-diaminopentane-N,N,N′,N′-tetraacetic acids (AC3O, AC4O, and AC5O) have been investigated by potentiometric titration, EPR and other spectroscopies. It has been confirmed that two or three different kinds of dinuclear complex species are formed in every ligand system, depending on the pH. In the complexes formed in the low-pH region, the two copper ions are coordinated independently by the two iminocarboxyl groups and have a weak magnetic dipolar interaction. In all of the three ligand systems the dinuclear complexes deprotonate the alcohol OH groups at low pH values (below 6) to form μ-alkoxo between the two copper ions. For AC3O and AC4O systems, the formation of μ-alkoxo and μ-hydroxo-double bridged complexes follows as the pH increases, while the AC5O system forms a double-bridged complex at a step from the non-bridged complex at pH 5.8. These mono-μ-alkoxo bridged and double-bridged complexes have fairly strong spin exchange interactions between the paramagnetic centers through the bridges. The length of the methylene linkage plays a role in determining the complex structures and magnetic interactions between the paramagnetic centers.
Photolyses of Polychloro- and Polybromobenzenes. Novel Isomerization in Solvents Resisting against Hydrogen Abstraction
Authors: Hirota Minoru , Nakada Masahiro
Published: August 2006

Polychloro- and polybromobenzenes were photolyzed in acetonitrile and perfluorohexane. Photolyses of polychlorobenzenes in acetonitrile gave isomerized products in addition to dechlorinated products, which appeared exclusively in the photolyses in hexane and other solvents carrying hydrogen atoms active to hydrogen abstraction. The photolyses in perfluorohexane gave isomerized products to a lesser extent. The reaction in this solvent gave predominantly polyhalobiphenyls which are assumed to be produced through coupling.

Without exception the isomerized products have the structure which can be expected to be formed via 1,3-migration of chlorine atom, though it is not sure at present whether it takes place actually. The isomerization was shown to proceed intramolecularly. Some evidence and theoretical rationalization in favor of the 1,3-chlorine migration mechanism are given.
Phenylacetaldehyde and Carbon Monoxide as Effective Additives for the Selective Hydrogenation of Cyclooctadienes to Cyclooctene over Palladium Catalysts
Authors: Higashijima Michio , Man Hó Soc , Nishimura Shigeo
Published: August 2006

Three isomeric cyclooctadienes (1,5-, 1,4-, and 1,3-COD) were hydrogenated with phenylacetaldehyde (PAA)- or carbon monoxide (CO)-treated palladium black in tetrahydrofuran at 25 °C and atmospheric pressure of hydrogen. A complete depression of the hydrogenation of cyclooctene (COE) to cyclooctane (COA) was attained with both of the poisoned catalysts. By PAA the hydrogenation of 1,5-COD to COE was not hindered and the isomerization of 1,5-COD to 1,4-COD was greatly promoted, while the rate of hydrogenation of 1,4- and 1,3-COD decreased in the presence of PAA. By CO the hydrogenation and isomerization of 1,5-COD, as well as the hydrogenation of 1,4- and 1,3-COD, was suppressed. In the hydrogenation of 1,5-COD the PAA-treated palladium was more active and selective than was the CO-treated palladium for the formation of COE. The differences in the effects of these catalyst poisons are discussed on the basis of kinetic data concerning the individual and competitive hydrogenation of the three isomeric cyclooctadienes.
A Novel Synthesis Including Asymmetric Synthesis of α,β-Unsaturated γ-Hydroxy Carbonyl Compounds from Enones with Carbon Homologation
Authors: Satoh Tsuyoshi , Motohashi Shigeyasu , Tokutake Norio , Yamakawa Koji
Published: August 2006

Reaction of the carbanion derived from 1-chloroalkyl aryl sulfoxides with enones gave 1,2-adducts in good yields. Treatment of the adduct with potassium benzenethiolate afforded α-phenylthio β,γ-unsaturated carbonyl compound through an α,β-epoxy sulfoxide. Oxidation of the sulfide with 2.1 equivalents of m-chloroperbenzoic acid gave α,β-unsaturated γ-phenylsulfinyloxy carbonyl compound via sulfoxide-sulfenate rearrangement. The sulfinate was easily hydrolyzed with aqueous potassium hydroxide to afford α,β-unsaturated γ-hydroxy carbonyl compound in good yield. When optically active (−)-1-chloroalkyl p-tolyl sulfoxides were used in this procedure, a synthesis of optically active α,β-unsaturated γ-hydroxy carbonyl compounds with moderate to good optical purity was realized.
Abnormal Diels–Alder Reaction of Oxazoles with 4-Phenyl-3H-1,2,4-triazole-3,5(4H)-dione and Diethyl Azodicarboxylate, and X-Ray Crystal Structure of an Adduct
Authors: Ibata Toshikazu , Suga Hiroyuki , Isogami Yasushi , Tamura Hatsue , Shi Xiaolan
Published: August 2006

The reaction of substituted oxazoles with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD) or diethyl azodicarboxylate gave the corresponding 1,2,4-triazoline derivatives through formal [3+2] cycloaddition accompanying ring opening of oxazoles. The molecular structure of an adduct of 5-methoxy-4-methyl-2-(p-tolyl)oxazole with PTAD was determined by means of X-ray crystallography.
19F Nuclear Magnetic Resonance Study on the Kinetics of the Fluoride Exchange in Uranium(VI) Fluoro Complex
Authors: Harada Masayuki , Fujii Yasuhiko , Sakamaki Satoshi , Tomiyasu Hiroshi
Published: August 2006

