bluuebunny/crossref_metadata_2025 huggingface dataset:
Multielement Determination of Trace Elements in Coastal Seawater by ICP-MS and ICP-AES after Aluminum Coprecipitation Associated with Magnesium
Authors: Sawatari Hideyuki , Hayashi Toshio , Fujimori Eiji , Hirose Akio , Haraguchi Hiroki
Published: June 2006

An analytical method for multielement determination of trace and ultratrace elements in seawater has been investigated by using ICP-MS. Trace and ultratrace elements were preconcentrated by 10- or 20-times with addition of aluminum into seawater and then the elements were determined by ICP-MS. In this procedure, aluminum was added as the carrier for coprecipitation; it precipitated together with magnesium in seawater. Some trace elements were also measured by ICP-AES after coprecipitation. In addition, major and minor elements in seawater were determined by ICP-AES after dilution with acidified water. As the result, 37 elements in total could be determined in coastal seawater. The present results are compared with the concentrations of the elements in open seawater.
Coordination of 2,5-Dihydroxy-p-benzoquinone to Nickel(II) Ion
Authors: Miyoshi Hirokazu , Mihara Hiroki , Kanda Seiichi
Published: June 2006

2,5-Dihydroxy-p-benzoquinonatonickel(II) [dhqNi(II)] coordination polymer was carefully prepared from 2,5-dihydroxy-p-benzoquinone (L) and anhydrous nickel(II) chloride. The elemental and thermal analyses indicate two coordinated and one additive water molecules in the dhqNi(II) complex. A strong peak in IR spectrum at 3330 cm−1 and a shoulder at 1660 cm−1attributed to O–H stretching vibration were detected. The paramagnetic moment of the complex, μeff = 2.94 μB, was calculated from the observed susceptibility. Consequently, dhqNi(II) coordination polymer seemed to be D4h structure, where Ni was coordinated by two ligand water molecules and four oxygen atoms from two ligand (dhq2−) molecules.
Synthesis and Characterization of Monomeric (Aryloxo)iron Complexes: [FeIIL(OAr)] and [FeIIIL(OAr)2] {L = BH(3,5-Pri2pz)3−}
Authors: Ito Masami , Amagai Hironobu , Fukui Hideno , Kitajima Nobumasa , Moro-oka Yoshihiko
Published: June 2006

A series of (aryloxo)iron(II) complexes [Fe{BH(3,5-Pri2pz3}(OAr)] (Ar = C6H5 (4); C6H4-p-Cl (5); C6H4-p-F (6); C6H4-p-Me (7); C6H3-2,6-Cl2 (8); C6F5 (9)) were synthesized by the anion ligand replacement of [Fe(Cl){BH(3,5-Pri2pz)3}] (1) with NaOAr. Crystallography was performed for 1 and 9. All these tetrahedral (aryloxo)iron(II) complexes react with dioxygen readily, to afford the bis(aryloxo)iron(III) complexes [Fe{BH(3,5-Pri2pz)3}(OAr)2] (Ar = C6H5 (10); C6H4-p-Cl (11); C6H4-p-F (12); C6H4-p-Me (13); C6H3-2,6-Cl2 (14); C6F5 (16)) as sole isolable products (the maximum yield based on the iron(II) complex was ca. 50%). The MeCN adduct of 13 was structurally characterized by X-ray crystallography.
Detection Method Based on a Surface Plasmon Resonance and Its Application to Flow Injection Analysis and Liquid Chromatography
Authors: Wu Xing-Zheng , Nakagawa Masamitsu , Nagamori Chiaki , Uchiyama Katsumi , Hobo Toshiyuki
Published: June 2006

A simple surface plasmon resonance (SPR) experimental set-up has been made for investigating further applications of the SPR detection method in analytical chemistry. In the home-made SPR experimental set-up, a Ag film with a thickness about 50 nm was deposited on the flat surface of a hemicyclindrical prism, and a flow cell was attached directly to the flat surface of the prism. It has been confirmed that SPR occurred in the experimental setup using model samples of water and alcohols. The SPR detection modes, based on changes in the coupling angle and reflectivity at a fixed angle, were investigated both theoretically and experimentally. It has been shown that the SPR detection mode based on the reflectivity change is much more sensitive than that based on a change in the coupling angle, for the SPR experimental set-up. A preliminary investigation indicates that the SPR method can be used as a universal detector for HPLC or FIA or other analytical methods. Its problems, improvements, and future applications in analytical chemistry are also discussed.
Preparation and Resolution of a Series of Cobalt(III) Complexes Containing 2,2′-Biimidazole and Ethylenediamine
Authors: Kanno Hideaki , Manriki Satoru , Yamazaki Emiko , Utsuno Shunji , Fujita Junnosuke
Published: June 2006

A new series of cobalt(III) complexes of the type [Co(H2biim)n(en)3−n]3+ (H2biim = 2,2′-biimidazole; n = 1—3) was obtained. All of the complexes were resolved into their antipodes by SP-Sephadex column chromatography. The absorption, circular dichroism, and 1H NMR spectra of the complexes in aqueous solutions were dependent on the pH due to deprotonation of the imino protons of H2biim. The pKa1 and pKa2 values for [Co(H2biim)(en)2]3+ were obtained as 5.9 and 9.9, respectively, from the absorption spectra in aqueous solutions. The optically active deprotonated complexes, (−)589-[Co(Hbiim)3]·2H2O and (−)589-Ba1.5[Co(biim)3]·2H2O, were also isolated from weakly and strongly basic aqueous solutions, respectively, of (−)589-[Co(H2biim)3](NO3)3·H2O.
Comparison of the Electrochemical and Enzymic Oxidation of 1,3,7-Trimethyluric Acid at Solid Electrodes
Authors: Goyal Rajendra Nath , Jain Ajay Kumar , Jain Neena
Published: June 2006

