bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Structure of 9-Chloromethyl-1,4-dimethoxytriptycene and Its Implications for the Presence of O···CH2C1 Interactions
Authors: Tamura Yoshio , Takizawa Hiroo , Yamamoto Gaku , Oki Michinori , Murata Shigeru
Published: July 2006

Changing the substituent at the 4-position of 9-chloromethyl-1-methoxytriptycene shows that the nitro group increases the sc conformation whereas the methoxyl group favors the ap conformation in a relative sense, as judged from the 1H NMR spectra at low temperatures. Examination of rotational barriers, solvent effects, and thermodynamic parameters has not been able to distinguish three possibilities, O···CH2Cl interactions, head-to-tail arrangement of two dipoles, and van der Waals repulsions as a main cause for the observed population change. X-Ray crystallographic analyses of the title compound and related ones suggest that in the crystalline state the 1-methoxyl group in the title compound takes an anomalous conformation in which the group is nonplanar with the benzeno bridge. This feature was not observed in 1,4-dimethoxy-9-methyltriptycene. This structural feature is attibuted to the presence of O···CH2Cl interactions in the title compound and eliminates the van der Waals repulsion and the head-to-tail arrangement of two dipoles from being the main cause that favors the ap form.
Rearrangement of 3-(Trimethylsilylmethylthio)allyllithium
Authors: Miura Katsukiyo , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Proton abstraction from 3-trimethylsilylmethylthio-1-propene by butyllithium followed by treatment with iodomethane provided 1-methylthio-4-trimethylsilyl-1-butene. Meanwhile, 1-trimethylsilylmethylthio-2-butene afforded 3-methyl-4-methylthio-1-trimethylsilyl-1-butene upon successive treatment with butyllithium and iodomethane.
A New Amperometric Glucose Sensor Based on Bilayer Film Coating of Redox-Active Clay Film and Glucose Oxidase Enzyme Film
Authors: Ohsaka Takeo , Yamaguchi Yoshio , Oyama Noboru
Published: July 2006

A new amperometric glucose sensor based on bilayer film coating has been fabricated and its sensor characteristics under a steady-state condition have been examined. The electrode substrate was coated with two kinds of polymer films in a bilayer state, i.e., first with the redox-active montmorillonite clay film into which [Ru(NH3)6]3+ complexes are incorporated electrostatically and they function as an electron shuttle which delivers electrons to redox-active sites in the clay film, and then with the enzyme film consisting of bovine serum albumin and glucose oxidase (GOx). The glucose concentration could be monitored by measuring the current for H2O2 reduction electrocatalyzed by the inner clay film where H2O2 was produced by the glucose–GOx enzyme reaction in the outer enzyme film. The mechanism of the overall electrode/enzyme reaction for this amperometric glucose sensor is represented as follows:

(Remark: Graphics omitted.)

where reactions 1,2,3, and 4 correspond to the glucose–glucose oxidase enzyme reaction, the hydrolysis reaction of d-glucono-δ-lactone, the electrocatalytic reduction of H2O2 by the montmorillonite clay containing [Ru(NH3)6]2+ and the electrode reaction of the [Ru(NH3)6]2+⁄3+ couple, respectively. The reproducible relationship between glucose concentration and sensor output was obtained. The sensitivity and the dynamic range were found to depend on the amount of GOx confined in the enzyme film and its thickness.
NAD(P)+-NAD(P)H Models. 72. Isotope Effects to Prove the Multi-Step Mechanism in the Reduction with an NAD(P)H Analog
Authors: Goto Mutsuo , Mikata Yuji , Ohno Atsuyoshi
Published: July 2006

Reduction of 1,4-benzoquinone and its various derivatives with 1-benzyl-1,4-dihydronicotinamide (BNAH) and its 4-deuteriated derivative was studied. The kinetic deuterium primary isotope effect (kH⁄kD) for this reaction appears always larger than the isotopic ratio in the product, BNA+(YH⁄YD; product isotope effect). In the absence of magnesium ion, YH⁄YD increases as the substrate becomes less electron-demanding. In the presence of magnesium ion which accelerates the reaction, YH⁄YD stays small whereas kH⁄kD is not affected. The results reveal that the reaction proceeds with a multi-step mechanism in which the product-determining and rate-determining steps differ each other.
A Simple Synthetic Method of trans-5-Aryl and 5-Cyclopropyl Derivatives of 2-Isoxazolin-4-ol via Intramolecular Ring Opening of α,β-Epoxy Ketone Oximes
Authors: Ito Shoei , Sato Masahiro
Published: July 2006

trans-5-Aryl and 5-cyclopropyl derivatives of 2-isoxazolin-4-ol were conveniently prepared from trans-2-aryl- and 2-cyclopropyl-3-benzoyloxiranes and hydroxylamine hydrochloride in the presence of pyridine via an intramolecular opening of oxirane by the oxygen nucleophile of the oxyimino group.
Parity-Violating Energy Shift of Glycine, Alanine, and Serine in the Zwitterionic Forms: Calculation Using HFO-NG Basis Sets
Authors: Kikuchi Osamu , Wang Hui
Published: July 2006

The parity-violating energy shift, Epv, was calculated for glycine, alanine, and serine using the HFO-5G and -6G minimal basis sets, which were determined so as to well reproduce the behavior of an atomic orbital near the nucleus. A clear basis set dependence was observed in both the sign and magnitude of Epv. For the zwitterionic form of glycine, the HFO-5G and -6G calculations gave an Epv similar to that obtained by the (14,14/10) minimal basis set. For the most stable conformation of l-alanine, these basis set gave a negative Epv, indicating that l-alanine is more stable than d-alanine, while the split-valence basis sets gave positive values. It was shown that l-serine is lower in energy than d-serine due to the parity-violating interaction for almost the entire range of the C–C rotation angle.
1H NMR Studies of Motions in Solid (CH3)3CBr, (CH3)3CCl, and (CH3)3CNO2: Methyl Group and t-Butyl Group Uniaxial Reorientations
Authors: Hasebe Tooru
Published: July 2006