Kinetics of the fluoride exchange in uranium(VI) (uranyl) fluoro complex was studied by using 19F NMR. The 19F NMR signal of coordinated fluoride at the equatorial positions of uranyl ion was first observed at about 80 ppm down field from that of bulk F−. From area measurements of the coordinated and free 19F NMR signals, penta-fluoro complex UO2F53− was confirmed to exist in aqueous solutions containing high concentration of fluoride ion. The stability constant K5 = [UO2F53−]/[UO2F42−][F−] was determined to be 1.31 mol−1 kg. The rate of F− exchange between coordinated and bulk F− was measured by the 19F NMR line-broadening method and the observed first-order rate constant kobsd was expressed as Kobsd = (k4 + k5K5[F−])[F−]/(1 + k5[F−]) where k4 and k5 are the exchange rate constants of F− between bulk and coordinated F− in UO2F42− and UO2F53−, respectively. The associative or associative interchange mechanism was proposed from the experimental results.
Syntheses of trans- and cis-3-Methoxy-4-methylthio-2-piperidinethiones. Previously Proposed Structures for Raphanusanins, Structural Revision, and Biological Activities of Their Congeners
Authors: Nishiyama Shigeru , Inagaki Tomio , Yamamura Shosuke , Hasegawa Koji , Mizutani Junya , Sakoda Masako
Published: August 2006

Related to raphanusanins, light-induced growth inhibitors of radish seedlings, syntheses of trans- and cis-3-methoxy-4-methylthio-2-piperidinethiones provided the structural revision of the natural products. During syntheses of several piperidinethione derivatives, the dihydropyridinethione derivative was found to possess twentyfold stronger inhibitory activity than the natural products.
Formation of 2-Imino-1,3-oxathioles and 2(3H)-Oxazolethione by the Rhodium(II) Acetate-Catalyzed Reaction of α-Diazocarbonyl Compounds with Isothiocyanates
Authors: Ibata Toshikazu , Nakano Hirofumi
Published: August 2006

The rhodium(II) acetate-catalyzed reaction of various α-diazocarbonyl compounds with alkyl, phenyl, and benzoyl isothiocyanates gave 2-imino-1,3-oxathioles in good yields. 2(3H)-Oxazolethione was obtained as a by- product only in the reaction of diazodimedone with methyl isothiocyanate. The mechanism through thiocarbonyl ylide and azomethine ylide was proposed for these reactions, and preferable formation of thiocarbonyl ylide was explained by heat of formation and frontier molecular orbital calculations.
Solution Properties of Poly(4-vinylpyridine) in Aqueous Solutions of Sulfuric Acid
Authors: Yoshida Masafumi , Sakamoto Noriyuki , Ikemi Kimiyoshi , Arichi Shizuo
Published: August 2006

The conformation of poly(4-vinylpyridine) (P4VP) in aqueous solutions of sulfuric acid was studied by light scattering and viscosity measurements at 25 °C. Comparing the experimental intramolecular particle scattering factor (P(θ)) and Debye’s theory, it was confirmed that in the Θ-state where the apparent second virial coefficient is zero, the conformation of P4VP is characterized as a Gaussian chain. The intrinsic viscosities of P4VP in aqueous solutions of sulfuric acid of various concentrations were analyzed according to the theoretical equation of Tanaka. The value of the characteristic ratio (C∞) increased with increasing H2SO4 concentration.
Thermal and Infrared Multiphoton Decompositions of γ-Butyrolactone in the Vapor Phase
Authors: Yamamoto Shunzo , Suzuki Minoru , Sueishi Yoshimi , Nishimura Norio , Ishikawa Yo-ichi , Arai Shigeyoshi
Published: August 2006

The thermal decomposition of γ-butyrolactone was studied in a static system at temperatures from 690 to 833 K and pressures from 70 to 4300 Pa. The major products were CO, CO2, ethylene, propylene, and cyclopropane. The first-order rate constant for the apparently homogeneous formation of CO is described in terms of Arrhenius parameters log A (s−1) = 16.44 ± 0.04 and Ea = 310.0 ± 4.2 kJ mol−1. Under the same conditions the ratio of CO2/CO increased with decreasing temperature, corresponding to an activation energy of about 294 kJ mol−1 for CO2 formation and a frequency factor of about 60-times lower than that for CO formation. The decomposition induced by a pulsed CO2 laser was also studied; the same decomposition products were observed and the dependences of their yields on the fluence were examined.
ESR Studies at High-Pressure. IV. Spin-Exchange Reactions of Various Types of Nitroxides in Some Low-Viscosity Solvents
Authors: Sueishi Yoshimi , Kuzukawa Masahiro , Yamamoto Shunzo , Nishimura Norio
Published: August 2006

The rate constants (kex) for the spin exchange of various types of nitroxides were determined from the concentration dependence of the ESR line-broadening. The exchange integral (J) and the steric factor (fs) for the spin exchange were estimated from the pressure dependence of kex. The estimated J-values are about 1011 s−1 and are almost independent of the radical species. For nitroxides having –OH or –NH2 in acetone and nitroxides having long-chain in acetone and toluene, the fs-values are about 0.3, while for other nitroxides in hexane and pentane, the fs-values are about 0.5. The results are discussed in terms of the solute–solvent interaction as well as the steric effect.
Theoretical Study of Structure and Thermodynamic Properties of Liquid Hydrogen Fluoride
Authors: Honda Kazuhiko , Kitaura Kazuo , Nishimoto Kichisuke
Published: August 2006

Monte Carlo (MC) simulations for liquid hydrogen fluoride (HF) were carried out using a new type of intermolecular potential function. The bonding energy distribution function was found to have three peaks corresponding to the distributions of molecules which have one, two, and three hydrogen bonds with neighbors. A partition function of liquid HF was derived referring to the results of MC simulations, where a simple Hamiltonian consisting of harmonic oscillators and hydrogen bond energies was employed. The thermodynamic properties calculated by the partition function reasonably reproduced the experimental data. Moreover, the effects of hydrogen bondings on various thermodynamic properties were revealed based on the partition function.
Optical Resolution of Phenylalanine and Mandelic Acid by Complex Formation with Copper(II) Ion
Authors: Yamamoto Yasushi , Kato Shinji , Yamashita Hiroshi , Maekawa Takashi
Published: August 2006