The electrochemical oxidation of 1,3,7-trimethyluric acid has been studied in phosphate buffers in the pH range 2.1—10.2 at solid electrodes. In cyclic voltammetry a single, well defined, pH-dependent oxidation peak was obtained at all of the three electrodes used. However, the reduction behavior of the oxidation product was different at pyrolytic graphite, glassy carbon (GCE), and platinum due to adsorption at PGE and GCE. The nature of the electrode reaction was established as EC, in which a charge transfer is followed by competitive chemical reactions. The formation of the same UV-absorbing intermediate and products and identical rate constants for the decay of the UV-absorbing intermediate indicated that the electrochemical oxidation of 1,3,7-trimethyluric acid proceeds by an identical mechanism at PGE, GCE, and Pt. The results of a peroxidase-catalyzed oxidation of 1,3,7-trimethyluric acid were compared with the electrochemical oxidation; it is concluded that both of the oxidations follow a similar pathway.
Facile Synthesis of Functionalized Nitroenamines. III. Aminolysis of 1-Methyl-5-nitropyrimidin-2(1H)-one
Authors: Nishiwaki Nagatoshi , Tohda Yasuo , Ariga Masahiro
Published: June 2006

The aminolysis of 1-methyl-5-nitropyrimidin-2(1H)-one furnished diimines of nitromalonaldehyde in good yields. One of the imino groups of the diimines was readily hydrolyzed on silica gel to give nitroenamines possessing a formyl group. These reagents behaved as the synthetic equivalent of unstable nitromalonaldehyde, affording azaheterocycles upon a treatment with hydrazines or diamines.
Electronic Structures and Oxidation Potentials of Some Azulene Derivatives
Authors: Kurihara Teruo , Suzuki Takanori , Wakabayashi Hidetsugu , Ishikawa Sumio , Shindo Kimio , Shimada Yuji , Chiba Hiroshi , Miyashi Tsutomu , Yasunami Masafumi , Nozoe Tetsuo
Published: June 2006

The electronic structures of azulene (1) and its alkylated derivatives were investigated on the basis of MO calculations by MNDO and PM3 method. There results were experimentally evaluated by measuring the oxidation potentials (Eox) of 1 and its alkylated derivatives, from which the additive property on Eox was suggested as shown by Eox(Az.subst) = Eox(AZ) − 0.10n1,3 + 0.06n2 − 0.02n4,8 − 0.11n5,7 − 0.01n6. Thus, the alkyl groups at the 1,3- and 5,7-positions lower the Eox values by ca. 0.1 V, and stronger donating properties were observed for 3-methylguaiazulene (Eox = +0.53 V) and 3,3′-biguaiazulene (Eox = +0.40 V). The redox properties of guaiazulenyl sulfides which were prepared from guaiazulene via a phenylsulfonylthio derivative were also studied. Unlike the alkylated azulenes they underwent reversible one-electron oxidations and exhibited stronger donating properties (Eox = +0.40 – +0.44).
Generation and Reactions of 2-(1-Adamantyl)adamantene. Rearrangement to 3-(1-Adamantyl)-4-protoadamantylidene
Authors: Okazaki Takao , Isobe Hiroshi , Kitagawa Toshikazu , Takeuchi Ken’ichi
Published: June 2006

The SN1 methanolysis of (1-adamantyl)(3-noradamantyl)methyl heptafluorobutyrate at 100 °C yielded (1-adamantyl)(3-noradamantyl)methyl methyl ether (17), 2-(1-adamantyl)-1-methoxyadamantane (18), and 4-(1-adamantyl)-3-methoxyprotoadamantane (19) in a 2 : 65 : 33 ratio. The methanolysis of (1-adamantyl)(3-noradamantyl)diazomethane (7) at 0 °C also yielded 17, 18, and 19 in a 4 : 33 : 63 ratio. On the other hand, the photolysis of 7 in 99 : 1 (v/v) hexane–methanol gave 17, 18, 2-(1-adamantyl)-2-methoxyadamantane (25), and 2-(1-adamantyl)-2,4-didehydroadamantane (20) in a 30 : 9 : 36 : 25 ratio. Presence of triethylamine decreased the yields of ethers 17, 18, and 25, and increased the yield of 20 to 46%. The formation of a considerable amount of 17 and the absence of 19 in the photolysis products indicate the generation of (1-adamantyl)(3-noradamantyl)methylidene (8). The formation of 25 and 20 suggests that the generated carbene 8 rearranges to 2-(1-adamantyl)adamantene (3b) and then gives 3-(1-adamantyl)-4-protoadamantylildene by the subsequent retro-insertion. An attempt to isolate 3b in the photolysis of 7 in cyclohexane failed, and the sole isolated product was 20.
Palladium-Catalyzed Double and Single Carbonylations of β-Amino Alcohols. Selective Synthesis of Morpholine-2,3-diones and Oxazolidin-2-ones and Applications for Synthesis of α-Oxo Carboxylic Acids
Authors: Imada Yasushi , Mitsue Yo , Ike Kazuo , Washizuka Ken-ichi , Murahashi Shun-Ichi
Published: June 2006

Catalytic cross double carbonylation of secondary amines and alcohols proceeds in the presence of [PdCl2(MeCN)2] and CuI under carbon monoxide (80 atm) and oxygen (5 atm). Catalytic intramolecular double carbonylation of β-amino alcohols gives morpholine-2,3-diones, which are excellent protecting compounds of amino alcohols and important precursors for biologically active nitrogen compounds. In contrast, catalytic single carbonylation of β-amino alcohols under a mixture (1 : 1) of carbon monoxide and oxygen (1.0 atm) proceeds to give oxazolidin-2-ones selectively. The reaction can be explained by assuming a mechanism which includes intramolecular nucleophilic attack of the hydroxy group of (hydroxyethyl)aminocarbonyl ligands on the CO ligand of the carbamoylpalladium(II) complexes, followed by reductive elimination to give morpholine-2,3-diones. In contrast, direct nucleophilic attack of the hydroxy group to the carbamoyl group affords oxazolidin-2-ones. As a common intermediate for the double and single carbonylations, carbamoylpalladium(II) complex has been isolated by the reaction of [PdCl2(PMe3)2] with β-amino alcohol under CO.

