bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mathematical Model for Adsorption of Boric Acid on a Boron-Specific Ion Exchanger
Authors: Sahin Sami 
Published: June 2006

Abstract
The present study was undertaken to investigate boron removal from the waste waters of borax and boric acid producing plants. A boron-specific resin, Amberlite XE 243, was selected for the present work. Experimental results show that the ion-exchange operations are effective in removing boron from the waste waters.
The variation of boron concentrations in the effluents has been observed to depend, for various initial boron concentrations, C0, on the ratio of the filtrate volume to the volume occupied by resin.
An empirical equation has been developed relating boron concentration, C, to filtrate and resin volumes V1 and V, respectively, as
C = 2.34 × 10−6·C0(V)−0.043(V1)2.80
Magneto-Structural Correlations in Alkoxo-Bridged Copper(II) Compounds
Authors: Emori Shuji , Goto Hirofumi , Mitsumasu Hiroshi 
Published: June 2006

Abstract
The magnetic susceptibilities of the compounds [Cu(bbip)(RO)]X (bbip = 1,3-bis(benzimidazol-2-yl)propane; R = CH3, C2H5; X = NO3, ClO4) and related alkoxo-bridged copper(II) compounds were determined over the temperature range 80—300 K. For the dinuclear entities [Cu(OR)2Cu′]2+, the strength of the exchange couplings is discussed in terms of the in-plane and out-of-plane tilts of the C–O vector from the bisector of the Cu–O–Cu′ angle.
Syntheses and Crystal Structures of Bis(dimethyldithiocarbamato)(4,6-diphenyl-4,6-diphosphanonane-1,9-diammonium)cobalt(III) and Chloro(4,9-diphenyl-4,9-diphosphadodecane-1,12-diamine)nickel(II) Complexes
Authors: Kashiwabara Kazuo , Watanabe Masayuki , Kita Masakazu , Suzuki Takayoshi 
Published: June 2006

Abstract
The reaction of tetramethylthiuram disulfide with a methanol solution containing CoCl2·6H2O and 4,6-diphenyl-4,6-diphosphanonane-1,9-diamine (313NPPN) gave complexes of [Co(dtc)2{rac(P)- or meso(P)-313HNPPNH}]3+ (313HNPPNH = diprotonated form of 313NPPN, dtc = dimethyldithiocarbamate ion). The crystal structure of the perchlorate salt of the meso(P) isomer was determined by X-ray analysis. Crystal data: monoclinic, P21/c, a = 10.789(2), b = 30.325(9), c = 12.888(2) Å, β = 102.06(1)°, V = 4123(1) Å3, Dx = 1.55 g cm−3, Z = 4, and R = 0.077 for 3347 reflections. The 313HNPPNH ligand in the complex coordinates to the Co(III) center through two phosphorus atoms as a didentate four-membered chelate ligand. The crystal structure of [Co(dtc)2{NH2(CH2)3P(CH2OH)(C6H5)}]B(C6H5)4, which formed as a by-product in the preparation of the above Co(III)–313HNPPNH complexes, was also determined. Crystal data: triclinic, , a = 13.817(2), b = 15.277(3), c = 10.737(2) Å, α = 109.90(1), β = 94.14(2), γ = 101.00(1)°, V = 2068.8(7) Å3, Dx = 1.31 g cm−3, Z = 2, and R = 0.053 for 4303 reflections. [NiCl{rac(P)-343NPPN}]PF6 (343NPPN = 4,9-diphenyl–4,9-diphosphadodecane-1,12-diamine) was prepared by the reaction of 343NPPN with NiCl2·6H2O, and the crystal structure was determined. Crystal data: monoclinic, P21/n, a = 8.367(2), b = 24.058(2), c = 13.988(2) Å, β = 106.17(1)°, V = 2704(1) Å3, Dx = 1.54 g cm−3, Z = 4, and R = 0.053 for 3043 reflections. The geometry of the complex is a distorted square pyramid with a chloride ion at the apical position, and the 343NPPN ligand functions as a tetradentate chelate ligand.
31P and 27Al NMR Studies on the Coordination of Aluminum(III) with Tetraphosphate
Authors: Miyazaki Yoshinobu , Kura Genichiro , Tsuzuki Hirohisa , Sakashita Hirofumi 
Published: June 2006

