bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Effects on Photochemical Cycloaddition of Phenanthrene-and Naphthalenecarboxylic Esters. Enhancement of Reactivity of an Ester Carbonyl Group by Interchromophoric Links
Authors: Itoh Hiroki , Takada Mahoko , Asano Fumihiro , Senda Yasuhisa , Sakuragi Hirochika , Tokumaru Katsumi
Published: August 2006

On irradiation in benzene, (E)-5-(p-methoxyphenyl)-4-pentenyl 3-, 9-phenanthrenecarboxylate, 1-, and 2-naphthalenecarboxylate gave novel olefinic aldehydes presumably derived from oxetane precursors, the intramolecular carbonyl adducts. Intermolecular carbonyl addition was not detected between the corresponding ester and olefinic chromophores. Enhancement of reactivity of the ester carbonyl group in the linked systems is discussed on the basis of experimental and theoretical studies.
Structures and Organization of Bacteriochlorophyll c’s in Chlorosomes from a New Thermophilic Bacterium Chlorobium tepidum
Authors: Nozawa Tsunenori , Ohtomo Katsunori , Suzuki Manabu , Morishita Yumi , Madigan Michael T
Published: August 2006

A new thermophilic bacterium Chlorobium tepidum contains two major bacteriochlorophyll c components whose periphery substituents at 4-position are either an ethyl or a propyl group. Both components possess ethyl groups at 5-position, and the ester alkyl groups at 7-position are farnesyl groups. As an aggregate structure in CDCl3 a piggy-back type dimer was suggested on the basis of variations of 1H NMR chemical shifts accompanied with the aggregate formation and of values of calculated ring current shifts. Bacteriochlorophyll c (BChl c) aggregates with absorption maxima around 677, 705, and 740 nm showed stepwise interchanges in hexane-dichloromethane with variations in BChl c concentrations and in solvent compositions. Exciton theoretical analysis of the stepwise spectral shifts predicted high ordered organization of BChl c, implying a model for rod-elements in chlorosomes.
The Rhodium(II) Acetate-Catalyzed Reaction of Diacyldiazomethanes with Isothiocyanates: Formation of 2-Thioxo-2H-1,3-oxazin-4(3H)-one
Authors: Nakano Hirofumi , Ibata Toshikazu
Published: August 2006

The rhodium(II) acetate-catalyzed reaction of diacyldiazomethanes such as dibenzoyldiazomethane, acetylaroyldiazomethanes, diacetyldiazomethane, and diazodimedone with isothiocyanates gave 2-thioxo-2H-1,3-oxazin-4(3H)-ones through the [4+2] cycloaddition of isothiocyanates with acylketenes which were derived by the Wolff rearrangement of the diacyldiazomethanes. Migration aptitude of methyl and aryl groups was discussed in the reaction of acetylaroyldiazomethanes.
Synthesis of a Polycyclic π-Conjugated System Containing an Azulene Unit by the Flash Vacuum Pyrolytic Method. IV. Synthesis and Properties of 1-Isopropylidene-1H- and 3-Isopropylidene-3H-cyclopent[a]azulene
Authors: Kitamori Yoichiro , Yasunami Masafumi , Kabuto Chizuko , Takase Kahei
Published: August 2006

A new π-conjugated system, 1-isopropylidene-1H-cyclopent[a]azulene was synthesized by the base-catalyzed condensation of 1H-cyclopent[a]azulene with acetone. An isomeric 3-isopropylidene-3H-cyclopent[a]azulene was also synthesized by the reaction of 3H-cyclopent[a]azulen-3-one with dimethylketene. The condensation of fulvene did not perturb the properties of the azulene moiety as shown by the spectral data. The X-ray analysis of 3-isopropylidene-3H-cyclopent[a]azulene also indicated that this π-conjugated system was an azulene moiety slightly perturbed by the fused fulvene ring.
Induction of Circular Dichroism on the Soret Bands of a Symmetric Water-Soluble Porphyrin by Poly(l-lysine) in Three Conformations
Authors: Nezu Takashi , Ikeda Shoichi
Published: August 2006

Absorption spectra and circular dichroism (CD) of aqueous solutions of porphine-meso-tetra(4-benzenesulfonic acid) (TPPS) in the presence of poly(l-lysine) have been measured at different pH and at different mixing ratios, and also after heated at alkaline pH higher than 10.5. Even at pH 3.0—8.0, where poly(l-lysine) is in the random coil conformation, strong CD is induced in the Soret region, giving many CD bands, and their magnitudes are not very dependent on the mixing ratio, [P]/[D], higher than 5. TPPS bound to random coil poly(l-lysine) is mostly in the dimeric form having a blue-shifted absorption band at 399 nm. The pH-induced helix-coil transition of poly(l-lysine) part occurs, accompanied by the conversion of bound TPPS from the dimeric form to the monomeric form. At pH 11 where poly(l-lysine) is in the perfect α-helix, strong CD is induced in the Soret region, consisting of a pair of positive and negative bands, and their magnitudes increase with decreasing [P]/[D] ratio and have a maximum at an intermediate [P]/[D] ratio. TPPS bound to helical poly(l-lysine) is monomeric, having an absorption band at 418nm. The induction of strong CD on the Soret region of TPPS when bound to either coiled or helical poly(l-lysine) can be attributed to dissymmetric electronic coupling of two or more TPPS ions bound to poly(l-lysine). Only weak CD is induced on the Soret transition of TPPS bound to β-form poly(l-lysine) that has been formed by heating aqueous solution of helical poly(l-lysine) at alkaline pH.
The Oxidation of 2,4,6-Trimethylphenol with Molecular Oxygen Catalyzed by a Copper(II)-Oxime or Copper(II)-Amine System
Authors: Shimizu Masao , Watanabe Yoshihito , Orita Hideo , Hayakawa Takashi , Takehira Katsuomi
Published: August 2006