The present double carbonylation of amino alcohols provides a novel and convenient method for synthesis of α-oxo carboxylic acids. Thus, the morpholine-2,3-diones obtained undergo reaction with Grignard reagents chemoselectively at the ester positions to give 2-substituted 2-hydroxymorpholin-3-ones, which undergo acid hydrolysis to give α-oxo carboxylic acids.
Electrochromism of Single Transition-Metal Phthalocyanine Thin Films: Effect of Central Metal and Composite Structure
Authors: Toshima Naoki , Tominaga Tsuyoshi
Published: June 2006

Electrochromism of various transition-metal phthalocyanine thin films is studied in a sodium nitrate solution. Copper and nickel phthalocyanine show reversible electrochromism, while, zinc, cobalt, and iron phthalocyanine show the irreversible type. The transition-metal phthalocyanine film, which gives irreversible electrochromism, exhibits a new absorption peak in the NIR region under oxidation. This result indicates that some chemical changes of molecular structure occur with oxidation, and consequently the cyclic voltammograms and the absorbance are diminished with repeated scans, even under the well-designed experimental conditions. As for composite phthalocyanine, the high dispersibility of the phthalocyanine molecules in the codeposited thin film can improve the reversibility in electrochromism. In this case, chemical changes of the molecular structure of metal phthalocyanine with irreversible electrochromism can be prevented to some extents by the codeposition with another phthalocyanine with reversible electrochromism. Sequentially deposited double-layered thin films, in contrast, give completely different results. The electrochromism depends on the order of the oxidation potentials of simple phthalocyanine thin film, and the designed hole transfer compatible with the concept of “sequential potential field” can be accomplished in the double-layered thin film.
Biological Activity of Water-Soluble Fullerenes. Structural Dependence of DNA Cleavage, Cytotoxicity, and Enzyme Inhibitory Activities Including HIV-Protease Inhibition
Authors: Nakamura Eiichi , Tokuyama Hidetoshi , Yamago Shigeru , Shiraki Takashi , Sugiura Yukio
Published: June 2006

Two different classes of water-soluble fullerene derivatives, detergent-type and sphere-type, were synthesized. The derivatives were evaluated for their biological activities including cytotoxicity, DNA cleavage, and inhibition of HIV-protease and other enzymes. Both classes of compounds display generally similar behavior except for their cytotoxicity spectra against several cell lines. The fullerene derivatives bearing N-methylpyrrole were found to be photo-inactive with respect to DNA cleaving activity and cytotoxicity. A study on the kinetics for the inhibition of HIV-protease with detergent type derivative revealed that the compound is a potent fullerene-based HIV protease inhibitor, inhibiting the enzyme activity in a reversible and competitive manner with a Ki value of 0.32 μM.
Analysis of the Excitation and Emission Spectra of Tungstates and Molybdate
Authors: Saito Nobuhiro , Sonoyama Noriyuki , Sakata Tadayoshi
Published: June 2006

The excitation and emission spectra of CaWO4, MgWO4, PbWO4, ZnWO4, and CaMoO4 were analyzed by a configurational coordination model. The spectral line shapes simulated by a configurational coordination model with a singlet ground state and an excited triplet state well explained the line shape of the luminescence spectra and the line shape at the rising part of the excitation spectra of these salts at room temperature. The energy level of the excited triplet state and the reorganization energies at the ground sate and the triplet state were determined. It was concluded that the potential curve at the excited state becomes shallower than that at the ground state for these systems.
Towards a Calculation of the Electronic Structures of Macromolecules. I. Quadratically Convergent Method for a Direct Calculation of Localized Molecular Orbitals
Authors: Sano Tatsuji , Matsuoka Osamu
Published: June 2006

A super configuration–interaction method is applied to a direct calculation of orthogonal localized molecular orbitals (LMO). Its iterative procedure converges quadratically, retaining the initial forms of the LMOs. When the basis sets of large sizes are employed for the calculation, Davidson’s diagonalization method can be adopted beneficially, where the time-consuming four-index transformation of LMO integrals is replaced by simpler two-index transformations. Test calculations using double-zeta basis sets are reported in detail for H2CO (formaldehyde). B2H6 (diborane), C3H4(1-propyne [metylacetylene]), and cytosine. The implication of the method concerning macromolecular calculations is discussed.
Aggregation of Phosphoric Acid, Phenyl Dihydrogenphosphate, and Related Organophosphorus Acids in Conductometric Titration with Triethylamine in DMF
Authors: Hojo Masashi , Hasegawa Hiroshi , Chen Zhidong
Published: June 2006

The conductance increased linearly up to the equivalence point in the conductometric titration of diphenyl hydrogenphosphate ((PhO)2PO(OH)) with triethylamine (Et3N) in DMF at 25 °C. However, it was found that the conductometric titration of phenyl dihydrogenphosphate (PhOPO(OH)2, 1.0 × 10−3—1.0 × 10−2 mol dm−3) gave a maximum at the half-equivalence point (CHA : [Et3N] = 1 : 1/2) and not the linear curve to the equivalence point. Phosphoric (PO(OH)3), phenylphosphonic (PhPO(OH)2), and vinylphosphonic (CH2CHPO(OH)2) acids also gave maxima at the half-equivalence points. The appearance of maxima was explained by homoconjugation between the acid (HA) and the conjugate anion (A−) upon neutralization with the base (B) in DMF : B + 2 HA BH+···HA2−. Dibutyl hydrogenphosphate ((n-BuO)2PO(OH)) of higher concentrations also gave a (small) maximum at the half-equivalence point, while dimethylphosphinic acid ((CH3)2PO(OH)) gave no maximum in DMF. In less basic solvents, acetonitrile and benzonitrile, even diphenyl hydrogenphosphate, gave a maximum. The cause for the appearance of maxima at the half-equivalence point in DMF is discussed from the viewpoint of the basicities of the conjugate anion (A−) and the number of hydrogen bondings involved in the homoconjugation reaction. The ion-pair and quadrupole (the dimer of ion pairs) formation constants of the organophosphorus acids in DMF were obtained by conductometry. The equilibrium concentration of the dimer (H2A2) of PhOPO(OH)2 was found to exceed that of the ion pair (HA) at >1.6 × 10−3 mol dm−3 of the acid.
Binding Data Analysis of the Interaction of Bovine Hemoglobin with Dodecyltrimethylammonium Bromide
Authors: Bordbar Abdul Khalegh , Moosavi-Movahedi Ali Akbar
Published: June 2006

The interaction of dodecyltrimethylammonium bromide, as a cationic surfactant, with bovine hemoglobin, as a biopolymer, has been investigated at different temperatures by an equilibrium dialysis technique. The obtained binding isotherms have been analyzed and interpreted by the Wyman binding potential model and other thermodynamic parameters which have been extracted on the basis of this model. A new method of analysis for evaluating the binding isotherms and estimating the free energy change, ΔGt, per mole of ligand has been proposed.

