bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Association of Protonated Poly(vinylamine) and Poly(ethylenimine) with Poly(vinyl sulfate) and Dodecylbenzenesulfonate as Special Reference for Colloidal Titration
Authors: Hattori Toshiaki , Katai Kazuhito , Hattori Sadao , Kato Masanao
Published: June 2006

Ion association constants of two types of poly(vinylamine) and poly(ethylenimine) were determined from pH measurements of the polyamine/counter ion mixtures at an aqueous solution of the polymers (5 × 10−4 equiv mol dm−3). The results are discussed in terms of chemical structure (distance between reacting groups, and straight or branched chain), molecular weight, and ionic strength. The ion association at very low concentration protonated polyamines was promoted by the close location of amino groups. When the bound counter ions became close to each other, further ion association was inhibited by counter ions which had already bounded. From the colloidal titration of these polyamines, the stoichiometry could be discussed, especially under the conditions where all amino groups on the polymer are converted into ammonium ions. The results of the colloidal titration indicated that the stability constant for the ion association was drastically increasing near the equivalence point of the colloidal titration.
Solubility Product and Solubility of Cyclodextrin Inclusion Complex Precipitates in an Aqueous Medium
Authors: Sanemasa Isao , Wu Ji-Shi , Toda Kei
Published: June 2006

Cyclodextrins (CyD’s) have been precipitated as inclusion complexes with guest hydrocarbons from an aqueous medium, in which the guest hydrocarbon of interest was present in various concentrations. The solubility product constant of the CyD precipitate at 25 °C was determined by measuring the CyD concentration in the supernatant aqueous solution. Five model hydrocarbons were used as guests: hexane, cyclohexane, benzene, naphthalene, and biphenyl. The solubility products and the solubility in water of α-, β-, and γ-CyD inclusion complex precipitates with 36 varieties of guests were calculated based on the solubility of the guest hydrocarbon in water and the concentration of free CyD in the supernatant aqueous medium.
Cyclodextrin Precipitates with Normal Alcohols in an Aqueous Medium and Their Stability on Being Left Standing in Air
Authors: Sanemasa Isao , Wu Ji-Shi , Toda Kei
Published: June 2006

Cyclodextrin (CyD) precipitates with normal alcohols (guests, 1-butanol to 1-decanol) were prepared at 25 °C by introducing an alcohol vapor into an aqueous CyD solution and circulating it in a closed system. The guest/CyD molar ratio of the precipitates was measured immediately after preparation and after having been allowed to stand in air at room temperature for 30 or 40 d. Precipitates were obtained with alcohols higher than 1-pentanol for α-CyD, 1-hexanol for β-CyD, and 1-butanol for γ-CyD. The reason that CyD does not precipitate with lower alcohols could be explained in terms of the solubility product. There was a linear relationship between the apparent solubility (derived from the solubility product) of the CyD precipitates in water and the guest–CyD association constant. Upon drying in air, the guest/CyD molar ratio in the precipitates gradually decreased with days allowed to stand. In the cases of α- and γ-CyDs, the ratio remained constant after one week.
Spin Trapping of Phosphorus-Centered Radicals Produced by the Reactions of Dibenzoyl Peroxide with Organophosphorus Compounds
Authors: Sueishi Yoshimi , Miyake Yuzo
Published: June 2006

The reactions of dibenzoyl peroxide (BPO) with organophosphorus compounds have been studied by means of an ESR technique combined with spin trapping. The intermediate phosphorus-centered radicals were trapped by N-benzylidene-t-butylamine N-oxide (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The spin adducts with a characteristic hyperfine coupling constant (hfcc) due to a phosphorus atom were observed. From identification of trapped radicals, possible mechanisms of the reactions have been proposed. The hfccs due to β-hydrogen and phosphorus atoms exhibited a large temperature dependence for phosphoranyl–PBN spin adducts, while for phosphinyl–PBN spin adduct the dependence was small. Based on the P and H hfccs, the conformational positions of the adducts trapped by PBN and DMPO are discussed.
Antioxidant Activities of Phenothiazines and Related Compounds: Correlation between the Antioxidant Activities and Dissociation Energies of O–H or N–H Bonds
Authors: Yamamura Tatsuo , Suzuki Kyouichi , Yamaguchi Tatsuya , Nishiyama Tomihiro
Published: June 2006

The antioxidant activities of phenothiazines, carbazoles, and related diphenylamines were evaluated in the oxidation of tetralin at 60 °C and linoleic acid micelles in aqueous dispersion at 37 °C induced by an azo initiator. Phenothiazines were highly antioxidant in both systems. Although diphenylamine and carbazole were not good antioxidants, those having a hydroxy group as a substituent at the ortho or para position to the amino group were potently antioxidant. The antioxidant activity of o-hydroxydiphenylamine was much greater than that of other compounds in both systems due to a stabilization of the phenoxyl radical by delocalization of the unpaired electron to the p-type lone pair of the amino group. A semiempirical MNDO-AM1 calculation was applied to study hydrogen abstractions of antioxidants in the chain process of autoxidation. These results indicated that the rates of oxidation during the induction period correlated with the dissociation energies of the O–H or N–H bonds.
A New
α
-Iodination of Ketones Using Iodine-Ammonium Cerium(IV) Nitrate in Alcohol or Acetic Acid
Authors: Horiuchi C Akira , Kiji Shinji
Published: June 2006

