bluuebunny/crossref_metadata_2025_split 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.