bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the Chain Length of Carboxylic Acids and Alcohols on the Extraction of Copper(II) with the Acids Using Alcohols as Solvents
Authors: Naito Tetsuyoshi , Yamada Hiromichi , Wada Hiroko 
Published: September 2002

Abstract
The solvent extraction of copper(II) with aliphatic carboxylic acids (CH3(CH2)nCOOH : n = 2—7) in alcohols (CH3(CH2)nOH : n = 4—7) was carried out at 25 °C and an aqueous ionic strength of 0.1 mol dm-3 (NaClO4). Each extraction equilibrium for these systems was determined in detail by a slope analysis and a curve-fitting method. In all of the extraction systems, except for butanoic acid ones, copper(II) carboxylates were found to be extracted as monomeric and dimeric species: CuA2, Cu2A4, and Cu2A4(HA)2. The dimerization and the adduct formation constants of copper(II) carboxylates in the organic phase were estimated. The dimerization and the adduct formation constants in the organic phase were found to be dependent on the chain length of the acids and alcohols, although the extraction constant of CuA2 were found to be independent of their chain length.
Lewis Acid-Catalyzed Hydrometalation and Carbometalation of Unactivated Alkynes
Authors: Asao Naoki , Yamamoto Yoshinori 
Published: September 2002

Abstract
Hydrosilylation, hydrostannation, carbosilylation, and carbostannation of unactivated alkynes with organosilanes, or organostannanes proceed effectively in the presence of catalytic amounts of Lewis acids to produce the corresponding vinylsilyl or vinylstannyl compounds in a highly regio- and stereoselective way. Although it is well known that transition metal catalyzed hydrometalations and carbometalations, in general, proceed in a cis-manner, the Lewis acid-catalyzed reactions proceed in a trans-manner exclusively. The coordination of a triple bond to Lewis acids is proposed as a key step for the Lewis acid catalyzed reactions.
Studies of Gel Structure and Thermal Deswelling on Poly(N-isopropylacrylamide) Gel Treated by Freeze-Drying
Authors: Kato Norihiro , Hasegawa Hiroto , Takahashi Fujio 
Published: September 2002

Abstract
Fast-responsive deswelling of poly(N-isopropylacrylamide) gel after a freeze-dry (FD) treatment was investigated by means of SEM images and a kinetic method using a N-isopropylacrylamide (NIPAAm) monomer from the viewpoint of the mesoscopic structure comprising a partitioned polymer-network.
It was deduced from SEM images that an elastic frame comprising a partitioned polymer-network is formed by a hydrophobic interaction between polymer chains in the FD-treated gel. Fast-deswelling of the FD-treated gel results from the elasticity of a partitioned polymer-network caused water to release. The kinetic parameters on deswelling of both the conventional gel and the FD-treated gel were determined in the presence of an NIPAAm monomer. This monomer in solution is considered to play two directly-opposed roles in making a skin on the surface of the conventional gel: One is for disturbing the formation of hydrogen bonding between amide groups in the polymer; the other is for accelerating the separation of hydrated water from isopropyl groups in the polymer. Cracking the surface of a conventional gel was investigated in connection with the monomer.
Complex Formation of Perfumes with Cationic Surfactants and the Enhanced Thermal Stability
Authors: Iimura Nahoko , Ohashi Yuji , Hirata Hirotaka 
Published: September 2002

Abstract
Seven crystalline molecular complexes were formed between perfumes such as guaiacol, 2-methylindole, and skatole and cationic surfactants such as hexadecyl-, tetradecyl-, dodecyl-, and decyltrimethylammonium bromide from an aqueous or methanol solution at low temperatures (&lt; 10 °C). The crystal structures were determined by X-rays. The structures are very similar to each other, that is, the perfume molecules are packed in the layers of the alkyl chains of the surfactant molecules. Those packings are substantially the same as the common packing pattern observed in complexes between the surfactants and the aromatic compounds. The thermal analysis showed that the volatilization temperatures of the perfumes increased significantly when the perfumes are packed in the complex crystals. Moreover, the molar loss ratio of the perfume with increasing the temperature decreased with increasing the length of the alkyl chain of the surfactant. This suggests that thermal stability of the perfumes can be controlled by forming the complexes with the surfactants containing different alkyl chains.
Hydrogen-Bonded Structure in Concentrated Aqueous Phosphoric Acid Solutions
Authors: Kameda Yasuo , Sugawara Kentaro , Hosaka Takayoshi , Usuki Takeshi , Uemura Osamu 
Published: September 2002