2,4,6-Trimethylphenol (1a) was selectively oxidized to 3,5-dimethyl-4-hydroxybenzaldehyde (2a) by molecular oxygen in the presence of a copper(II) chloride-oxime or copper(II) chloride-amine catalyst in alcohol at ambient temperature. When an acid was present in the catalyst system, the formation of both 2,6-dimethyl-p-benzoquinone (3) and a formaldehyde dialkyl acetal was accelerated. It is likely that 2a is produced by way of the formation of a quinonemethide intermediate, followed by a repeated 1,6-addition of alcohol on the intermediate to form a 4-(alkoxymethyl)-2,6-dimethylphenol (5a), and then 3,5-dimethyl-4-hydroxybenzaldehyde dialkyl acetal, which would be hydrolyzed to 2a. When the reaction time was shortened, 5a was isolated in good yield. Oxidations of the other p-methyl-substituted phenols were also examined using the present oxidation system.
Trifluoropropenes as Dipolarophiles
Authors: Tanaka Kiyoshi , Mori Takami , Mitsuhashi Keiryo
Published: August 2006

The cycloaddition of C-phenyl-N-methylnitrone with 3,3,3-trifluoropropene and methyl 4,4,4-trifluoro-2-butenoate regio- and stereoselectively gave trans-2-methyl-3-phenyl-5-trifluoromethylisoxazolidine (3a) and methyl 2-methyl-c-3-phenyl-t-5-trifluoromethyl-r-4-isoxazolidinecarboxylate (3b), respectively, as major products. The cycloaddition with 3,3,3-trifluoro-1-nitropropene proceeded regiospecifically to give 2-methyl-c-4-nitro-r-3-phenyl-t-5-trifluoromethylisoxazolidine (3c) and 2-methyl-t-4-nitro-r-3-phenyl-c-5-trifluoromethylisoxazolidine (4c), stereoisomer with 3,4-cis-configuration being predominantly produced. This regioselectivity is explained by both the nitrone-HOMO controlled orbital interaction and the steric hindrance in a transition state. Under more drastic conditions c-3, r-4-isoxazolidine 3b isomerized to the more stable c-3, t-4- and regioisomeric isoxazolidines via 1,3-dipolar cycloreversion. The similar treatment of 3c and 4c resulted in the formation of trans-1-methyl-4-phenyl-3-trifluoromethyl-2-azetidinone.
Photochemical Cycloaddition of Phenanthrene-Fused Lactones to (E)-Anethole. Structural Effects and Dual Collapse Processes of an Exciplex Leading to Cycloadducts
Authors: Itoh Hiroki , Maruyama Syuji , Fujii Yoshiharu , Senda Yasuhisa , Sakuragi Hirochika , Tokumaru Katsumi
Published: August 2006

On irradiation with (E)-anethole in benzene 10-hydroxymethyl-9-phenanthrenecarboxylic acid lactone (s-trans lactone, STL) gave an intermolecular [2+2] cycloadduct, a cyclobutane derivative, while 8-hydroxymethyl-9-phenanthrenecarboxylic acid lactone (s-cis lactone, SCL) afforded a cyclobutane derivative and an olefinic product derived from an oxetane precursor, the carbonyl adduct. The formation of cycloadducts of highly different structures in SCL was ascribed to competitive collapse of the involved exciplex to the products. The features of intermolecular cycloaddition of the phenanthrene derivatives are discussed on the basis of results obtained from molecular orbital calculations.
Synthesis, Structural and Conformational Analysis of Methanohomo[15]annulene and Methanohomo[19]annulene
Authors: Higuchi Hiroyuki , Hashimoto Tamae , Nakafuku Kaori , Ojima Juro , Yamamoto Gaku
Published: August 2006

Methanohomo[15]annulene and methanohomo[19]annulene were synthesized by the Wittig reactions of 1,3-bis(triphenylphosphonio)propane dibromide with 1,6-bis(2-formylvinyl)- and 1,6-bis(4-formyl-1,3-butadienyl)-1,3,5-cycloheptatriene, respectively. Conformational properties of these homoannulenes are discussed. Attempts to convert these homoannulenes into the corresponding 14π- and 18π-methanoannulenyl cations were unsuccessful.
Factors Influencing the Antioxidant Activities of Phenols by an Ab Initio Study
Authors: Tomiyama Shogo , Sakai Shogo , Nishiyama Tomihiro , Yamada Fukiko
Published: August 2006

An ab initio molecular orbital theory has been applied to the elucidation of the hydrogen abstraction mechanism of phenolic antioxidants in the chain process of autoxidations. The optimum structures of o-, m-, and p-substituted phenols, of peroxides, and of those compounds in the transition states were obtained with a Hartree-Fock/STO-3G basis set. From the values of the enthalpy (ΔH), activation (Ea), and OH bond dissociation (D(O–H)) energies obtained, it was found that these three parameters indicate a good relationship with each other; particularly, the relation between the ΔH and Ea values follows the Evans-Polanyi rule. The electron-releasing substituents in the o- and p-positions in phenols decrease the activation parameters for hydrogen abstraction, while those in the m-position increase. The electron densities on the ipso-carbon, oxygen, and hydrogen of the OH substituent and their bond populations are obtained. Variations of the electron densities from the reactants to the transition states lead to a clarification of the reaction mechanism as an antioxidant. Namely, the gain or loss of electrons in the reaction states may be correlated to the experimental data, 13C chemical shifts of the ipso-carbon of the OH substituent, and the values of the induction period as an antioxidant activity.
Preparation of Microporous Gold Films by Two-Step Replicating Process Using Anodic Alumina as Template
Authors: Masuda Hideki , Tanaka Hideki , Baba Nobuyoshi
Published: August 2006

A new method to prepare microporous Au films was demonstrated. Microporous Au films were fabricated by using a two-step replicating process in which an anodic porous alumina film was used as a template for replication. The Au films had straight micropores, and the distribution of their diameters was very sharp. In addition, the dimensions of the microstructure of the Au films could be controlled by changing the anodizing condition of the porous alumina. The surface morphologies of the porous films examined by scanning electron microscopy and the detailed condition of the fabrication are shown.
19F and 1H NMR Study of Intermolecular Hydrogen Bond between Phenols and a Fluoroalkane in Solution
Authors: Shibakami Motonari , Sekiya Akira
Published: August 2006

Although the intermolecular hydrogen bonds between the fluorine atom attached to the carbon and the hydroxy group have hitherto been observed only in crystals, the hydrogen bond was confirmed by 19F and 1H NMR spectroscopy in solution for the first time.
Thermodynamics of Association of Tris(acetylacetonato)chromium(III) and -cobalt(III) with 3,5-Dichlorophenol through Hydrogen Bonding
Authors: Katsuta Shoichi , Suzuki Nobuo
Published: August 2006