Abstract
The binding isomerization of Al(III) with linear tetraphosphate has been investigated in the pH range of 1 to 9 using 31P and 27Al NMR spectroscopy. The complexes of 1 : 1 (=Al(III) : P4O13) stoichiometry with monodentate and didentate bindings, and the complex of 2 : 1 stoichiometry with two didentate bindings coexist in equilibrium. The concentration ratio of the 1 : 1 complexes with didentate to monodentate binding is 2.02 ± 0.19 at pH 3. The relative concentration of the monodentate complex increases along with decreasing the pH. The possible binding positions of Al(III) to tetraphosphate in these complexes are discussed.
Crystal Structures and Acetonitrile Exchange of Palladium(II) Complexes with Bis(3-aminopropyl)amine and Diethylenetriamine. Effects of Ion-Pair Formation
Authors: Yagyu Takeyoshi , Aizawa Sen-ichi , Hatano Keiichiro , Funahashi Shigenobu 
Published: June 2006

Abstract
The crystal structures of palladium(II) complexes with tridentate amine and acetonitrile, [Pd(CH3CN)(dptn)](CF3SO3)2 (1) and [Pd(CH3CN)(dien)](CF3SO3)2 (2) (dptn = bis(3-aminopropyl)amine and dien = diethylenetriamine), have been determined by X-ray crystal structure analysis. The central palladium(II) ion has a distorted square-planar geometry. The five-membered chelate rings of the dien ligand in 2 are more strained than the six-membered chelate rings of the dptn ligand in 1, as indicated from the difference in the angles of terminal N–Pd–terminal N and the averaged Pd–N–C angles around the terminal nitrogens. The kinetics of acetonitrile exchange of 1, 2, and [Pd(CH3CN)(dien)](BF4)2 (3) have been investigated by the 1H NMR line-broadening technique. The observed rate constants can be expressed by kobs = k1 + k2 [CH3CN] from the dependence of kobs on the acetonitrile concentration. It has been indicated that the k1 and k2 paths proceed via the dissociative and associative modes of activation, respectively. The dissociative k1 path is promoted by the ion-pair formation where the bound ligand effect is enhanced by the electrostatic interaction between the counter anions and amine protons. The reaction mechanisms are discussed in terms of the steric and electronic factors of the bound ligands (dptn and dien) and the effect of the ion-pair formation with the counter anions (CF3SO3− and BF4−).
Effect of 2,2′-Bipyridine and 1,10-Phenanthroline on the Redox Reaction of Metal Ions and Its Application to Potentiometric Titrations of Vanadium(IV) and Cobalt(II)
Authors: Teshima Norio , Kawashima Takuji 
Published: June 2006

Abstract
The effect of 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) on the redox reactions of vanadium(IV) with iron(III), cobalt(II) with vanadium(V), and cobalt(II) with chromium(VI) was studied potentiometrically. In the presence of bpy or phen, the formal potential of the Fe(III)/Fe(II) system is higher than that of the V(V)/V(IV) system in the pH range 3—6. A large potential break was thus observed at the equivalence point when the titration of 1 × 10−3mol dm−3 vanadium(IV) with iron(III) was carried out in the presence of 2 × 10−2 mol dm−3 bpy or phen at pH 5, while the potentiometric determination of vanadium(IV) with iron(III) was impossible in the absence of these ligands. On the other hand, the oxidation reactions of cobalt(II) to cobalt(III) by vanadium(V) or chromium(VI) took place easily in the presence of bpy or phen at a pH around 1. Using these reactions, we propose a titrimetric procedure for the determination of 1 × 10−3 mol dm−3 cobalt(II). A visual end point detection with Variamine Blue B (N-(4-methoxyphenyl)-1,4-phenylenediamine) as a redox indicator was presented for the titration of 1 × 10−3 mol dm−3 cobalt(II) with chromium(VI) in the presence of 2.5 × 10−2 mol dm−3 phen.
Gas-Phase Substituent Effects in Stabilized Benzylic Carbocations. Basicities of Benzaldehydes, Acetophenones, and Methyl Benzoates in the Gas Phase
Authors: Mishima Masaaki , Mustanir  , Fujio Mizue , Tsuno Yuho 
Published: June 2006