The direct α-iodination of various ketones using iodine-ammonium cerium(IV) nitrate in acetic acid or alcohol gave the corresponding α-iodo ketones in high yields. The effect of cerium salt on the iodination of ketones, and the iodination of 5α-cholestan-3-one using several methods are also discussed. In the reaction of 3,3,5-trimethylcyclohexanone and unsymmetrical ketones, such as 2-hexanone and 2-heptanone, using methanol, ethanol, 1-propanol, and 2-propanol, the regioselective iodination product was obtained. In the case of bromination, the reaction of ketones with bromine and ammonium cerium(IV) nitrate also yielded the corresponding α-bromo ketones.
The Total Synthesis of a Glycosidase Inhibitor, Nagstatin
Authors: Tatsuta Kuniaki , Miura Shozo , Gunji Hiroki
Published: June 2006

A glycosidase inhibitor, nagstatin, has been synthesized from protected l-ribofuranose through the inter- and intra-molecular nucleophilic reactions of the imidazole moieties and the regioselective introduction of a carboxymethyl group.
Palladium-Catalyzed Cross-Coupling Reaction of Alkyltrifluorosilanes with Aryl Halides
Authors: Matsuhashi Hayao , Asai Satoshi , Hirabayashi Kazunori , Hatanaka Yasuo , Mori Atsunori , Hiyama Tamejiro
Published: June 2006

A cross-coupling reaction of alkyltrifluorosilanes with aryl halides was achieved using a catalytic amount of tetrakis(triphenylphosphine)palladium(0) and excess of tetrabutylammonium fluoride (TBAF) at 100 °C with high chemoselectitvity. Functional groups like nitro, ketone carbonyl, and formyl tolerated the coupling conditions. Because potassium(18-crown-6) alkyltetrafluorosilicates also underwent a cross-coupling reaction in the presence of an additional molar amount of TBAF, the active species of the coupling reaction was assumed to be pentacoordinate silicates. TBAF in excess was considered to be required for trapping the tetrafluorosilane produced in the catalytic cycle of the cross-coupling reaction.
Aromatic Allylsulfenylation with in Situ Generated Allylic Thiols under the Heck Conditions
Authors: Harayama Hiroto , Nagahama Takayuki , Kozera Toyohiro , Kimura Masanari , Fugami Keigo , Tanaka Shuji , Tamaru Yoshinao
Published: June 2006

A wide structural variety of S-allylic thiocarbamates 2 can be prepared in good yields by the rearrangement of O-allylic thiocarbamates 1 under three different conditions: thermal activation (neat, 120—150 °C), palladium(0) (25—65 °C), and palladium(II) catalysis (25—65 °C). Of the two possible regioisomers of unsymmetrical S-allylic thiocarbamates 2, those of higher thermodynamic stability can be prepared in high purity under either thermal activation or palladium(0) catalysis. Although the thermodynamically less stable regioisomers of 2 are, in general, hard to be prepared in high purity, some of them (e.g., 2d and 2h′) can be obtained with an exclusive or high selectivity by the catalysis of palladium(II). The stereoisomeric pair of 2j and 2j′ can be prepared selectively by the palladium(0)-catalyzed rearrangement of 1j and 1k, respectively. These reactions proceed with retention of configuration at the allylic stereocenters. S-Allylic (2) and S-alkyl thiocarbamates (7) undergo fragmentation to generate thiolates in the presence of inorganic bases (e.g., K2CO3, K2CO3·Et4N+I−) by heating in an aprotic solvent; the thus-formed thiolates react with aromatic iodides and vinyl bromides in the presence of palladium(0) complexes to furnish aryl and vinyl sulfides, respectively. A wide variety of aryl sulfides can be prepared in good yields irrespective of the kind of substituents and their substitution positions (o-, m-, p-) under conditions B [Pd(OAc)2, PPh3, K2CO3·Et4N+I−, dioxane, 100 °C]. Under conditions E [Pd(OAc)2, PPh3, Cs2CO3, dioxane, 100 °C], better yields result specifically for the sulfenylation of aromatic iodides bearing substituents having large Hammett σ constants.
The Short-Range Structure around Li+ in Highly Concentrated Aqueous LiBr Solutions
Authors: Kameda Yasuo , Suzuki Shun , Ebata Hidekazu , Usuki Takeshi , Uemura Osamu
Published: June 2006

Neutron diffraction measurements have been carried out on aqueous 10, 25, and 33 mol% LiBr solutions. The 6Li/7Li isotopic substitution technique was applied to determine the local structure around Li+ in these solutions. The least-squares fitting analysis was successfully adopted both for the observed Li+ difference interference function, ΔLi(Q), and for the Li+ distribution function GLi(r). The nearest neighbor Li+···O distance in the solutions was obtained to be 1.96 ± 0.02 Å, which agrees well with that reported in previous neutron diffraction studies. The average hydration number of Li+ decreases from ca. 6 for the 10 mol% LiBr solution to ca. 4 for the 25 mol% LiBr solution. The tetrahedral hydration structure around Li+ appeared to stay even in the 33 mol% LiBr solution. The Li+···Br− correlation was found at 3.4 Å in the 33 mol% LiBr solution. This value rather suggests the formation of the solvent-shared ion pair, Li+···D2O···Br−.
Synthesis and Properties of the Inner Salt, 3,3-Dipiperidino-3-propylium-1-dithioate: Adduct of 1,1-Dipiperidinoethene and Carbon Disulfide
Authors: Akimoto Keiichi , Masaki Kazuto , Nakayama Juzo
Published: June 2006