1H NMR line shapes and their second moments for t-butyl compounds {(CH3)3CX where X=Br, Cl, and NO2} have been studied as a function of temperature. It is shown that the methyl group and the t-butyl group uniaxial reorientations are distinguished by 1H NMR technique. The dipolar interactions modulated by these motions are reported in three cases: the first where methyl reorientation is fast while t-butyl reorientation is slow, the second where t-butyl reorientation is faster than methyl reorientation, and the third where both reorientations are in almost the same rate. The results obtained here are consistent with the results of 1H NMR relaxation studies reported previously.
Analysis of Molecular Motions in SiCl4 by 35Cl NQR Spectroscopy
Authors: Koukoulas Alexander A , Whitehead M A
Published: July 2006

The temperature dependence of the 35Cl nuclear quadrupole resonance frequencies, spin-lattice relaxation times and line widths were analyzed for the presence of a solid–solid phase transition in SiCl4. The brittle phase was verified to temperatures approaching the melting point. Evidence suggesting the formation of a plastic phase at elevated temperature is discussed.
Strong Thermochromic and Solvatochromic Effects of Ni(II) and Cu(II) Complexes in DMF/Nitromethane Mixtures: A Probe for Investigation of Binary Solvent
Authors: Bourdin D , Lavabre D , Béteille J P , Levy G , Micheau J C
Published: July 2006

Thermochromic and solvatochromic equilibria involving the ions [Ni(tmen)(acac)]+ and [Cu(tmen)(acac)]+ respectively are highly sensitive to the polarity of the solvent. These probes are thus suited for the study of binary mixtures. In nitromethane (NM)/dimethylformamide (DMF) binary solvent the Ni(II) complex displays strong thermochromism in a zone of low DMF concentration. This result is surprising because neither of the two solvents are intrinsically thermochromic since NM is a weak donor while DMF is a strong donor. NM/DMF binary mixtures behave like solvents with intermediate donor properties. In the same solvent mixtures (low DMF concentration), the solvatochromic behavior of the Cu(II) complex is reflected by a large shift in the maximum absorption of more than 70 nm. This was accounted for by the considerable variation in donor power of the solvent mixture in this concentration range. Quantitative analysis of the thermochromic and solvatochromic equilibria as a function of DMF concentration in NM indicated the existence of self-associations of DMF. The relatively small effects of dilution of DMF on the donor properties of the solvent mixture was explained in terms of the discharge of free DMF from self-associations with increasing dilution. In DCE, DMF self-associates to a greater extent than in NM.
Thermodynamics of Formation of Ternary (2,2′-Bipyridine)thiocyanatocadmium(II) Complexes in N,N-Dimethylformamide
Authors: Ishiguro Shin-ichi , Ozutsumi Kazuhiko , Yagasaki Atsushi
Published: July 2006

The formation of ternary (2,2′-bipyridine)thiocyanatocadmium(II) complexes has been studied by calorimetry in N,N-dimethylformamide containing 0.4 mol dm−3 (C2H5)4NClO4 as a constant ionic medium at 25 °C. The formation of [CdA(bpy)]+, [CdA2(bpy)], [CdA3(bpy)]−, [CdA(bpy)2]+, and [CdA2(bpy)2] (A=SCN, bpy=2,2-bipyridine) is revealed, and their formation constants, enthalpies, and entropies were obtained. The result is compared with that in the corresponding halide systems in the same solvent.
Synthesis of cis-transoid-cis- and cis-cisoid-cis-Tetracyclo[6.6.0.01,11.03,7]tetradecan-12-ones via Novel Rearrangement
Authors: Kakiuchi Kiyomi , Hirano Naoki , Shimizu Toshihiro , Suwa Mitsuhito , Kobiro Kazuya , Tobe Yoshito , Odaira Yoshinobu
Published: July 2006

A new type of tetracyclic compounds, cis-transoid-cis- and cis-cisoid-cis-tetracyclo[6.6.0.01,11.03.7] tetradecan-12-ones, having a tetraquinane framework, has been synthesized by the novel acid-catalyzed rearrangement.
Metal Nitrosyls as Antimicrobial Agents
Authors: Mishra Lallan , Pandey D S , Agarwala U C
Published: July 2006

Five known nitrosyl complexes of Fe and Co have been evaluated for their antiviral, antibacterial, and antifungal activities.
Efficient Activation of Acetals, Aldehydes, and Imines toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of [Rh(COD)Cl]2 and TMS-CN under Almost Neutral Conditions
Authors: Soga Tsunehiko , Takenoshita Haruhiro , Yamada Masaaki , Mukaiyama Teruaki
Published: July 2006

In the presence of a catalytic amount of a transition metal compound such as [Rh(COD)Cl]2, Co(acac)2, or NiCl2, trimethylsilyl cyanide smoothly reacts with acetals to form α-methoxy carbonitriles in good yields. In the coexistence of catalytic amounts of [Rh(COD)Cl]2 and TMS-CN, silyl enol ethers or ketene silyl acetals react with acetals, aldehyes, or imines to yield the corresponding coupling products in good yields under almost neutral conditions.
Effect of Heat Treatment of Hydrous Metal Oxides on Their Cation-Exchange Selectivity
Authors: Yamazaki Hiromichi , Kaneda Masakadzu , Inoue Yasushi
Published: July 2006

The effect of a heat treatment on the ion-exchange selectivity of hydrous metal oxides was studied by measuring the distribution coefficients of Cs+, Ba2+, Co2+, and Eu3+ on hydrous oxides of TiIV, SnIV, ZrIV, and NbV. The distribution coefficients decreased with increasing temperature for the heat treatment, except on hydrous Nbv oxide, in which the reverse effect was observed (except for Cs+). The decrease in the hydrous SnIVand ZrIV oxides is ascribed to a decrease in their ion-exchange capacity. In the case of hydrous TiIV and NbVoxides, the distribution coefficients were strongly affected by a change in the acidity of the most dissociable OH groups by the heat treatment. The selectivity of the exchangers has no direct correlation with the change in the porosity, the specific surface area and the density of the materials by the heat treatment.
NMR Studies on Reorientational Motion of Hydrated D2O Molecules in Tetraalkylammonium Bromide Dilute Aqueous Solutions
Authors: Shimizu Akio , Taniguchi Yoshihiro
Published: July 2006