The association constants of tris(acetylacetonato)chromium(III) and -cobalt(III) with 3,5-dichlorophenol in heptane were determined by a liquid-liquid partition technique at 287.7—308.2 K; the association enthalpies and entropies were calculated. The obtained enthalpies indicate considerably strong hydrogen bonds between these chelates and the phenol.
A Novel, Nonelectrochemical Synthesis of the Organic Superconductor κ-(BEDT-TTF)2Cu(NCS)2
Authors: Müller Harald , Ueba Yoshinobu
Published: August 2006

Bis(ethylendithio)tetrathiafulvalene (BEDT-TTF or ET) can be oxidized with Cu(SCN)2 to yield superconducting, microcrystalline κ-(ET)2Cu(NCS)2. The reaction is achieved either by heating a suspension of the reactants in various organic solvents or by ultrasound agitation at room temperature. The formation of the title compound was established by X-ray diffractograms, FT-IR and ESR spectroscopy. Susceptibility measurements revealed superconducting transition temperatures of 9.5—10 K. The clearly observed Meissner effect suggests superconductivity to be a bulk property of the so-obtained powder samples.
Inclusion Complexation of Cholestanol, Cholesterol, Sitosterol, Stigmasterol, and Ergosterol with Various Guest Compounds
Authors: Toda Fumio , Tanaka Koichi , Krupitsky Helena , Goldberg Israel
Published: August 2006

The title steroids were found to form crystalline inclusion complexes with a wide variety of guest compounds. Crystal structures, interaction modes and molecular recognition features of selected host-guest systems have been characterized.
Preparation of An 8-Membered Ring via Intramolecular [2+2]Photocycloadduct: Formal Total Synthesis of (±)-Precapnelladiene
Authors: Inouye Yoshinobu , Shirai Michio , Michino Tetsuyuki , Kakisawa Hiroshi
Published: August 2006

Irradiation of 4,4-dimethyl-3-[(2-cyclopentenyl)methoxy]-2-cyclohexen-1-one, prepared from 4,4-dimethyl-3-phenylthio-2-cyclohexen-1-one and (2-cyclopentenyl) methanol, gave a tetracyclic intramolecular [2+2]photocycloadduct 7. Treatment of 7 with iodotrimethylsilane followed with tributyltin hydride afforded 3,3,11-trimethylbicyclo[6.3.0]undecane-2,6-dione(12). Methylenation of 12 afforded 6-methylene-3,3,11-trimethylbicyclo[6.3.0] undecan-2-one, the known intermediate to precapnelladiene.
Synthesis and Electric Conductivity of Poly[(dodecamethyl-1,6-hexasilanediyl)-1,1′-ferrocenediyl]
Authors: Tanaka Masato , Hayashi Teruyuki
Published: August 2006

Poly[(dodecamethyl-1,6-hexasilanediyl)-1,1′-ferrocenediyl] was prepared from dilithioferrocene and 1,6-dichlorododecamethylhexasilane. The polymer exhibited electric conductivities of 3 × 10−5 S cm−1 upon iodine doping and 2 × 10−6 S cm−1 upon SbF5 doping.
The Reaction of 2,4,6-Trihalophenols with Tropylium Perchlorate. A New Route for Triphenylmethane-Type Pigments
Authors: Morita Tadayoshi , Takahashi Kazuko , Nozoe Tetsuo
Published: August 2006

The reaction of 2,4,6-tribromo- and triiodophenols with tropylium perchlorate in the presence of triethylamine gave 4-(3,5-dihalo-4-hydroxy-α-phenylbenzylidene)-2,6-dihalo-2,5-cyclohexadien-1-ones, respectively.
Cycloreversion of 2,3-Disilabicyclo[2.2.2]octa-5,7-dienes Induced by Electron-Transfer
Authors: Nakadaira Yasuhiro , Gomi Yasushiro , Hosoe Hisashi , Kyushin Soichiro , Kako Masahiro , Hatakenaka Kaname , Ohashi Mamoru
Published: August 2006

Photolysis of 1-phenyl-2,2,3,3-tetramethyl-2,3-disilabicyclo[2.2.2]octa-5,7-diene (1) with 9,10-dicyanoanthracene as a sensitizer yielded biphenyl as a tetramethyldisilene extrusion product. The mass spectrum of 1 provides access to the understanding of the reaction mechanism involving cycloreversion of a cation radical of 1.
Catalytic Activities of Layered Metal Chloride Oxides for the Dehydrohalogenation of t-Butyl Halides
Authors: Ueda Wataru , Yamazaki Masato , Morikawa Yutaka
Published: August 2006

Various metal chloride oxides having layered structures have been tested as catalysts for the dehydrohalogenation of t-butyl chloride and t-butyl bromide to form olefins and were found active for the reaction, depending on the metal constituents and the structure.
Miscibility of Octyldimethylphosphine Oxide and Decyldimethylphosphine Oxide in the Adsorbed Film and Micelle
Authors: Todoroki Natsuko , Tanaka Fudeko , Ikeda Norihiro , Aratono Makoto , Motomura Kinsi
Published: August 2006

The surface tension of the aqueous solution of octyldimethylphosphine oxide (OPO) and decyldimethylphosphine oxide (DePO) mixture was measured as a function of the total molality and the composition of the mixture at 298.15 K under atmospheric pressure. The experimental data were analyzed thermodynamically to evaluate the total surface density ΓH, the composition in the adsorbed film X2H, and the composition in the micelle X2M. The relations among the compositions of bulk solution, adsorbed film, and micelle were expressed in the form of phase diagram similar to the three-dimensional one; they were compared with the phase diagrams of ideal mixed film and micelle obtained theoretically. It was concluded that the OPO and DePO molecules mix ideally in the adsorbed film while the difference in their hydrophobic chain length causes a weaker interaction in the micelle because of a spherical shape of the micelle. This conclusion was supported by the fact that the 2-(octylsulfinyl)ethanol and 2-(decylsulfinyl)ethanol mixture behaves quite analogously.
Molecular and Electronic Structures of Model Compounds of Doped Polyacetylene
Authors: Tanaka Chizuko , Tanaka Jiro
Published: August 2006