The nucleophilic addition of 1,1-dipiperidinoethene to carbon disulfide gives an inner salt, 3,3-dipiperidino-3-propylium-1-dithioate (8), in good yield. The inner salt 8 exists as an equilibrium mixture with its tautomer 3,3-dipiperidinodithioacrylic acid in the ratio of 9 : 1 in CDCl3 at 22 °C. The air-oxidation of 8 leads to bis(3,3-dipiperidinothioacryloyl) disulfide. The inner salt 8, prepared in situ, reacts with a wide variety of alkyl halides to provide a convenient synthesis of alkyl 3,3-dipiperidinodithioacrylates in one-pot.
Rearrangement Approaches to Cyclic Skeletons. XI. Chemoenzymatic Preparation of Chiral Bridged Compounds for Rearrangement Approaches
Authors: Uyehara Tadao , Ishikawa Miyuki , Iikura Fumi , Yoneta Noriko , Ueno Masako , Sato Toshio
Published: June 2006

Both enantiomers of 1-methoxybicyclo[2.2.2]oct-5-en-2-ones were prepared in more than 80%ee on the basis of a chemoenzymatic reaction sequence. The optical resolution was achieved by the enantioselective hydrolysis of chloroacetyl esters 1-methoxybicyclo[2.2.2]oct-5-en-endo-2-ols using commercially available lipases.
Preparation of Sulfur-Containing Optically Active Secondary Alcohols Based on Pichia farinosa-Catalyzed anti-Prelog-Rule Reduction as the Key Step
Authors: Ohtsuka Yoshikazu , Katoh Osamu , Sugai Takeshi , Ohta Hiromichi
Published: June 2006

A Pichia farinosa IAM 4682 mediated reduction of sulfur containing ketones afforded secondary alcohols with (R)-absolute configuration. For example, 4-(phenylthio)-2-butanone and 4-(phenylsulfonyl)-2-butanone afforded (R)-4-(phenylthio)-2-butanol (91%ee) in 90% yield and (R)-4-(phenylsulfonyl)-2-butanol (97%ee) in 94% yield, respectively. In the case that the ee of the product was not satisfactory, any contaminating (S)-enantiomer was selectively oxidized by Rhodococcus rhodochrous IFO 15564 to leave pure (R)-enantiomer. The substrate specificity of Pichia farinosa-mediated reduction and Rhodococcus rhodochrous-mediated oxidation was further examined.
Additive Effect of Silver on the Catalytic Activity of TiO2–ZrO2 for the Selective Reduction of NO with Propene, 2-Propanol, and Acetone
Authors: Haneda Masaaki , Kintaichi Yoshiaki , Inaba Megumu , Hamada Hideaki
Published: June 2006

The catalytic performance of metal-impregnated TiO2–ZrO2 binary metal oxide for the selective reduction of NO was investigated. The addition of silver to TiO2–ZrO2 catalyst caused a drastic enhancement of NO reduction activity with propene. This silver additive effect was accounted for by the assumption that silver promotes the reaction of NO2 with propene to form a partially oxidized hydrocarbon, which is the rate-determining step. However, the catalytic activity of silver-supported TiO2–ZrO2 was depressed by the presence of water vapor because of its inhibiting effect on the formation of the oxygenated intermediate. Oxygen-containing compounds such as 2-propanol and acetone were also found to be good reductants on silver-supported TiO2–ZrO2 in the absence of water vapor. Moreover, the presence of water vapor significantly enhanced NO reduction activity of silver-supported TiO2–ZrO2 with these reductants. It was presumed that water vapor accelerates the selective reduction of NO by suppressing the undesirable oxidation of the reductants by O2.
Effect of Substrates on the Infrared External Reflection Spectra of Langmuir–Blodgett Films
Authors: Hasegawa Takeshi , Nishijo Jujiro , Kobayashi Yoshihiro , Umemura Junzo
Published: June 2006

The Fourier transform infrared (FTIR) polarized external reflection (ER) spectra of 9-monolayer cadmium stearate Langmuir–Blodgett (LB) films were measured on various kinds of materials (Ge, ZnSe, and GaAs) in order to investigate whether their spectra could be used for a quantitative analysis of the molecular orientation. The FTIR ER spectra on double-side-polished substrates with LB films on both sides would not fit in, even qualitatively, with the 5-layer system (IR//air/LB/substrate/LB/air) theoretical prediction. On the other hand, the ER spectra of a single-side-deposited LB film (IR//air/substrate/LB/air) were qualitatively explained by a simple 3-layer system (IR//substrate/LB/air) in which the reflection in the substrate was treated as a single reflection. This indicated that the output rays from the substrate in the conventional 5-layer system did not interfere sufficiently with each other. A 5-layer system calculation without any interference effect qualitatively explained the ER spectra of LB films on a double-side-polished substrate. It was eventually concluded that double-side-polished materials are not suitable for a precise analysis of ER spectra, since it is almost impossible to estimate the area ratio of interferential and non-interferential rays.
Ab Initio Computational Studies on the Structures and Energetics of Hole Transport Molecules: Triphenylamine
Authors: Pacansky Jacob , Waltman Robert J , Seki Hajime
Published: June 2006

Triphenylamine neutral and hole (radical cation) molecules are optimized by ab initio Hartree–Fock calculations at the 3-21G basis set. Modest changes in geometry are computed upon oxidation. The unpaired electron is 59% localized on the amine nitrogen atom. The energy barrier for the hopping process involving the electron transfer between a neutral and ionized (hole) triphenylamine is 0.15 eV. The vibrational mode that is primarily associated with the change in geometry upon hole formation is the C–N stretching mode.
Membrane Phenomena in Nonisothermal Systems: Part 1. Theory
Authors: Tasaka Masayasu , Kiyono Ryotaro , Huda Masud Shamsul
Published: June 2006