The optical resolutions of phenylalanine and mandelic acid were performed by complex formation with Cu2+. d- and l-mandelic acids were completely resolved by forming a complex with l-phenylalanine, while the maximum optical purity of d- and l-phenylalanine by using d-mandelic acid was about 65%. The mole ratio of Cu2+ to phenylalanine and/or mandelic acid in the complexes was 0.5. These results were interpreted in terms of the relative stability of the complexes, i.e., the optical absorption energies in the aqueous media.
Theoretical Investigation on the Reactions of Dichlorosilane with Ammonia
Authors: Koseki Shiro , Ishitani Akihiko
Published: August 2006

SiH2Cl2 decomposition into SiCl2 and H2, SiCl2 insertions into NH3 and SiH4, and 1,1-HCl elimination from SiHCl2NH2, which seem to occur in chemical vapor deposition processes of the silicon-nitride film growth, were theoretically investigated using second-order Moller–Plesset perturbation theory based on ab initio restricted Hartree–Fock method. The calculated results suggest that the Cl atoms create an energy barrier larger in Si–Si bond formation and facilitate the growth of stoichiometrically better films.
Photochemical Nitration of Benzoic Acid Derivatives by Irradiation to Nitrate Ions
Authors: Usui Yoshiharu , Takebayashi Shigeharu , Takeuchi Manabu
Published: August 2006

Photochemical nitration of p-hydroxybenzoate, HBA, initiated by UV irradiation to sodium nitrate of sodium nitrite was observed in aqueous solutions. 4-Hydroxy-3-nitrobenzoate was formed, with maximum quantum yields of 0.007 and 0.09 for NaNO3 and NaNO2, respectively. From the dependence of the yields on the pH and concentrations of oxygen and OH-scavengers, we propose a mechanism involving the addition of OH· to the aromatic ring of HBA and electron abstraction NO2 by the OH· adduct for the photonitration.
Preparation and Properties of Mixed Ligand Dinuclear Copper(II) Complexes Bridged by Deprotonated Oximato and Hydroxo or Acetato
Authors: Mori Wasuke , Suzuki Shinnichiro , Nakao Yasuo , Nishimura Tsukasa , Ichimura Akio
Published: August 2006

Mixed ligand dinuclear copper(II) complexes bridged by one deprotonated oximato and one hydroxo or two acetato were prepared and characterized according to their magnetic susceptibilities, electric conductivities, visible absorption spectra, and cyclic voltammograms. A very strong antiferromagnetic interaction between two copper(II) ions in hydroxo-bridged complexes has been observed (coupling constants J = −520 – −530 cm−1, H = −2JS1·S2). Two acetato-containing complexes comprise triply (one deprotonated oximato and two acetato) bridged coppers, which are characterized by J = −130 – −235 cm−1.
Sonolysis Studies of Alcohols in Aqueous Solutions by Gaseous Products Analysis
Authors: Koike Tohru
Published: August 2006

Sonolysis studies of alcohol–water mixtures were carried out for CH3OH, C2H5OH, n-C3H7OH, and i-C3H7OH by analyzing the gaseous products of CH4, C2H6, C2H4, C2H2, and C3H6. By comparing the product distributions which depended on the four alcohol–water mixtures it was found that alcohols decay in a similar manner as in the pyrolysis of alcohols at high temperatures and that sonolysis progresses through radical reactions.
Study of the Charge Transfer Band Observed in Dialkoxo-Bridged Binuclear Copper(II) Complexes
Authors: Handa Makoto , Idehara Tsutomu , Nakano Kenji , Kasuga Kuninobu , Mikuriya Masahiro , Matsumoto Naohide , Kodera Masahito , Kida Sigeo
Published: August 2006

The near-ultraviolet absorption band characteristic of dialkoxo-bridged binuclear copper(II) complexes was reinvestigated by using a series of binuclear copper(II) complexes with N,N-dialkyldiaminoalcohols, Cu2{R2N(CH2)mNH(CH2)nO}2X′2 (abbreviated as Cu(R-m-n)X′, X′ = ClO4, BF4). In this study eighteen complexes including ten new compounds were prepared and classified into two types, i.e., type-A and B according to Kida’s classification, based on their temperature dependencies of magnetic susceptibilities (80–300 K) and reflectance spectra. The crystal structures of Cu(n-Bu-3-2)ClO4 (10), Cu(H-3-3)BF4·EtOH (11b), and Cu(Me-3-3)ClO4 (12a) were determined by the single-crystal X-ray diffraction method. The detailed analysis of the structures and reflectance spectra led to the same conclusion as Kida’s one in assigning the near-ultraviolet absorption band. That is, the absorption was ascribed to the charge transfer (CT) from the bridging oxygen’s nonbonding orbital to vacant copper d-orbital. On the other hand, in assigning the origin of the appearance of the CT band in the near-ultraviolet region, the conclusion different from Kida’s one was presented. The origin was interpreted in terms of the red-shift of the band owing to the electrostatic repulsion between the bridging oxygen atoms. Moreover, the unusually low frequency and low intensity of the CT band of 12a were also reasonably explained.
Pressure Effects on the Aquation Reactions of Tris(2,2′-bipyridine)chromium(III) Ion and Tris(1,10-phenanthroline)chromium(III) Ion
Authors: Kita Shouichi , Shibata Masayasu , Uchida Kengo
Published: August 2006