The spin-lattice relaxation times of D and 17O nuclei of hydrated D2O molecules in tetraalkylammonium bromide (Me4NBr, Et4NBr, Pr4NBr, and Bu4NBr) dilute aqueous solutions in the concentration range of 0.2 to 1.0 mol kg−1 at 25°C were measured by NMR spectroscopy. The relaxation rates of D and 17O nuclei varied linearly with increasing the concentration below 1.0 mol kg−1. The dynamic hydration number, Bx+, is defined by Bx+=(k·τx+⁄τx0−1)nx+⁄50.0, where τx+ and τx0 (X=D or 17O) are the reorientational correlation times of hydrated D2O molecules (nx+) in R4N+ (R: alkyl group) and pure D2O molecule. The Bx+ increases with increasing the alkyl chain length of R4N+ ions. The abnormally large Bx+ values, compared with those of alkali metal ions, are caused by the hydrophobic hydration around the alkyl group of the R4N+ ion. The reorientational motion of a hydrated D2O molecule in the hydration sphere of R4N+ ions is isotropic, though the motion of a D2O molecule in the ionic hydration of alkali metal ions is anisotropic.
Effect of Poly(oxyethylene) Chain Length on Electrosorption of Hexa and Octa(ethylene glycol) Mono n-Dodecyl Ethers at the Polarized Nitrobenzene–Water Interface
Authors: Kakiuchi Takashi , Usui Taketoshi , Senda Mitsugi
Published: July 2006

The interfacial tension at the interface between a nitrobenzene solution of 0.1 mol dm−3 tetrapentylammonium tetraphenylborate and an aqueous solution of 0.05 mol dm−3 lithium chloride has been measured as a function of the applied voltage across the interface at 25°C in the presence of hexa- and octaethylene glycol monododecyl ethers, C12E6 and C12E8, in the nitrobenzene phase. Both C12E6 and C12E8 strongly adsorbed over the entire potential range of the polarized interface. The adsorption of C12E6 and C12E8 was stabilized by complex formation with Li+ ions in the aqueous phase, as is the case of C12E4 (T. Kakiuchi, T. Usui, and M. Senda, Bull. Chem. Soc. Jpn, 63, 2044 (1990).). The difference in the standard adsorption Gibbs energies between n=6 and 8, where n is the number of oxyethylene units, was twice as large as that between n=4 and 6, indicating that a chain length longer than 6 is preferable for the complex formation with Li+ ions at the interface. The surface activities of both C12E6 and C12E8 were markedly enhanced by a positive increase in the potential of the aqueous phase with respect to the potential in the nitrobenzene phase. This dependence of adsorption on the electrical potential difference indicates that the adsorbed C12E6 and C12E8 molecules behave as cationic surfactants, owing to the complex formation at the interface.
Divalent Cation-Induced Phase Transition of Phosphatidylserine Monolayer at the Polarized Oil–Water Interface and Its Influence on the Ion-Transfer Processes
Authors: Kakiuchi Takashi , Kondo Tetsuya , Senda Mitsugi
Published: July 2006

The phase properties of dipalmitoylphosphatidylserine(DPPS) monolayer at a polarized nitrobenzene–water interface have been studied by measuring the double-layer capacitance of the interface, Cdl, under precise control of the potential drop across the interface. When a saturated DPPS monolayer was in contact with an aqueous 0.1 mol dm−3 LiCl solution, the Cdl took a value of 9.5 μF cm−2. The presence of Ca2+ or Mg2+ at greater than 2 mmol dm−3 in the aqueous phase induced a decrease in Cdl down to 1.5 μF cm−2, corresponding to the phase transition of the monolayer from a liquid-expanded to a condensed phase. The condensed DPPS monolayer was stable against a change in the applied potential across the interface between ΔOWφ=−0.14 and 0.10 V, where ΔOWφ is the potential of the aqueous phase with respect to that in the nitrobenzene phase. Cyclic voltammetric measurements of ion transfer showed that the DPPS monolayer in the liquid-expanded state decreased the rate of ClO4− transfer from the aqueous to the nitrobenzene phase, but did not affect the rate of tetramethylammonium ion, TMA+, transfer. This indicates the importance of the electrostatic interaction between the negatively charged DPPS monolayer and the transferring ions in determining the rate of ion transfer across the monolayer. In contrast, the condensed monolayer significantly diminished the rates of ion transfer for both TMA+ and ClO4− ions, suggesting that the presence of the condensed monolayer altered the rate-determining step and that the condensed monolayer exerted an additional hydrodynamic friction on the ion-transfer processes.
Substituent Effects on the 1H, 13C, and 15N NMR Spectra of Substituted Benzanilides
Authors: Suezawa Hiroko , Yuzuri Tomoaki , Hirota Minoru , Ito Yoshio , Hamada Yoshiki
Published: July 2006

The 15N, carbonyl 13C, and amide 1H NMR spectra of a series of substituted benzanilides, XC6H4CONHC6H4Y, measured in four solvents of different polarity were correlated with the electronic effects of substituents by the use of the Hammett equation. Except for the 13C chemical shift vs. the σx plot, the ρ-values are positive, showing that the chemical shift tends to move down-field as the substituent becomes electron-withdrawing. Substituent effects could be assumed to arise from a cross conjugation of competing amide and benzoyl resonance structures perturbed via an inductive mechanism by the substituent on the anilino ring. The 15N chemical shifts of XC6H4CONHC6H5 can be expected to be correlated with the rotational barrier, since the down-field shift of the 15N chemical shift (in reference to unsubstituted) benzanilide was ascribed to a steric inhibition of the aryl-carbonyl conjugation. This trend is actually shown by a plot of the 15N chemical shift vs. the rotational barrier of a similarly substituted N,N-dimethylbenzamide. The NH group of 2-methoxy- and 2-chlorobenzanilides was shown to be intramolecularly hydrogen bonded with the ortho substituent (CH3O or Cl) by their 1H NMR and infrared NH spectra.
Structures of Hydrated Titanium and Vanadium Ions in Aqueous Solutions Studied by X-Ray Absorption Spectroscopy
Authors: Miyanaga Takafumi , Watanabe Iwao , Ikeda Shigero
Published: July 2006