Using the ab initio HF SCF MO method optimized molecular structures were calculated on twenty five model compounds of doped polyacetylene, which were charge-transfer complexes between dopants (Na, Li, and Cl atoms) and trans-polyenes (C6H8, C8H10, C12H14, C14H16, and C16H18) or trans-odd polyene radicals (C3H5·, C5H7·, C7H9·, C9H11·, C11H13·, and C13H15·). In alkali metal-doped complexes, each alkali atom is located at the vertex of the trigonal pyramid, whose basal triangle consists of an allylic group, (CH)3. On the other hand, each chlorine atom is coplanar with the (CH)n chain and is connected with an allylic group by hydrogen bonding. The allylic group acts as a bidentate or tridentate ligand, forming an ionic closed-shell structure with the dopants. The molecular orbitals of the singly doped complexes are correlated with those of parent trans-polyene or odd polyene radical chains. The molecular orbitals of doubly doped complexes are analyzed on the basis of those of singly doped complexes. The molecular structure of the polson unit is presented, which is important for heavily doped polyacetylene to be metallic.
Diamagnetic Susceptibilities of Various Inorganic Phosphates and Organic Phosphate Esters
Authors: Takahashi Fujio , Sakai Yasuzo , Yoshida Toshihito
Published: August 2006

The diamagnetic susceptibilities of various inorganic phosphates as well as various organic phosphate esters, such as ATP, ADP, and phosphocreatine, were determined by Gouy’s method. The diamagnetic susceptibility of H3PO4 was estimated to be −43.5 × 10−6 cm3 mol−1 from plots of the diamagnetic susceptibility against the total number of electrons in the cation by measuring various inorganic phosphates. The free-energy changes (ΔG’s) for the hydrolysis of the phosphate ester were found to correlate with the differences in the diamagnetic susceptibilities between the phosphate esters and their products of hydrolysis. The diamagnetic susceptibility of :PO3H2 was obtained to be −28—39 × 10−6 cm3 mol−1, which decreased with increasing ΔG.
Crystal Structure of Nystose Trihydrate
Authors: Okuyama Kenji , Noguchi Keiichi , Saitoh Megumi , Ohno Shigeru , Fujii Satoshi , Tsukada Masayuki , Takeda Hiroyuki , Hidano Tetsuhiro
Published: August 2006

A tetrasaccharide, O-α-d-glucopyranosyl-(1→2)-O-β-d-fructofuranosyl-(1→2)-O-β-d-fructofuranosyl-(1→2)-O-β-d-fructofuranoside (nystose) trihydrate (C24H42O21·3H2O), was crystallized from its aqueous solution by using seed crystals. The crystal structure has been determined by an X-ray diffraction method. The crystal data are as follows: orthorhombic, P212121, Z = 4, a = 13.582(3), b = 23.385(6), and c = 10.198(2) Å. The α-d-glucopyranose ring has the normal type 4C1 chair conformation, and three fructofuranose rings have the 4T3, E4, and 4T3 (or E3) conformations. As in the 1-kestose crystal, all of the hydrogen bonds found made connections between adjacent molecules. Although the linkage conformation (∠C1O1C1–2C1–1, ∠C2C1O1C1–2) of the sucrose component in nystose (100.3°, −137.1°) was different from that in 1-kestose (53.3°, −152.9°), the linkage conformation (φ,ψ,ω) of the inulobiose component at the end of nystose (71.3°, −165.9°, 68.0°) was very similar to that of 1-kestose (80.5°, −169.6°, 56.5°).
Neutron Diffraction Study on the Structure of Highly Concentrated Aqueous LiBr Solutions
Authors: Kameda Yasuo , Uemura Osamu
Published: August 2006

Neutron diffraction measurements have been carried out on aqueous solutions with 20 mol% lithium bromide. The isotopic substitution technique was applied to lithium ions and hydrogen atoms of the water molecule. The measured results were used to determine the partial pair distribution functions gLiO(r), gLiH(r), and gHH(r). The Li+···water molecule configuration is characterized by the intermolecular distances rLiO = 1.96 ± 0.02 Å and rLiH = 2.60 ± 0.02 Å, and the tilt angle between the Li+···O axis and the molecular plane of water molecule, φ = 27 ± 10°. The mean coordination number of water molecules around Li+ is computed to be 3.9 ± 0.5. The hydrogen–hydrogen pair correlation function gHH(r) obtained from observed cross sections of these solutions with different isotopic compositions exhibits that each hydrogen atom in a given water molecule is surrounded with 3.7 ± 0.5 hydrogen atoms of neighboring molecules located at rHH = 2.65 ± 0.05 Å. The hydrogen bond among water molecules may be considered to be markedly destroyed in the present concentrated LiBr solution, compared with that in pure liquid water.
Specific Acidities of the Surface Hydroxyl Groups on Maghemite
Authors: Watanabe Haruo , Seto Jun’etsu
Published: August 2006

Two types of surface hydroxyl groups on maghemite have been identified and their acidities evaluated. One of these surface groups bonds to the surface iron ions of the octahedral sites and shows a stretching vibration mode of infrared absorption at 3690 cm−1. The other bonds to the tetrahedral sites and vibrates at 3630 cm−1. The acidity of the groups positioned at the octahedral sites was evaluated as 12.5 in the pKa value while that of those on the tetrahedral sites was found to be 7.9. A charge transfer mechanism between these neighboring two types of hydroxyl groups is proposed as an explanation for these acidities.
Characterization of Silica-Supported Nickel Catalysts by the Temperature-Programed Desorption of Hydrogen Adsorbed at Various Temperatures
Authors: Arai Masahiko , Suzuki Kyosuke , Nishiyama Yoshiyuki
Published: August 2006

The temperature-programed desorption (TPD) of hydrogen adsorbed at various temperatures and at nearly saturated coverage has been used to characterize the surface of nickel particles dispersed on silica gel. The TPD spectra have two major peaks, the first and second peaks, at about 375 and 560 K. The second peak has a strong functional relation with the nickel weight loading and the heat-treatment temperature. It decreases with decreasing metal loading and increasing treatment temperature. As the adsorption temperature is increased the amount of hydrogen desorbing in the second peak is mainly increased; this is more remarkable for smaller metal loading. The two observed major peaks suggest the presence of two types of adsorption sites on nickel particles. The adsorption of hydrogen can easily occur on sites for the first peak, while it should go over some energy barrier on sites for the second one. It is assumed that these two types depend on the surface morphology of nickel particles, which is affected by their size and thermal history.
Extended Molecular Mechanics Simulation of Thermodynamic Quantities, Structures, and Vibrational Spectra of Fatty Acids
Authors: Yokoyama Isao , Miwa Yoshihisa , Machida Katsunosuke , Umemura Junzo , Hayashi Soichi
Published: August 2006