The effects of high pressure on the rates of aquation reactions of Cr(bpy)33+ and Cr(phen)33+ have been measured. The activation volumes of aquation were derived as −0.9 ± 0.5 and +5.2 ± 0.4 cm3 mol−1 for Cr(bpy)33+ and Cr(phen)33+, respectively. These values are consistent with those expected from an interchange mechanism involving water penetration to the coordination sphere and an extension of one or both of the Cr-polypyridine bonds.
Synthesis of a Polycyclic π-Conjugated System Containing an Azulene Unit by the Flash Vacuum Pyrolytic Method. III. Synthesis and Properties of 4-Hydroxy-3H-cyclopent[a]azulen-3-one
Authors: Kitamori Yoichiro , Yasunami Masafumi , Hioki Takanori , Takase Kahei , Yoshifuji Masaaki
Published: August 2006

4-Hydroxy-3H-cyclopent[a]azulen-3-one, a new tricyclic π-conjugated system containing a hydroxyazulene unit and a cyclopentadienone moiety, was synthesized by the application of flash vacuum pyrolysis in the final step. All the proton magnetic resonances of the compound shifted up-field compared with those of the referenced 1,2-dihydro compound in terms of an induced paramagnetic ring current in the periphery of this molecule. The characteristic prototropic tautomerization of 4-hydroxyazulenes was not observed in this system.
Optical Resolution by Preferential Crystallization of 2-(3,4-Carbonyldioxyphenyl)-2-(phthalimidooxy)acetic Acid, a Key Intermediate of Cephalosporin Antibiotic M-14659
Authors: Murakami Kimihiro , Ohashi Masayuki , Matsunaga Atsuo , Yamamoto Ichiro , Tomiguchi Akira , Nohira Hiroyuki
Published: August 2006

(±)-2-(3,4-Carbonyldioxyphenyl)-2-(phthalimidooxy)acetic acid [(±)-1] was efficiently resolved into a pair of optically active forms by preferential crystallization. Successive preferential crystallization of (±)-1 was experimented at 15 °C under stirring in acetone, and (+)- and (−)-1 with optical purity of 68–85% were obtained. The racemization of (−)-1 proceeded smoothly in the presence of triethylamine to give (±)-1 which was reusable for the preferential crystallization procedure. A potent antipseudomonal cephalosporin M-14659 (2) was prepared from (+)-1.
Highly Regioselective Allylation of α-Enones and Epoxides with Lithium Tetraallyllanthanoid Ate Complex
Authors: Fukuzawa Shin-ichi , Sakai Shizuyoshi
Published: August 2006

Tetraallyllanthanoid ate complex (1), which was readily prepared in situ from tetraallyltin, lanthanoid trichloride, and butyllithium in tetrahydrofuran (THF), reacts smoothly with α-enones (3–11) with a high degree of 1,2-regioselectivity (1,2 : 1,4 = >99 : 1) to give 1,5-diene-3-ols in good to excellent yields. The mechanistic study with 4,4-(ethylenedioxy)-2,6-dimethyl-2,5-cyclohexadienone (29) as a probe suggests that single electron transfer (SET) may be involved in this carbonyl allylation reaction with 1. Allylative ring opening of styrene oxide with 1 occurs at the more subsituted carbon (α-attack) in higher selectivity (α : β = 85 : 15) than with allyllithium and allylmagnesium bromide in diethyl ether. The complex 1 reacts with 3,4-epoxy-1-butene (35) in diethyl ether predominantly at the most substituted carbon of the oxirane to give 3-hydroxymethyl-1,5-hexadiene (36) together with 1,6-heptadien-3-ol (37), (E) and (Z)-2,6-heptadienols (38) (36 : 37 : 38 = 87 : 9 : 4)
Abnormal Diels-Alder Reaction of 5-Alkoxythiazoles with Highly Reactive Dienophiles; 4-Phenyl-3H-1,2,4-triazole-3,5(4H)-dione, Diethyl Azodicarboxylate, and Diethyl Oxomalonate
Authors: Shi Xiaolan , Ibata Toshikazu , Suga Hiroyuki , Matsumoto Kiyoshi
Published: August 2006

The reaction of 5-alkoxythiazoles with equimolar amount of 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD) in an acetonitrile solution at room temperature gave the corresponding O-alkyl 6,7-dihydro-5,7-dioxo-6-phenyl-1H,5H-[1,2,4]triazolo[1,2-a] [1,2,4]triazole-1-carbothioate in high yields. The reaction was assumed to proceed through stepwise addition of PTAD toward thiazole accompanying thiazole ring opening. Diethyl azodicarboxylate also gave 2,3-dihydro-1H-1,2,4-triazole derivatives in moderate yields. High pressure improved the yields a little. On the other hand, the reaction of diethyl oxomalonate in the presence of tin tetrachloride with 4-unsubstituted thiazoles did not give an adduct of similar type but gave diethyl 2-hydroxy-2-(4-thiazolyl)malonate through the usual electrophilic substitution reaction of thiazole at C-4.
Oxidation of 2,2,3,3-Tetramethyl-1,4-diphenyl-5,6-dithiabicyclo[2.1.1]hexane and Its Oxidation Products: An Important Role of 1,3-Transannular Interaction in the 1,3-Dithietane Part
Authors: Ishii Akihiko , Ding Meng-Xin , Maeda Kiyoto , Nakayama Juzo , Hoshino Masamatsu
Published: August 2006