Abstract
Polarized Raman scattering, X-ray, and time-of-flight (TOF) neutron-diffraction measurements were carried out for highly concentrated aqueous phosphoric acid solutions, in order to deduce detailed structural information on both the PO4-intramolecular geometry and intermolecular hydrogen bonds in the solution. Isotropic Raman spectra observed for (H3PO4)x(H2O)1-x with x = 0.1—0.6 exhibited a single band assigned to the symmetrical stretching vibrational mode of the PO4 structural unit, which suggests that all P-O bonds in the unit are spectroscopically equivalent. The results of X-ray and neutron-diffraction measurements for the 53 mol% phosphoric acid solution indicated that the structure of the PO4 unit is a regular tetrahedron with a P-O bond-length of 1.540(3) Å. From a least-squares fit to the observed X-ray and neutron intermolecular interference terms, the nearest-neighbor intermolecular distances, reflecting intermolecular hydrogen-bonded interactions in the solution, were determined to be r(O…D) = 1.77(1) Å and r(O…O) = 2.73(2) Å, respectively, which are both ca. 0.1 Å shorter than those observed for pure liquid water. Therefore, it has been clarified that a strongly hydrogen-bonded network exists in such concentrated aqueous phosphoric acid solutions.
Salt Effect on Stability and Solvation Structure of Peptide: An Integral Equation Study
Authors: Imai Takashi , Kinoshita Masahiro , Hirata Fumio 
Published: September 2002

Abstract
Salt effects on the stability and on the solvation structure of a peptide in a variety of aqueous solutions of the alkali-halide ions are studied by means of the reference interaction site model (RISM) theory. The order of salt effect on the peptide stability is consistent with the experimental results; the order follows the Hofmeister series. The results are further analyzed in order to clarify the nature of the salt effect which determines the Hofmeister series and to find the reason why the Hofmeister series applies so generally to a variety of solutes in aqueous solutions. A heuristic model for explaining salt effects on the solvation structure of the peptide is proposed based on changes in the peptide-water pair correlation functions due to the ion perturbation.
IR Characterization of Mesoporous Tantalum Oxide, Ta-TMS-1
Authors: Kondo Junko N , Lu Lianhai , Takahara Yoshiko , Maruya Ken-ichi , Domen Kazunari , Igarashi Naoko , Tatsumi Takashi 
Published: September 2002

Abstract
By IR observation, Lewis acid sites of medium strength were found by CO adsorption on a mesoporous Ta-TMS-1 while no basic sites were detected by CO2 adsorption. Methyl migration of methoxy species and formation of methoxy species from adsorbed dimethyl ether were quantitatively demonstrated.
pH-Dependence of the Fractionation of Boron Isotopes with N-Methyl-D-Glucamine Resin in Aqueous Solution Systems
Authors: Sonoda Akinari , Makita Yoji , Ooi Kenta , Takagi Norio , Hirotsu Takahiro 
Published: September 2002

Abstract
We have found a unique pH dependence of the fractionation of boron isotopes with N-methyl-D-glucamine resin in aqueous solution systems. The fractionation is due to the adsorption of 10B isotopes from the solution phase to the resin phase. For pH values less than 7, the boron-isotope separation factors are 1.027, indicating that 10B isotopes are concentrated in the resin more selectively than 11B isotopes. On the other hand, for the pH values greater than 11, the factors are 0.998, revealing no fractionation of boron isotopes. In the intermediate pH range, the factors are decreased significantly with an increase in pH. This finding confirms that 10B is fractionated as boron complexes with a tetrahedral coordination geometry in resin phase more selectively than as those with a planar trigonal coordination geometry in solution phase, while 11B exhibits the opposite relation. This finding will provide a very important basis for separation of boron isotopes with novel chelating resins in aqueous solution systems.
Isomer Distribution and Stereoselectivity in Electron Transfer Reactions of [Co(dien)2]2+ with Anionic Cobalt(III) Complexes
Authors: Tatehata Akira , Yamada Shigeo , Muraida Akira 
Published: September 2002