Abstract
The gas-phase basicities of a series of aromatic carbonyl compounds (ArCOR; R = OMe, Me, H) were measured based on the proton-transfer equilibrium method using a pulsed ICR mass spectrometer. The effects of ring-substituents on the gas-phase basicities were analyzed in terms of the Yukawa–Tsuno equation. It was shown that the resonance demand parameter (r+) decreases significantly from 1.06 for the benzaldehyde to 0.50 for the methyl benzoate in increasing order of the electron-donating ability of the R group directly linked to the carbonyl carbon. This indicates that the π-charge formed in the conjugate acid ion is competitively delocalized into an aryl group and an R group. In contrast, the ρ value is nearly constant at −11 (in kcal mol−1 per σ unit) in all series. Most importantly, it was found that the r+ value in the gas phase is in agreement with that for the basicities in aqueous solution, whereas the ρ value is significantly reduced in aqueous solution. This fact led us to the conclusion that the solvation of a cation reduces the central charge so as to lower the response to substituent perturbation, essentially without changing the nature of the intramolecular charge-delocalization.
Simple and Rapid Determination of the Activation Parameters of Organic Reactions by Temperature-Dependent NMR Spectroscopy I. Application to Irreversible Reactions
Authors: Satoh Masahiro , Hirota Minoru 
Published: June 2006

Abstract
A rapid and convenient method for the evaluation of activation enthalpies and entropies of reactions in solutions was contrived. This was realized by the stepwise elevation of the temperature of a reaction system using a variable temperature apparatus of NMR spectrometer. A repetition of rapid collection of FIDs (Free Inductive Decays) at every plateau part of temperature at regular intervals allows us to determine the time-conversion curve, from which the rates at various temperatures were obtained as the first derivatives. Several examples of applications are shown.
Chiral Bimetallic Boronic Esters: A Donor–Acceptor Coexisting Receptor for Amines
Authors: Nozaki Kyoko , Yoshida Masanori , Takaya Hidemasa 
Published: June 2006

Abstract
A chiral bimetallic Lewis acid, 2,2′-(1,2-phenylene)bis[(4R,5R)-4,5-diphenyl-1,3,2-ioxaborolane] (1a), has been synthesized. The exceptionally strong binding of 1a with benzylamine was demonstrated by titrations. The complex formation ratio of 1a : amine = 1 : 2 was determined by a Job plot. The binding constants, K1 and K2, were determined by non-linear curve fitting to be K1 &lt;&lt; K2. The results can be explained in terms of an allosteric effect. The first amine molecule coordinates with one of the two boron atoms of 1a; at the same time, one NH proton interacts with one of the two oxygen atoms in the other dioxaborolane ring to form a hydrogen bond. As a result, the two dioxaborolane rings are conformationally fixed by two-point binding to provide a preferable binding site for the second amine molecule. Although only a small chiral recognition of 1-phenylethylamine has been obtained with 1a, the clear separation of the peaks of the amine provides the possibility to use 1a as an NMR chiral-shift reagent.
Synthesis of (±)-Stemonamide by the Application of Oxidative Coupling Reactions of Stannyl Compounds with Silyl Enol Ethers
Authors: Kohno Yasushi , Narasaka Koichi 
Published: June 2006

Abstract
A tricyclic Stemona alkaloid, (±)-stemonamide, can be synthesized by applying the oxidative coupling reactions of stannyl compounds with silyl enol ethers to construct the carbon skeleton.
Synthesis of 2-Geranyl- and 2-Farnesyl-Substituted Geranylgeraniols and Their Phosphates
Authors: Nagano Hajime , Kudo Kaori 
Published: June 2006

