bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Behavior of Bipolar Fatty Acid Monolayers
Authors: Huda Masud S , Fujio Katsuhiko , Uzu Yuhei 
Published: June 2006

Abstract
The phase behaviors of the monohydroxy- and dihydroxy-substituted fatty acids at an air–water interface were investigated in the presence of different substrates. All of the hydroxylated fatty acids studied, except for 2-hydroxyoctadecanoic acid (2-HOA) and 9,10-dihydroxyoctadecanoic acid (9,10-DHOA), showed an intermediate region (“plateau”) for a transition from a liquid-expanded state (LE) to a liquid-condensed state (LC) in the π–A isotherms, regardless of the substrate composition. In contrast, 9,10-DHOA exhibited a pressure plateau region on only 3 M NaCl. In order to assess the effect of adding an extra polar group (i.e., a hydroxy group) for a 9,10-DHOA monolayer compared to a 9-hydroxyoctadecanoic acid (9-HOA) monolayer, the monolayer-substrate interactions were considered based on the thermodynamic parameters for the LE/LC phase transition, using a two-dimensional Clausius–Clapeyron equation. This can be explained by assuming that a greater energy was generated for breaking of hydrogen bonds between the two hydroxy groups of 9,10-DHOA and water. In this regard, the dynamic properties of the monolayer for these acids were examined using the surface pressure relaxation method as well as an equilibrium spreading pressure (ESP) measurement.
MO-Theoretical Description of Electronic Structures of Tricentric Bisdesmiphiles in the Ground and Excited States
Authors: Yoshioka Yasunori , Yamaki Daisuke , Maruta Goro , Tsunesada Tsunaki , Takada Kazuhiro , Noro Takeshi , Yamaguchi Kizashi 
Published: June 2006

Abstract
A systematic MO-theoretical description of electronic structures of tricentric bisdesmiphiles in the ground state is presented in response to contradictory arguments on the biradical character of the species by Huisgen, Firestone, and others. The approximately spin-projected but size-consistent (AP) UHF and UMP methods remedy artifact arising from the spin contamination effect involved in the singlet UHF and UMP wavefunctions, giving reasonable a different-orbitals-for-different-spins (DODS) MO description for oxygenated dipoles such as O3 and CH2OO and 1,3-biradicals without octet stabilization such as OCH2O and CH2CH2CH2. The RHF method provides well-accepted MO description for diszonimum and nitrilium betaines having little biradical character, and the RMP method works well even for species with weak biradical character. They are successfully applied to calculating relative energies between nonradical ring- and biradical open-forms of tricentric species, singlet–triplet energy gaps of tricentric biradicals, and high- and low-spin energy gaps of polyradicals constructed of 1,3-biradical units. Reliability of the projected UHF and UMP scheme for biradical species was confirmed by the complete active space (CAS) configuration interaction (CI) by the use of UHF natural orbitals (UNO). The UNO CASCI calculations are also carried out both for the ground and excited of 1,3-biradicals. The energy gradient technique based on UNO CASSCF is applied to the full geometry optimizations of tricentric systems, followed by the UNO CASSCF MP2 calculations for dynamical correlation corrections. On the other hand, the UNO MR SDCI method by the use of the UNO CASCI reference gives a well-balanced MO-theoretical description of the ground and excited states. Comparisons of different definitions of biradical character are given in relation to theoretical explanations of 1,3-dipoles and 1,3-dipolar reactions. It is shown that the present MO-theoretical description based on both delocalized and localized natural orbitals is wholly compatible with experimental data obtained by Huisgen and others.
Several Factors Affecting the Detection Sensitivity of the Reaction Heat-Induced Optical Beam Deflection Method
Authors: Wu Xing-Zheng , Kitatani Hideki , Uchiyama Katsumi , Hobo Toshiyuki 
Published: June 2006