Theoretical equations for the thermoosmosis and thermal membrane potential across a charged membrane were derived using a set comprising the energy flux and the coupled logarithmic temperature-difference force as a dissipation function of irreversible processes. In order to obtain phenomenological equations in discontinuous systems by integrating phenomenological equations in continuous systems, it was assumed that temperature and total chemical potential are continuous at the interface between the membrane and the external solution. The new equations were compared with approximate equations derived previously from a set comprising the entropy flux and the coupled temperature-difference force as the dissipation function. Moreover, an equation for the thermal membrane potential was also derived using an alternative method by summing two parts: the equilibrium potential differences between the membrane and the external solutions on both sides of the membrane (two Donnan potentials) and the thermal-diffusion potential in the membrane.
Supersonic Jet Spectroscopic Study of 1-Methyl-2(1H)-pyridinimine and Its Deuterated Analog
Authors: Young Mark A , DeBoer Gary , Fujimoto Akira , Iwasaki Naoya , Traore Hassime , Yourshaw Ivan
Published: June 2006

The laser-induced fluorescence spectra and the fluorescence lifetimes of 1-methyl-2(1H)-pyridinimine and its deuterated analog were measured in a supersonic jet. The spectral results reveal a number of low frequency modes which are assigned to torsional motions involving the methyl group. The two major groups of peaks observed are ascribed to the presence of cis/trans conformers in the supersonic expansion.
Binding of Local Anesthetic Tetracaine to Phosphatidylinositol/Dipalmitoylphosphatidylcholine Mixed Vesicles
Authors: Someya Masayuki , Fukushima Kohsuke , Shimozawa Ryosuke
Published: June 2006

We measured the binding of local anesthetic tetracaine to phosphatidylinositol (PI), dipalmitoylphoshpatidylcholine (DPPC) and PI/DPPC mixed vesicles by an equilibrium dialysis method at different pH (5.5, 7.0, 8.0) at 35 °C. The results obtained for the pure phospholipid vesicles show that tetracaine binds to PI with the polyhydroxy headgroup, rather than to twitter ionic DPPC. For mixed vesicles, the higher is the ratio of the PI in mixed vesicles, the higher is the binding number. The change in pH slightly influences the binding to PI, while it strongly influences the binding to DPPC. We calculated the binding parameters which characterize the binding isotherms based on Langmuir-type and Hill equations. The binding parameters for pure PI and DPPC vesicles well reproduce the binding isotherms for PI/DPPC mixed vesicles with different mixing ratios. The results for pure PI were compared with those previously obtained for dilauroylphosphatidic acid (DLPA) in order to examine the influence of inositol in the head group of PI on the binding of tetracaine to phospholipid vesicles.
Effect of Hydrogen Bond on Second-Order Nonlinear Optical Property of 2-Alkylcarboxamido-4′-methoxy-4-nitrotolan Derivatives
Authors: Kato Midori , Okunaka Masaaki , Sugita Nami , Kiguchi Masashi , Taniguchi Yoshio
Published: June 2006

We have synthesized a series of 2-alkylcarboxamido-4′-methoxy-4-nitrotolan derivatives and studied the second-order nonlinear optical properties using the total reflection technique. We measured the infrared absorption spectra of the derivatives and examined the absorption peak of the N–H stretching vibration around 3300 cm−1, which is sensitive to hydrogen bonding. We observed that the peak frequencies of the nonlinear optical active materials were lower than those of the inactive ones, and thus found that for 2-alkylcarboxamido-4′-methoxy-4-nitrotolan derivatives the hydrogen bond plays an important role in activating the second-order optical nonlinearity of the material.
A New Titration Method Based on Concentration-Variable Patterns. Principles and Applications to Acid–Base and Redox Titrations
Authors: Zhang Chong-Liang , Narusawa Yoshio
Published: June 2006

A new titration method based on concentration-variable patterns is presented. Since this titration method is characterized by a non-dilution and a non-gradient operation, no volume correction is necessary, and the influence of the matrix is indifferent. The proposed method is applied to acid–base and redox titrations. In addition, a new approach for equivalence-point detection is established, where the equivalence point can be mathematically determined by solving simultaneous linear equations before and after the equivalence point. Indicators or first-derivative and second-derivative treatments are no longer necessary, and the accuracy and precision in the equivalence point have been improved, compared with the traditional titration method. The titration error has been decreased to such levels as 0.1 pH for acid–base titrations, and of 0.01 V unit for redox titrations.
Comparative Studies on the Solvent Extraction of Pd(II) Using Alkane-1,ω-diyl Bis(O,O-diisobutyl phosphorodithioate)s
Authors: Chowdhury Didarul A , Kamata Satsuo
Published: June 2006

A series of new bis-type derivatives of O,O-diisobutyl phosphorodithioate, namely, the alkane-1,ω-diyl bis(O,O-diisobutyl phosphorodithioate)s (ADBDiBPDT), were synthesized for use in the solvent extraction of precious metals. These compounds having the general formula (i-BuO)2P(S)S(CH2)nS(S)P(Oi-Bu)2, have considerable selectivity for extraction of Pd(II) over Au(III), Ag(I), and Pt(IV) when extracted from 0.1 M (1 M = 1 mol dm−3) perchlorate, nitrate, and chloride media. The extractability of individual metal ions increases with the increase in the length of the alkane-1,ω-diyl chain (n = 1—4), joining the two phosphorodithioate groups in the bis-structure. The extraction of palladium(II) from 1.0 M chloride solution at pH 3 in 1,2-dichloroethane (DCE) proceeds through the formation of either a 1 : 2 (n = 1) or a 1 : 1 (n = 2,3,4) palladium-ligand complex involving ligand displacement in PdCl42− species. When compared with the monofunctional triisobutylphosphine sulfide (TIBPS) and dihexyl sulfide (DHS), the new reagents were found to provide higher Pd(II) extraction and better extraction selectivity, under identical conditions. The higher members of the ADBDiBPDT series acting as bidentate ligands are also characterized by better stripping properties compared with those of the monodentate sulfur ligands. The metal loading capability, the extraction constants, and the kinetic properties of palladium extraction using these reagents are discussed.
Study of Synthetic Clay Minerals. V. Lamellar Fraipontite–Silica Composite as a New Adsorbent
Authors: Takahashi Noriyuki , Tanaka Masanori , Satoh Teiji , Endo Tadashi
Published: June 2006