An extended molecular mechanics calculation of thermodynamic quantities, structure parameters, infrared absorption spectra, and Raman spectra of normal fatty acids was carried out on the basis of the potential and the intensity parameters transferred from those determined for acetic acid and normal paraffins in the gas phase. The overall features of the infrared absorption spectra of propionic acid and its deuterated species in the solid state at liquid-nitrogen temperature are successfully reproduced. The multiple CH2 wagging bands of the cis-configuration of long-chain fatty acids are ascribed to the coupling between the C–O stretching mode and the CαH2 or the CβH2 wagging mode. The infrared absorption spectra of lauric through palmitic acids at room temperature are well simulated by superimposing the spectra of the cis- and the trans-configurations. The simulated Raman spectrum of crystalline palmitic acid based on the bond polarizability model agrees well with the observed spectrum at room temperature.
Characterization of Amino Hydroxamic Acids and Their Metal Chelates. Determination of Protonation and Formation Constants between 2-Amino-N-hydroxy-3-methylpentanamide and Copper(II), Nickel(II), Cobalt(II), and Hydrogen Ions in Aqueous Solution
Authors: Leporati Enrico
Published: August 2006

The equilibria and relevant stability constant of species present in aqueous solutions of H+, CuII, NiII, and CoII with “l-isoleucinehydroxamic acid” (2-amino-N-hydroxy-3-methyl pentanamide, ahmpe1) have been investigated by using potentiometric and spectrophotometric titrations at 25 ± 0.1 °C and I = 0.5 mol dm−3 (KCl). The protonation constants of the ligand and the overall formation constants of several metal complexes were calculated from potentiometric and spectrophotometric data with the aid of the SUPERQUAD, and SQUAD programs, respectively. The following cumulative association constants (relative standard deviation values are given in parentheses) βpqr = [MpHqLr]/[M]p [H]q [L]r were obtained : log β011 = 9.15(1), log β021 = 16.40(1); CoII-ahmpe1, log β111 = 12.26(1), logβ101 = 5.50(1), logβ102 = 9.46(6), logβ1–11 = −1.71(2); NiII-ahmpe1, logβ101 = 6.90(2), logβ102 = 14.28(5), logβ1–12 = 6.06(2); CuII-ahmpe1, logβ101 = 10.36(1), logβ102 = 19.85(1), logβ2–12 = 20.90(1), logβ1–12 = 10.29(1). The ligand is bound to the metal ions through the coordination of the N atoms of the α-amino and the deprotonated –NHO− groups. The UV-vis studies can be used to follow the appearance of the individual species, to estimate the coordination sphere around the metal ion and to observe the equilibria between different complexes. So the solution electronic spectra have been also employed to suppose a weak tetragonal coordination in the [CuL2(H2O)2] complex. Equilibrium constants for their formation and the probable structure of the chelated compound formed in aqueous solution are the object of discussions in terms of their possible significance to biological reactions, and their stability is compared with that of analogous chelated compounds.
Bis(phenylethynyl)hafnocene as an Organometallic Chelate Ligand
Authors: Lang Heinrich , Herres Mathias , Zsolnai Laszlo
Published: August 2006

The application of (η5-C5H4SiMe3)2Hf(C≡CPh)2 (1) as an organometallic chelate ligand towards different organometallic building blocks will be discussed. 1 reacts with Ni(CO)4 (2) or Co2(CO)8 (4) to yield {(η5-C5H4SiMe3)2Hf(C≡CPh)2}M(CO) (M = Ni: 3, M = Co: 5) and (η5-C5H4SiMe3)2Hf(C≡CPh) [μ-(η2-C≡CPh)Co2(CO)6] (6). In 6 one of the two phenylethynyl units is η2-side-on coordinated to Co2(CO)6 forming a 1,2-dicobaltatetrahedrane unit. However, the reaction of 1 with Fe2(CO)9 (7) affords (η5-C5H4SiMe3)2Hf[(η2-C≡CPh)Fe(CO)4]2 (8), a compound, in which both of the phenylethynyl ligands are η2-side-on coordinated to Fe(CO)4 complex fragments. All new synthesized compounds have been characterized by analytical and spectroscopic data. Additionally, the structure of 3 was established by X-ray diffraction study.
Crystal Structure and Luminescence Site of Na9[EuW10O36]·32H2O
Authors: Sugeta Moriyasu , Yamase Toshihiro
Published: August 2006

Na9[EuW10O36]·32H2O, obtained from aqueous solutions, crystallizes in space group Cc with a = 11.484(5), b = 23.020(7), c = 23.581(6) Å, β = 91.71(3)°, V = 6231(3) Å3, Mr = 3349.4, Dx = 3.57 Mg m−3, and Z = 4. A full-matrix least-squares refinement finally yields R = 0.070 and Rw = 0.086 for 6473 independent reflections. The local symmetry around Eu3+ for the [EuW10O36]9− anion is approximately square antiprismatic. Photoexcitation into the oxygen-to-tungsten charge transfer bands of a solid sample leads to red emission due to f–f transitions within Eu3+, as a result of an intramolecular energy transfer from the W5O18 group to the Eu atom. The spectral transitions of photoluminescence recorded at 4.2 K can be interpreted based on the assumption of a C4v point group for Eu3+, which is consistent with the co-ordination geometry for the Eu atom.
Effect of a Solvent on the Extraction of the Europium(III) 2-Thenoyltrifluoroacetonate Anionic Complex as Ion-Pairs with Tetrabutylammonium Ions
Authors: Noro Junji , Sekine Tatsuya
Published: August 2006