Abstract
In order to improve the detection sensitivity of the reaction heat-induced optical beam deflection method, the experimental factors that affect the detection sensitivity were investigated in detail. Firstly, different types of deflection detectors were compared. The experimental results showed that the bi-cell photodiode detector is most sensitive to the deflection signal. Secondly, the effect of the size of the reaction cell on the detection sensitivity was investigated. A small reaction cell gave a stable baseline and small noise in flow injection experiments, and thus gave a high detection sensitivity. Thirdly, the effects of the optical arrangements on the detection sensitivity were investigated. Focusing the probe beam close to the gold film/CCl4 interface enhanced the detection sensitivity. Also, refocusing the deflected probe beam improved the sensitivity. Under the selected experimental conditions, the detection of the neutralization reaction between HCl and NaOH at sub-nanomol level became possible. Further improvements are also discussed.
Through-Bond and Through-Space Interactions of Organic Radicals Coupled by m-Phenylene
Authors: Yoshizawa Kazunari , Kuga Takako , Sato Tohru , Hatanaka Masashi , Tanaka Kazuyoshi , Yamabe Tokio 
Published: June 2006

Abstract
Through-bond and through-space magnetic interactions in tricarbene and its related triradicals coupled through m-phenylene units are discussed with a semiempirical molecular orbital method including configuration interactions (PM3-CI method). The high-spin (HS) and low-spin (LS) states have quite similar geometries, but the methylene bridging angle is larger in the HS states. The HS states of these lie well below the corresponding LS states, except for one which contains nitroxide and aminiumyl radicals. Instability of the HS state of the heteroatomic system is a consequence of significant mixing between NBMOs and benzene e1g-type orbitals, which can be explained in terms of simple perturbation theory. The energy difference between the HS and LS states is not explicitly influenced by the conformation of the molecules examined. This shows that such conformations have little effect on the magnetic properties in possible polymer ferromagnets which contain m-phenylene coupling units, as far as the second nearest neighbor interaction.
Viscosity-Dependent Decay Dynamics of the S2 State of Cyanine Dyes with 3, 5, and 7 Methine Units by Picosecond Fluorescence Lifetime Measurements
Authors: Kasatani Kazuo , Sato Hiroyasu 
Published: June 2006

Abstract
The lifetimes of the short-wavelength (SW) fluorescence of some cyanine dyes with 3, 5, and 7 methine units were measured using a synchronously pumped picosecond dye laser in conjunction with the time-correlated single-photon counting method. The lifetimes were longest for dyes with 5 methine units, and decreased in the order of 5, 7, and 3 methine units. The lifetimes were highly dependent on the solvent viscosity. The dependences were compared with those of the fluorescence quantum yields previously reported by the authors in order to determine the relative importance of direct internal conversion (viscosity-independent) relaxation channel and that of the crossing-over to the photoisomer potential energy curve (viscosity-dependent channel). It was determined that origin of the SW fluorescence was the second excited singlet state by semiempirical molecular orbital calculations. The absolute SW fluorescence quantum yield of one of the cyanine dyes, DODC, was found to be less than 0.002 in ethanol. The relaxation rates of these cyanine dyes in the first and second excited singlet states were compared.
Speciation of Trace Metals in Pond Water as Studied by Liquid Chromatography/Inductively Coupled Plasma Mass Spectorometry
Authors: Itoh Akihide , Kimata Chisen , Miwa Hajime , Sawatari Hideyuki , Haraguchi Hiroki 
Published: June 2006

Abstract
An on-line separation-detection system, liquid chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS), has been developed and applied to the study on speciation of trace metals in pond water. First, the total concentrations of dissolved metal ions in pond water were determined by ICP-MS after chelating resin preconcentration. Then, pond water was preconcentrated by ultrafiltration using a filter with a molecular weight permeation limit of 10000, providing size exclusion chromatography. Large organic molecules which had combined with trace metals in the preconcentrated samples were separated with a gel filtration column and detected by UV absorption and ICP-MS, sequentially. In consequence, large organic molecules with the molecular weight of ≥300000 and 10000—50000 could be observed. A large number of trace metals (41 elements) were found in those organic molecules. Furthermore, the percentages of metal ions in the forms of large organic molecule–metal complexes were estimated from their concentrations as determined by the flow injection method.
Silver Extraction for Pollution Control of Photographic Fixing Solution with Tetramethylthiuram Disulfide
Authors: Mendoza Concepcion S , Kamata Satsuo 
Published: June 2006