A novel porous adsorbent was prepared by adding an aqueous solution having Zn, Al, and Si components into a suspension of silica hydrogel at 40 °C. According to the results of XRD, NMR, TEM etc., the adsorbent was identified as being a new composite consisting of lamellar fraipontite and silica. The layer structure of the resulting fraipontite was not stratified three-dimensionally. NMR data also verified that the structural framework consisted of a single ZnO6 octahedral sheet with Aloct and a single SiO4 tetrahedral sheet with Altet, which bonded with silica. The formation process of this porous adsorbent, incorporated by silica particles, was systematically examined in some detail.
Analysis of Chemical Phenomena by Solving the Constrained Hartree–Fock Equation. II. Relationship between π-Electronic Structure and Its Energy in Benzene
Authors: Ichikawa Hiroshi , Kagawa Hirotaka
Published: June 2006

The constrained Hartree–Fock method provides quantum-mechanically acceptable wave functions of an arbitrary electronic structure without changing the molecular geometry. We have applied this method to the analysis of the behavior of π electrons in benzene finding that there are two types of resonance energy, simple resonance between double bonds and super-stabilization due to the topology of benzene, which were estimated as 54 and 168 kJ mol−1, respectively. According to our method, π electrons in benzene were found to have a propensity for uniform distribution. Namely, the D6h distribution of π electrons gives the minimum values concerning both the π-electronic and total energies, which are brought forth by lowering the kinetic energy of π electrons. The origin of delocalization of π electrons in benzene was attributed to relaxation of the kinetic-energy pressure of π electrons.
Raman Studies on the Identification of Isopolymolybdates in Aqueous Solution
Authors: Himeno Sadayuki , Niiya Hirotaka , Ueda Tadaharu
Published: June 2006

Molybdenum(VI) solutions were investigated in detail by Raman spectroscopy with a view to establishing the speciation of the predominant polynuclear species (isopolymolybdates) formed in aqueous solution. The most intense Raman frequencies due to asymmetric stretching vibration of Mo=O were very sensitive to even small changes of the structure of the isopolymolybdates. As the pH was lowered, the major Raman line showed no gradual shift but exhibited a discrete change. Evidence was obtained for the existence of Mo7O246− (pH 4—6), Mo3O102− (pH 3.5—5), α-Mo8O264− (pH 2—5), β-Mo8O264− (pH 1.5—4), and Mo36O1128− (pH 0.5—1.5). On the other hand, neither of Mo6O192− and γ-Mo8O264− existed in any appreciable amount in aqueous solution.
Bismuth(III) Complexes of 2-Mercaptoethanol: Preparation, Structural and Spectroscopic Characterization, Antibactericidal Activity toward Helicobacter pylori, and Inhibitory Effect toward H. pylory-Produced Urease
Authors: Asato Eiji , Kamamuta Koji , Akamine Yasutoshi , Fukami Takanori , Nukada Ryoji , Mikuriya Masahiro , Deguchi Shuhei , Yokota Yoshiko
Published: June 2006

In order to examine the potential ability of bismuth(III) thiolate complexes as new Bi-based chemotherapeutic agents, three bismuth(III) complexes of 2-mercaptoethanol (H2meret) —[Bi(Hmeret)2](NO3)·H2O (1), [Bi(Hmeret)(meret)] (2), and [Bi(Hmeret)3] (3)— have been synthesized. X-ray structure determination of 1 and 2 showed that both complexes have one-dimensional polymeric structures where thiolato-S atoms bridge Bi atoms in 1 and alkoxo-O atoms bridge them in 2. On the other hand, their NMR study revealed that both complexes completely dissociate and behave as mononuclear species in solution. For the three and several Bi-containing compounds as references, antibacterial activities toward Helicobacter pylori, a pathogenic factor of clonic gastritis and peptic ulcer, were tested in vitro. All the complexes including the reference samples showed nearly the same and moderately strong activities. The inhibitory effect toward H. pylory-produced urease was also tested for the three and the reference samples, and further for free 2-mercaptoethanol, which is a well-known urease inhibitor. It was found that the activity of 2-mercaptoethanol was significantly enhanced on forming complex(es) with Bi(III).
Mononuclear and Mixed-Valence Trinuclear Manganese Complexes Containing Tripodal Tetradentate Ligands. Phenolato, Carboxylato, and Alkoxo Bridges
Authors: Hirotsu Masakazu , Kojima Masaaki , Yoshikawa Yuzo
Published: June 2006