Abstract
The product distribution of the three geometrical isomers and the stereoselectivity of the u-fac isomer in the oxidation of [Co(dien)2]2+ (dien = diethylenetriamine) by optically active anionic cobalt(III) complexes were significantly influenced by the geometrical arragement of the coordinated atoms in the oxidants, reflecting the differences in the stabilization of the precursor assemblies due to the hydrogen bonding interactions between the reactants. Solvent effects on the isomer proportions and the stereoselectivity were examined in water, methanol, ethanol, formamide, dimethylformamide, and dimethyl sulfoxide. The results are explained in terms of the differences in the degree of oxidant-solvent interactions depending on acceptor number of solvents.
Synthesis and Structural Characterization of Silver(I) and Gold(I) Complexes with 2-Mercaptonicotinic Acid (H2mna) and Triphenylphosphine Ligands, and Their Antimicrobial Activities. Crystal Structures of Monomeric, 3- and 4-Coordinate Silver(I) Complexes [Ag(Hmna)(PPh3)2] and [Ag(Hmna)(PPh3)3] in the Solid State
Authors: Nomiya Kenji , Noguchi Ryusuke , Shigeta Takaye , Kondoh Yoshihiro , Tsuda Kazuhiro , Ohsawa Katsunori , Chikaraishi-Kasuga Noriko , Oda Munehiro 
Published: September 2002

Abstract
Two types of silver(I)-triphenylphosphine complexes with 2-mercaptonicotinic acid (H2mna) were prepared as [Ag(Hmna)(PPh3)n] (1, n = 2; 2, n = 3); their crystal structures determined by single-crystal X-ray diffraction. These complexes were obtained from reactions of the precursor, [Ag(Hmna)]n, with less excess (3 equiv) and large excess (20 equiv) amounts of PPh3, respectively. Complex 1 was also obtained from a reaction among another precursor [AgCl(PPh3)3], H2mna and aqueous NaOH. The coordination geometry of 1 was a trigonal pyramid with an AgSP2 core; there was a weak interaction between the silver(I) center and the pyridine nitrogen atom, while that of 2 was a distorted tetrahedron with an AgSP3 core. In both 1 and 2, the carboxyl group was protonated and its oxygen atoms did not participate in the coordination. In contrast to the formation of 1 and 2, a related complex, [Ag(Hmba)(PPh3)3] 4 (H2mba = 2–mercaptobenzoic acid), has been obtained from a reaction of [Ag(Hmba)]n with a stoichiometric amount (3 equiv) of PPh3. On the other hand, the gold(I) complex, [Au(Hmna)(PPh3)] 3, with a 2-coordinate AuSP core, was prepared by a stoichiometric reaction among [AuCl(PPh3)], H2mna and aqueous NaOH. Complex 3 in the solid state showed a supramolecular array based on a repetition of hydrogen-bonding interactions between the carboxyl group and the pyridine nitrogen atom, also being contrasted to the related complex, [Au(Hmba)(PPh3)] 5, with a hydrogen-bonding dimer structure in the solid state. In CHCl3, both 1 and 2 were present as several equilibrium species due to a successive dissociation of PPh3 ligands, while 3 was present as an almost monomer. The antimicrobial activities in aqueous media of 1—5, evaluated by minimum inhibitory concentration (MIC), were also tested.
Preparation of Ammonium Polyphosphate Form II from the System of Ammonium Orthophosphate-Urea
Authors: Watanabe Makoto , Watanabe Masami , Narita Noriaki , Sakurai Makoto , Suzuki Hirokazu 
Published: September 2002

