bluuebunny/crossref_metadata_2025 huggingface dataset:
Green land and blue sea: a coloured landscape in the orientation of the sandhopperTalitrus saltator(Montagu) (Amphipoda, Talitridae)
Authors: Ugolini Alberto , Somigli Silvia , Mercatelli Luca
Published: June 2006

The use of the landscape in the zonal recovery of Talitrus saltator (Montagu) was demonstrated in the past using natural and artificial landscapes. Here we evaluate the importance of colour in the landscape orientation of sandhoppers. Adult individuals of T. saltator were released in a Plexiglas bowl under the sun, with a view of an artificial landscape: a black cardboard strip or a pair of differently coloured filters, each occupying 180° of the horizon. Our results not only confirm the influence of the black and white artificial landscape-based compass cue on the zonal orientation of T. saltator, but also show that vision of a blue and green artificial landscape affects the direction of orientation; in fact, the orientation agreed with the directional indication of the landscape even when it contrasted with the sun compass indication. The same result was obtained with a blue–grey and green–grey landscape, but not with pairs of grey filters. Therefore, in the sandhoppers'visual world, a coloured landscape that matches the prevalent natural field colours greatly contributes to their directional choice.
Controlled Growth of Bi-Based Cuprate Whiskers
Authors: Matsubara Ichiro , Funahashi Ryoji , Miyaji Nobuhiro , Ueno Kazuo , Ishikawa Hiroshi
Published: June 2006

Cuprate whiskers with different crystal phases, Bi2Sr2CuOx (Bi-2201) and Bi4Sr8Cu5Ox (Bi-485), have been obtained by heating melt-quenched glass precursors. The crystal phase of the grown whiskers were controllable by changing the precursor composition and heating conditions. The Bi-2201 whiskers were identified to be of the R-phase, written in a general formula as Bi2+xSr2−xCuOy. The hole concentration of the as-grown Bi-2201 whiskers was also controlled from the underdoped to the overdoped state by changing the precursor composition. The temperature dependence of resistivity changed from a semiconducting to a metallic behavior corresponding to the hole concentration.
Synthesis and Properties of a Nitridomolybdenum(VI) Complex Having Benzenedithiolate Ligands. Effect of the Thiolate on the Activation of the Nitrido Ligand
Authors: Kondo Mitsuru , Oku Hiroyuki , Ueyama Norikazu , Nakamura Akira
Published: June 2006

A nitridomolybdenum(VI) complex having 1,2-benzenedithiolate (bdt2−) (NEt4)2[MoVIN(bdt)2Cl] was synthesized by the reaction of (NEt4)[MoVINCl4] with 2 equiv of Li2bdt in DMF/THF solution. This complex was characterized by measurements of the absorption, Raman, IR, and 14N NMR spectra. A lower Mo≡N band (1010 cm−1) in the Raman spectrum and the upfield shifted 14N NMR signal (−374 ppm) of the nitrido ligand compared to those of (NEt4)[MoVINCl4] (1055 cm−1 and −350 ppm) were observed, which strongly suggest the existence of a competitive π-electron donation from S (pπ) to Mo (dπ). The complex readily reacts with O2 or H2O to produce an oxomolybdenum(IV) complex [MoIVO(bdt)2]2−. This extremely air-sensitive complex shows a higher reactivity to O2 than that of (NEt4)[MoVINCl4]. It is concluded that the observed high reactivity is the result of a weakened Mo≡N bond by thiolate coordination.
Selective Adsorption of Metal Ions to Surface-Template Resins Prepared by Emulsion Polymerization Using 10-(p-Vinylphenyl)decanoic Acid
Authors: Koide Yoshifumi , Senba Hirofumi , Shosenji Hideto , Maeda Mizuo , Takagi Makoto
Published: June 2006

A monomer-type surfactant, 10-(p-vinylphenyl)decanoic acid (1), has been prepared and applied to an emulsifier for the preparation of surface-template resins. The hydrophobicity of 1 corresponded to that of C15H31COONa on the basis of the cmc values, while that of 1 on the emulsification corresponded to that of C12H25COONa. The monomers (DVB + St + 1) were copolymerized in a metal ion solution and the resulting polymers were evaluated for their surface-template effects. The suspension polymerization gave resins 0.08 mm in diameter and the adsorption of metal ions on Cu2+-imprinted resins attained equilibrium in 2 h. The surface-template effects based on the oriented 1 exceeded the inner-template resins in selective adsorption. On the other hand, the emulsion polymerization gave fine particles 200—300 nm in diameter. The resins showed excellent surface-template effects. The adsorption of metal ions was 50—100 times as much as that on the resins prepared by suspension polymerization (see and ). The metal-imprinted resins was 1.88 times more effective than the unimprinted resins, and the Zn2+-imprinted resins showed more effective adsorption for Zn2+ than for Cu2+ and for Ni2+. Such surface-template effects were also seen for Cu2+- and Ni2+-imprinted resins. The selectivity (Cu2+/Zn2+) from the mixture of both metal ions was 3.7 for the Cu2+-imprinted resins prepared at 0.25 mol% 1. Furthermore, the metal-imprinted resins could be used repeatedly.
One-Pot Synthesis of Unsymmetrical Ketones by the Reaction of Decacarbonyldimanganese with Two Kinds of Alkyllithiums
Authors: Yamamoto Hiroshi M , Sakurai Hidehiro , Narasaka Koichi
Published: June 2006

Decacarbonyldimanganese (Mn2(CO)10) is utilized as a phosgene equivalent for the one-pot preparation of unsymmetrical ketones. By a successive treatment of Mn2(CO)10 with two kinds of alkyllithiums, unsymmetrical ketones are obtained in high selectivity. Unsymmetrical α-diketones are generated when the above reaction is carried out in the presence of trimethyl phosphite and is quenched with N-bromosuccinimide.
Enzymatic Synthesis and Thermal Properties of a New Class of Polyphenol
Authors: Uyama Hiroshi , Kurioka Hideharu , Sugihara Junji , Kobayashi Shiro
Published: June 2006