The structures of titanium(III) and (IV), as well as vanadium(II), (III), and (IV) ions in aqueous solutions were investigated by the use of EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure). The TiIV ion in a sulfuric acid solution was found to form a–TiIV–O–TiIV–chain structure which is known to be present in the TiOSO4·2H2O crystal. The XANES spectrum of a mixed-valence complex, TiIII–IV, in solution agrees with the sum of the individual XANES spectra of TiIII and TIIV, indicating a retention of individual oxidation states and coordination structures. While the peaks pertaining to Ti–Ti and V–V interactions were observed in the EXAFS Fourier transform spectra for TiIV in a sulfuric acid solution and for VIII in a hydrochloric acid solution, the mixed-valence complex, TiIII–IV, did not show the T1–Ti peak.
Photoelectrochemical Properties of Thin Films of Cadmium, Zinc, and Magnesium Porphyrins with Pyridyl Group
Authors: Takahashi Kohshin , Katsurada Hisashi , Komura Teruhisa , Imanaga Hiroto
Published: July 2006

Cadmium and zinc porphyrins with pyridyl or aminophenyl group gave smaller activation energy for the transfer of the carriers photoproduced in the solid thin film and larger cathodic photocurrent in quinhydrone solution than tetraphenylporphyrinato-cadmium and -zinc. The properties may be ascribed to the molecular arrangement of the porphyrins in the film.
2,6-Bis[N-(8-quinolyl)carbamoyl]pyridine as a Highly Selective Extractant for Cu(II)
Authors: Hiratani Kazuhisa , Taguchi Kazuhiro
Published: July 2006

Pyridine derivatives containing two 8-quinolyl-amino groups were newly synthesized for heavy metal ion-cheletion. It was shown in solvent extraction that 2, 6-bis[N,N′-(8-quinolyl)aminocarbonyl]pyridine can extract only Cu(II) with excellent selectivity and efficiency from the aqueous phase(pH 6.2) containing Cu(II), Ni(II), Co(II), and Zn(II) into the chloroform phase.
Photochemical Properties of TiO2 Microcrystallites Prepared in Nafion
Authors: Miyoshi Hirokazu , Nippa Satoru , Uchida Hiroyuki , Mori Hirotaro , Yoneyama Hiroshi
Published: July 2006

TiO2 microcrystallites of different sizes were prepared in Nafion and the energy diagrams of these were determined from the onset potential of photocurrents due to oxidation of tartrate ions and the bandgap energy which was estimated from absorption spectra. The smallest particle prepared in the present study had the diameter less than 2 nm and the bandgap energy of 3.95 eV. Photocatalytic activities of the TiO2 microcrystallites prepared in Nafion for photodecomposition of acetic acid were very low compared to those of TiO2 microcrystallites prepared in clay interlayers and were comparable to those of the latter photocatalysts obtained in the presence of SO42−, suggesting that sulfonate groups of Nafion made the photocatalytic activity of TiO2 microcrystallites decrease.
EPR Investigation of the Binuclear Copper(II) Complexes with 3,12-Bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioic Acid
Authors: Kawata Satoshi , Yokoi Hiroshi , Iwaizumi Masamoto
Published: July 2006

Binuclear copper(II) complexes of 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioic acid have been investigated by EPR. It has been confirmed that three different binuclear complexes are formed, depending on the pH of the solution. The complex formed in the low pH region has a copper–copper distance of 5.5 Å and a weak magnetic dipolar interaction. The other two are of olated forms with strong magnetic interactions between the copper atoms through oxygen bridges. One of them has an antiferromagnetic interaction; though the other has a weak antiferromagnetic interaction, it shows a large zero-field splitting. Such differences between the magnetic properties of the two olated complexes are attributed to a difference in the bridged style, i.e., the former is a mono-μ-hydroxo-bridged complex and the latter is a double-μ-hydroxobridged complex.
An X-ray Diffraction Study on Zinc(II) Complexes with α-Alaninate Ion in Aqueous Solution
Authors: Radnai Tamas , Inoue Kenta , Ohtaki Hitoshi
Published: July 2006

The structures of mono(α-alaninato)zinc(Il), bis(α-alaninato)zinc(II), and tris(α-alaninato)zincate(II) complexes in aqueous solutions were determined by the X-ray diffraction method. All the three complexes have the octahedral structure in the form [Zn(α-ala)(H2O)4]+, [Zn(α-ala)2(H2O)2], and [Zn(α-ala)3]−. The structures of the complexes were different from those of the glycinato complexes of zinc(II) ion, which were all regular octahedral. The length of the Zn–O bond in the α-alaninato complexes was shorter than that of the Zn–N bond due to the inductive effect of the substituted methyl group at the α-carbon on the oxygen atom in the amino acid. The lengths of the Zn–O and Zn–N bonds in the complexes determined are, respectively, as follows: [Zn(α-ala)(H2O)4]+, 202 and 214 pm; [Zn(α-ala)2(H2O)2], 203 and 214 pm; [Zn(α-ala)3]−, 202 and 213 pm.
Synthesis and Characterization of Palladium(II) and Platinum(II) Complexes Containing Monodentate Phosphorus Donating or Chelating 2-(Dimethylphosphino)pyridine (PMe2py)
Authors: Suzuki Takayoshi , Kita Masakazu , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

The complexes [MX2(PMe2py-P)2] (M=Pd(II), Pt(II); X=Cl, Br, and I) have been synthesized and characterized both in the solid state and in solution by their infrared and 1H, 13C, and 31P NMR spectra, in addition to an X-ray crystallographic analysis of cis-[PdCl2(PMe2py-P)2]. The latter complex exists as a cis–trans equilibrium mixture in solution, while only the cis isomer has been isolated in the solid state. The [PdBr2(PMe2py-P)2] complex which has been isolated as the trans isomer shows also the same isomerization in solution, in contrast to [PdBr2(PMe2Ph)2] which exists only as the trans isomer both in the solid state and in solution. Furthermore, PMe2py has been found to have the ability for chelation via the nitrogen and phosphorus atoms to make a four-membered chelate ring. The chelate ring in the complexes [PdX(PMe2py)2]Y (X=Cl, Br, and I; Y=ClO4−, PF6−) has been confirmed by infrared spectra and X-ray analysis of cis(P,P)-[PdCl(PMe2py-P,N)(PMe2py-P)]ClO4. This is the first example in which PMe2py is acting as a chelating ligand.
Preparation of 14-, 18-, and 22-Membered Tetraaza Macrocycles and Their Complexing Ability for Copper(II) and Nickel(II) Ions
Authors: Fujiwara Manabu , Wakita Hisanobu , Matsushita Takayuki , Shono Toshiyuki
Published: July 2006