The solvent extraction of europium(III) in aqueous 0.1 mol dm−3 sodium nitrate or sodium chloride solutions with 2-thenoyltrifluoroacetone (Htta) into chloroform, toluene, and 4-methyl-2-pentanone (MIBK) was studied in both the absence and presence of tetrabutylammonium ions (tba+); the results were compared with those into carbon tetrachloride. When the diluent was chloroform or toluene, the extraction was greatly enhanced by the addition of tba+, just as with carbon tetrachloride. This could be explained in terms of the extraction of the Eu(tta)4−tba+ species, in addition to the Eu(tta)3 species. However, this did not occur in the MIBK system, and was explained in terms of stable solvates with MIBK, which interfere with the addition of tta−tba+ ion-pairs on the Eu(tta)3 species. The enhancement due to the extraction of Eu(tta)4−tba+ was not very much different from that in the other solvent systems. This could be explained by assuming that although the amount of tta−tba+ in the organic phase was smaller in the order chloroform > toluene > carbon tetrachloride, the degree of association of this ion-pair with the Eu(tta)3 in the organic phase was larger in the inverse order, and that these two opposite tendencies canceled each other out. The results were compared with the synergistic enhancement of the extraction of europium(III) with Htta by organophilic neutral ligands, such as tributylphosphate.
Crystal Structure and Polymorphism of Antiferroelectric Mesogen, 4-[(S)-1-Methylheptyloxycarbonyl]phenyl 4′-Octyloxybiphenyl-4-carboxylate (MHPOBC)
Authors: Hori Kayako , Endo Kyoko
Published: August 2006

Single crystal X-ray analysis has been carried out for the title compound, –COOCH(CH3)C6H13, which has antiferroelectric liquid crystalline phases. Crystal data; monoclinic, P21, T = 298 K, a = 32.285(7), b = 5.520(2), c = 9.320(2) Å, β = 95.34(2)°, V = 1653.7(7) Å3, Z = 2, dx = 1.123 g cm−3. The crystal has a smectic-like layer structure composed of largely bent molecules; a chain of the chiral group is almost perpendicular (93°) to the core moiety. DSC and temperature dependence of powder X-ray diffraction patterns show that the crystal is a metastable phase, which transforms to a more stable crystalline phase with longer spacing of layer.
Nitriles in Heterocyclic Synthesis. The Reaction of Polyhydric Naphthalenes, 4-Methylcoumarin-3-carbonitrile, and Alkylidenemalononitrile with Methylenemalononitrile
Authors: Elagamey Abdel Ghani Ali , El-Taweel Fathy Mohamed Abdel-Aziz , Khodeir Mohamed Nabil Mohamed , Elnagdi Mohamed Hilmy
Published: August 2006

2-Naphthol and naphthalenediols react with methylenemalononitrile, generated in situ from reaction of formaldehyde and malononitrile, to yield naphthopyrans and naphthodipyrans. 5-Hydroxynaphtho[2,1-b]pyrans reacted further with methylenemalononitrile to yield naphthodipyrans. The reaction of methylenemalononitrile with 4-methylcoumarin-3-carbonitrile afforded benzopyrano[4,3-h]quinoline. 6-Cyanomethyl-3-pyridinecarbonitriles, prepared via reacting 1-arylethylidenemalononitriles with malononitrile, afforded 4H-quinolizines on treatment with methylenemalononitrile.
Syntheses and Reactions of Metal Organics. XVII. Synthesis of Silane Coupling Agent Having Fluorocarbon Chain and Surface Modification of Glass Plate
Authors: Yoshino Norio , Yamamoto Yasushi , Seto Tsuyoshi , Tominaga Shin-ichi , Kawase Tokuzo
Published: August 2006

Four silane coupling agents,1H,1H,2H,2H-polyfluoroalkyl(dimethoxy)(methyl)silanes (1H,1H,2H,2H-henicosafluorododecyl(dimethoxy)(methyl)silane, C10F21C2H4Si(CH3)(OCH3)2, 1H,1H,2H,2H-heptadecafluorodecyl(dimethoxy)(methyl)silane, C8F17C2H4Si(CH3)(OCH3)2, 1H,1H,2H,2H-tridecafluorooctyl(dimethoxy)(methyl)silane, C6F13C2H4Si(CH3)(OCH3)2, and 1H,1H,2H,2H-nonafluorohexyl(dimethoxy)(methyl)silane, C4F9C2H4Si(CH3)(OCH3)2), were prepared by the hydrosilylation of dichloro(methyl)silane with the corresponding 1H,1H,2H-polyfluoro-1-alkene in the presence of hydrogen hexachloroplatinate(IV), followed by the reaction with sodium methoxide. The surface modification of glass plate was attempted using these products. From measurements of the contact angles θ(°) of water and oleic acid against a modified glass plate surface, the coupling agents were found to have high modification ability. The oxidation resistance of the modified glass surface was also investigated.
The Solubility and Conformation of Protected Tri- to Heptapeptides in a Variety of Organic Solvents and the Classification of Organic Solvents Based on Their Solvating Potential for Protected Peptides
Authors: Narita Mitsuaki , Lee Jin-Shik , Hayashi Shizue , Yamazaki Yasunobu , Hitomi Mitsuo
Published: August 2006

The solubility in a variety of organic solvents was examined for 75 kinds of protected tri- to heptapeptide fragments of E. coli ribosomal protein L7/L12. The organic solvents examined were classified into six groups mainly by considering their solvating potential and supplementarily by using their acceptor number (AN) and donor number (DN). The result of the classification of the organic solvents was practically explained by the DN and AN of the organic solvents, indicating that the electron-donating or -accepting ability of organic solvents is much more important for the solvation of protected peptides than their ability to form van der Waals interactions. Nevertheless, the solvation mechanism of protected peptides in organic solvents could be explained by two types of intermolecular interactions, namely, intermolecular hydrogen bonding and van der Waals interactions. The  values of protected peptieds, difined in a previous paper, properly reflected their β-sheet-structure stability in a variety of organic solvents regardless of their amino acid sequence. The solubility of protected peptides in organic solvents was also strongly related to their  values. In fact, peptides having a low  value were easily soluble in various organic solvents and had an unordered structure in solution.
The Heteroselective Solvation of Protected Hexapeptides in a Variety of Mixed Solvents and the Criteria for the Choice of Mixed Solvents Effective for Peptide and Protein Synthesis
Authors: Narita Mitsuaki , Lee Jin-Shik , Hayashi Shizue , Yamazaki Yasunobu , Sugiyama Tomoko
Published: August 2006