Enzymatic oxidative polymerization of phenol has been carried out in an aqueous organic solvent using horseradish peroxidase as catalyst. The polymerization in a mixture of 1,4-dioxane and phosphate buffer (pH 7.0) (80 : 20 vol%) produced powdery polymeric materials, which were partly soluble in DMF and DMSO. The molecular weight of the DMF-soluble part determined by GPC was 3.5 × 104. Polymerization conditions have been investigated with respect to the polymer yield, solubility, and molecular weight. The solvent composition enormously affected the polymerization. The polymer structure was estimated by IR and NMR spectroscopies and found to contain a mixture of phenylene and oxyphenylene units. From TG analysis, the polymer was found to possess high thermal stability; 43 weight % of the polymer remained up to 1000 °C under nitrogen. DSC measurement showed no clear glass transition temperature or melting point.
Alcoholysis of Epoxides Catalyzed by Tetracyanoethylene and Dicyanoketene Acetals
Authors: Masaki Yukio , Miura Tsuyoshi , Ochiai Masahito
Published: June 2006

A typical π-acid tetracyanoethylene and capto-dative olefin dicyanoketene acetals were found to catalyze stereospecific alcoholysis of epoxides at the ambient temperature to 50 °C in good yields. Mildness and significant chemoselectivity of the catalysts were demonstrated by intactness of tetrahydropyranyl ether and ethylene acetal groups. A novel regioselectivity associated with anchimeric assistance of the ethereal group on the side chain was observed in the ring opening reaction of the 1,2-disubstituted epoxides.
CH-π Interaction as an Important Driving Force of Host–Guest Complexation. Further Evidence for the Selective Incorporation of Alkyl Groups in the Polyhydroxy Aromatic Cavity of Calix[4]resorcarene Host
Authors: Kikuchi Yasuaki , Aoyama Yasuhiro
Published: June 2006

The complexation of a calix[4]resorcarene host (2,8,14,20-tetraundecylcalix[4]arene-4,6,10,12,16,18,22,24-octol) with borneol in benzene or alkylbenzene was investigated by circular dichroism (CD) spectroscopy. The binding constants are dramatically solvent-dependent and decrease with respect to the substituents on the benzene ring in the order H > methyl > ethyl > propyl > butyl. The complexation of the same host with alkyl benzoates in limonene as a chiral hydrocarbon solvent was readily monitored by following their competitive inhibition effects on the CD intensities, reflecting the chiral host-solvent interaction. The binding constants for alkyl benzoates were again highly dependent on the alkyl groups, and changed in the order decyl < hexyl < methyl < propyl ≈ pentyl << butyl. There is thus an optimal chain length at butyl. These results provide further evidence for the selective incorporation of alkyl groups in the polyhydroxy aromatic cavity of the host.
Aerobic Oxidation of 3-Iodomethyl-Δ3-cephem-4-carboxylate to 3-Formyl-Δ3-cephem-4-carboxylate through 3-Hydroperoxymethyl-Δ3-cephem-4-carboxylate
Authors: Tanaka Hideo , Kikuchi Ryo , Torii Sigeru
Published: June 2006

Aerobic oxidation of p-methoxybenzyl 3-iodomethyl-8-oxo-7-phenylacetamido-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate (3-iodomethyl-7-phenylacetamido-Δ3-cephem-4-carboxylate) in N-methyl-2-pyrrolidone in the presence of phosphomolybdic acid mainly afforded the corresponding 3-formyl-Δ3-cephem-4-carboxylate, while similar aerobic oxidation in the presence of potassium iodide gave 3-hydroxymethyl-Δ3-cephem-4-carboxylate as a major product. 3-Hydroperoxymethyl-Δ3-cephem-4-carboxylate was isolated as a primary product in the aerobic oxidation, which was subsequently converted to either 3-formyl-Δ3-cephem-4-carboxylate by dehydration with phosphomolybdic acid or 3-hydroxymethyl-Δ3-cephem-4-carboxylate by reduction with potassium iodide.
Analysis of Facilitated Oxygen Transport in a Liquid Membrane of Hemoglobin
Authors: Chen Xue-si , Nishide Hiroyuki , Tsuchida Eishun
Published: June 2006

A liquid membrane containing bovine hemoglobin (Hb) as an oxygen carrier was prepared, and oxygen permeation through the membrane was measured by the electrochemical reduction of the permeated oxygen. The oxygen permeation was facilitated, as analyzed by a dual-mode model, to give permeation parameters of the membranes such as the diffusion coefficient (DHb) of the mobile carrier Hb and the solution-diffusion coefficient of oxygen (DO2). The facilitated permeation was the product of the Hb concentration ([Hb]0) and DHb in the membrane solution. DHb decreased with [Hb]0 or the solution viscosity; the maximum of the oxygen permeability (6.2 × 10−8 cm3(STP)cm cm−2s−1 cmHg−1 at the feed stream oxygen pressure of 0.54 cmHg) was observed at [Hb]0 = 12.8 g dl−1, where the facilitation factor and the oxygen/nitrogen permselectivity were ca. 10 and 18, respectively.
Apparent Molar Volume and Viscosity of N-Ethylpyridinium Iodide in Water
Authors: Panda B B , Dixit G , Behera B
Published: June 2006

The apparent molar volume and the viscosities of N-ethylpyridinium iodide in water at 25, 30, 35, and 40 °C are reported. The apparent molar volumes decrease with increasing temperature and obey Masson’s equation. The high values of φv° and Sv* indicate strong ion–ion interactions in water. φv° is linearly related to temperature. The viscosity data were analyzed by the Jones–Dole equation. The B values indicate greater solvation. The thermodynamic parameters of viscous flow and hydration number are discussed in terms of hydrophobic hydration and solvent-shared ion-pairs.
Ab Initio MO Calculations of NMR 15N–6Li Coupling Constants in Lithium Amide Monomers, Oligomers, and Mixed Aggregates with LiCl
Authors: Koizumi Terutake , Morihashi Kenji , Kikuchi Osamu
Published: June 2006