The unusual behavior of the Scatchard plot at 300 K was analyzed in terms of two sets of binding sites. The first set of binding sites was considered as electrostatic and the second as hydrophobic. The free energy of interaction () from the Wyman model was also resolved according to electrostatic and hydrophobic binding free energies.
A Willgerodt–Kindler Type Selenation of Dihalomethane Derivatives, Chloroform, and Sodium Trichloroacetate by Treating with a Base, Elemental Selenium, and an Amine
Authors: Shimada Kazuaki , Yamaguchi Minoru , Sasaki Tohru , Ohnishi Kenji , Takikawa Yuji
Published: June 2006

Treatment of dihalomethane derivatives, chloroform, or sodium trichloroacetate with elemental selenium in the presence of NaH and an excess amount of an amine gave the corresponding selenoamides, selenoureas, and bis(selenocarbamoyl) triselenides in modest yields. These products were afforded from reactive intermediates related to “selenocarbonyl halides” and “selenophosgenoids” generated by the reaction of dichloromethanide ions and trichloromethanide ion with N-alkylated aminopolyselenide species (R2N–(Se)n−).
Examination of the Conformational Properties of the Prymnesin System : A Computational Chemistry Approach
Authors: Glendenning Lionel , Igarashi Tomoji , Yasumoto Takeshi
Published: June 2006

Prymnesins are potent ichthyotoxic and hemolytic glycoside molecules isolated from the red tide alga Prymnesium parvum. Their unique molecular structure is conformationally rich with a number of key torsional bonds which were probed with contemporary conformational searching techniques in order to describe the three-dimensional structure of the prymnesin molecule. Important topological features include a backbone twist of 60° and an elongation length of 39.5 Å from ring “A” to ring “N” for the prymnesin-2 molecule in the nOe preferred conformation. An appreciation of these and other molecular structural and energetic features determined by computational techniques were examined with the aim of understanding how prymnesin-2 exhibits it’s potent biological activity in relation to these inherent structural traits.
Asymmetric Transformation of Phenylglyoxal into Mandelic Acid Catalyzed by Cyclodextrin-Based Glyoxalase Models
Authors: Tamagaki Seizo , Narikawa Jun , Katayama Atsushi
Published: June 2006

(2-Mercaptoethyl)amino-attached cyclodextrin provides a highly enantioselective environment during the transformation of phenylglyoxal into (S)-mandelic acid, although simple inclusion into native α-,β-, and γ-cyclodextrins and their 2-hydroxypropyl and methyl variants is not sufficient to cause appreciable asymmetric induction.
Enantioselectivity Enhancement of Ester Cleavage by a β-Sheet Polypeptide Containing Catalytic Triads in a Serine Protease
Authors: Fukushima Yasumasa
Published: June 2006

Catalytic activity and enantioselectivity of Poly(Asp–Leu–His–Leu–Ser–Leu) with a β-sheet structure for the hydrolysis of chiral phenylalanine p-nitrophenyl esters were compared with those of the peptide hexamer, under various conditions. The relationship between the β-sheet structure of the polypeptide and the hydrolytic properties was also investigated. Both the activity and the enantioselectivity for the polypeptide were higher than those for the peptide hexamer. The activity increased with pH, but the enantioselectivity was independent of pH. An increase of ethanol content in reaction solution led to a relatively lower rate constant and a higher enantioselectivity. The enantioselectivity decreased with increasing temperature; the activity increased to 25 °C and it reduced above 35 °C. Because the nucleophilicity of the polypeptide and the concentration effect of the substrate reduced by a decrease of the β-sheet content with temperature, the regular secondary structure may play an important role in these hydrolytic reactions. In addition, the efficient hydrolytic activity and the enantioselectivity were derived from activation parameters. The polypeptide may provide a good model for studying the relationship between enzymatic activity and steric structural formation.
Changes of the Aromatic Character of the Ring in Exocyclically Substituted Derivatives of Benzylic Cation as a Result of Varying Charge at the exo-Carbon Atom
Authors: Krygowski Tadeusz Marek , Wisiorowski Marcin , Nakata Kazuhide , Fujio Mizue , Tsuno Yuho
Published: June 2006

Analysis of the molecular geometry of the ring in 18 exocyclically substituted benzylic cation derivatives shows that an increase of delocalization of the positive charge over the ring is associated with a considerable decrease of its aromatic character. Separation of the aromatic character into energetic and geometric terms allows one to conclude that the effect of dearomatization due to delocalization of the positive charge in the ring is mostly reflected in the geometric term, i.e. by an increase of the alternation of bond lengths in the ring.
Dehydrooligopeptides. XIV. Syntheses of 2-[(Z)-1-Amino-1-alken-1-yl]oxazole-4-carboxylic Acid and the Main Common Skeleton of Thiostrepton Peptide Antibiotics, A10255G and J
Authors: Okumura Kazuo , Ito Akio , Saito Hiroyuki , Nakamura Yutaka , Shin Chung-gi
Published: June 2006

The practical synthesis of a unique dehydropentapeptide (2), the common main skeleton of thiostrepton macrocyclic peptide antibiotics, A10255G and J, is described. Peptide 2 is constructed from a novel 2-[(Z)-1-amino-1-propen-1-yl]oxazole-4-carboxylic acid, 2-(1-aminomethyl)- and 2-[(S)-1-aminoethyl]thiazole-4-carboxylic acid residues, besides L-threonine and dehydroalanine residues at the N- and C-termini, respectively. First, the general syntheses of various 2-[(Z)-1-amino-1-alken-1-yl]oxazole-4-carboxylic acid derivatives (11) and preparation of N-terminal dehydrodipeptides (17) containing the acid (11a) were done. Subsequent coupling of 17 with the C-terminal tripeptide comprised of the above two 2-(aminoalkyl)thiazole-4-carboxylic acid moieties (22) and (23) and serine moiety (4), and final β-elimination were tried and gave the desired protected 2 [(P)-2].
Radical Dissociation of 2,2′-Bis(2-aryl-3-benzothiophenonyl)s by Mechanical Energy
Authors: Mori Yukie , Yamada Naho , Kanazawa Miho , Horikoshi Yumiko , Watanabe Yuka , Maeda Koko
Published: June 2006