Oxidation of 2,2,3,3-tetramethyl-1,4-diphenyl-5,6-dithiabicyclo[2.1.1]hexane with m-chloroperbenzoic acid gives two isomeric endo- (4a) and exo-sulfoxides (4b), three S,S′-dioxides (endo, exo-5a, exo, exo-5b, and endo, endo-5c), and an S,S,S′-trioxide (6). The relative reactivity to further oxidation is 4b >> 4a and 5b > 5a, which suggests that the attractive 1,3-transannular interaction operative in 1,3-dithietane part of 4a and 5a decreases the reactivity of 4a and 5a. 4b isomerizes to 4a on standing over silica gel at room temperature and also 5b is converted to 5a on heating. Heating 6 in refluxing toluene yields 3,3,4,4-tetramethyl-1,2-diphenylcyclobutene, 2,5-dimethyl-3,4-diphenyl-2,4-hexadiene, and the isomeric trioxide.
Crystal Structures of Metallic and Insulating Molecular Complexes between Naphthaceno[5,6-cd: 11,12-c′d′]bis[1,2]diselenole and 4,8-Bis(dicyanomethylene)-4H,8H-benzo[1,2-c: 4,5-c′]bis[1,2,5]thiadiazole: (TSeN)(BTDA-TCNQ) and (TSeN)(BTDA-TCNQ)(C6H5Cl)
Authors: Iwasaki Kentaro , Ugawa Akito , Kawamoto Atsushi , Yamashita Yoshiro , Yakushi Kyuya , Suzuki Takanori , Miyashi Tsutomu
Published: August 2006

The charge-transfer complex between naphthaceno[5,6-cd:11,12-c′d′]bis[1,2]diselenole (TSeN) and 4,8-bis(dicyanomethylene)-4H,8H-benzo[1,2-c:4,5-c′]bis[1,2,5]thiadiazole (BTDA-TCNQ) is found to show at least three different types of crystal modifications; insulating Type-I has a (1 : 1 : 1) ratio containing solvent molecules (chlorobenzene), metallic Type-II has a (1 : 1) stoichiometry, and semiconductive Type-III is conjectured to have a (1 : 2) or (2 : 1) stoichiometry. The crystal structures of Type-I and Type-II were determined by a single-crystal X-ray diffraction method. Type-I comprises mixed-stack molecular columns, and Type-II segregated-stack molecular columns. In both types the neighboring columns are linked along short molecular axes by two Se···N contacts that are shorter than the corresponding van der Waals contact. In the Type-II crystal, there are other short distances between TSeN and BTDA-TCNQ in the direction of the long molecular axes. From the C=C bond length in the C=C(CN)2 group of BTDA-TCNQ, the degrees of charge transfer of these molecular complexes were estimated as 0.2 ± 0.3 in Type-I and 0.9 ± 0.2 in Type-II.
Equilibrium and X-Ray Structural Studies on Dimeric and Trimeric Species Formed in the Extraction of Nickel(II) with 2-Methyl-8-quinolinol
Authors: Yuchi Akio , Murakami Hiroshi , Shiro Motoo , Wada Hiroko , Nakagawa Genkichi
Published: August 2006

Nickel(II) has been extracted with 2-methyl-8-quinolinol (Hmq) into chloroform under the following conditions: CNi = 2 × 10−5–4 × 10−3; CHmq = 7.5 × 10−3–4.8 × 10−1 mol dm−3; supporting electrolyte: 0.1 mol dm−3 NaClO4 or Na2SO4; −log [H+] = 4.5–9. An equilibrium analysis has demonstrated that neutral species, (Ni2(mq)4)o and (Ni3(mq)6)o, are responsible for extraction from sulfate solutions, whereas ion-pair species, ([Ni3H(mq)6]ClO4)o and ([Ni2H3(mq)6]ClO4)o, are predominant from perchlorate solutions. The dimeric structure of (Ni2(mq)4)o is cleaved stoichiometrically along with adduct formation upon adding 1,10-phenanthroline, while being converted to (NiH(mq)3)o and/or (Ni2H2(mq)6)o at high concentrations of Hmq. X-ray crystallographic studies show that the complexes, [Ni3(mq)6]·2C2H5OH and [Ni3H(mq)6]ClO4·C2H5OH, have discrete bent-trimeric structures, and maintain all the nickel atoms octahedral by two μ- and two μ3-bridgings at the phenolate oxygen atoms. In the [Ni2H3(mq)6]ClO4 complex, each nickel atom is surrounded by three ligands in a fac configuration and two octahedrons are connected by three hydrogen bondings. All the three structures in solids are discrete and possibly the same as those in organic solvents. Compared with 8-quinolinol, the methyl group of Hmq makes the coordination of the third ligand unfavorable for both neutral and ion-pair species. Bridging at the phenolate oxygen atoms yields extractable oligomeric species.
The Crystal Water Affecting the 2Eg→4A2g Relaxation in Tris(oxalato)chromate(III) Complexes
Authors: Otsuka Takuhiro , Sekine Akiko , Ohashi Yuji , Kaizu Youkoh
Published: August 2006

The measurements of absorption and luminescence spectra and luminescence decay are carried out on pure crystals of Na3[Cr(ox)3]·xH2O (ox2− = C2O42−) (x = 5 or 4) and Li3 [Cr(ox)3]·yH2O (y = 6 or 5). In sodium salt, dehydration of one crystal water (x = 4) causes the luminescence intensity to be about thirty times larger and the lifetime to be about thirty times longer than those of the most hydrated crystal (x = 5) while the opposite trend is obtained in lithium salt. However, in both salts, no change of the position of luminescence maximum is observed by the dehydration of one crystal water from the most hydrated crystals. Comparing these results with X-ray crystallographic analyses shows that a crystal water located near the oxalato-oxygen atom, which is coordinated to Cr3+ ion, affects the 2Eg→4A2g (all in Oh notation) relaxation of [Cr(ox)3]3− complexes in the pure crystal.
Stability and Reactivity of Dihydroxobis(trimethylphosphine)platinum(II), an Intermediate Species for the Synthesis of a Variety of Water-Soluble Phosphine Complexes
Authors: Miyamoto T Ken , Suzuki Yoshitsugu , Ichida Hikaru
Published: August 2006