The NMR 15N–6Li coupling constants 1JNLi in LiNH2 and LiN(CH3)2 monomers and their oligomers and mixed aggregates with LiCl were calculated using ab initio self-consistent perturbation theory and the relation between the molecular structure and 1JNLi values was examined. The calculated 1JNLi values in the monomers are influenced by solvation and agree well with experimetal values when model solvent molecules are coordinated at the lithium atom. The calculated 1JNLi values in cyclic oligomers also agree well with experiment and support the structures derived from NMR experiments in solution. For the mixed trimer, (LiNH2)2LiCl, a ladder form was obtained as the most stable structure when the lithium atoms are solvated by two H2O or two NH3 molecules.
Electrochemical Study of the Thermodynamics of Micellization of Hexadecylpyridinium Bromide
Authors: Shamsipur Mojtaba , Alizadeh Naader , Gharibi Hossein
Published: June 2006

A membrane electrode selective for hexadecylpyridinum bromide was used to study the micellization of the surfactant at various temperatures (25—50 °C). The thermodynamic parameters ΔH°m and ΔS°m were calculated from the temperature dependence of the equilibrium constants for micellization of the surfactant. It was clearly shown that the entropy of micellization obtained by the usual approximate method from ΔG°m = (2 − α)RTln Xcmc is much more positive than the corresponding exact value calculated from direct activity measurements.
Emulsification of Calix[4]arenes Bearing Four Chains and Transportation of Cesium Ion through Liquid Surfactant-Membrane
Authors: Koide Yoshifumi , Sato Hirotaka , Shosenji Hideto , Yamada Kimiho
Published: June 2006

Resorcinol-type calix[4]arenes bearing four alkyl side chains ([4]Ar-Rn) have been applied as a liquid surfactant-membrane in the concentration process of Cs+. [4]Ar-Rn formed a highly stable water-in-oil (w/o) emulsion for a mixture of toluene and HCl solution, and the w/o emulsion became a w/o/w emulsion by stirring it in a Cs+ solution. The Cs+ in the outer aqueous solution was transported through the liquid surfactant-membrane of w/o/w emulsion into the inner HCl solution. [4]Ar-R6 was the most effective emulsifier capable carrying Cs+ in the [4]Ar-Rn bearing alkyl chains of various lengths. The final amount of the transported Cs+ was 9 times as much as the molar of [4]Ar-R6 in 100 min at the initially 10 times molar Cs+ in the outer solution (turnover number: 9). Moreover, the Cs+ was transported selectively from a mixture of alkali metal ions (Cs+, Na+, and K+) by using 2 × 10−4 mol of [4]Ar-R6.
Electronic and Magnetic Properties of Activated Carbon Fibers
Authors: Nakayama Atsuko , Suzuki Kazuya , Enoki Toshiaki , Koga Kei-ichi , Endo Morinobu , Shindo Norifumi
Published: June 2006

Activated carbon fibers (ACF) consist of microporous carbon with a huge specific surface area (SSA) ranging from 700 m2 g−1 to 3000 m2 g−1, and a having random structures consisting of an assembly of micrographites with a dimension of ca. 20 × 20 Å2. The electrical conductivity and magnetic susceptibility were investigated for ACFs with SSA = 1000 and 2000 m2 g−1 in order to clarify the relation between the electronic properties and the structure of ACF having a random network of micrographites. The electrical conductivity is explained by the two-dimensional variable-range hopping conduction at lower temperatures and thermally activated conduction at higher temperatures. The introduction of N2 or O2 gas to a sample induces a change in the conductivity, which is considered to be caused by a structural change and a charge transfer between dangling bonds and O2 gas. The observed value of the orbital diamagnetic susceptibility is considerably small compared with that of a condensed polycyclic aromatic hydrocarbon having the same dimensions as that of the micrographite in ACF. This implies that the micrographitic domains have a deformed planar structure with the presence of defects.
Oxidation of a Dipeptide by Electrolytically Generated Manganese(III) in Aqueous Sulfuric Acid Medium: A Kinetic and Mechanistic Study
Authors: Bhat D Krishna , Sherigara B Sheena , Gowda B Thimme
Published: June 2006

The kinetics of oxidation of the simplest dipeptide, glycylglycine (GG) by electrolytically generated manganeseIII-sulfate in aqueous sulfuric acid has been studied. The rate shows first order dependence on [MnIII] and a fractional order each on [GG] and [H+]. The reduced product, MnII has no significant effect on the rate. An increase in ionic strength or decrease in dielectric constant of the medium increases the rate, while addition of complexing agents such as Cl−, F−, and P2O74− decreases the rate. A Michaelis–Menten type mechanism has been suggested to explain the results. The coefficient of the rate-determining step has been evaluated as a function of temperature, by measuring the rates at different temperatures. The corresponding activation parameters have also been computed. Evidence for transient existence of a free radical reaction intermediate has been given. The kinetics of oxidation of GG have also been compared with those of the monomer amino acid, glycine.
Stable β-Sheet Formation and Enhanced Hydrolytic Catalysis of a Sequential Alternating Amphiphilic Polypeptide Containing Catalytic Triads in a Serine Protease
Authors: Fukushima Yasumasa
Published: June 2006

The alternating amphiphilic copolypeptide poly(Asp–Leu–His–Leu–Ser–Leu) was prepared by the synthesis and polymerization of the respective hexapeptide in order to obtain a stable β-sheet polypeptide with hydrolytic catalytic activity, like that of a serine protease. The conformation and conformational transitions in aqueous solution and in water–organic solvent mixtures were determined by circular dichroism measurements. The polypeptide reveals a very strong tendency to adopt a β-sheet structure, which is accomplished at below pH 10.0, and even by adding sodium chloride or various alcohols. However, a partial α-helical conformation is observed in an aqueous solution at pH 12.0; also, an α-helix to β-sheet conformational transition occurs upon adding 1 M NaCl. The polypeptide is a more effective catalyst than the peptide hexamer, the amino acids mixture, or imidazole for the hydrolysis of p-nitrophenyl derivatives, and catalyzed the hydrolytic reaction of the substrates more effectively with increasing their hydrophobicity. It is likely that the enhanced hydrolytic catalyst of the polypeptide may be responsible for increasing the nucleophilicity by the electrostatic interactions or condensation effect of the substrates by hydrophobic interactions. The polypeptide would make good models for constructing novel proteins with catalytic properties involving β-sheet structures.
Gas Phase Basicities of Phenylacetylenes. Intrinsic Resonance Demand of the 1-Phenylvinyl Cation
Authors: Mishima Masaaki , Ariga Toshifumi , Matsumoto Takatsugu , Kobayashi Shinjiro , Taniguchi Hiroshi , Fujio Mizue , Tsuno Yuho , Rappoport Zvi
Published: June 2006