On applying pressure with a press in the solid state, the title compounds undergo homolysis of the central C–C bond to give green-colored radicals. X-Ray structure analysis for p-chloro derivative showed that the central C(2)–C(2′) bond was not elongated but had a normal distance (1.576 Å) as a hexa-substituted Csp3–Csp3 bond. The amount of the radical formed by mechanical energy depended on the substituents on the 2-phenyl rings and on the solvent of crystallization. As for the crystals containing no solvent, p-bromo and p-chloro derivatives showed higher reactivity than the unsubstituted compound, probably due to smaller dissociation enthalpy. The radical dissociation was suppressed by the presence of some solvent of crystallization. In the solvated crystals, the excess energy supplied by external mechanical energy would be transferred mainly to vibrational modes of the solvent molecules rather than to the substrate.
Cation-Exchanged Montmorillonite (Mn+-Mont)-Catalyzed Prins Reaction
Authors: Tateiwa Jun-ichi , Hashimoto Keiji , Yamauchi Takayoshi , Uemura Sakae
Published: June 2006

The Prins reaction of styrenes with paraformaldehyde or 1,3,5-trioxane in toluene in the presence of cation-exchanged montmorillonite (Mn+-mont), which worked as a Brønsted acid catalyst, at 80 °C produced 4-aryl-1,3-dioxanes selectively in up to 99% isolated yield with a turnover number of up to 5.9 × 102. Among the examined 21 Mn+-monts, Ce3+- and Fe3+-monts were revealed to be quite effective. Regeneration of the catalyst was confirmed with the Ce3+-mont, which could be effectively recycled at least three times. Many lanthanide metal ion-exchanged montmorillonites (Ln3+-monts) were prepared and characterized by X-ray powder diffraction (XRD) and temperature-programmed desorption of ammonia gas (NH3-TPD) methods.
Photomechanical Response of Azobenzene Containing Monolayers on Water Surface
Authors: Seki Takahiro , Fukuda Ryo-ichi , Yokoi Makoto , Tamaki Takashi , Ichimura Kunihiro
Published: June 2006

Monolayers of amphiphilic poly(vinyl alcohol)s and related low-molecular-mass compounds containing photochromic azobenzene (Az) were spread on a water surface. Their photomechanical responses induced by photoirradiation of UV (365 nm) and visible (436 nm) light were investigated. Illumination by UV light induced area expansion of Az monolayers up to ca. three times in magnitude, which strongly depended on the material, monitoring surface pressure, and subphase conditions. The expanded film of these molecular films reverted to the original area upon illumination with visible light. Use of a polymeric material was found to be advantageous to attain sufficient mechanical strength for full reproducibility and faster response. At a fixed area, reversible surface pressure changes were observed upon alternate UV and visible light illumination, and at 10—15 mN m−1 with the 6Az10-PVA monolayer the changes could be visualized plainly by watching motions of camphor grains. In the case of an Az amphiphile having the dissociative carboxylic acid head group, the photoresponsiveness was altered by pH changes and addition of Cd2+ ion in the subphase. Variations in the magnitude and response time of the photoinduced deformation were related to the packing state of Az monolayers evaluated by UV-visible absorption spectroscopy at the air–water interface.
Bioactivity of M2O–TiO2–SiO2 (M = Na, K) Glasses: An In vitro Evaluation
Authors: Kim Hyun-Min , Miyaji Fumiaki , Kokubo Tadashi , Kobayashi Masahiko , Nakamura Takashi
Published: June 2006

The formation of biologically active bonelike apatite on the surfaces of glasses and glass-ceramics is an essential condition for their bonding living bone. In the present study, apatite formation on the surfaces of M2O–TiO2–SiO2 (M = Na, K) glasses was examined in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma in order to evaluate their bioactivity. While none of the Na2O–TiO2–SiO2 ternary glasses formed the surface apatite, K2O–TiO2–SiO2 glasses, not only as SiO2-rich glasses but also as TiO2-rich glasses, formed the apatite. The alkali ions in the glasses exchanged with H3O+ ions in the fluid. The TiO2-rich or SiO2-rich hydrogel which was formed on the surfaces of the glasses induced apatite nucleation. The increased degree of the supersaturation of the fluid with respect to the apatite due to the increase in pH provided favorable conditions for apatite nucleation. This indicates that alkali titanates as well as alkali silicates can be basic components of bioactive glasses.
Multiplex Proton-Transfer and Electron-Transfer Natures Based on the 2,2′-Bi-1H-imidazole System. II. Crystal Structures and Charge-Transfer Complex Formations
Authors: Akutagawa Tomoyuki , Saito Gunzi , Kusunoki Masami , Sakaguchi Ken-ichi
Published: June 2006