14-,18-, and 22-membered tetraaza macrocycles have been prepared by the reaction of acetylacetone with ethylenediamine, 1,4-butanediamine, or 1,6-hexanediamine, respectively. Their copper(II) and nickel(II) complexes were characterized by electronic and infrared spectroscopies. The 14-membered macrocycle forms a mononuclear copper(II) complex with a planar structure, whereas the 18-membered macrocycle forms a mononuclear copper(II) complex with a pseudo-tetrahedral structure, and the 22-membered macrocycle forms di- and trinuclear copper(II) complexes. The complexation and extraction abilities of these macrocycles toward copper(II) and nickel(II) ions are discussed.
Synthesis and Properties of a Heterodetic Cyclic Peptide: Gramicidin S Analog Containing Disulfide Bond
Authors: Satoh Ken-ichi , Okuda Hirofumi , Horimoto Hideaki , Kodama Hiroaki , Kondo Michio
Published: July 2006

In order to investigate the relationship between the structure of a peptide backbone and the formation of an intramolecular disulfide bond (S–S) in the peptide, a linear analog (1) of gramicidin S and a heterodetic cyclic peptide containing an S–S bond (2) were synthesized by the conventional solution method. Since a disulfide bonded compound (2) was easily formed by a treatment of the acetamidomethyl(Acm)-protected linear peptide (1) with iodine in good yield (70%), it is suggested that the mutual position between Cys1 and Cys8 residues becomes approximate, owing to the contribution of –d-Phe–Pro– part of the sequence. A heterodetic cyclic peptide (2) showed about 1/16–1/8 fold activity compared to that of GS; 1 as inactive. By the construction of an S–S bridge on the peptide backbone (1), an inactive peptide derivative was effectively converted to an active analog (2). The CD spectrum pattern also suggests that the heterodetic cyclic peptide (2) has a GS-like structure.
Stereoselectivity in the Oxidation of 5-Thioglucose Derivatives with 3-Chloroperoxybenzoic Acid
Authors: Yuasa Hideya , Takenaka Akio , Hashimoto Hironobu
Published: July 2006

5-Thio-α-d-glucopyranose derivatives were oxidized with 3-chloroperoxybenzoic acid in various conditions to give axial and equatorial sulfoxides. Structure of an axial sulfoxide obtained was determined by X-ray crystallography. Configuration of other sulfoxides was determined by 1HNMR spectroscopy according to empirical rules of chemical shift. The anomeric substituent was decisive for the stereoselectivity and the ratios of axial to equatorial sulfoxide were 3–11.5 for methoxy derivatives and 0.4–1.0 for acetoxy derivatives.
“pKa” of Calixarenes and Analogs in Nonaqueous Solvents
Authors: Araki Koji , Iwamoto Koji , Shinkai Seiji , Matsuda Tsutomu
Published: July 2006

The acid dissociation constants (Kapp) of p-t-butylcalix[n]arenes (1n: n=4, 6, and 8), O-methylated p-t-butylcalix[4]arene (2Men), and their noncyclic analogs (3n) were estimated in THF at 25°C. As pH indicators, Et4N+ salts of p-nitrophenolate, 2,4-dinitrophenolate, and picrate were employed. The pKapp values for 1n were lowered by at least four pK units from that of p-t-butylphenol because of strong intramolecular hydrogen-bonding interactions. Compounds 2n involved both the strong and weak hydrogen bonds: the proton in the strong hydrogen bond showed the acidity comparable with that of 1n whereas that in the weak hydrogen bond showed the relatively high pKapp. These properties were discussed in relation to δOH (chemical shift in 1HNMR) and νOH(OH vibration band in IR). This is the first systematic discussion on “pKa” of p-t-butylcalix[n]arenes.
Solution Behavior of Sodium Dodecyl Sulfate in Methanol
Authors: Miyata Isamu , Takada Akira , Yonese Masakatsu , Kishimoto Hiroshi
Published: July 2006

The electric conductivities of sodium dodecyl sulfate (SDS) in methanol and water were measured at 298 K in a concentration range up to 10 mmol dm−3. The values of the limiting molar conductivities of SDS, Λ0, in methanol and water were estimated to be 81.5 and 74.0 S cm2mol−1, respectively, and compared with each other. From those values and the values of NaCl in both solvents, the limiting molar conductivities of dodecyl sulfate ion in methanol and water were estimated to be 36.27 and 23.90 S cm2mol−1, respectively. Also, the vapor-pressure depression of SDS in methanol was measured at 298 K in the concentration range up to 42 mmol kg−1. From the results, and according to the theory regarding strong electrolytes, the mean ionic activity coefficient, γ±, of SDS in methanol at 298 K was calculated. Further, the solubility and heat of solution of SDS in methanol at various temperatures and at 298 K, respectively, were measured. From a thermodynamic analysis of these results, the theoretical relation between lnγ± and m was obtained over the range of temperatures 285–295 K.
Cooperative Effect of Lipophilic Amine and Neutral Crown Ether on Potassium Ion Active Transport through a Chloroform Membrane
Authors: Yoshida Shoichiro , Watanabe Tadashi
Published: July 2006

A competitive proton-driven transport of alkali metal ions with co-transported picrate anion was investigated in a chloroform membrane system containing either dicyclohexano-18-crown-6 (DCl8C6), octadecylamine (C18NH2), or a DCl8C6/C18NH2 mixture as cooperative carrier. The cooperative carrier effectively transported K+ against its concentration gradient between the two aqueous phases. The DCl8C6 alone, though being a proton-unionizable carrier, also mediated the uphill transport of K+ when the receiving phase was strongly acidic. The mechanisms for these transport behaviors are discussed referring to additional data on the partitioning of species at membrane/aqueous phase interfaces.
Restricted Rotation Involving the Tetrahedral Carbon. LX. peri-Substituent Effect on the Rotational Barrier of the 9-Methyl Group in Several Triptycene Derivatives
Authors: Yamamoto Gaku , Oki Michinori
Published: July 2006