Gas-phase basicities (GB) of a series of substituted phenylacetylenes were determined by measuring the standard free energy changes of proton transfer equilibria using a pulsed ion cyclotron resonance mass spectrometer. The LArSR analysis of the substituent effect on the GB values gave an r+ value of 1.18 and a ρ value of −14.0. The r+ value is significantly larger than that obtained for the GB of α-methylstyrenes but is smaller than that for chloride ion affinities of benzyl cations, while the ρ value is similar in the three systems. This means that the 1-phenylvinyl cation has an intermediate resonance demand between those of the α-cumyl cation and the benzyl cation. Further, the r+ value of 1.18 for 1-phenylvinyl cation obeys the same “resonance demand vs. carbocation stability" relationship observed for a series of ordinary sp2-hybridized benzylic carbocations. This reveals that the π-delocalization mechanism in the vinyl cation system has no unique feature but it is a part of a continuous spectrum of resonance demands of varying benzylic carbocations characterized by r+ = 1.18. A comparison of the present GB values with the substituent effect for the acid-catalyzed hydration of phenylacetylenes in solution has shown that the r+ value is perceptibly smaller in the latter case. This suggests that the π-delocalization in the transition state differs considerably from that of the stable phenylvinyl cation intermediate. This is in contrast to the situation in the SN1 solvolysis where the r+ value is identical to the value characteristic for the formation of the fully developed carbocation.
Complex Metal Halide Oxides (1): Bismuth Chloride Oxides Having Various Structures as Catalysts for Oxidative Coupling of Methane
Authors: Ueda Wataru , Isozaki Toshio , Sakyu Fuyuhiko , Nishiyama Satoshi , Morikawa Yutaka
Published: June 2006

Bismuth chloride oxides having four distinct structural types and lanthanum-substituted bismuth chloride oxides were tested as catalysts for the oxidative coupling reaction of methane. Their catalytic properties were compared in relation with their structure. BiClO, which has a layer structure with a double chlorine sheet, so-called X2 type structure, was most active for the methane conversion but less selective for the formation of C2 hydrocarbons. The catalyst structure was quite unstable, so that the activity decreased markedly until reaching a constant level, while the selectivity increased. During these changes of the catalytic performance BiClO changed by liberating chlorine to Bi24Cl10O31, the so-called Arppe’s phase, and then finally to a highly stable and selective Bi3ClO4 phase which was constructed with a double metal oxygen sheet and a single chlorine sheet. When more chlorine was removed from Bi3ClO4, Bi12Cl2O17, which has quintuple oxide sheets and a single chlorine sheet, was formed as an intermediate phase to be less selective for C2 hydrocarbons and ultimately Bi2O3 was formed with no chlorine, to be nonselective. The substitution of Bi in Bi3ClO4 for La caused a decrease of the C2 selectivity, whereas the Bi3−xLaxClO4 catalysts treated with NaCl brought about a maximum yield of C2 hydrocarbons.
Characteristics of Iron Phosphate and Its Catalytic Activity for Oxidative Dehydrogenation of Isobutyric Acid
Authors: Muneyama Etsuhiro , Kunishige Atsuhiro , Ohdan Kyoji , Ai Mamoru
Published: June 2006

In the absence of oxygen, P/Fe = 1.2 catalyst samples are reduced by hydrogen or isobutyric acid to form Fe2P2O7 via Fe3(P2O7)2, while the P/Fe = 1.0 samples are reduced directly to Fe2P2O7; without passing through Fe3(P2O7)2. Fe2P2O7 is oxidized by air to an unknown compound (Y-phase), but not to Fe3(P2O7)2 nor FePO4. The Y-phase is reduced to Fe2P2O7. During the use in the oxidative dehydrogenation of isobutyric acid, freshly calcined catalysts are reduced to Fe3(P2O7)2, while the Fe2P2O7 catalysts are oxidized to Y-phase, though the rates are very slow. The catalytic activity and selectivity are scarcely affected by variation in the structure of the iron phosphate catalyst and in the oxidation states of iron ions. The P/Fe and Fe2+/(Fe2++Fe3+) ratios on the surface, which were measured from cooled catalyst samples, are almost the same as those in the bulk.
The Excimer Fluorescence of 2-Methylnaphthalene in β- and γ-Cyclodextrin Aqueous Solutions
Authors: Hamai Sanyo
Published: June 2006

2-Methylnaphthalene (MN) exhibits MN excimer fluorescence in both β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) neutral aqueous solutions. β-CD forms a 1 : 1 inclusion complex with MN, which self-associates to form a 2 : 2 inclusion complex emitting the MN excimer fluorescence. In 0.4 mol dm−3 NaOH solutions, no excimer fluorescence has been observed, indicating that the 2 : 2 inclusion complex dissociates to two 1 : 1 inclusion complexes because of an electrostatic repulsion between the negatively charged hydroxy groups of the two β-CD molecules contained in the 2 : 2 inclusion complex. For the γ-CD–MN system as well as the β-CD–MN system, the excimer fluorescence can be explained in terms of the formation of a 2 : 2 inclusion complex through a self-association of 1 : 1 inclusion complexes.
The Thermal Behavior of 1,3 : 2,4-Di-O-benzylidene-d-sorbitol/Ethylene Glycol Gel
Authors: Yamasaki Seiji , Tsutsumi Hisao
Published: June 2006