Abstract
Ammonium polyphosphate (APP) form II was prepared by heating of a mixture of ammonium orthophosphates (triammonium, diammonium, and monoammonium orthophosphates) and urea at 280 to 300 °C under wet ammonia, which was made by passing air through 3 to 5% aqueous ammonia. The following reaction process is proposed:
Ammonium orthophosphate → APP form I → Amorphous APP → APP form II.
The addition of APP form II shortened the preparation time significantly. A wider range of concentrations (1 to 8%) of aqueous ammonia was available to prepare APP form II. The average particle size of the obtained APP form II was larger than 5 μm.
Electroreduction of μ-Oxo Iron(III) Porphyrins Adsorbed on an Electrode Leading to a Cofacial Geometry for the Iron(II) Complex: Unexpected Active Site for the Catalytic Reduction of O2 to H2O
Authors: Oyaizu Kenichi , Haryono Agus , Natori Junichiro , Shinoda Hiroshi , Tsuchida Eishun 
Published: September 2002

Abstract
Acidification of a solution of (μ-oxo)bis[(5,10,15,20-tetraphenylporphyrinato)iron(III)] ([{Fe(tpp)}2O], II) in CH2Cl2 produced equimolar amounts of a hydroxoiron(III) complex [(tpp)FeIII(OH)] (III) and an iron(III) complex [(tpp)FeIII(ClO4)] (IV). The complex IV was isolated as a perchlorate salt, which crystallyzed in the triclinic space group P1-(#2); a = 11.909(3), b = 19.603(4), c = 10.494(3) Å, α = 95.74(2)°, β = 107.91(2)°, γ = 89.14(2)°, V = 2319.1(9) Å3, Z = 2, Dcalc = 1.328 g cm-3, μ(Mo Kα) = 4.35 cm-1, final R = 0.055 and Rw = 0.050. The crystal structure of IV revealed that ClO4- is coordinated to the iron atom, which may be driven by the preference of iron(III) to be five coordinate rather than four coordinate. Reduction of the complex II in the presence of acid by electrolysis and/or by a reducing agent, such as sodium dithionite, under argon produced [FeII(tpp)]. The addition of O2 to a solution of [Fe(tpp)] in acidic CH2Cl2 in the presence of an equimolar amount of the reducing agent produced the complex III. When the complex II was adsorbed on an electrode surface and placed in aqueous acidic electrolyte solutions, electroreduction of the adsorbate proceeded according to the half-reaction:
[{Fe(tpp)}2O]+2H++2e-→2[Fe(tpp)]+H2O, at 0.031—0.059 pH V (vs. SCE, pH&gt;1.0). Based on these results, oxo-bridged iron(III) porphyrin dimers were used as electrocatalysts for the reduction of O2. The catalytic reduction of O2 proceeded at potentials in the vicinity of those for II. As a whole, the proportion of H2O as the product increased from 50% for adsorbed [(tpp)FeIIICl] to &gt;90% for the adsorbed dimer. Thus, electroreduction of the dimer adsorbed on a carbon electrode immersed in aqueous acid produced two solid state, cofacially fixed iron(II) porphyrin molecules:
[PFeIIIOfeIIIP]ad+2H++2e-→[PFeII FeIIP]ad+H2O (P = porphyrin dianion). Coordination of molecular oxygen to the adjacent two iron(II) centers under acidic conditions allowed formation of O2-bridged iron(III) porphyrin [PFeIII(O2)FeIIIP]ad at the electrode surface. Electroreduction of the adsorbate under acidic conditions produced H2O and allowed the reformation of [PFeII FeIIP]ad. The implication is that the electroreduction of the adsorbed oxo-bridged dimer gives a cofacial geometry for PFeII on the electrode, facilitating the coordination and subsequent splitting of O2.
Extraction of Alkali Metal Ions and Tetraalkylammonium Ions with Ionic Surfactants Containing a Poly(oxyethylene) Chain
Authors: Sakai Yukio , Ono Kanako , Hidaka Tamotsu , Takagi Makoto , Cattrall Robert W 
Published: September 2002