A dihydroxoplatinum(II) compound, cis-[Pt(OH)2(PMe3)2]·nH2O (Me = methyl, n = 2–3; 1), has been characterized by 31P, 195Pt, 13C, and 1H NMR spectroscopy. The thermal stability of 1 was examined. The presence of several water molecules is required for the stabilization of 1. The solution equilibria and the reaction of 1 with aqueous hydrogen peroxide were observed by 31P NMR spectroscopy. The neutralization of 1 with several dicarboxylic acids afforded water-soluble phosphine complexes in quantitative yields. Exposure of 1 toward air gives the carbonatoplatinum(II), cis-[Pt(CO3)(PMe3)2]·2H2O. Its crystal structure determination has revealed that the carbonate anion forms four-membered ring with a platinum atom.
Synthesis and Biological Evaluation of Dehydrophenylalanine Containing Substance P Fragments
Authors: Kaur Paramjeet , Patnaik Gyanedra Kumar , Raghubir Ram , Chauhan Virander Singh
Published: August 2006

Peptide fragments of Substance P corresponding to the C-terminal segments (6-11) and (4-11), which contain a putative β-turn, were synthesised using solution phase methodology. Analogs of Substance P were synthesised where the phenylalanine residue at position 8 was replaced by dehydrophenylalanine (ΔPhe) and the glycine residue in position 9 was replaced by alanine, valine, sarcosine (N–Me–Gly) and α-aminoisobutyric acid. In two of the analogs [8-ΔPhe, 9-Sar]–SP (4-11) (5) and [5,8-ΔPhe, 9-Aib]–SP (4-11) (7) glutamine residue at position 5 was also substituted by ΔPhe. These analogs were evaluated for their ability to cause smooth muscle contraction in guinea pig ileum preparation (in vitro) and for hypotensive activity (in vivo) in female rats anesthetized with urethane. In the hexapeptide series [8-ΔPhe]–SP (6-11) (1) and [8-ΔPhe, 9-Sar]–SP (6-11) (4) showed significant activity in both the assays. Octapeptide [5,8-ΔPhe, 9-Sar]–SP (4-11) (5) with ΔPhe residue in positions 5 and 8 and sarcosine in position 9 was found to be the most potent analog both in vitro and in vivo systems.
Chiral Stationary Phases Derived from (−)-anti Head-to-Head Coumarin Dimer: Preparation, Characterization, and Chiral Recognition Ability
Authors: Chen Yun , Shiao Ming-Tang
Published: August 2006

A monoamide derived from (−)-anti head-to-head coumarin dimer [(−)-CD] with propylamine has been successfully bonded to silica gel (Lichrospher 100 NH2: Merck) through amide linkage to prepare CSP-1. Another monoamide derivative CSP-2 was prepared by direct nucleophilic opening of one lactone ring of (−)-CD by Lichospher 100 NH2, followed by hydrolysis of the other lactone. CSP-1 and CSP-2 showed high enantioselectivity to trans-stilbene oxide with separation factors (α) at 2.42 and 2.46, respectively, and the (−)-isomer eluted first. The capacity factor (k′) and α decrease with increasing polarity of the eluent (hexane/2-propanol), indicating that hydrogen bonding plays important role in chiral recognition. CSP-3, obtained by ligand exchange of CSP-2 with CuSO4(aq), resolved Dl-tryptophan, Dl-tyrosine, and Dl-phenylalanine (α = kD′/kL′ = 1.14–1.33), which all contain aromatic chromophore. The stability difference of the ternary complexes formed with d-isomer and l-isomer is explained by steric hindrance and aromatic π-π interactions.
The Effect of the Coexistent Gases on the Thermal Reaction of Toluene or Methane in a Clusius-Dickel Type Thermal Diffusion Column
Authors: Kawakami Shigenobu , Kanaguchi Takeshi , Tagami Hiroshi , Nakada Masahiro , Yamaguchi Tatsuaki
Published: August 2006

The thermal reactions of toluene or methane in a Clusius–Dickel type thermal diffusion column was investigated in the temperature range from 1300 K to 1470 K under atmospheric pressure from the viewpoint of the effect of coexistent gases to clarify the effect of thermal diffusion on the reactions. The addition of hydrogen accelerated the hydrogenolysis of toluene resulting in the high selectivity of benzene. Contrarily, by the addition of either helium or nitrogen, the reactions were retarded. On the other hand, the reactions of methane were promoted by the addition of nitrogen, and retarded by the addition of helium. This difference of the effect of coexistent gases of helium and nitrogen shows that the partial separation of reaction mixture due to thermal diffusion and convection actually occurs and has a great influence on the reaction results in a Clusius–Dickel type thermal diffusion column.
Diastereoselective Construction of 2,2,6-Trisubstituted Tetrahydropyrans by Intramolecular Alkylation Reaction of Lithium Enolates Generated from α-Alkoxy Carboxylates
Authors: Fujisawa Tamotsu , Okumura Yoshiyuki , Morita Kazuhisa , Ukaji Yutaka
Published: August 2006

The intramolecular alkylation reaction of enolates of t-butyl α-alkoxy carboxylates in THF–HMPA proceeded stereoselectively to afford 2,2,6-trisubstituted tetrahydropyrans with high cis-selectivity.
Syntheses of Aryltetralin Lignans: Concise Syntheses of (±)-Isopodophyllotoxone, (±)-Picropodophyllone and Their Related Compounds
Authors: Ogiku Tsuyoshi , Yoshida Shin-ichi , Kuroda Tooru , Takahashi Masami , Ohmizu Hiroshi , Iwasaki Tameo
Published: August 2006