The so-called 1,3 : 2,4-di-O-benzylidene-d-sorbitol (D-DBS) can cause the gelation of alcoholic solvents. The thermal behavior of a 1 wt% d-DBS/ethylene glycol gel was studied using thermal, optical, mechanical, and spectroscopic measurements. Changes in the optical and mechanical properties were observed at around 45 and 80 °C. Upon heating, the diameter of the spherulitic texture in the gel decreased above around 45 °C and disappeared at around 80 °C. In a thermal analysis, an endothermic peak was observed at around 80 °C, which agreed with the gel state-isotropic solution phase-transition point. The aggregated structure of d-DBS in ethylene glycol was studied, using UV absorption and circular dichroism (CD) measurements. The relative orientation of the benzene rings changed above 45 °C, due to the hypochromism of the UV absorptions. The gel showed a temperature dependence of the CD spectra. With increasing temperature, the value of the molar ellipticities increased at 27—82 °C, and drastically decreased at 82—93 °C, indicating that the aggregated structure underwent a change at between 45—80 °C and disappeared above 80 °C. The macroscopic level, as well as the optical and mechanical properties were related to the change in the aggregated structure formed by d-DBS.
GPC Analysis of Polymer Network Formation: 1. Bifunctional Siloxane Monomer/Crosslinker System
Authors: Kohjiya Shinzo , Takada Yasuhiro , Urayama Kenji , Tezuka Yasuyuki , Kidera Akinori
Published: June 2006

The size distribution of polymer clusters in the pre-gel state was investigated as a function of the conversion by gel permeation chromatography (GPC) in order to elucidate the process of polysiloxane network formation. Polysiloxane networks were synthesized by hydrosilylation between a bifunctional monomer and a tri- or tetrafunctional crosslinker. Experimental chromatograms for the pre-gel system were compared with a theoretical one based on the distribution for the mean-square radius of gyration () of polymer clusters predicted by the Flory–Stockmayer theory and the Gaussian chain statistics. Experimental chromatograms at high conversion showed a longer tailed distribution in the large  region compared with a theoretical one. A comparison of experimental chromatograms with theoretical ones suggests the structure of a precursor network in which branched clusters are linearly linked.
Theoretical Studies of the Chemical Processes of Producing Methylamine and Methanol in the Interstellar Space
Authors: Sonoda Yoko , Iwata Suehiro
Published: June 2006

A hypothesis for the mechanism forming CH3NH2 and CH3OH in interstellar space is examined with the ab initio MO calculations. In the hypothesis, both of CH3NH2 and CH3OH are assumed to be formed via two steps, radiative association reaction and dissociative recombination reaction. The calculations support the possibility of the two-step mechanism for CH3OH, but the first step radiative association reaction for CH3NH2 is proved to be unfavorable. Based on the calculational results, an alternative reaction mechanism is proposed.
Synthesis, Spectral, Thermal, and Biological Studies of Adducts of Organotin(IV) Halides with Schiff Bases Derived from 2-Amino-5-(o-methoxyphenyl)-1,3,4-thiadiazole
Authors: Nath Mala , Goyal Savita , Eng George , Whalen D
Published: June 2006

Some new organotin(IV) complexes of the general formula, RnSnCl4−n·L [where n = 3, R = CH3 or C6H5; n = 2, R = C6H5; L = Schiff bases derived from the condensation of 2-amino-5-(o-methoxyphenyl)-1,3,4-thiadiazole with salicylaldehyde (L-1), 2-hydroxy-1-naphthaldehyde (L-2), 2′-hydroxyacetophenone (L-3), benzyl methyl ketone (L-4), acetylacetone (L-5), and 2-furancarbaldehyde (L-6)] have been synthesized and characterized by elemental analyses, molar conductances, electronic, infrared, far-infrared, 1H and 119Sn NMR and Mössbauer spectral studies. Thermal studies of three complexes, viz., Ph3SnCl(L-2), Me3SnCl(L-4), and Ph3SnCl(L-5) have been carried out in the temperature range 25—1000 °C using TG, DTG, and DTA techniques. All these complexes decompose gradually with the formation of SnO2 as an end product. In vitro antimicrobial activity of the ligands and their complexes has also been determined against Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus Penicillin resistance (2500 units), Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii, Trichophyton mentagrophytes, and Aspergillus fumigatus.
Formation of Peroxodiphosphate by the Copper(II)-Catalyzed Oxidation Reaction of the Phosphinate Ion by the Molecular Oxygen. Kinetics and Mechanisms in Aqueous Solutions
Authors: Kimura Masaru , Seki Kyouko , Horie Hitomi , Tsukahara Keiichi
Published: June 2006

It was found that peroxodiphosphate ions (denoted by PDP and meaning all forms of P2O84−, HP2O83−, H2P2O82−, etc.) were formed by the oxidation of the phosphinate ion (PH2O2−) by molecular oxygen (O2) using trace amounts of the copper(II) ion as a catalyst in aqueous solutions. The formation rate was dependent on the acidity being maximum at around pH 3.5, and was inhibited by the presence of radical scavengers or a complex-forming substance of ethylenediaminetetraacetic acid (EDTA). The formation of PDP was not observed when ions such as IrIV and CeIV were used in place of the copper(II) ion. Thus, this reaction is specific only for the copper(II) ion, which can be easily reduced to Cu+ by the phosphinate ion, where the reduced species are capable of reacting with molecular oxygen to efficiently produce the superoxide of O2−• or HO2•. After some PDP had been formed in the presence of air or oxygen, if the reacting solution was changed to be anaerobic by bubbling nitrogen through the solution, the PDP began to decompose according to the first-order rate law with respect to the concentrations of PDP. The kinetics and mechanisms for not only the formation, but also the decomposition of PDP, are presented.
Template-Dependent Selectivity in Metal Adsorption on Phosphoric Diester-Carrying Resins Prepared by Surface Template Polymerization Technique
Authors: Murata Masaharu , Hijiya Shinji , Maeda Mizuo , Takagi Makoto
Published: June 2006