Studies of the crystal structures and formation of a charge-transfer (CT) complex proved that 2,2′-bi-1H-imidazole (H2BIM0) forms a new system concerned with the interplay of proton-transfer (PT) and electron-transfer (or charge-transfer (CT)) interactions. X-Ray crystal analyses of newly isolated species, 2-(2-1H-imidazolyl)-1H-imidazolium (H3BIM+) and 2,2′-bi-1H-imidazolium (H4BIM2+), revealed the formation of strong hydrogen bonds along the side-by-side direction of the molecular plane. CT complexes of H3BIM+ and H4BIM2+ with the 7,7,8,8-tetracyanoquinodimethane derivatives (TCNQs) were synthesized by a method metathesis, and the crystal structure of (H3BIM+)2(TCNQ−)2(TCNQ0) was determined. During CT complex formation, the initial simple protonated states of [H3BIM+] or [H4BIM2+] changed to different ones, for example, [H4BIM2+]x[H3BIM+]1−x, [H3BIM+]x[H2BIM0]1−x, and H2BIM0. According to the protonated states of the H2BIM system, the formal charge of the TCNQs in the CT complexes varies from completely ionic, partial CT, to neutral. The mechanism of these complex formations was explained by differences in the acidities between the TCNQ anion radicals (TCNQs−•) and H3BIM+ or H4BIM2+. Higher acidities of H3BIM+ and H4BIM2+ than the TCNQs−• induce the following PT reaction: H3BIM+ (or H4BIM2+) + TCNQs−• → H2BIM0 (or H3BIM+) + HTCNQ•. The isolation of HTCNQ• was a failure due to the following disproportional reaction: 2HTCNQ• → TCNQ0 + H2TCNQ0. However, the formation of the 1,4-benzenedimalononitrile (H2TCNQ0) was confirmed by an analysis of the residual compounds after complex formation. Although the electronic absorptions of TCNQ complexes indicated both the partial CT state of TCNQ and a segregated stacking manner, semiconductive characters were observed. In a crystal of (H3BIM+)2(TCNQ−)2(TCNQ0), the H3BIM+ formed a planar dimer connected by two N–H···N hydrogen bonds, and TCNQ molecules existed as a charge-separated state with segregated trimer stacks. These dimer and TCNQ stacks were tightly connected by both N–H···N≡C hydrogen bonds, which spread into the overall crystal, and by the CT interaction. For the PT and CT system, we propose a synthetic strategy based on the redox potentials and acid dissociation constants.
Solvent-Dependent Photophysical Properties of a Phenothiazone Dye as an Optical Probe
Authors: Otsuki Soichi , Taguchi Takahisa
Published: June 2006

A phenothiazone dye, 7-dimethylamino-3H-phenothiazin-3-one, was investigated as an optical probe in homogeneous media. Two absorption bands appeared in aprotic solvents and dioxane–water and exhibited different dependencies on the solvent polarity/polarizability scale, π*. Both of the bands were quite different from that corresponding to the aggregated molecules or the protonated species of the dye. These results suggest the existence of two ground-state species with non-twisted and twisted conformations of the 7-amino group. The π* dependencies of the fluorescence maxima and the rate constants of the fluorescence decays showed three types of behavior in dioxane–water. The Lippert–Mataga plot of the spectral shift was interpreted by assuming two types of behavior in aprotic solvents. These facts suggest that the fluorescence comes from three emitting states which exist in fast equilibria. The strong polarity dependencies and the long wavelengths of the absorption and fluorescence, the large Stokes shift, and the appreciable fluorescence quantum yield make the dye useful as an optical probe of the polarity of a variety of microenvironments.
Reversal in Solvatochromism: An ET(30) Switch for a New Class of Cyanine Dyes
Authors: Mishra Bijay K , Kuanar Minati , Mishra Amaresh , Behera Gopa B
Published: June 2006

This paper reports the analysis of reversal in solvatochromism of a new class of cyanine dyes by using the ET(30) scale. The point of reversion is defined as a switch that identifies the hydrogen bond donor and hydrogen bond acceptor solvents.
Stereochemical Control in Microbial Reduction. XXVIII. Asymmetric Reduction of α,β-Unsaturated Ketones with Bakers’ Yeast
Authors: Kawai Yasushi , Saitou Kentarou , Hida Kouichi , Dao Duc Hai , Ohno Atsuyoshi
Published: June 2006

Bakers’ yeast reduction of α,β-unsaturated ketones affords optically active saturated ketones contaminated by allylic and saturated alcohols as minor components. Stereoselectivity of the reduction of carbon–carbon double bond strongly depends on the structure of β-aryl substituent. The bakers’ yeast reduction of β-phenyl enones gives saturated ketones in moderate stereoselectivity. Stereoselectivity is not altered by substitution at the para-position, whereas introduction of a substituent at the ortho- or meta-position drastically improves the stereoselectivity. Deuterium-labeling experiments reveal that the enzymatic reduction of carbon–carbon double bond proceeds with formal trans-addition of hydrogens regardless the efficiency of stereoselectivity. The resulting optically active ketone was converted to the precursor of (S)-iopanoic acid, an inhibitor of thyroxine 5′-deiodinase that is a thyroid hormone-converting enzyme and an oral cholecystographic agent.
Micelle Formation by Sodium Dodecyl Sulfate in Water–Additive Systems
Authors: Bakshi Mandeep Singh
Published: June 2006

The conductances of sodium dodecyl sulfate (SDS) have been determined in water in the presence of various additives, such as strong nitrogen organic bases (pyridine, 3- and 4-methylpyridines, and 2,6-dimethylpyridine), carboxylic acids (acetic acid, propionic acid, and butyric), and alcohols (methanol (MeOH), 1-butanol (BuOH), 2-methyl-1-propanol, 2-methyl-2-propanol, and 2-methyl-2-butanol) at 25 °C. The conductances of SDS in water in the presence of pyridine and acetic acid at temperatures between 15 and 45 °C have also been measured. From the conductivity data, the critical micellar concentration (cmc), degree of counter-ion association (α), molar conductivities at infinite dilution (Λ0), limiting ionic molar conductivities (), free energy of transfer of the surfactant hydrocarbon chain from medium to the micelle (), free energy of transfer of surface contributions (), and standard enthalpies of micellisation () of SDS have been computed. It has been found that the presence of strong nitrogen organic bases causes strong micelle denaturation, whereas the presence of carboxylic acids and alcohols stabilizes the micelles, with the exception of MeOH and 2-methyl-2-butanol.