Dynamic 1H NMR study was made on several 1-substituted 8,13-dichloro-9-methyltriptycenes and 8-chloro-13-fluoro-9-methyltriptycenes to examine the effect of the peri-substituents on the rotational barrier of the 9-methyl group. The rotational barrier height increases in the expected order as the 1-hydrogen is replaced by a bulkier group up to CH3, but shows a very low value when a t-butyl group is introduced into 1-position to show that destabilization of the ground state by the bulky t-butyl group exceeds that of the transition state for rotation.
Molecular Dynamics Calculation for the Complexes of a Macrotricyclic Receptor with Organic Substrates
Authors: Kimoto Hiroki , Saigo Kazuhiko , Kihara Nobuhiro , Ohno Mami , Hirano Tsuneo , Hasegawa Masaki
Published: July 2006

Molecular dynamics calculation was performed in order to obtain structural information about the complexes of a macrotricyclic receptor (1), which has crown ether and cyclophane subunits as binding sites, with organic substrates, ω-(phenylalkyl)ammonium picrates (2; the methylene number, n=4, 5, 7), taking account of solvent effect. The resulting equilibrium structures were in good agreement with experimental data; among the three complexes, the complex of 1 with 2 (n=5) gave the largest stability constant. Furthermore, the quantitative evaluation of the difference in Gibbs free energy between two complexes, calculated by the perturbation method, was also consistent with the experimental data.
Some Properties of Cyclopropenone Oximes under Beckmann Reaction Conditions
Authors: Yoshida Hiroshi , Yoshida Keisuke , Totani Hiroyuki , Ogata Tsuyoshi , Matsumoto Kiyoshi
Published: July 2006

The reaction of diphenylcyclopropenone oxime (1a) with acetyl or tosyl isocyanate, carboxylic anhydrides, or nitrohalobenzenes yielded the cyclopropenone O-substituted oxime derivatives. Treating with thionyl bromide and chloride 1a gave 3-haloacrylonitriles. Whereas 1a as well as other cyclopropenone oximes, were stable under acidic conditions, heating in methanolic sodium hydroxide gave the ring-opened α,α-dimethoxyketones oximes.
Synthesis of Pyrrole Derivatives from 5,6-Dihydro-4H-1,2-oxazines via Reductive Deoxygenation by Use of Fe3(CO)12
Authors: Nakanishi Saburo , Otsuji Yoshio , Itoh Keiji , Hayashi Nobuaki
Published: July 2006

α-Bromooximes such as α-bromoacetophenone oxime and ethyl 3-bromo-2-(hydroxyimino)propanoate react with enamines to give 5,6-dihydro-4H-1,2-oxazines in good yields. Dihydro-1,2-oxazine derivatives are also obtained by the reaction of α-bromooximes with vinyl ethers and silyl enol ethers in the presence of Na2CO3. Dihydro-1,2-oxazines can be converted into pyrrole derivatives via reductive deoxygenation by treating with Fe3(CO)12 in moderate to excellent yields. Iron carbonyl complexes other than Fe3(CO)12 are also effective for the pyrrole-forming reaction. The efficiency of the complexes for this reaction decreases in the order: Fe3(CO)12>>Et3NH[HFe3(CO)11]>Fe2(CO)9>>Fe(CO)5. Both of the dihydro-1,2-oxazine- and pyrrole-forming reactions can be carried out in a single flask, giving pyrrole derivatives in good yields.
Optical Resolving Ability of 3,5-Dimethylphenylcarbamates of Oligosaccharides and Cyclodextrins
Authors: Aburatani Ryo , Okamoto Yoshio , Hatada Koichi
Published: July 2006

3,5-Dimethylphenylcarbamates of oligosaccharides and cyclodextrins were synthesized and their chiral recognition abilities were evaluated as chiral stationary phases for high-performance liquid chromatography. In case of the carbamates of linear maltooligosaccharides, the optical resolution abilities of 4–7-mer were similar to each other and were not so different from the ability of amylose tris(3,5-dimethylphenylcarbamate). The chiral recognition abilities of the carbamates of cellooligosaccharides were lower than that of the cellulose tris(3,5-dimethylphenylcarbamate). The intensities of the CD spectra of the cellooligosaccharide derivatives were smaller than that of the cellulose derivative. These results suggest that the less ordered structure of the cellooligosaccharide derivatives may be correlated to the lower chiral recognition. On the other hand, 3,5-dimethylphenylcarbamates of cydodextrins showed quite different optical resolution abilities from that of amylose tris(3,5-dimethylphenylcarbamate), probably because of a quite different high-order structure.
Boron Analogues of α-Amino Acids: Synthesis and Characterization of Some Amine-methoxycarbonylboranes and Trimethylamine-(alkylcarbamoyl)boranes
Authors: Das Mrinal K , Mukherjee Purnendu , Roy Sarbari
Published: July 2006

Syntheses of a number of amine-methoxycarbonylboranes R2−nHnN·BH2COOCH3 and trimethylamine-(alkylcarbamoyl)boranes, Me3N·BH2CONRR′ are reported. Both types of compounds have been prepared by condensing appropriate amine-carboxyboranes with methanol and an amine, respectively, in presence of dicyclohexylcarbodiimide, and have bean characterized by elemental analysis, IR and NMR (1H and 11B) spectra.
Anodic Voltammetry of Hydroxylamine at Rotating Disc Electrode of Platinum
Authors: Sultan Salah M , Bishop E
Published: July 2006

Hydroxylamine has been examined by anodic voltammetry at platinum electrode in sulphuric acid media. Obedience to Levich relationship was shown at platinum electrode in 0.01 M sulphuric acid concentration in the range 2.0×10−4 to 1.0×10−3 M, (M=mol dm−3). Electrode kinetics parameters have been evaluated and a possibility of the reaction mechanism path is suggested.
Substituent Effects on the Electronic Absorption and MCD Spectra of Five- and Six-Coordinate Nitrosyl(tetraphenylporphyrinato)iron(II) Complexes
Authors: Yoshimura Tetsuhiko
Published: July 2006