The surface templated resins for three different metal ions such as Cu2+, Zn2+ or Cd2+ as the template guest were prepared by emulsion polymerization using oleyl phenyl hydrogenphosphate as a host surfactant, sodium dodecyl sulfate (SDS) as a co-surfactant and divinylbenzene as a resin matrix-forming monomer. The Cu2+-imprinted resin adsorbed Cu2+ much more effectively than did the nonimprinted, the Zn2+- and Cd2+-imprinted ones. On the other hand, the Cd2+-imprinted resin showed a more highly effective binding to Cd2+ than those of the Cu2+-imprinted, Zn2+-imprinted, and nonimprinted resins. In fact, the Cu2+-imprinted resin did not adsorb any significant amount of Cd2+. The selective feature of the surface templated resins to the target ion was thus successfully demonstrated. The template-dependent selectivity should be ascribed to a favorable placement of the surface-anchored metallophilic groups for multidentate coordination to the specific metal ion.
Crystal Structure and Chemical Properties of Tris(2,6-dimethoxyphenyl)phosphine Selenide
Authors: Wada Masanori , Hayase Shuichi , Fujiwara Masanobu , Kawaguchi Tetsuji , Iwasaki Toshio , Uo Akira , Erabi Tatsuo
Published: June 2006

The X-ray crystal structure of the title compound, Φ3PSe [Φ = 2,6-(MeO)2C6H3], showed that the P=Se bond distance [2.136(2) Å] was the longest among those of the reported triarylphosphine selenides, that the P–C bond distances [av. 1.839 Å] were longer than those of triphenylphosphine selenide, and that all the P···O interatomic distances [2.794—3.189 Å] were shorter than the sum of the van der Waals radii, implying a direct electron-donative interaction from the methoxy oxygen atom to the phosphorus atom. Some chemical evidence also showed that the P=Se bond was weaker than that of triphenylphosphine selenide. Alkyl halides, RX, reacted with Φ3PSe to give a mixture of alkylselenophosphonium salts, [Φ3P–SeR]X, and alkylphosphonium salts, [Φ3P–R]X, while they reacted with PhΦ2PSe to give [PhΦ2P-SeR]X almost selectively. Measurements of the reaction rates of Ph3−nΦnPY (n = 0—3; Y = none, O, S, Se) with butyl bromide in acetonitrile showed that the rate decreased in the order of Y = none > Se > S > O and n = 3 > 2 > 1 > 0. Benzylselenophosphonium salts, [Φ3P–SeCH2C6H4Z-4]Cl (Z = H, Me, Cl) and [PhΦ2P–SeCH2Ph]Cl, reacted easily with aqueous sodium hydroxide or with aqueous tin(II) chloride to give the diselenides, (4-ZC6H4CH2Se)2, and most of ArΦ2P [Ar = Φ or Ph] was recovered after these reactions. These properties of [ArΦ2P–SeR]X, as well as of ArΦ2PSe, were discussed in terms of the electronic effect and/or steric effect of methoxy groups at 2,6-positions.
Isomerization and Racemization of the Tris(4,4′-dimethoxy- or 4,4′-diethoxy-2,2′-bipyridine 1,1′-dioxide)chromium(III) Complexes
Authors: Kanno Hideaki , Yamamoto Junko , Utsuno Shunji , Fujita Junnosuke
Published: June 2006

Two new chromium(III) complexes, [Cr(4,4′-X2bpdo)3]3+ (X = MeO or EtO; bpdo = 2,2′–bipyridine 1,1′-dioxide), were prepared. These complexes form two diastereomers, lel3(Δ(λλλ), Λ(δδδ)) and lel2ob(Δ(λλδ), Λ(δδλ)), which were separated and resolved by an SP-Sephadex column chromatographic method using achiral eluting agents, such as Na2SO4 or NaCl. The isomers isomerized to each other (lel3  lel2ob) fairly rapidly in water along with changes in the absorption spectra, and then racemized very slowly (Δ    Λ). These reactions, including conformational (δ    λ) and configurational (Δ    Λ) changes, are independent of H+ and free ligand concentrations, and are supposed to proceed by an intramolecular mechanism. For a series of [Cr(4,4′-X2bpdo)3]3+ (X = H, Me, MeO, EtO), both the rates of isomerization and racemization are remarkably reduced along with an increase in the electron-releasing ability of the 4,4′-X2 substituents on bpdo.
Direct Measurement of the Intermolecular Potentials of CH4–Xe, CH4–Kr, CH4–Ar, and CH4–Ne from the Extended Principle of Corresponding States
Authors: Boushehri Ali , Hashemi Fariba S
Published: June 2006

An inversion procedure is used to obtain from the extended principle of corresponding states the interaction potentials over a range of reduced temperature extending from 1 to the onset of ionization. These directly measured potentials for CH4–Xe, CH4–Kr, CH4–Ar, and CH4–Ne agree excellently with the potentials independently known from the crossed molecular-beam technique.
Cycloaddition and Oxidation Reactions of a Stable Thioaldehyde, (2,4,6-Tri-t-butyl)thiobenzaldehyde
Authors: Watanabe Soichiro , Yamamoto Toshio , Kawashima Takayuki , Inamoto Naoki , Okazaki Renji
Published: June 2006

The title thioaldehyde 1 undergoes [4 + 2] cycloaddition with 2,3-dimethyl-1,3-butadiene at 160 °C and [3 + 2] cycloadditions with diphenylnitrilimine and mesitonitrile oxide at room temperature. The intermediary cycloadduct with mesitonitrile oxide undergoes cycloreversion to give 2,4,6-tri-t-butylbenzaldehyde and mesityl isothiocyanate as the final products. Oxidation of 1 with m-chloroperbenzoic acid (mCPBA) and dimethyldioxirane (9) gives a mixture of (E)- and (Z)-isomers of the corresponding S-oxides (sulfines), the former and the latter being kinetically and thermodynamically controlled products, respectively. Although both (E)- and (Z)-sulfines are not further oxidized by mCPBA, the (Z)-sulfine is oxidized with 9 to give 7-oxa-8-thia-2,4,6-tri-t-butylbicyclo[4.3.0]nona-2,4,9-triene 8,8-dioxide and 6,8-di-t-butyl-3,4-dihydro-4,4-dimethyl-1H-2-benzothiopyran 2,2-dioxide, both of which are intramolecular cyclization products of an intermediary thioaldehyde dioxide (sulfene).
Syntheses of Novel Hybrid Vitamin C Derivatives: Stability and Biological Activity
Authors: Morisaki Kazuo , Ozaki Shoichiro
Published: June 2006