The temperature effect on the micellisation of SDS in the presence of pyridine shows that the enthalpy of micellisation becomes less negative along with an increase in temperature. However, the enthalpy of transfer of a hydrocarbon group from an aqueous to a nonpolar environment in the presence of acetic acid is endothermic.
SNP Studies on the Structure of the Short-Lived Radical Pair Generated in the Hydrogen Abstraction Reaction of Anthraquinone from Xanthene
Authors: Shindo Koji , Yamamoto Kaoru , Maeda Kiminori , Azumi Tohru
Published: June 2006

Nuclear-polarization-detected ESR (NP-detected ESR) spectra were measured in the hydrogen abstraction reaction of anthraquinone from xanthene for the purpose of assigning of the radical pair and the geminate product generated from the radical pair. By properly choosing of the nuclear spin of the product, we can obtain the SNP spectra of the two component radicals individually. The sign of the hyperfine coupling constant is discussed and the SNP spectra are assigned as 9-xanthenyl radical and 10-hydroxy-9-anthryloxyl radical from the spectrum simulated by the radical pair theory. Additionally, the features of the cross relaxation process in the intermediate free radical are discussed by examining the DNP components of spectra.
Remarkable Difference between the Kinetic Parameters of a Selective Catalytic Reduction of NO by Ethene on a Copper Ion-Exchanged MFI Zeolite and Al2O3
Authors: Takeda Hiroshi , Iwamoto Masakazu
Published: June 2006

The kinetic parameters have been determined in reaction systems of NO + O2 + C2H4, NO2 + O2 + C2H4, NO + O2, and O2 + C2H4 over a copper ion-exchanged MFI zeolite (Cu-MFI) and Al2O3. The rate equations for the N2 formation in the NO + O2 + C2H4 system on Cu-MFI (553—593 K) and Al2O3 (673—773 K) were expressed by exp (−168000/RT) and exp (−294000/RT), respectively. The significant difference between the equations reveals that the reaction mechanisms or rate-determining steps on Cu-MFI and Al2O3 greatly differ. In addition, the rate equations for N2 and CO2 production were the same on Cu-MFI, while they were different on Al2O3. The reaction mechanism is discussed based on the equations.
Crystal and Molecular Structures of Novel Metal–Carbene Complexes II. Tris{1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(ethylimino)methanethiolato-κ2SS′]}tripalladium(II) and {1,1′-(Perhydropyrimidine-1,3-diyl-κC2)bis[(methylimino)methanethiolato-κ2SS′]}(pyridine)palladium(II); Intensity Measurements Using Rapid X-Ray Diffractometers
Authors: Iwasaki Fujiko , Manabe Noriko , Yasui Masanori , Matsumura Noboru , Kamiya Nobuo , Iwasaki Hitoshi
Published: June 2006

The crystal structures of tris{1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(ethylimino)methanethiolato-κ2SS′]}tripalladium(II) (5b) and {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(methylimino)methanethiolato-κ2SS′]}(pyridine)palladium(II) (6a) were determined by X-ray structure analyses. When {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(alkylimino)methanethiolato-κ2SS′]}(triphenylphosphine)palladium(II) (3) was treated with 18% HCl aq, a compound (5) was obtained with an elimination of the triphenylphosphine group. A reaction of 5 with pyridine gave a pyridine-coordinating metal–carbene complex (6). Complex 5 has a trimeric structure of the metal–pentalenes consisting of a cyclic (Pd–S)3 framework. In the trimer, each Pd atom is coordinated by three S atoms and one C atom in a square-planar arrangement. Two of the S atoms belong to the same pentalene ring and one belongs to the next pentalene ring. The lengths of interpentalene Pd–S (2.38 Å) are significantly longer than those of intrapentalene Pd–S (2.28 Å). This difference suggests that a trimer is easily cleaved in pyridine to form a pyridine complex 6. The trimeric structure is considered to show an intermediate-like structure of the ligand exchange reaction. Intensity data of 5 were measured by rapid X-ray diffractometers with imaging plates as a two-dimensional detector.
Orbital Phase Control of the Stabilities of π-Conjugated Diradicals
Authors: Iwase Koji , Inagaki Satoshi
Published: June 2006

The concept of orbital phase continuity–discontinuity was applied to π-conjugated diradicals. Cyclic orbital interactions are involved in the spin polarization and delocalization in acyclic π-conjugated diradicals. The relative stabilities of the singlet isomers, those of the triplet isomers, and the spin multiplicities of the ground states were shown to be predicted by the orbital phase properties. The heteroatom effects on the spin preference was shown to be related to the degree of the continuity (discontinuity) of the orbital phase.
Cycloaddition of Carbon Dioxide to 1,2-Epoxypropane Catalyzed by Tetra-t-butylphthalocyaninatoaluminium(III) Hydroxide
Authors: Kasuga Kuninobu , Kato Takao , Kabata Naohiko , Handa Makoto
Published: June 2006

Carbon dioxide was fixed as propane-1,2-diol carbonate (PDC) with 1,2-epoxypropane (EP) catalyzed by Al(OH){pc(t-Bu)4} in the presence of such a quaternary ammonium halide (HAX) as [HO(CH2)2N(CH3)2(C4H9)]X (X = Cl, Br, I). Although the yield was scarcely affected by the structure of HAX, it was dependent on the kind of halide ion. While PDC was formed in chloroform or dichloromethane, the yield decreased extremely in DMSO or pyridine, and PDC was not prepared in methanol. Although halohydrin was formed in a chloroform solution of EP, Al(OH){pc(t-Bu)4}, and HAX, it was not an intermediate.

The formation of a hexa-coordinate complex of Al(OH){pc(t-Bu)4} with HAX and EP was spectroscopically confirmed, and the complex catalyzed the preparation of PDC from carbon dioxide and EP.
Biopolymer–Surfactant Interaction 2: Kinetics of Binding of Cetyltrimethylammonium Bromide with Bovine Serum Albumin
Authors: Maulik Sudeshna , Moulik Satya Priya , Chattoraj Dipti Kumar
Published: June 2006

The results of the kinetics of binding of the surfactant cetyltrimethylammonium bromide (CTAB) with bovine serum albumin (BSA) under varied conditions of CTAB concentration, pH, ionic strength and temperature are presented. The kinetic process has been found to be comprised of either two or three stages; the rate constants of the first, second, and third stages follow the general order of k1 >> k2 > k3. The three-stage kinetic process has been observed at higher CTAB concentrations, higher temperature and in presence of the protein denaturant urea. The activation parameters for this three-stage kinetic process have been determined. Most entropies of activation have been found to be negative (a very few are positive) whereas the activation enthalpies and energies are both positive and negative. The enthalpy and entropy for all the kinetic stages in different environmental conditions have been found to compensate each other, whereas the free energy of activation has remained unaffected. A model for the three-stage kinetic process has been proposed.
Selective Oxyfunctionalization of Ketones Using 1-Oxopiperidinium Salt
Authors: Ren Tan , Liu You-Cheng , Guo Qing-Xiang
Published: June 2006