Abstract
The effect of the poly(oxyethylene) (POE) chain length of ionic surfactants, expressed as C12H25-(OCH2CH2)-nOCH2C6H3(OH)(NO2) (n = 2—9), on the extraction of monovalent cations, including alkali metal and tetraalkylammonium (TAA) ions, was investigated. The extraction constants (Kex) with surfactants having a POE chain of n ≥ 6 were almost constant for each alkali metal ion. The Kex sequence was Li+ &lt; Na+ &lt; Cs+ ≤ K+ = Rb+. The extractability and selectivity largely decreased as n in the surfactant decreased (n &lt; 6). The effect of the POE chain length was related to the stability of the alkali metal-POE complex. Unlike an alkali metal ion, the Kex values for all TAA ions were almost constant with surfactants of n = 2—8. These facts indicated that the surfactant extracts alkali metal ions by both complex formation with its POE chain and ion-pair formation with a terminal p-nitrophenolate anion. On the other hand, TAA ions were extracted simply by ion-pair formation with a p-nitrophenolate anion of the surfactant. The proposed structures are discussed from the viewpoint of the spectrum shift of the extracted species.
Solvent Extraction of Chromium(III) Perchlorate, Thiocyanate, Nitrate, Bromide, and Iodide with Trioctylphosphine Oxide in Hexane
Authors: Kusakabe Satoshi 
Published: September 2002

Abstract
Chromium(III) ion was extracted from aqueous 1 mol dm-3 NaX (X- = ClO4-, SCN-, NO3-, Br-, and I-) solutions with trioctylphosphine oxide (TOPO) in hexane at 298 K. The extraction was rapidly equilibrated, except from a NaNO3 solution. The number of TOPO molecules solvating to the extracted chromium(III) perchlorate and thiocyanate was 6. That to the bromide and iodide was 5. That to the nitrate was 5 at the beginning of extraction, and changed to 3 within a few hours of two-phase agitation. The hydration number of extracted Cr(ClO4)3·6TOPO was 17.2±0.5. The different solvation number of TOPO among these salts is supposed to be an unstable second hydration sphere of the extracted chromium(III) ion, which may be easily removed by the counter anions.
Fractional Distributions of Major-to-Ultratrace Elements in Coastal Seawater and Their Partitionings in Laboratory-Made Salts as Investigated by Inductively Coupled Plasma Atomic Emission Spectrometry and Inductively Coupled Plasma Mass Spectrometry with Aid of Membrane- and Ultra-filtration Techniques
Authors: Ji Shan , Yabutani Tomoki , Itoh Akihide , Haraguchi Hiroki 
Published: September 2002

Abstract
The coastal seawater sample was filtered with a membrane filter (pore size 0.45 μm), and the filtrate was further filtered with an ultrafiltration filter (molecular weight permeation limit of 10000 Da). Then, major-to-ultratrace elements in the particles which remained on the membrane filter, the membrane-filtered seawater, and the ultrafiltered seawater were determined by ICP-AES (inductively coupled plasma atomic emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry). From these analytical results, the fractional distributions of each element in the particle, large molecule and small molecule fractions of seawater were estimated, where the distributions of the elements in the large molecule fraction were obtained as the differences between the elemental concentrations in membrane-filtered and ultrafiltered seawaters.
Furthermore, laboratory-made salts (Salts I—III) were prepared from original, membrane-filtered, and ultrafiltered seawaters. The concentrations of major-to-ultratrace elements in laboratory-made salts were also determined by ICP-AES and ICP-MS. It was found that alkali metals, alkaline earth metals, oxoanion-forming elements (V, Mo, W, U) and Cd were mostly contained in the small molecule fraction of seawater, and ca. 95—100% of them in salt, except for V, originated from those in the small molecule fraction. More than 50% of Al, Mn, Fe, Co, Ga, Y, rare earth elements (REEs) and Pb were contained as the particle constituents in seawater, but their intakes into salt were less than 50%. In addition, the fractional distributions of the following elements in the large molecule fraction of seawater were: Al 10%, Mn 4%, Fe 2%, Cu 23%, Zn 7%, Y 5%, REEs 3—15%, and Pb 30%. On the other hand, the intake factors of these elements in salt from the large molecule fraction were: Al 40%, Mn 5%, Fe 28%, Cu 20%, Zn 30%, Y 7%, REEs 5—30%, and Pb 55%. The results obtained in the present experiment suggest that the distributions of the elements in natural salt greatly depend on the chemical forms in seawater.
Chemical Approach to the Cu(II)-Phenoxyl Radical Site in Galactose Oxidase: Dependence of the Radical Stability on N-Donor Properties
Authors: Shimazaki Yuichi , Huth Stefan , Hirota Shun , Yamauchi Osamu 
Published: September 2002