A novel series of hybrid L-ascorbic acid (vitamin C) derivatives linking other biologically active substances glycolic acid, myo-inositol, and α-tocopherol (vitamin E) at the C-2 or C-3 hydroxyl group were synthesized, and their thermal stability and inhibitory activities against tyrosinase-catalyzed melanin formation, active oxygen species (AOS), and free radicals were evaluated in vitro. Among these derivatives, 2-O-carboxymethylascorbic acid had high thermal stability as well as moderate inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals compared to other typical inhibitors and scavengers. On the other hand, 3-O-carboxymethylascorbic acid was markedly unstable in aqueous solution. The 2-O-carbonylmethyl derivatives linking myo-inositol or vitamin E were susceptible to degrading, however the vitamin E derivative had stronger inhibitory activities against AOS and free radicals than free vitamin C.
Asymmetric Bis(alkoxycarbonylation) Reaction of Homoallylic Alcohols Catalyzed by Palladium in the Presence of Cu(I) Triflate Using the Chiral Bioxazoline Ligand
Authors: Ukaji Yutaka , Miyamoto Masanori , Mikuni Miho , Takeuchi Susumu , Inomata Katsuhiko
Published: June 2006

Palladium-catalyzed asymmetric intra- and intermolecular bis(alkoxycarbonylation) reactions of homoallylic alcohols in the presence of copper(I) triflate were achieved by using the chiral bioxazoline ligand, (S,S)-4,4′-dibenzyl-4,4′,5,5′-tetrahydro-2,2′-bioxazole, under normal pressure of carbon monoxide and oxygen at 25 °C to give the corresponding optically active γ-butyrolactones in 19—65% ee.
Reactivities and Site-Selectivities of Hydrolyses of ATP and UTP Promoted by Metal Complexes of Adenine-Linked Di-2-pyridylamine Derivatives
Authors: Sawa Masaaki , Ogino Kenji , Tagaki Waichiro
Published: June 2006

The reactivities and the site-selectivities of the hydrolyses of ATP and UTP by the catalysts of the metal complexes of adenine-linked di-2-pyridylamine ligands, (Py)2N–(CH2)n–Ade (L: n = 3, 4, 5, and 6), were examined. It was found that these adenine–dipyridylamine coordinated Cu2+ complexes (with 2 : 1 ratios of [CuII(L)]2+ : ATP or [CuII(L)]2+ : UTP) were more reactive for the hydrolyses of ATP and UTP than the complexes of ligands containing other metal ions (Mg2+, Ni2+, and Zn2+) at 40 °C and pH 7.3 (HEPES buffer), as reflected in much higher product ratios of ADP/AMP and UDP/UMP than those of Cu2+ alone. The observed high reactivity and selectivity are interpreted in terms of the base-base stackings between an adenine moiety of ATP or an uracil moiety of UTP and an adenine of the ligands, and of the selective coordination of Cu2+ to oxide ions in phosphate residues in the ternary complexes of ligand–Cu2+–ATP. The Cu2+-complex of di-2-pyridylamine having no adenine moiety, which is the active center of [CuII(L)]2+, promoted the hydrolyses of ATP and UTP less efficiently than the aquacopper(II) ion. The number of spacer methylene groups of the ligands influenced the hydrolytic activity of the Cu2+-complexes of these adenine–dipyridylamine ligands. The complexes of [CuII(L-4)]2+ and [CuII(L-5)]2+ were the most reactive and site-selective for the hydrolyses of ATP and UTP, respectively.
Base-Catalyzed Acyl Exchange Reactions of N,O-Diacyl-o-aminophenols. Substituent and Temperature Effects on the Equilibrium Constants
Authors: Sakurai Tadamitsu , Nagaoka Tohru , Kamiya Jun , Inoue Hiroyasu
Published: June 2006

Substituent and temperature effects on the equilibrium constants for the triethylamine-catalyzed acyl exchange reactions of N-(substituted benzoyl)-O-acetyl-o-aminophenols have been investigated by 1H NMR spectroscopy. It was found that the standard enthalpy change ΔH° in acyl exchange processes, estimated from temperature dependence of the equilibrium constant, correlates well with the standard free energy change ΔG° which was used as a measure of the relative stability of isomer pairs, while the standard entropy change ΔS° is approximately constant (−6 ± 2 J K−1 mol−1) irrespective of the substituents in benzoyl introduced. The finding of enthalpy-controlled acyl exchange reactions confirms that the relative stability of a given isomer pair is determined by the difference in electrostatic force of attraction between the amide nitrogen with a partial positive charge and the ester carbonyl oxygen having a partial negative charge in both isomers.
Modification of Transport Properties of Ion Exchange Membranes.XV. Preparation and Properties of Cation Exchange Membranes Having a Single Cationic Charged Layer on the Membrane Surface by Sulfonyl–Amide Bonding
Authors: Takata Kuniaki , Yamamoto Yoshihisa , Sata Toshikatu
Published: June 2006

In order to prepare an excellent monovalent cation permselective cation exchange membrane, a polyethyleneimine (PEI) layer was formed with sulfonyl–amide bonding between PEI and sulfonyl chloride groups on one surface of the membrane. Two methods were tried: 1) one surface of the membrane reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed, and 2) after one surface of the sulfonyl chloride groups had been hydrolyzed, the other surface of the membrane was reacted with PEI and the remaining sulfonyl chloride groups were hydrolyzed. The cation exchange membranes, which had been prepared using both methods, had excellent monovalent cation permselectivity, low electrical membrane resistance and high current efficiency for the long-term electrodialytic concentration of seawater. The reacted amount of PEI on the membrane was about 10% of the cation exchange capacity.
Kinetics of a Thermolysin-Catalyzed Peptide Formation Reaction in Acetonitrile–Water
Authors: Kunugi Shigeru , Yoshida Masumi
Published: June 2006