Manganese complexes containing tripodal tetradentate ligands with an N2O2 donor set (H2L1: N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L2: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L3: N,N-bis(3,5-di-t-butyl-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine) have been prepared. The mononuclear and trinuclear complexes with the additional carboxylate ligand were isolated. The steric effect of the 3-positioned t-butyl groups on the aromatic rings of the tripodal ligand controls the type of the complex structure. The L3 ligand gave a mononuclear complex, [Mn(L3)(mcba)(CH3OH)], where mcba is a m-chlorobenzoate anion; the structure has been determined by X-ray analysis. The trinuclear complexes are formulated as [Mn3(Ln)2(carboxylato)2(OCH3)2] (n = 1, 2). For the L4 and L5 ligands (H2L4: N,N-bis(5-methoxy-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L5: N,N-bis(5-chloro-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine), trinuclear complexes were also obtained. Three trinuclear complexes were also structurally characterized by X-ray analysis. The three manganese cores are arranged linearly, and the structural parameters indicate that the oxidation states are MnIII–MnII–MnIII. The MnIII and MnII cores are bridged by phenolate, carboxylate, and alkoxide groups, and the manganese cores are separated in the range of 3.14 and 3.17 Å. The variable-temperature magnetic susceptibility measurements of the mixed-valence trinuclear complexes revealed that the spin exchange coupling constants (J) between MnIII and MnII ions range from −0.25 to 1.9 cm−1. The exchange interactions are weak, and both antiferromagnetic and ferromagnetic interactions were observed.
Cyclocopolymerization of α,ω-Dienes with Carbon Monoxide Catalyzed by (R,S)-BINAPHOS–Pd(II)
Authors: Nozaki Kyoko , Sato Naomasa , Nakamoto Koji , Takaya Hidemasa
Published: June 2006

Cyclocopolymerization of 1,4-pentadiene with carbon monoxide gave polyketone 3 in the presence of a Pd(II) catalyst bearing an unsymmetrical bidentate ligand, (R,S)-BINAPHOS {=(R)-2-(diphenylphosphino)-1,1′-binaphthalen-2′yl (S)-1,1′-binaphthalene-2,2′-diyl phsophite}. In the repeating unit of 3, exclusive formation of a cyclopentanone framework rather than cyclohexanone has been revealed by 13C NMR and IR spectroscopies. A single-unit analog 2 was prepared to identify the structure of 3. In the cyclopentanone unit of 3, the two substituents are cis and trans to each other in almost 1 : 1 ratio. The polymer 3 showed different behavior in thermal analysis from that of propene–CO alternating copolymer. 1,5-Hexadiene also afforded the corresponding cyclocopolymer 5. The molar optical rotation of polymer 3 was much lower than that of 5.
UV-Visible and NMR Spectroscopic Studies of Disilanylene 1,2-Dianions. Questions of Charge Delocalization of Silyl Anions
Authors: Wakahara Takatsugu , Kodama Ryuji , Akasaka Takeshi , Ando Wataru
Published: June 2006

The reaction of 1,2-dichloro-1,2-diisopropyl-1,2-disilaacenaphthene with an excess of alkali metal resulted in the formation of the corresponding dialkali metal, 1,2-disila-1,2-acenaphthenediide, as the disilanylene 1,2-dianion. UV-vis and NMR spectroscopic analyses strongly support the delocalization of the silyl anion.
A Bis-Crown Ether Derivative of Triaminotriazine: Synthesis and Behavior of the Ion-Selective and Hydrogen-Bonding Responsive Rotamers
Authors: Otsuki Joe , Russell Keith C , Lehn Jean-Marie
Published: June 2006

A bis-crown ether derivative of triaminotriazine was synthesized via a phthalic acid derivative of a polyether macrocycle obtained from benzo-18-crown-6. It exists in different conformers distinguishable by 1H NMR at room temperature, in which the macrocyclic side-arms take a closed, half-open, or fully open form, due to the rotational barrier of the C(triazine)–N bond. Large alkali metal ions, such as Rb+ and Cs+, the latter being particularly effective, promote the formation of the closed conformer. A barbiturate derivative also causes a similar equilibrium shift to the closed form by establishing complementary hydrogen bonds. The half-open and fully open conformers are induced by smaller alkali metal ions than Rb+, among which K+ is the most effective.
A Novel Sugar Sensing System Designed with a Cooperative Action of a Boronic-Acid-Appended Zinc Porphyrin and a 3-Pyridylboronic Acid Axial Ligand
Authors: Takeuchi Masayuki , Kijima Hideomi , Hamachi Itaru , Shinkai Seiji
Published: June 2006

The cooperative action of two boronic acids is indispensable to the selective binding of saccharides in aqueous solution and the binding process can be spectrophotometrically monitored by using porphyrins as a chromophoric probe. It is not so easy, however, to synthesize porphyrins that satisfy these prerequisites, i.e., porphyrins bearing two appropriately-arranged boronic acid groups within a molecule. In this paper, we report that such a diboronic-acid-based porphyrin receptor can be easily designed by utilizing the self-assembling nature of a Zn(II) porphyrin and an axial ligand: That is, a mixture of boronic-acid-appended Zn(II) porphyrin (1-Zn) and 3-pyridylboronic acid (2) self-organizes to create a novel diboronic acid system for saccharide (S) recognition. Thus, the 1-Zn·2·S ternary complexes give the CD spectral pattern inherent to saccharide absolute configuration. The present study is a new example for sugar sensing using a boronic acid-porphyrin self-assembly system.
Organoaluminum-Promoted Cyclization of Olefinic Epoxides. A New and Stereoselective Approach to Cyclohexane Frameworks
Authors: Murase Noriaki , Maruoka Keiji , Ooi Takashi , Yamamoto Hisashi
Published: June 2006

A new, general synthetic method of six-membered carbocycles has been demonstrated, which involves the stereocontrolled cyclization of olefinic epoxides with methylaluminum bis(4-bromo-2,6-di-t-butylphenoxide) (MABR) via the epoxide rearrangement and subsequent intramolecular ene reaction with high stereoselectivity. This strategy is shown to be highly useful in the stereoselective synthesis of the basic skeleton of various terpenes.
A New Method of Determining the Rate Constants for State-to-state Vibrational Relaxation: An Integrated Profiles Method
Authors: Yamasaki Katsuyoshi , Watanabe Akihiro
Published: June 2006