Abstract
Silver recovery from photographic fixing solutions can be performed by solvent extraction with thiuram disulfides. Tetramethylthiuram disulfide (TMTDS) was selected for further studies because it had the highest distribution ratio among the three extractants. Its selectivity for silver extraction from a thiosulfate medium and from an analytical photographic fixing solution were evaluated. A 1 : 1 silver(I)–TMTDS complex is formed. For a one-stage and one-hour silver(I) extraction process, a 96% recovery was obtained from an analytical fixing solution containing 1 g dm−3 silver(I), starting with a 0.02 M (1 M = mol dm−3) TMTDS solution. The possible extraction mechanism involves the reduction of TMTDS in the presence of thiosulfate ions, followed by chelation of the silver(I) with the reduced TMTDS. Effective stripping can be performed by using 3 M hydrochloric acid. By dilution of the fixing solution with water (1 : 1), and the use of 0.1 M TMTDS, recycling of the organic phase between the extraction and stripping stages for silver extraction can be achieved in a few times. The results for the analytical solutions were further shown to be applicable to a black and white photographic industrial solution.
Study on Efficient Synthetic Routes for 7-Fluoroprostaglandin F2α and 7-Fluoro-17,20-dimethyl-2,4-methyleneprostacyclin
Authors: Matsumura Yasushi , Shimada Toyomichi , Wang Shu-Zhong , Asai Tomoyuki , Morizawa Yoshitomi , Yasuda Arata 
Published: June 2006

Abstract
New and facile syntheses of 7-fluoroprostaglandin F2α 1 and chemically stable 7-fluoro-17,20-dimethyl-2,4-methyleneprostacyclin 2 from commercially available methylenecyclopentanone are described. Construction of the key 7-hydroxyprostaglandin skeleton has been efficiently accomplished by the coupling of acetylenic acids with cyclopentanecarbaldehyde 4 under mild conditions.
Photo-Induced Reactions of Oxime O-Ethers Derived from 3-Acyl-1,2-dihydrocinnoline-1,2-dicarboximides
Authors: Tanaka Satoko , Seguchi Kazuyoshi , Itoh Kuniaki , Sera Akira 
Published: June 2006

Abstract
The irradiation of oxime O-ethers 2, derived from N-substituted 3-acyl-1,2-dihydrocinnoline-1,2-dicarboximides in benzene, afforded rearranged products 3 possessing a [1,3,5]triazino[1,2-a]indole skeleton in good yields. Upon irradiation, 7-methoxy-substituted 1,2-dihydrocinnoline-1,2-dicarboximides 2 gave a novel dimer 5 together with the rearranged triazinoindole derivatives 3 in benzene, while in nucleophiles they gave the nucleophile-incorporated dihydrotriazinoindoles 6. However, the 7-nitro-substituted one was inert under the same conditions. The dimer and dihydrotriazinoindole derivatives were thought to be formed by a nucleophilic attack of the initial photoproduct 3 and nucleophiles to 2, respectively. From these results and the observation of a remarkable solvent-dependency of the fluorescence and UV spectra of 2, it was suggested that these photoreactions should occur through a nitrogen–nitrogen bond cleavage at polar excited states followed by skeletal rearrangements.
Total Syntheses of PI-201 and Related Compounds
Authors: Murata Takeshi , Kumagai Toshihito , Ishikawa Makoto , Tadano Kin-ichi , Ogawa Seiichiro 
Published: June 2006

Abstract
The thermal intramolecular Diels–Alder cycloaddition of a 2 : 1 mixture of ethyl (2E,8E and Z, 10E,13R)-13-(t-butyldimethylsilyl) oxy-2,10-dimethyl-2,8,10-pentadecatrienoate provided four diastereomeric cycloadducts. Deprotection of one of the cycloadducts provided PI-201, a novel platelet aggregation inhibitor, as its natural form. Three stereoisomers of PI-201 were prepared from the other cycloadducts. The intramolecular cycloadditions of some structurally similar trienes were also investigated.
Supramolecular Stacks of Bis(imidazolyl)porphyrin through Metal Coordination
Authors: Kobuke Yoshiaki , Miyaji Hidekazu 
Published: June 2006

Abstract
cis- and trans-bis(1-methyl-2-imidazolyl)tetraethyltetramethylporphyrin Mg complexes were prepared. 1H NMR, absorption, and fluorescence spectra suggest that Mg has a high tendency toward dimer formation through coordination from imidazolyl to metal in a similar way to Zn, and accepts further the sixth coordination, which never occurred in Zn complexes. Propagation of the organization from a dimer to a trimer for trans-Mg complex starts at such a low concentration level as 10−5 M (1 M = 1 mol dm−3) and a 2 × 10−3 M solution organized the system to a 2.34 mer on average.
Relation between the Activity of Catalytic Antibodies and the Properties of Substrates
Authors: Kodaka Masato , Hase Anneli 
Published: June 2006