Thermolysin-catalyzed peptide condensation reactions from acylamino acids and amino acid amides were studied in an acetonitrile (MeCN)–water mixed solvent in a homogeneous system. A kinetic analysis of the condensation reaction was performed by taking into account the simultaneous, solvent-induced, gradual inactivation of the enzyme. Although the dependence on the concentration of the carboxyl component gave linear double-reciprocal plots, that on the amine component at 70% MeCN showed an apparent substrate inhibition profile. An analysis of the apparent Km and kcat parameters for both components at 40% MeCN indicated that the condensation reaction proceeded by a random Bi–Bi mechanism. The Km values were estimated to be 5.5 mM for Cbz–Phe and 110 mM for LeuNH2, and kcat was 4—5 s−1. The Km values for Cbz–Phe and LeuNH2 were also evaluated at 70% MeCN to be 5 and 100—150 mM, respectively. This indicates that the catalytic property of this enzyme is not significantly influenced by the existence of a higher concentration of such an organic solvent, except for the second nonproductive binding of the amine component.
Influence of Size of Dispersed Silica Particles on Preparation of Thick Silica Films by Using Electrophoretic Sol–Gel Deposition
Authors: Nishimori Hideki , Tatsumisago Masahiro , Minami Tsutomu
Published: June 2006

Monodispersed silica particles, which ranged from 0.14 to 0.42 μm in diameter, were prepared by the sol–gel method. These particles were first separated from original sols, and dried, heat-treated, and then re-dispersed in a mixture of ethanol, water, and triethoxy(methyl)silane. Thick silica films without micro-cracks were formed by electrophoretic deposition of the particles on a stainless steel sheet in the re-dispersed sols. The weight of the silica films deposited was increased with increasing particle size at a given applied voltage. On the other hand, density of the films was increased with decreasing particle size. When the particle size was 0.32 μm in diameter, crack-free films of ca. 20 μm in thickness were prepared after heat treatment at 800 °C for 1 h.
Crystal Structures and Physical Properties of 1,6-Diaminopyrene-p-chloranil (DAP-CHL) Charge-Transfer Complex. Two Polymorphs and Their Unusual Electrical Properties
Authors: Goto Hirotoshi , Fujinawa Tasuku , Asahi Hidemasa , Inabe Tamotsu , Ogata Hironori , Miyajima Seiichi , Maruyama Yusei
Published: June 2006

A combination of 1,6-diaminopyrene and p-chloranil gives two kinds of 1 : 1 charge-transfer complex crystals from a benzene solution. The α-form is triclinic, space group , a = 8.963(1), b = 9.112(2), c = 6.730(1) Å, α = 99.59(1), β = 99.65(1), γ = 114.43(1)°, V = 476.0(1) Å3, and Z = 1; the β-form is also triclinic, space group , a = 8.123(3), b = 9.708(3), c = 6.791(2) Å, α = 110.73(2), β = 108.89(2), γ = 79.11(3)°, V = 472.3(3) Å3, and Z = 1. In both crystals, the donors and acceptors are neutral, and stack alternately. The main difference between the α- and β-forms is in the overlapping mode. Both crystals are electrically insulating at the initial states. The α-form single crystal, however, undergoes and irreversible conductivity change upon mild heating (< 380 K) or fracture of the crystal into powder. In both cases, the conductivity change amounts to 106 to 108, and the resultant solids are highly conducting semiconductors. Structural, optical, magnetic, and solid-state NMR studies suggest that the low-resistance state mainly comprises neutral molecules, despite its high conductivity. The resistivity of β-DAP-CHL also decreases upon heating to above 400 K, while fracture of the crystal has no effects. The resistivity change in β-DAP-CHL is considered as simple ionization of a part of the components.
Enzyme-Mediated Enantioselective Protonation to Enolates in an Aqueous Medium
Authors: Ohta Hiromichi
Published: June 2006

An enzyme sometimes provides a entirely hydrophobic chiral reaction field to a synthetic substrate. This is one of the most characteristic features of an enzyme compared to ordinary chemical catalyst. Taking advantage of being able to carry out a reaction of a prochiral compound in this special pocket, it is possible to prepare an optically active product via asymmetric protonation in an aqueous medium. Two such examples are demonstrated in this article, i.e., asymmetric hydrolysis of enol esters, and asymmetric decarboxylation of α-aryl-α-methylmalonic acid to give optically active ketones and α-arylpropionic acids, respectively. Some related reactions are described as well.
Structures and Magnetic Properties of Some Fe(III) Complexes with Hexadentate Ligands: in Connection with Spin-Crossover Behavior
Authors: Hayami Shinya , Matoba Takashi , Nomiyama Shuichi , Kojima Takahiko , Osaki Susumu , Maeda Yonezo
Published: June 2006

Several iron(III) complexes with the different hexadentate Schiff-base ligands of N4O2 donor sets were synthesized; these are 1 : 2 condensation products of linear tetramines (3,3,3-, 3,2,3-, 2,3,2- or 2,2,2-tetramine) and salicylaldehyde, acetophenone or benzophenone derivatives. Their crystal structures, Mössbauer spectra, magnetic susceptibilities, electronic spectra and cyclic voltammetry of the complexes were examined. The X-ray structures of the single crystals of [Fe(3,2,3-sal2tet)]NO3 (1), [Fe(3,2,3-sal2tet)]BPh4 (2), [Fe(3,2,3-mpk2tet)]PF6 (3), [Fe(2,3,2-sal2tet)]ClO4 (4), [Fe(2,3,2-3MeO-sal2tet)]ClO4 (5), [Fe(2,3,2-mpk2tet)]ClO4 (6), [Fe(2,3,2-bpk2tet)]ClO4 (7), and [Fe(2,2,2-bpk2tet)]ClO4·EtOH (8) were determined.

The moieties of the iron atoms of (1), (2), and (3) with 3,2,3-tetramine, and (7) with 2,3,2-tetramine were pseudo octahedral with trans-FeN4O2 geometry. Those of (4), (5), and (6) with 2,3,2-tetramine, and (8) with 2,2,2-tetramine were cis-FeN4O2 geometry. The iron(III) complexes (1), (2), (3), and (7) were in the low-spin state, and the iron(III) complexes (4), (5), (6), and (8) were in the high-spin state.

In the electronic spectra, the wave lengths of the LMCT bands for the low-spin complexes were longer than those for the high-spin complexes. The values of redox potentials for the low-spin states were suggested to be 0.12 V more negative than those for the high-spin states.

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