Electronic absorption and MCD spectra of five- and six-coordinate nitrosyl iron(II) complexes of a series of tetrakis(para-substituted phenyl)porphyrins have been investigated in order to elucidate the cis-effect of para-substituents. The MCD spectroscopy was more sensitive to the substituent effect than the electronic absorption spectroscopy.
Cis/Trans Isomerization of Thioindigo Derivatives Adsorbed on Silica Gel Modified with Octadecyl Groups
Authors: Fukunishi Koushi , Tatsuma Masahiko , Fatah Ur Rahman S M , Kuwabara Masaki , Yamanaka Hiroki , Nomura Mototeru
Published: July 2006

A photochromic behavior based on the cis/trans isomerization of thioindigo derivatives (I) adsorbed on alkylated silica gel is described. The reversible cis/trans isomerization of I in the adsorbed state can be induced by irradiation, and the signal is read out as fluorescence. The thermal cis-to-trans isomerization of I adsorbed on modified silica gel is extremely slow, compared with that obtained on untreated silica gel.
Temperature Effect of the High-Pressure Diels–Alder Reaction of Tropone with Acrylonitrile
Authors: Li Zhi-Hong , Mori Akira , Takeshita Hitoshi
Published: July 2006

The high-pressure (to 10000 bar) Diels–Alder reaction of tropone with acrylonitrile showed temperature-dependent product distributions: at 80 °C, the product distribution was very similar to that obtained under atmospheric pressure to give four products, among which 9-endo-cyanobicyclo[3.2.2]nona-3,6-dien-2-one, in 38% yield, was the major product, while at room temperature there were only three products, i.e., 8-endo-, 9-endo-, and 9-exo-cyano derivatives. The absence of the 8-exo-cyano derivative might be due to an electrostatic repulsive interaction of cyano and carbonyl groups in the transition state geometry.
Synthesis and Conformational Properties of 2-Carboxy-15-crown-5 and Its Cation Complexes
Authors: Takahashi Toshio , Mallen Jesus , Lorenzo Dalia , Khanna Raj K , Nishikawa Masanori , Gokel George W
Published: July 2006

2-Carboxy-15-crown-5 has been prepared by potassium permanganate oxidation in modest yield. Its native conformation has been assessed by using infrared, NMR, and both MM2′ and MNDO calculations. Neutral cation complexes (of the form crown-COOH.MX) of this macrocycle with NaCl, NaBr, NaI, KCl, and CaCl2 have been prepared and studied. It is concluded that the carbonyl oxygen atom is a donor for the ring bound cation, an observation supported by the calculated lowest energy conformation of the non-complexed macrocycle.
Synthesis and β-Lactamase Inhibitory Activity of 3-Cyano-3-cephem Derivatives
Authors: Nishimura Shintaro , Yasuda Nobuyoshi , Sasaki Hiroshi , Matsumoto Yoshimi , Kamimura Toshiaki , Sakane Kazuo , Takaya Takao
Published: July 2006

Two new 3-cyano-3-cephem derivatives, potassium 3-cyano-3-cephem-4-carboxylate (2) and potassium 7α-phenylacetamido-3-cyano-3-cephem-4-carboxylate (3), were prepared from 7β-aminocephalosporanic acid. Compounds 2 and 3 showed only weak β-lactamase inhibitory activity in contrast to sodium 7α-[(1R)-1-hydroxyethyl]-3-cyano-3-cephem-4-carboxylate (1), indicating the important role of the 7α-(1-hydroxyethyl) substituent for β-lactamase inhibitory activity.
A Convenient Synthesis of 1,2,4-Tri-O-acetyl-5-deoxy-5-[(R)- and (S)-ethylphosphino and phenylphosphino]-3-O-methyl-α,β-d-xylopyranoses and Their Phosphinothioyl Derivatives
Authors: Hanaya Tadashi , Shigetoh Nobuyuki , Yamamoto Hiroshi , Armour Margaret-Ann , Hogg Alan M
Published: July 2006

1,2,4-Tri-O-acetyl-5-deoxy-5-[(R)- and (S)-ethylphosphinyl]-3-O-methyl-α,β-d-xylopyranoses (8a–d) were prepared from 5-deoxy-5-[(R)- and (S)-(ethoxy)ethylphosphinyl]-1,2-O-isopropylidene-3-O-methyl-α-d-xylofuranoses in two steps. Reduction of 8a–d and their 5-(phenylphosphinyl) congeners with trichlorosilane- triethylamine in benzene smoothly afforded the corresponding title 5-deoxy-5-phosphino-d-xylopyranoses (9a–d and 14a–d) without causing inversion of the ring-phosphorus atom. Treatment of 9a–d and 14a–d with sulfur in benzene efficiently provided the corresponding (phosphinothioyl)-in-ring d-xylopyranoses. Structural and conformational assignments of these newly obtained compounds were made on the basis of mass and NMR (1H and 31P) spectral data.
Michael Addition of Methyl 2-(Trimethylsilyl)propenoate with Organomagnesiums or Organolithiums Leading to 1:1 and/or 2:1 Adducts and Subsequent Peterson Olefination by Condensation with Carbonyl Compounds
Authors: Tanaka Junji , Kanemasa Shuji , Ninomiya Yusuke , Tsuge Otohiko
Published: July 2006

Michael addition of methyl 2-(trimethylsilyl)propenoate with organomagnesiums or organolithiums leads to 1:1 and/or 1:2 adduct anions which can be utilized in the subsequent step of Peterson olefination with carbonyl compounds. The 1:1/1:2 ratio depends upon the nature of donor molecules, the reaction conditions such as reaction temperature, polarity of solvent, and rate of addition of the acceptor molecule. Use of acceptors in excess results in the selective formation of 1:2 and/or 1:3 adducts.
Lewis Acid-Promoted Cross Aldol Reaction of Aldehydes with Ketones Utilizing 3-Methyl-2-phenyl-2-(2-oxoalkyl)benzothiazolines as an Enolate-Transferring Reagent
Authors: Chikashita Hidenori , Tame Shin-ichiro , Yamada Seiji , Itoh Kazuyoshi
Published: July 2006