Focusing our attention on both the van der Waals interactions between solvents and peptide side chains and the electron donor–acceptor interactions between mixed solvents, the solubility and conformation in a variety of mixed solvents were examined for protected hexapeptide fragments of E. coli ribosomal protein L7/L12. Although it was difficult to precisely evaluate the van der Waals interactions between solvents and peptide side chains, it was confirmed that the van der Waals interactions between solvents and peptide side chains were important for the solvation of protected peptides in mixed solvents. The electron donor–acceptor interactions between mixed solvents remarkably decreased the β-sheet-structure-disrupting potential of a variety of mixed solvents. In connection with the β-sheet-structure-stabilizing potential, , of protected peptides, it was also confirmed that the  value of protected peptides properly reflected their β-sheet-structure stability in a variety of mixed solvents. The criteria for the choice of mixed solvents effective in peptide and protein synthesis was led on the basis of both the heteroselective solvation mechanism in mixed solvents and the electron donor–acceptor interactions between mixed solvents. The significance of the present study in the choice of effective solvents for liquid- and solid-phases peptides synthesis is elaborately discussed.
Pressure Dependence of the Rate Constant for the Reaction of CH3O + NO
Authors: Ohmori Kenji , Yamasaki Katsuyoshi , Matsui Hiroyuki
Published: August 2006

The reaction of CH3O with NO was examined at room temperature (T = 296 ± 6 K), where, CH3O was produced in 266 and 355 nm photolysis of CH3ONO, and detected by laser-induced fluorescence technique. From the time resolved analysis of CH3O with excess amount of NO, the rate constant for reaction CH3O + NO (+ M) → products (+M) (1) was measured over the total pressure range of 7—100 Torr[He], 10—70 Torr[N2], 15—50 Torr[CF4], and 10—50 Torr[SF6] (1 Torr = 133.322 Pa). The high-pressure limiting rate constant for reaction (1) has been evaluated to be k1∞ = (4.5 ± 1.5) × 10−11 cm3 molecule−1 s−1 with Hinshellwood-Lindemann theory. The present result is found to be consistent with that obtained recently by Frost and Smith.
Addition Reaction of Phenyl Isocyanate and Phenyl Isothiocyanate to Partially Cyclic 1,3-Diaza-1,3-butadienes. Synthesis of Annulated 1,3,5-Triazine-2,4(1H,3H)-diones and -2,4(1H,3H)-dithiones
Authors: Abdel-Rahman Mahmoud A
Published: August 2006

Annulated 1,3,5-triazine-2,4(1H,3H)-diones and -2,4(1H,3H)-dithiones (8 and 9) are synthesized by a 4π+2π cyclodimerization of heterocyclic heterocumulenes (6 and 7). These heterocumulenes are generated from partially cyclic 1,3-diaza-1,3-butadienes (1a—c) by means of a 2π+2π cycloaddition reaction with phenyl isocyanate or phenyl isothiocyanate and followed by dissociation of the resulting cycloadducts (1,3-diazetidinones (3) and 1,3-diazetidithiones (4)).
Effect of Methyl Substitution on Conformation and Molecular Arrangement of BEDT-TTF Derivatives in the Crystalline Environment
Authors: Matsumiya Shigeki , Izuoka Akira , Sugawara Tadashi , Taruishi Tomohiro , Kawada Yuzo
Published: August 2006

Two methylated bis(ethylenedithio)tetrathiafulvalene (ET) derivatives, Me2ET and Me4ET were stereoselectively synthesized to examine the effect of methylation on conformations of dihydrodithiin rings and molecular arrangements in the crystalline state. Since the donating ability of Me2ET and Me4ET are similar to that of ET, the methylated ET derivatives are considered to be appropriate to investigate the “lattice pressure” effect on ET radical salts by changing the volume of donor molecules. The upper limit of an activation energy for the ring inversion of the dimethylated dihydrodithiin in solution was estimated to be 32 kJ mol−1 by 13C NMR spectroscopy. The X-ray structure analyses revealed that orientations of methyl groups are fixed to axial in Me2ET and to equatorial in Me4ET, accompanied by the change of molecular stacking. The “volume of a methyl group” was evaluated by comparing the molecular volumes of Me2ET and Me4ET with that of ET, and the effective volume for the axial methyl group turns out to be 15% larger than that of the equatorial. The solid state 13C NMR (CP/MAS) spectra of ET and its derivatives showed that the chemical shifts of resonance lines reflect the conformations of dihydrodithiin rings in crystals.
Total Synthesis of Grahamimycin A1
Authors: Ohta Kazuo , Miyagawa Osamu , Tsutsui Hironori , Mitsunobu Oyo
Published: August 2006

(3R)- and (3S)-3-Hydroxybutanoates were respectively converted into (2E,5R)- and (2E,5S)-5-t-butyldimethylsiloxy-2-hexenoic acids, corresponding to the O-1–C-6 fragment of grahamimycin A1 (1). The O-7–C-14 fragment [(4S,5S,7R)- or (4R,5R,7R)-7-hydroxy-4,5-isopropylidenedioxyoctanoate] was synthesized from 4,6-dideoxy-α-D-xylo -hexopyranoside. Condensation of the both fragments, followed by deprotection at the terminal hydroxyl- and carboxyl-functions afforded the seco acids of the precursors of 1. While the reaction of the seco acids having 13S-configuration with diethyl azodicarboxylate and triphenylphosphine afforded the corresponding lactones in low yields, macrolactonization of the seco acid having 13R-configuration by Yamaguchi procedure gave the desired lactone in 56% yield. Deprotection of vic-diol moiety of the lactone indicated the completion of relay synthesis of 1.
Preparations of Optically Active Homocysteine and Homocystine by Asymmetric Transformation of (RS)-1,3-Thiazane-4-carboxylic Acid
Authors: Miyazaki Hideya , Ohta Atsushi , Kawakatsu Nobuyuki , Waki Yukitaka , Gogun Yasuhiro , Shiraiwa Tadashi , Kurokawa Hidemoto
Published: August 2006

Dl-Homocysteine [Dl-Hcy] from (RS)-homocysteine thiolactone hydrochloride [(RS)-HTL·HCl] was subjected to reaction with formaldehyde in acetic acid to give (RS)-1,3-thiazane-4-carboxylic acid monohydrate [(RS)-THA·H2O]. An asymmetric transformation of (RS)-THA·H2O was achieved via salt formation with optically active tartaric acid in the presence of salicylaldehyde in acetic acid. The (R)- and (S)-THA obtained, respectively, from the salt of (R)-THA with (2R, 3R)-tartaric acid and its enantiomeric salt were treated with hydroxylamine hydrochloride to give d- and l-Hcy of 100% optical purity, respectively, in 50% yield from (RS)-HTL·HCl. Oxidation of d- and l-Hcy with hydrogen peroxide gave d- and l-homocystine, respectively, in 47% yield.
Reaction of (Cyano)thioacetamide with Arylhydrazones of β-Diketones: Novel Synthesis of 2(1H)-Pyridinethiones, Thieno[2,3-b]pyridines, and Pyrazolo[3,4-b]pyridines
Authors: Elgemeie Galal Eldin Hamza , El-Zanate Ali Mahmoud , Mansour Abdel-Kader E
Published: August 2006