Abstract
Allylation of the lithiated cyclohexylimine of (2E,6E,10E)-geranylgeranial with (2E)-geranyl bromide followed by acid-catalyzed hydrolysis gave (2E)-α-, (2Z)-α-, and γ-geranyl-substituted geranylgeranials. Farnesyl-substituted geranylgeranials were also prepared. (2Z)-α-Geranyl- and (2Z)-α-farnesyl-substituted geranylgeranials were photoisomerized to the corresponding (2E)-isomers, respectively. The branched polyprenyl alcohols, obtained by the reduction of these aldehydes, were transformed to geranyl- and farnesyl-substituted geranylgeranyl phosphates.
Cycloaddition of Bis[3,3-bis(diethylamino)thioacryloyl] Disulfide with Alkynic Dienophiles: A New Access to 2H-Thiopyran-2-thiones
Authors: Akimoto Keiichi , Masaki Kazuto , Nakayama Juzo 
Published: June 2006

Abstract
The reaction of bis[3,3-bis(diethylamino)thioacryloyl] disulfide (1) with dimethyl acetylenedicarboxylate gave dimethyl 4-diethylamino-2-thioxo-2H-thiopyran-5,6-dicarboxylate in 69% yield. Similarly, a series of alkynic dienophiles reacted with 1 to give the corresponding 2H-thiopyran-2-thione derivatives in modest-to-reasonable yields. A full experimental description of this 2H-thiopyran-2-thione formation is given and a mechanism involving [4+2]cycloaddition followed by homolytic cleavage of the S–S bond is presented.
Physical and Catalytic Properties of MgO Prepared Using Citric Acid
Authors: Nakayama Tomohiro , Sato Satoshi , Nozaki Fumio 
Published: June 2006

Abstract
The physical properties, particularly the pore structure and specific surface area, of MgO prepared using citric acid was investigated. Both the specific surface area and the pore volume increased steeply with the weight loss at around 600 K at which citric acid was decomposed. The pore size distribution of the sample was controlled by the ratio of citric acid and the temperature of heat treatment. In a catalytic decomposition of 4-hydroxy-4-methyl-2-pentanone into acetone, the reaction rate was proportional to the specific surface area of the sample, and the catalysts prepared by this technique had high reaction rates because of their high specific surface areas.
Synthesis of Vinyl Polymers Incorporating Different Crowned Azobenzene Moieties and Their Application to Photoresponsive Ion-Conducting System
Authors: Tokuhisa Hideo , Yokoyama Masaaki , Kimura Keiichi 
Published: June 2006

Abstract
Vinyl polymers carrying a crowned azobenzene side chain, which have a crown ether moiety and an azobenzene moiety in two different ways, were synthesized and their ion-conducting behavior investigated. The crowned azobenzene vinyl polymer carrying a crown ether moiety apart from its azobenzene moiety, 1, exhibited distinct liquid crystal phases, which were stabilized by the addition of alkali metal perchlorates. Ion-conducting composite films containing crowned azobenzene vinyl polymer 1 underwent remarkable photoinduced ionic-conductivity switching. The system of vinyl polymer 2, which carries a crown-ether ring in the vicinity of its azobenzene moiety, is greater in the magnitude of photoinduced ionic-conductivity change (ionic-conductivity ratio) than the system of vinyl polymer 1. X-Ray diffraction measurements suggested that the difference in the ionic-conductivity switching between the two crowned azobenzene polymers is derived from the difference in the order–disorder arrangement of the crown ether moiety on the photoisomerization of the azobenzene moiety from its trans form to the corresponding cis one.
Endohedral Metallofullerenes: New Spherical Cage Molecules with Interesting Properties
Authors: Nagase Shigeru , Kobayashi Kaoru , Akasaka Takeshi 
Published: June 2006