Abstract
Copper(II) complexes of several new N3O-type tripodal ligands, 2,4-di(t-butyl)-6-{[bis(2-pyridyl)methyl]aminomethyl}phenol (HtbuL), 2,4-di(t-butyl)-6-{[(6-methyl-2-pyridyl)methyl](2-pyridylmethyl)aminomethyl}phenol (HtbuL(Mepy)), 2,4-di(t-butyl)-6-{bis[(6-methyl-2-pyridyl)methyl]aminomethyl}phenol (HtbuL(Mepy)2), and 2,4-di(t-butyl)-6-{[(1-methyl-2-imidazolyl)methyl][(6-methyl-2-pyridyl)methyl]aminomethyl}phenol (HtbuL(im)(Mepy)), were prepared. They were structurally characterized by the X-ray crystallographic method to have a square-pyramidal structure with a weakly coordinating group at an apical position. The phenol moiety of [CuCl(tbuL(Mepy))] (2), [CuCl(tbuL(Mepy)2)] (3), and [CuCl(tbuL(im)(Mepy))] (4) was revealed to be coordinated equatorially; it was converted to the phenoxyl radical upon oxidation with Ce(IV), giving a new absorption peak at 405—420 nm. ESR measurements at low temperatures and resonance Raman spectra established that the radical species has a Cu(II)-phenoxyl radical bond. The cyclic voltammograms exhibited a quasi-reversible redox wave at E1/2 = 0.56—0.61 V (vs. Ag/AgCl) corresponding to the formation of the phenoxyl radical, which displayed a first order decay with a half life of 65 and 62 min at -20 °C for 2 and 4, respectively, while that for 3 was only 9.0 min at -40 °C. The radical stability increased with the donor ability of the equatorial N ligands.
Characterization of LaCrO4 and NdCrO4 by XRD, Raman Spectroscopy, and ab Initio Molecular Orbital Calculations
Authors: Aoki Yoshitaka , Konno Hidetaka , Tachikawa Hiroto , Inagaki Michio 
Published: September 2002

Abstract
Single phase LnCrO4 (Ln = La-Nd) compounds were attempted to synthesize by the pyrolysis of precursors prepared from LnIII-CrVI mixed solutions. Only LaCrO4 and NdCrO4 were obtained as a single phase. LaCrO4 was monazite type (monoclinic, P21/n), as reported, and the cell parameters were refined to be a = 0.70369, b = 0.72348, c = 0.66918 nm and β = 104.950° by an X-ray Rietveld method. NdCrO4 was zircon type (tetragonal, I41/amd) and the cell parameters were a = 0.73107 and c = 0.66999 nm. It was found that CrO43- tetrahedra in LaCrO4 have C1 symmetry and the four Cr-O bond lengths are different, whereas those in NdCrO4 have D2d symmetry and all Cr-O bond lengths are 0.1702 nm. Detailed Raman spectra of LaCrO4 and NdCrO4 were measured and assigned to the vibrational modes of the CrO43- tetrahedra. Molecular orbital calculations indicated that the charge density on the chromium ions in the tetrahedra is much less than the nominal 5+ due to the migratory electrons from oxygen atoms, and nearly the same irrespective of the symmetry of tetrahedron, suggesting that the Cr-O bonds are strongly covalent in nature.