A new method of analysis for determining the rate constants of vibrational relaxation has been developed. Linearization of the equations of regression makes it possible to resolve the various problems and disadvantages of the conventional non-linear least-squares analyses. Not only the rate constants but also the relative detection sensitivities of different vibrational levels can be determined without information on photochemical parameters by which excitation spectra are usually corrected. Consequently, nascent vibrational distributions of the molecules produced in photolyses or chemical reactions can also be determined from the profiles recorded even under multiple collision conditions. The principles of the new method and how some advantage is offered are described, along with the comparison with the conventional analyses. Application of the method to practical schemes is also shown in detail.
13C and 1H MAS NMR Study of Benzene and p-Xylene in Zeolites and a Mesoporous Material FSM-16
Authors: Satozawa Masatoshi , Kunimori Kimio , Hayashi Shigenobu
Published: June 2006

13C and 1H MAS NMR spectra have been measured at room temperature for benzene and p-xylene adsorbed in H-ZSM-5, Na-, and H-type mordenites with different Si/Al2 ratios, H-Y, Na-Y, Na-X, and FSM-16 to study the dynamics of the guest species in the host materials. The second moments M2 evaluated from the SSB intensity in 13C CP/MAS NMR spectra were used to predict the motion of the guest species. Benzene molecules rotate about the C6 axis freely, and reorientation of the C6 axis takes place in H-ZSM-5. The para axis of p-xylene molecule is fixed in H-ZSM-5. The reorientations of the guest species become isotropic in the faujasite-type zeolites, Na-Y, H-Y, and Na-X. In FSM-16, translation diffusion takes place in addition to the isotropic rotation like in the liquid state. The mobilities of benzene molecules are in the following order, mordenite < H-ZSM-5 < Na-Y < Na-X < H-Y < FSM-16, while those of p-xylene molecules are in the following order. H-ZSM-5 < mordenite < Na-Y < Na-X ≈ H-Y < FSM-16. There is a good correlation between the pore size and the mobility of the guest species, with the exception of the mordenite/benzene systems.
Low Multielectron Reduction Potentials of Emerald Green [60]Fullerenes
Authors: Canteenwala Taizoon , Li Wenguang , Wang Hsing-Ling , Chiang Long Y
Published: June 2006

Unique double-triphenylene interconnected all-trans 18-trannulene electronic configuration of dodecaethylated emerald green fullerene (EFn), C60[–C(CH3)(CO2Et)2]6 or EF-6MC2, allows the fullerene cage to retain similar affinity for electrons as C60 and high multielectron accepting capability with E1Red = −0.36 V, E2Red = −0.88 V, and E3Red = −1.45 V vs. Ag/AgCl.
Greenish-yellow Light-emitting, Long-lasting Phosphorescence in Eu2+-doped CaO–CaBr2–SiO2 Phosphor System
Authors: Xia Zhiguo , Li Qiang , Sun Jiayue
Published: June 2006

Novel greenish-yellow light long-lasting afterglow material, Eu2+-doped CaO–CaBr2–SiO2 phosphor system, is prepared by the conventional high-temperature solid-state method. Photoluminescence (PL) spectrum reveals that it exhibits a strong blue emission band centered at 469 nm with some asymmetry on the long wavelength side, while this phosphor emits greenish-yellow light and shows strong long-lasting phosphorescence after it is excited with 365-nm UV light. The phosphorescence lasts for more than 1 h in the light perception of the dark-adapted human eye (0.32 mcd/m2). The possible phosphorescence mechanism is also investigated.
Selective Hydrogenation of Naphthols to Tetralones over Supported Palladium Catalysts in Supercritical Carbon Dioxide Solvent
Authors: Mine Eiichi , Hiyoshi Norihito , Sato Osamu , Rode Chandrashekhar V , Shirai Masayuki
Published: June 2006

Naphthols were selectively hydrogenated to the corresponding tetralones over supported palladium metal catalysts in supercritical carbon dioxide solvent.
Organic Nanoparticles of Porphyrin without Self-aggregation
Authors: Ou Zhong-min , Yao Hiroshi , Kimura Keisaku
Published: June 2006

Well-dispersed organic nanoparticles of porphyrin with narrow size distribution were successfully prepared in aqueous solution based on the “ion-association” method. No self-aggregation of the constituent porphyrin chromophores was confirmed. The nanoparticles exhibit interesting optical properties; a large bathochromic shift in the absorption and a remarkable resolution increase in the fluorescence compared to those for the corresponding aqueous-phase porphyrin.
Effects of aerosols on trade wind cumuli over the Indian Ocean: Model simulations
Authors: Mcfarquhar Greg M. , Wang Hailong
Published: June 2006

An Eulerian non‐hydrostatic anelastic fluid model using a warm cloud bulk parametrization is used to study responses of trade wind cumuli to increased cloud drop concentrations produced by enhanced aerosol numbers and to absorption from aerosols containing soot. Simulations are initialized using temperature and moisture profiles measured during the Indian Ocean Experiment (INDOEX) and sea surface temperatures retrieved from the Tropical Rainfall Measuring Mission microwave imager. Cloud covers between 4 and 10% and cloud‐averaged liquid water contents of between 0.01 and 0.6 g m−3 more closely match values retrieved and measured in situ during INDOEX than those modelled in past studies; previous studies found larger cloud coverage associated with cloud spreading below a strong inversion not present in the INDOEX soundings.