Abstract
Endohedral metallofullerenes (fullerenes containing metals inside the carbon cage) have long attracted special interest as new spherical molecules with novel properties. Recent important progress has been marked by successful isolation and purification in macroscopic quantities. With the availability of such purified samples, it has been possible to investigate the structures, electronic properties, and chemical reactivities. Very recent progress in the theoretical and experimental studies of endohedral metallofullerenes is summarized to show what are known or still unknown for the future material, catalytic, and biological applications.
The Study of the Electron–Positron Pair in CS2
Authors: Hirade Tetsuya 
Published: June 2006

Abstract
Ole E. Mogensen reported that CS2 was the only liquid which showed large decrease of the Ps intensity with lowering the temperature, even though electron and positron could encounter with each other at low temperatures such as −100 °C. The intensity change by the positron annihilation lifetime was observed at a little lower temperature by the positron annihilation angular correlation. Here I measured the change of intensity and lifetime of the longest lifetime component caused by varying the surface tension, the dielectric constant, and the temperature, to clarify the positron state in CS2. These experimental results confirm the ideas of the “fourth positron state” and the “squeezed positronium state” which were proposed by Ole E. Mogensen.
Electrochemical Reduction of N2O on Gas-Diffusion Electrodes
Authors: Konishi Nozomi , Hara Kohjiro , Kudo Akihiko , Sakata Tadayoshi 
Published: June 2006

Abstract
The electrochemical reduction of N2O to N2 on gas-diffusion electrodes (GDEs) modified by Pt and Ni electrocatalysts at room temperature was studied. The Faradaic efficiency for the reduction of N2O was 100%, even for a low concentration of N2O gas at a low current density. When 0.6 mmol of N2O was electrolyzed, 99.7% of the N2O was decomposed at a constant current density of 6.4 mA cm−2. The Faradaic efficiency of N2O reduction was increased by using pulse electrolysis.
Inclusion Complexation of 4-Biphenylcarboxylate, 4-Biphenylacetate, and 4-Biphenylsulfonate with α-Cyclodextrin, Studied by Pulse Radiolysis
Authors: Yamamoto Yukio , Yoshida Yoichi , Tagawa Seiichi 
Published: June 2006

Abstract
Inclusion complexation of 4-biphenylcarboxylate (BPC−), 4-biphenylacetate (BPA−), and 4-biphenylsulfonate (BPS−) with α-cyclodextrin (α-CD) has been investigated by a pulse radiolysis method. The one-electron reduction of BPC− and BPS− by the hydrated electron was effectively retarded by the 1 : 2 complexation with α-CD as well as by the 1 : 1 complexation with β-CD investigated in our previous study. The retarding effect of α-CD was observed at much higher host concentrations than that of β-CD. No apparent effect of α-CD was observed on the one-electron reduction of BPA−, but the effect of β-CD was similar to those for BPC− and BPS−. The result indicates that the methylene group of BPA− sterically inhibits the formation of the 1 : 2 complex. The rate constant for the one-electron reduction of the 1 : 2 complex of BPC− with α-CD was 1.0 × 109 dm3 mol−1 s−1, which is smaller than that of the 1 : 1 complex with β-CD, 2.5 × 109 dm3 mol−1 s−1. It is demonstrated that the biphenylyl group of the 1 : 2 complex with α-CD is screened from the attack of the hydrated electron more effectively than that of the 1 : 1 complex with β-CD.
Photoinduced Electron Transfer from Cyclic Organogermanium Compounds to C60 Studied by Laser Flash Photolysis
Authors: Ito Osamu , Sasaki Yoshiko , Watanabe Akira , Mochida Kunio 
Published: June 2006

Abstract
The electron transfer from cyclic organogermanium compounds to photo-excited C60 in benzonitrile solution has been investigated by the 532 nm-laser flash photolysis with observation of the transient absorption bands in the near-IR region. The transient absorption band of the C60 triplet state (TC60*) appeared at 730 nm immediately after nanosecond laser exposure. With the decay of TC60*, the absorption bands of the radical anion of C60 appeared at 1070 nm, showing that the electron transfer takes place from organogermanium compounds to TC60*. The efficiencies and rates of the electron-transfer reactions vary with ring size of the germanium compounds.
A Simple New Method for Determining Diffusion Coefficients of Interacting Particles in Porous Silica and Gels
Authors: Sasaki Shigeo , Maeda Hiroshi 
Published: June 2006