A novel synthesis of 2(1H)-pyridinethiones, thieno[2,3-b]pyridines and pyrazolo[3,4-b]pyridines utilizing (cyano)thioacetamide and arylhydrazones of 1,3-diketones as starting components is described.
Ferroelectric Liquid Crystals Having Various Cores. Effect of Core Structure on Physical Properties
Authors: Sugita Shin-ichi , Toda Susumu , Yamashita Tetsuo , Teraji Tsutomu
Published: August 2006

Ferroelectric liquid crystals (FLC’s) having various cores were synthesized and the effect of the different core structures on the spontaneous polarization (Ps) values was investigated. The results indicate that the core structure has a great influence on the Ps value and introduction of a heterocycles such as pyrimidine and thiadiazole ring in the core increases the Ps value. Moreover, several compounds in this series are interesting as chiral dopants for FLC, because the mixtures containing them showed superior properties as FLC mixture.
General Graph Theory of Superaromaticity
Authors: Aihara Jun-ichi
Published: August 2006

A conjugated super-ring molecule with a cavity inside may exhibit superaromaticity, i.e., extra thermodynamic stabilization due to the super-ring structure. General graph theory of superaromaticity was developed so as to analyze superaromatic character of all kinds of conjugated super-ring molecules. Typical conjugated super-ring molecules, such as kekulene, azulenoid kekulene, anti-kekulene, octadecabenzokekulene, hexa-m-phenylene, and hexabenz[18]annulene, were predicted to be essentially non-superaromatic.
Syntheses and Properties of New Liquid-Crystalline Polymers Having 1,3,2-Dioxaborinane Pendants
Authors: Matsubara Hiroshi , Seto Koji , Tabuchi Hitoshi , Imazaki Hideyuki , Takahashi Shigetoshi
Published: August 2006

Polyacrylates and polymethacrylates having various 1,3,2-dioxaborinane derivatives as pendants have been synthesized and demonstrated to form chiral smectic C and/or smectic A phases which are more stable than those formed by the corresponding monomes. They provide a new family of chiral liquid crystalline side-chain polymers containing boron atoms in the pendant group.
Free Volume Holes of Rubbery Polymers Probed by Positron Annihilation
Authors: Okamoto Ken-ichi , Tanaka Kazuhiro , Katsube Mikio , Kita Hidetoshi , Ito Yasuo
Published: August 2006

The lifetime and the intensity of ortho-positronium (o-Ps), τ3 and I3, respectively, were measured for various polymers below and above glass transition temperatures Tg. The average size of micro-vacancies probed by o-Ps, vh,Ps, was evaluated from τ3 using an empirical equation. Both temperature dependence of τ3 and comparison of magnitude of vh,Ps between the polymers and molecular liquids having similar cohesive energy density reveal that the micro-vacancies probed by o-Ps at temperatures not much above Tg are pre-existing and momentarily frozen free volume holes rather than Ps bubbles. A method to evaluate the volume fraction and the concentration of free volume holes probed by o-Ps, VF, Ps, and Ch, Ps respectively, is proposed by assuming that the size-distribution is approximated by an exponential function with a mean size , and that the volume fraction of total free volume holes is equal to fractional free volume calculated by the Bondi method. This model predicts clear correlations between  and the concentration of total free volume holes and also between VF,Ps and vh,Ps. There is no clear correlation between Ch,Ps and I3, suggesting that I3 is not a good measure of the concentration of free volume holes.
Nucleophilic Aromatic Substitution on 1-Alkoxy-2-naphthoates with 1-Naphthyl Grignard Reagents. A Practical and Convenient Asymmetric Synthesis of 1,1′-Binaphthyl-2-carboxylates
Authors: Hattori Tetsutaro , Hotta Hiroki , Suzuki Takatsugu , Miyano Sotaro
Published: August 2006

1-Naphthyl Grignard reagents efficiently displace the 1-alkoxyl group of 1-alkoxy-2-naphthoic esters to provide an easy access to the corresponding 1,1′-binaphthyl-2-carboxylates in excellent yields; isopropyl ester is bulky enough to prevent the Grignard addition to the ester carbonyl function. High levels of asymmetric induction (up to 98% optical yield) have been achieved in the joining of the two naphthalene rings by using 1-(l-p-menth-3-yloxy)-2-naphthoates, while the reaction of chiral alkyl esters of 1-methoxy-2-naphthoic acid proceeded with appreciable to moderate stereoselectivity. The probable reaction mechanisms are discussed for the binaphthyl coupling and the asymmetric induction.
A Convenient Synthesis of 1,2-Dithietes and 1,2-Dithioxo Compounds Stabilized by Buttressing and Resonance Effects, Respectively, by Sulfuration of Alkynes with Elemental Sulfur
Authors: Choi Keun Soo , Akiyama Isao , Hoshino Masamatsu , Nakayama Juzo
Published: August 2006

Sulfuration of a series of alkynes by elemental sulfur was investigated. Alkynes carrying highly bulky substituents, 2,2,5,5-tetramethyl-3-hexyne (6a), 1,2-di-(1-adamantyl)ethyne (6b), 3,3-dimethyl-1-phenyl-1-butyne (6c), and 1-(1-adamantyl)-2-phenylethyne (6d), reacted with sulfur to give the corresponding stable 1,2-dithietes 7a—d in 46—65% yields. Less hindered alkynes reacted with sulfur to afford 1,4-dithiins and thiophenes as the final products which were derived from the initial products, 1,2-dithietes, via their tautomerization to the corresponding 1,2-dithioxo compounds, while extremely congested alkynes failed to react with sulfur even under forcing conditions. On the other hand, ynamines, a typical electron-rich alkyne, 1-diethylamino-2-phenylthioethyne (6o), 1-diethylamino-2-phenylselenoethyne (6p), and tetraethylethynediamine (6q) were sulfurated under milder conditions to afford resonance-stabilized 1,2-dithioxo compounds 19o—q as the principal products. Mechanism of the formation of 1,2-dithietes, 1,2-dithioxo compounds, and other products is discussed.