As in previous studies, a diurnal cycle with reductions of cloud cover and liquid water path (LWP) after sunrise is seen, with absorbing aerosols within cloud augmenting the decrease in cloud cover. Variations in aerosol vertical profiles can change semi‐direct radiative forcing at the surface (top of the atmosphere) from +1.6(+1.3)W m−2 when aerosols are confined to cloud compared to −0.4(−0.6)W m−2 when aerosols occur below cloud. Low‐level water‐vapour mixing ratios decrease as vertical motions increase, the vertical motions being enhanced by below‐cloud solar heating and cloud‐top radiative cooling and suppressed by in‐cloud heating. Cloud cover and LWP are larger for stronger vertical motions, explaining the dependence of radiative forcing on aerosol profile. In the late afternoon and evening, increases in radiative cooling and sensible and latent heat flux, occurring due to reductions in mixed‐layer temperature and vapour, allow cloud cover and LWP to recover to values like those found in simulations without absorbing aerosols. Copyright © 2006 Royal Meteorological Society.
Observations of the depth of ice particle evaporation beneath frontal cloud to improve NWP modelling
Authors: Forbes Richard M. , Hogan Robin J.
Published: June 2006

The evaporation (sublimation) of ice particles beneath frontal ice cloud can provide a significant source of diabatic cooling which can lead to enhanced slantwise descent below the frontal surface. The strength and vertical extent of the cooling play a role in determining the dynamic response of the atmosphere, and an adequate representation is required in numerical weather‐prediction (NWP) models for accurate forecasts of frontal dynamics. In this paper, data from a vertically pointing 94 GHz radar are used to determine the characteristic depth‐scale of ice particle sublimation beneath frontal ice cloud. A statistical comparison is made with equivalent data extracted from the NWP mesoscale model operational at the Met Office, defining the evaporation depth‐scale as the distance for the ice water content to fall to 10% of its peak value in the cloud. The results show that the depth of the ice evaporation zone derived from observations is less than 1 km for 90% of the time. The model significantly overestimates the sublimation depth‐scales by a factor of between two and three, and underestimates the local ice water content by a factor of between two and four. Consequently the results suggest the model significantly underestimates the strength of the evaporative cooling, with implications for the prediction of frontal dynamics. A number of reasons for the model discrepancy are suggested. A comparison with radiosonde relative humidity data suggests part of the overestimation in evaporation depth may be due to a high RH bias in the dry slot beneath the frontal cloud, but other possible reasons include poor vertical resolution and deficiencies in the evaporation rate or ice particle fall‐speed parametrizations. © Royal Meteorological Society, 2006. The contribution of R. M. Forbes is Crown copyright..
Simulations of low‐level convergence lines over north‐eastern Australia
Authors: Thomsen Gerald L. , Smith Roger K.
Published: June 2006

We describe high‐resolution numerical model simulations of low‐level convergence lines over north‐eastern Australia using the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5). The simulations are for selected events that were documented during the Gulf Lines Experiment, held in September–October 2002. The calculations provide further insights into the dynamics of the convergence lines and the mechanisms involved in their formation. In particular they show two clearly distinct convergence lines, one that corresponds to the morning glory and one which corresponds to the North Australian Cloud Line; the former originates from the east‐coast sea breeze over Cape York Peninsula south of about 14°S, while the latter originates from the east‐coast sea breeze north of this latitude. They support also a recently proposed conceptual model for the generation of southerly morning glories and show for the first time the separation of a bore‐like disturbance following the collision of a nocturnal cold front to the south of the inland trough with a sea‐breeze front to the north of the trough. Moreover, they show the progressive transition of the east‐coast sea‐breeze front and the inland cold front from gravity‐current‐like flows to bore‐like disturbances overnight to form north‐easterly and southerly morning glories, respectively. Copyright © 2006 Royal Meteorological Society.
An estimate of the global impact of multiple scattering by clouds on outgoing long‐wave radiation
Authors: Costa S. M. S. , Shine K. P.
Published: June 2006

Although the potential importance of scattering of long‐wave radiation by clouds has been recognised, most studies have concentrated on the impact of high clouds and few estimates of the global impact of scattering have been presented. This study shows that scattering in low clouds has a significant impact on outgoing long‐wave radiation (OLR) in regions of marine stratocumulus (−3.5 W m−2 for overcast conditions) where the column water vapour is relatively low. This corresponds to an enhancement of the greenhouse effect of such clouds by 10%. The near‐global impact of scattering on OLR is estimated to be −3.0 W m−2, with low clouds contributing −0.9 W m−2, mid‐level cloud −0.7 W m−2 and high clouds −1.4 W m−2. Although this effect appears small compared to the global mean OLR of 240 W m−2, it indicates that neglect of scattering will lead to an error in cloud long‐wave forcing of about 10% and an error in net cloud forcing of about 20%. Copyright © 2006 Royal Meteorological Society.
An improved implicit predictor–corrector scheme for boundary layer vertical diffusion
Authors: Diamantakis Michail , Wood Nigel , Davies Terry
Published: June 2006

Time integration of the parametrized boundary layer vertical diffusion in models of the atmosphere, used in numerical weather prediction (NWP) and climate modelling, can produce noise which appears as two‐time‐step oscillations in boundary layer tendencies. The origin of this noise was considered by Kalnay and Kanamitsu who analysed a number of schemes, two of which were based on a predictor–corrector approach. Here, a generalization of these two schemes is presented which results in unconditional stability for practical NWP vertical diffusion problems. The proposed generalization improves the stability of the original schemes. Asymptotic error analysis shows that this improvement is achieved without loss of accuracy, and that a small reduction in the leading error term is possible. Second‐order accuracy is feasible but in this case unconditional stability can be achieved only for linear or mildly nonlinear problems. Numerical experiments and model simulations support the analysis presented in this paper. The limitations and strengths of the scheme are exposed and suggestions for a practical implementation are made. This scheme is ideally suited as a component of a more general predictor–corrector algorithm for the problem of physics–dynamics coupling, for example that of Cullen and Salmond. © Crown copyright, 2006.