(±)-Isopodophyllotoxone and (±)-picropodophyllone were synthesized stereoselectively from the O-(t-butyldimethylsilyl) cyanohydrins (3a) in good yields. This new method was successfully applied to the syntheses of a variety of lignans of the aryltetralin series.
Asymmetric Diels–Alder Reaction of Cyclopentadiene and Methyl Acrylate Catalyzed by Chiral Organoaluminum Reagents
Authors: Maruoka Keiji , Concepcion Arnel B , Yamamoto Hisashi
Published: August 2006

The asymmetric Diels–Alder reaction of cyclopentadiene and methyl acrylate has been effected with high enantioselectivity under the influences of catalytic amounts of chiral organoaluminum reagents.
Synthesis and Reactions of 1-Heteroaryl-5-phenyl-4-pentyne-1,3-diones
Authors: Marei Mohamed Gaber , El-Ghanam Moneim
Published: August 2006

The synthesis of the title acetylenic β-diketones which are starting materials to prepare cyclic and bicyclic compounds is described.
General and Convenient Approach to Flavan-3-ols: Stereoselective Synthesis of (−)-Gallocatechin
Authors: Higuchi Takashi , Ohmori Ken , Suzuki Keisuke
Published: August 2006

General synthetic route to flavan-3-ols was developed. Union of two fragments was accomplished by an efficient three-step protocol, enabling the stereoselective synthesis of (−)-gallocatechin.
Polymerization of a Butadiyne Derivative in Crystalline State Stimulated by Radical Initiators
Authors: Arai Makoto , Okada Shuji
Published: August 2006

Solid-state polymerization of a butadiyne derivative initiated by radical species was investigated for the first time. In the nanocrystals, monomers were fully converted to the polydiacetylenes as the case of conventional photopolymerization. In bulk crystals, polymerization occurred only the parts near the specific crystal surfaces.
Synthesis of Highly Monodispersed Core/Shell Mesoporous Silica Spheres
Authors: Yano Kazuhisa , Nakamura Tadashi
Published: August 2006

Highly monodispersed core/shell mesoporous silica spheres with radially aligned pore structure have been successfully obtained by adding different type of silica precursor to the existed particles in the preparation.
The ratio of apoB/apoAI, apoB and lipoprotein(a) are the best predictors of stable coronary artery disease
Authors: Rasouli Mehdi , Kiasari Asadollah Mohseni , Mokhberi Vahid
Published: August 2006

Clin Chem Lab Med 2006;44:1015–21.
Polymorphisms of the inflammatory system and risk of ischemic cerebrovascular events
Authors: Lalouschek Wolfgang , Schillinger Martin , Hsieh Kety , Endler Georg , Greisenegger Stefan , Marculescu Rodrig , Lang Wilfried , Wagner Oswald , Cheng Suzanne , Mannhalter Christine
Published: August 2006

Clin Chem Lab Med 2006;44:918–23.
Influence of the needle bore size used for collecting venous blood samples on routine clinical chemistry testing
Authors: Lippi Giuseppe , Salvagno Gian Luca , Montagnana Martina , Brocco Giorgio , Cesare Guidi Gian
Published: August 2006

Clin Chem Lab Med 2006;44:1009–14.
Relationship between serum uric acid, creatinine, albumin and gestational diabetes mellitus
Authors: Güngör Emre Sinan , Danişman Nuri , Mollamahmutoğlu Leyla
Published: August 2006

Clin Chem Lab Med 2006;44:974–7.
Association of aminothiols with the clinical outcome in hemodialysis patients: comparison of chromatography and immunoassay for homocysteine determination
Authors: Badiou Stéphanie , Terrier Nathalie , Jaussent Isabelle , Naudin Estelle , Maurice François , Dupuy Anne-Marie , Leray-Moragues Hélène , Rivory Jean-Pierre , Delcourt Cécile , Canaud Bernard , Cristol Jean-Paul
Published: August 2006

Clin Chem Lab Med 2006;44:949–54.
Preliminary performance evaluation of blood gas analyzers
Authors: Couck Pedro , Ghys Timothy , Gastel Evelyne Van , Coillie Mia Van , Gorus Frans , Gerlo Erik
Published: August 2006

Clin Chem Lab Med 2006;44:1030–4.
Unchanged androgen-binding properties of sex hormone-binding globulin in male patients with liver cirrhosis
Authors: Luppa Peter B. , Thaler Markus , Schulte-Frohlinde Ewert , Schreiegg Anita , Huber Ursula , Metzger Jochen
Published: August 2006

Clin Chem Lab Med 2006;44:967–73.
Fracture, aging, and disease in bone
Authors: Ager J.W. , Balooch G. , Ritchie R.O.
Published: August 2006

From a public health perspective, developing a detailed mechanistic understanding of the well-known increase with age in fracture risk of human bone is essential. This also represents a challenge from materials science and fracture mechanics viewpoints. Bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions; it is therefore significantly more complex than most engineering materials. Nevertheless, by examining the micro-/nanostructural changes accompanying the process of aging using appropriate multiscale experimental methods and relating them to fracture mechanics data, it is possible to obtain a quantitative picture of how bone resists fracture. As human cortical bone exhibits rising ex vivo crack-growth resistance with crack extension, its fracture toughness must be evaluated in terms of resistance-curve (R-curve) behavior. While the crack initiation toughness declines with age, the more striking finding is that the crack-growth toughness declines even more significantly and is essentially absent in bone from donors exceeding 85 years in age. To explain such an age-induced deterioration in the toughness of bone, we evaluate its fracture properties at multiple length scales, specifically at the molecular and nano dimensions using vibrational spectroscopies, at the microscale using electron microscopy and hard/soft x-ray computed tomography, and at the macroscale using R-curve measurements. We show that the reduction in crack-growth toughness is associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging, and that this occurs at relatively coarse size scales in the range of tens to hundreds of micrometers. Finally, we briefly describe how specific clinical treatments, e.g., with steroid hormones to treat various inflammatory conditions, can prematurely damage bone, thereby reducing its fracture resistance, whereas regulating the level of the cytokine Transforming Growth Factor-β can offer significant improvements in the stiffness, strength, and toughness of bone and as such may be considered a therapeutic target to treat increased bone fragility induced by aging, drugs, and disease.
Nanomechanics and morphology of salivary pellicle
Authors: Dickinson Michelle E. , Mann Adrian B.
Published: August 2006

