bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.