4-Methoxy-2,2,6,6-tetramethyl-1-oxopiperidinium chloride, made from the corresponding 1-piperidinyloxyl radical and chlorine gas, was used as an oxyfunctionalizing reagent for a number of enolizable ketones. Regioselective α- or γ-oxygenated carbonyl compounds were obtained smoothly at ambient temperature in moderate to good yields. Oxyfunctionalization of (+)-carvone and (−)-carvone proceeded stereoselectively, and provided cis-product (5R, 6S)- and (5S, 6R)-2-cyclohexen-1-ones, respectively. Interestingly, unsymmetrical ketones afforded isomeric α- and α′-oxygenated ketones, while allyl ketones gave the regiospecific γ-oxygenated products with the migration of the double bond in the allylic group.
Selective Synthesis of Sulfoxides and Sulfones by Methyltrioxorhenium-Catalyzed Oxidation of Sulfides with Hydrogen Peroxide
Authors: Yamazaki Shigekazu
Published: June 2006

Methyltrioxorhenium-catalyzed oxidation of sulfides with hydrogen peroxide in ethanol has been found to be an efficient catalytic system for the selective formation of sulfoxides and sulfones. The oxidation using an equimolar amount of hydrogen peroxide afforded sulfoxides in excellent yield, and the use of two molar amounts of hydrogen peroxide gave sulfones quantitatively. Strongly deactivated sulfide, bis(4-nitrophenyl) sulfide, was converted smoothly to the corresponding sulfoxide and sulfone in excellent yields. The functional group in the side chain of sulfide such as a carbon–carbon double bond was not affected under the reaction conditions, and the sulfur atom was selectively oxidized.
Fluorescent α,β-Unsaturated Carbonyl Compounds and 2-Methylpyridines. Their Application to a Quantitative Analysis of Carnitine
Authors: Nakaya Ken-ichi , Funabiki Kazumasa , Shibata Katsuyoshi , Muramatsu Hiroshige , Matsui Masaki
Published: June 2006

α,β-Unsaturated carbonyl compounds and 2-methylpyridines containing a 4-(dialkylamino)phenyl substituent can be used as fluorescent labeling reagents for the quantitative analysis of carnitine. 6-(4-Aminophenyl)-3-cyano-4-[4-(diethylamino)phenyl]-2-methylpyridine showed the best properties among the synthesized reagents.
Novel Zirconium–Iron Multinuclear Complex Catalysts for Olefin Polymerizations
Authors: Mitani Makoto , Hayakawa Michiya , Yamada Tohru , Mukaiyama Teruaki
Published: June 2006

Novel zirconium–iron dinuclear complexes, [FcSiMe2(R1R2Cp)ZrCl2Cp] (Fc; Ferrocenyl, R1 = R2 = H; 2a, R1 = Me, R2 = H; 2b, R1 = R2 = Me; 2c, R1 = Ph, R2 = H; 2d), [FcSiMe2Cp{ZrCl2(Me5Cp)}] (3a), hafnium–iron dinuclear complex, [FcSiMe2Cp{HfCl2(Me5Cp)}] (3b) and zirconium–iron trinuclear complex, [ZrCl2(FcSiMe2Cp)2] (4), were synthesized and complexes 2d and 4 were characterized by an X-ray diffraction method. Olefin polymerizations were conducted by using these multimetallic zirconocene catalysts with the coexistence of methylaluminoxane or tetrakis(pentafluorophenyl)borates. The maximum catalytic activities of complexes 2, 3 and 4 were observed at low temperatures (15—45 °C) in ethylene polymerization, contrary to the conventional zirconocene catalyst ([ZrCl2Cp2]), showing the maximum activity at between 70—80 °C. A detailed investigation of ethylene polymerization and NMR measurements of the active species suggested that the interesting behavior of these complexes arose from an electronic cooperative effect between the zirconium and iron atoms. It was also revealed that complexes 2 were highly reactive toward propylene or diene in the copolymerization of ethylene and propylene or terpolymerization of ethylene, propylene and diene.
Preparation of Optically Active Diol Derivatives by the Enzymatic Hydrolysis of Cyclic Carbonates
Authors: Matsumoto Kazutsugu , Fuwa Seiji , Shimojo Megumi , Kitajima Hidehiko
Published: June 2006

A simple enzymatic method for the preparation of optically active 1,2- and 1,3-diol derivatives is disclosed. In the screening of enzymes, racemic 4-[(2-benzyloxy)ethyl]-1,3-dioxolan-2-one (1a) was enantioselectively hydrolyzed by porcine pancreas lipase (PPL) to give optically active (R)-1a and (S)-4-(benzyloxy)butane-1,2-diol (2a). The addition of 10% i-Pr2O to the reaction system dramatically improved the reactivity to afford optically pure (R)-1a in 31% yield. PPL also catalyzed the hydrolysis of several five-membered cyclic carbonates with high enatioselectivity. It is noteworthy that the increment of the carbon number of the substituents reflects the drastic increase in enantioselectivity. On the other hand, the hydrolyses of six- and seven-membered cyclic carbonates were also catalyzed by PPL. In particular, the reaction of a six-membered substrate enantioselectively proceeded. This reaction afforded optically active 1,3-diol derivatives which could not be directly prepared by hitherto known methods using hydrolytic enzymes.
Novel Degradation of Sugar Skeleton by Diazidation
Authors: Yokoyama Masataka , Kobayashi Naoki , Hachiya Takeshi , Kubo Misao , Togo Hideo
Published: June 2006

O-Benzylated acyclic sugars are allowed to react with azidotrimethylsilane in the presence of boron trifluoride–diethyl ether to afford the corresponding 1,1-diazido sugars, cyano sugars, and interestingly, 1,1-diazido sugars degradated at the 1-position of carbon.