Acquired salivary pellicle is a thin protein-rich film formed by the adsorption of saliva onto teeth. It plays important roles in lubrication during mastication and protecting the teeth from chemical attack. Pellicle can become colonized by bacteria to form dental plaque which can lead to dental caries if the bacteria are acidogenic. Abrasive polishing with a dentrifice is used periodically to remove the pellicle from teeth. Pellicle can interact with dietary polyphenolic compounds (tannins) to create extrinsic stains on the tooth surface. The staining can modify the pellicle's mechanical properties and change its morphology resulting in a “squeaky” feeling when the tongue is rubbed over the teeth. Atomic force microscopy imaging and nanoscale mechanical measurements show that unstained pellicle has a dense undulating morphology and is a surprisingly stiff, viscoelastic solid. In contrast, tannin-stained pellicle has fewer but larger surface undulations and exhibits substantial viscous creep.
Crush absorbing energy of white spot lesions measured by indentation tests
Authors: Fallgatter Alison M. , Ko Ching-Chang
Published: August 2006

White spot lesions are clinically detectable areas of demineralized enamel that often form during orthodontic treatment. Fluoride has been shown to prevent demineralization from occurring. Mechanical properties of white spot lesions are not well characterized. Bovine enamel slabs, with and without fluoride treatment, were placed under demineralization conditions. Through a series of microindentations at incremental loads, mechanical strength was measured using a novel method, specific volume absorbing energy (SVAE). SVAE is equal to work energy divided by the indentation volume. The supra-surface area (outermost 5 μm) of enamel slabs with fluoride demonstrated decreased mechanical strength compared to enamel slabs without fluoride. Fluoride may not impart protection over long periods of demineralization.
Bioenergetics and mechanical actuation analysis with membrane transport experiments for use in biomimetic nastic structures
Authors: Matthews Luke , Sundaresan Vishnu Baba , Giurgiutiu Victor , Leo Donald J.
Published: August 2006

Nastic structures are synthetic constructs capable of controllable deformation and shape change similar to plant motility, designed to imitate the biological process of nastic movement found in plants. This paper considers the mechanics and bioenergetics of a prototype nastic structure system consisting of an array of cylindrical microhydraulic actuators embedded in a polymeric plate. Non-uniform expansion/contraction of the actuators in the array may yield an overall shape change resulting in structural morphing. Actuator expansion/contraction is achieved through pressure changes produced by active transport across a bilayer membrane. The active transport process relies on ion-channel proteins that pump sucrose and water molecules across a plasma membrane against the pressure gradient. The energy required by this process is supplied by the hydrolysis of adenosine triphosphate. After reviewing the biochemistry and bioenergetics of the active transport process, the paper presents an analysis of the microhydraulic actuator mechanics predicting the resulting displacement and output energy. Experimental demonstration of fluid transport through a protein transporter follows this discussion. The bilayer membrane is formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine lipids to support the AtSUT4 H+-sucrose cotransporter.
Micromechanical model for hydroxyapatite whisker reinforced polymer biocomposites
Authors: Yue Weimin , Roeder Ryan K.
Published: August 2006

A micromechanical model was developed to predict the elastic moduli of hydroxyapatite (HA) whisker reinforced polymer biocomposites based upon the elastic properties of each phase and the reinforcement volume fraction, morphology, and preferred orientation. The effects of the HA whisker volume fraction, morphology, and orientation distribution were investigated by comparing model predictions with experimentally measured elastic moduli for HA whisker reinforced high-density polyethylene composites. Predictions using experimental measurements of the HA whisker aspect ratio distribution and orientation distribution were also compared to common idealized assumptions. The best model predictions were obtained using the experimentally measured HA whisker aspect ratio distribution and orientation distribution.
Microstructure and interfacial fracture at the cementum-enamel junctions in equine and bovine teeth
Authors: Wang Rizhi , Hu Youxin , Ng Cathy
Published: August 2006

The cementum–enamel junction (CEJ) is a unique interface that plays a critical role in effectively transferring force from the top of the tooth to the jawbone. A comparative study of bovine and equine teeth has been carried out experimentally to establish the relationship among the interfacial structure, fracture resistance, and mechanical functions. The CEJs were analyzed by optical microscopy and scanning electron microscopy (SEM). Microhardness and elastic modulus were measured with a Vickers microhardness tester and a nanoindentation system. A modified cantilever beam technique was used to study CEJ fracture process and the toughness (Gc,). It was observed that CEJ is a distinct interface connecting the hard enamel (200–350 kg/mm2) with the soft cementum (∼20–30 kg/mm2). Bovine CEJ was macroscopically flat and smooth. However, under SEM, a close integration of cementum bumps and enamel pits at the 5 μm level and dimples at the 200 nm level were clearly seen. In equine CEJ, the similar flat cementum–enamel interface was interrupted by hemispherical cementum protrusions (average size of 28.3 μm) at high density (340/mm2). Despite the microscopic roughness, bovine CEJ was easy to fracture at relatively low toughness (128 J/m2). The measured toughness for equine CEJ was about seven times that of bovine (1140 J/m2). The high toughness has been attributed to the mechanical interlocking provided by the cementum protrusions. The underlying crack bridging mechanism and the applications to the design of orthopaedic implants are briefly discussed.