Abstract
A new experimental method to measure the diffusion coefficients of interacting particles in porous silica is described. The diffusion behavior of NaNO3 from a porous silica sphere into a solution of NaCl was found to be very sensitive to the cross diffusion term when the concentration ratio of NaCl to NaNO3 was high. The diffusion behavior of NaCl, KNO3, and KI from the inside to the outside of the sphere was also examined. Theoretical equations to analyze the cross diffusion flows of interacting particles were derived. The cross diffusion coefficient of NaNO3 and NaCl as well as the diffusion coefficients NaNO3, NaCl, KNO3, and KI in porous silica were evaluated from the present experimental results. The obtained diffusion coefficients were found to be about one third of those in solution. The diffusion behavior of NaNO3, NaCl, KNO3, and KI from spherical polyacrylamide gel was also examined for comparison.
Hydration and Pressure Effects on the Inter- and Intramolecular Vibrations of Tetramethylpyrazine Crystals
Authors: Maehara Masayoshi , Suzuki Yoshio , Mizobe Hideki , Kawano Hiroshi , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi 
Published: June 2006

Abstract
The Raman active inter- and intramolecular vibrations of tetramethylpyrazine and trihydrated tetramethylpyrazine crystals were studied under various pressures between 1 atm and 5 GPa. The pressure effect on the Raman frequency due to the intermolecular vibrations indicates that a tetramethylpyrazine crystal undergoes phase transitions under about 1.2 and 2.2 GPa and a trihydrated tetramethylpyrazine crystal undergoes phase transition under about 3.5 GPa. The pressure effect on the Raman frequency due to the intramolecular vibrations indicates that the pressure-induced frequency shift for the skeletal vibrations of trihydrated tetramethylpyrazine is larger than the corresponding shift of unhydrated tetramethylpyrazine, while the shift for the characteristic vibrations of the methyl groups of trihydrated tetramethylpyrazine is smaller than the corresponding shift of unhydrated tetramethylpyrazine. These observations suggest that the attractive force induced by the hydration plays a considerable role in the intermolecular interaction under high pressure in the molecular crystal, in addition to the repulsive force. The change of electron distribution, which strengthens the chemical bonds of the pyrazine ring more strongly than the bonds in the methyl groups, takes place with increasing pressure.
EPR and ENDOR Study of Trigonal Bipyramidal Copper Complexes with a Nitrogen Donor Tripodal Ligand
Authors: Ehsan Muhammad Q , Ohba Yasunori , Yamauchi Seigo , Iwaizumi Masamoto 
Published: June 2006

Abstract
The characteristic features of the electronic structure of some trigonal bipyramidal (tbp) copper complexes of the quadridentate tripodal nitrogen donor ligands, tris(2-aminoethyl)amine (tren) and tris(2-dimethylaminoethyl)amine (trenMe6), with different ligands at the fifth coordination position of tbp were studied in a powder form doped in diamagnetic zinc complexes by EPR and ENDOR. EPR shows that the copper complexes of tren and trenMe6 have a ground state with a dz2 unpaired electron orbital, and that some of the complexes are distorted from a trigonal symmetry to rhombic, to the contrary to expectations from the molecular formula. It is shown that a small structural or ligand-field distortion would give a recognizable spectral deviation from trigonal symmetry. It should be noticed that the hyperfine couplings of all the coordinating nitrogen atoms in each complex were observed by ENDOR, and that they were useful for calrifying the characteristic features of the electronic structures of the tbp complexes. The ligand fields at the fifth coordination position of tbp affects all of the coordination bonds as well as the spin distribution among the ligands. These ligand field effects on the electronic structures are discussed in reference to the ligand field parameters obtained by an EPR analysis. It is also shown that the ENDOR analysis well predicts the sp ratios of the coordinating orbitals of nitrogens, consistent with those obtained from the X-ray structural data on the complexes.