The treatment of a variety of 3-methyl-2-phenyl-2-(2-oxoalkyl)benzothiazolines with aldehydes in the presence of 2 equivalents of SnCl4 in dichloromethane at −78°C underwent a carbon–carbon bond cleavage at the 2-position of the benzothiazoline ring releasing an 2-oxoalkyl moiety followed by the concurrent aldol-type reaction with aldehydes to afford the corresponding β-hydroxy ketones. Among the Lewis acids examined, SnCl4 was found to be most effective, while a similar reaction employing trimethylsilyl trifluoromethanesulfonate as an electrophilic promoter mainly gave the corresponding aldol-condensation product. In the case of the reaction with 3-methyl-2-phenyl-2-(1-substituted 2-oxoalkyl)benzothiazolines, a diastereomeric mixture of α-substituted β-hydroxy ketones as cross aldol products was obtained and the anti preference was generally observed for reactions with the benzothiazolines possessing an aromatic ketone moiety in modest to poor selectivity ranging between 69:31 and 57:43. In contrast to this, the reaction of the benzothiazoline possessing an alkyl ketone moiety, 3-methyl-2-phenyl-2-(1-methyl-2-oxobutyl)benzothiazoline, with benzaldehyde showed syn preference in modest selectivity of 70:30.
The Kinetics of Oxidation of Formaldehyde at a Platinum Electrode in an Acid Solution
Authors: Matsui Hiroshi , Kunugi Akira
Published: July 2006

Three types of the retardation were found for the rate of oxidation of formaldehyde at a platinum electrode in 0.5 mol dm−3 sulfuric acid. These rate retardations are attributed to the blocking of individual reaction sites by strongly chemisorbed species, the inhibition of the pairing of adjacent sites indispensable for the oxidation of formaldehyde, and the accumulation of oxidation intermediates. The oxidation rate under conditions excluding these rate retardations was independent of the potential in the potential range of about 0.4–0.6 V vs. a reversible hydrogen electrode and corresponded to first-order kinetics with respect to the formaldehyde concentrations. These kinetic data are explained in terms of a slow adsorption of formaldehyde molecules.
ESR Studies of the Adsorption Behavior of Styrene–Methyl Methacrylate Copolymer at the Solid–Liquid Interface
Authors: Kobayashi Kazutoshi , Araki Kazuo , Imamura Yoshio , Endo Ryuichi
Published: July 2006

The conformation of the copolymer of styrene and spin-labeled methyl methacrylate adsorbed on nonporous silica from solution was investigated by the use of the ESR method. The attached segment fraction of methyl methacrylate, PMMA, in the copolymer was evaluated experimentally. The attached segment fraction of styrene, PST, and the total attached segment fraction, PTOT, in the copolymer were estimated by means of numerical calculations from the value of PMMA. The amounts of saturated adsorption, AS, were obtained as a function of the mole fraction of styrene in the copolymer. The AS values of the copolymers through the mole fractions of styrene of 0.8 increased slightly with the mole fraction of styrene. The AS values of the copolymers at the mole fractions of styrene in excess of 0.8 decreased steeply to that of the styrene homopolymer. The change in the AS values of the copolymers was explicable in terms of the changes in the values of the surface coverage and the values of PTOT. The adsorbed methyl methacrylate homopolymer had a flat conformation, whereas the adsorbed styrene homopolymer had a loopy conformation. When the styrene content in the copolymer increased, the adsorbed conformations of the copolymers varied gradually from the conformation of the methyl methacrylate homopolymer to that of the styrene homopolymer.
Diffusion of Polar and Nonpolar Molecules in Water and Ethanol
Authors: Tominaga Toshihiro , Matsumoto Shigetoshi
Published: July 2006

Interdiffusion coefficients of 1,2-butanediol, 1,4-butanediol, meso-erythritol, xylitol, mannitol, and myo-inositol in water, and of 1-butanol, 1,2-ethanediol, 1,2-butanediol, 1,4-butanediol, 1,2,3-propanetriol, water, and benzene in ethanol have been measured at concentrations close to infinite dilution and temperatures between 278 and 373 K. In water, activation energies are not sensitive to the solutes, decrease with increasing temperature, and are close to that for the self-diffusion of pure water. In ethanol the activation energy is largest for water and smallest for benzene. The quantity Dη⁄T (D, η and T are diffusivity, viscosity, and absolute temperature, respectively) is not sensitive to temperature in water, but shows strong dependence on the temperature for benzene and water in ethanol. Using the corrected Stokes–Einstein equation, the effective radii of the solutes were obtained in ethanol. Some differences in diffusion behavior in ethanol and water are discussed.
A Linear Relationship between the Glass Transition Temperature and Local Distortion of Calcium Gallate, Barium Gallate, and Calcium Aluminate Glasses
Authors: Nishida Tetsuaki , Ide Hiroshi , Takashima Yoshimasa
Published: July 2006

The isomer shift in the 57Fe-Mössbauer spectra of xCaO·(90−x)Ga2O3·10Fe2O3 (x=40–60) and xBaO ·(90−x)Ga2O3·10Fe2O3(x=65–70) glasses decreases gradually from 0.28 to 0.16 mm s−1 with increasing CaO or BaO contents. This indicates a formation of nonbridging oxygen atoms in the GaO4 and FeO4 tetrahedra. Large quadrupole splitting (Δ) values ranging from 0.98 to 1.24 mm s−1 indicate a noticeable distortion of the GaO4 and FeO4 tetrahedra. Mössbauer parameters of xCaO·(95−x)Al2O3·10Fe2O3 glasses (x=55–60) are comparable to those of the xCaO·(90−x)Ga2O3·10Fe2O3 glasses, suggesting that the local structures are essentially the same with each other. The glass transition temperatures (Tg) of the calcium gallate, barium gallate, and calcium aluminate glasses are 702–728, 580–583, and 750–773 °C, respectively. It is found that the Tg of several oxide glasses is proportional to the Δ, being expressed by Tg=aΔ+b, where “a” is 680 °C mm1 s and “b” is −180°C when the Fe3+ ions are present at substitutional sites of the network former (NWF). The “Tg–Δ rule” is also applicable to the Fe3+ ions present at interstitial sites, in which case “a” and “b” are 35°C mm−1 s and 260°C, respectively. These findings indicate that the Tg is primarily determined by the distortion of NWF–oxygen polyhedra.