Abstract
The free energy of binding between catalytic antibodies and substrates is correlated with the properties of the substrates, both in the transition state (TS) and the ground state (GS). The free energy of binding was calculated from the kinetic parameters and four properties of the substrates; the solvent accessible surface area (SAS), enthalpy of hydration (ΔH), polarizability (α), and dipole moment (μ) were calculated using AM1. As a whole, TS shows a higher correlation than does GS, which is compatible with the fundamental concept of a catalytic antibody. Among these four properties, SAS gives the highest correlation coefficient (0.7616) while μ has a small correlation. Antibody-TS complexes seem to be stabilized by van der Waals force rather than a hydrophobic interaction.
Facile Optical Resolution of a Dibenzopyrazinoazepine Derivative and the Nature of Molecular Recognition of Amines by Chiral 2,3-Di-O-(arylcarbonyl)tartaric Acids
Authors: Tomori Hiroshi , Yoshihara Hisayoshi , Ogura Katsuyuki 
Published: June 2006

Abstract
A facile optical resolution of recemic 1,2,3,4,10,14b-hexahydrodibenzo[c,f]pyrazino[1,2-a]azepine (1) was developed using 2,3-di-O-benzoyl-d-(−)-tartaric acid ((+)-DBT) as a resolving agent. The resolution efficiency depends remarkably on the (+)-DBT : 1 ratio. When (+)-DBT and recemic 1 were mixed in methanol–water (9 : 1 v/v) in a 1 : 4 stoichiometry, a crystalline salt consisting of (+)-DBT, (R)-1, methanol, and water in a 1 : 2 : 2 : 2 ratio crystallized preferentially in a fair yield. X-Ray crystallographic analysis showed its highly ordered supramolecular structure: (+)-DBT molecules self-assemble via hydrogen bonding with the aid of water and methanol to form a puckered layer, and stacking of (R)-1 molecules constructs a column which is sandwiched in between the puckered layers. The X-ray crystallographic data reported for the salts that consist of amines and DBT were reinvestigated to reveal that most of the host frameworks derived from DBT have a layer structure similar to the above puckered one.
On the Conformation of the Substrate Binding to the Active Site during the Course of Enzymatic Decarboxylation
Authors: Kawasaki Takayasu , Horimai Emiko , Ohta Hiromichi 
Published: June 2006

Abstract
The activation parameters of the enzymatic decarboxylation of malonic acid derivatives catalyzed by arylmalonate decarboxylase (AMDase) were obtained by means of kinetics. In order to understand the conformation of the substrate at the transition state, the activation entropy (ΔS‡) for indane-1,1-dicarboxylic acid, a representative molecule that is conformationally restricted, was compared with those of phenylmalonic acid and ortho-chlorophenylmalonic acid, of which the aromatic ring can freely rotate. The obtained value for the former molecule was about 10 cal mol−1 K−1 smaller than those of the latter compounds, clearly indicating that a conformationally restricted substrate, such as the indane derivative, is entropically advantageous for enzymatic decarboxylation. These kinetic studies evidently disclose that the conformation of the substrate at the transition state in the course of AMDase-catalyzed decarboxylation should be synperiplanar with regard to ortho- and α-substituents.
Preparation and Properties of 1,1′-Disubstituted Δ2,2′-Bi-5,6-dihydropyrrolo[2,1-a]isoquinolin-3(2H)-one Dimers with a Twisted C=C Bond
Authors: Irikawa Hajime , Ishikawa Kaori , Akasaka Tomoko 
Published: June 2006

Abstract
1,1′-Dimethyl and 1,1′-dichloro derivatives of the titled dimeric compound were prepared. A twisting of the central C2=C2′ double bond in the above-mentioned dimers was suggested based on the bathochromism observed in the absorption spectra. The 1,1′-dimethyl dimer was autoxidized at the enamine-type C1=C10b double bond to give 1,10b-dioxygenated products, while the 1,1′-dichloro dimer underwent a chlorine–hydrogen exchange to yield a 1,1′-dihydro compound upon heating in n-BuOH and 1,1,2,2-tetrachloroethane. These reactions might result from a strain around the twisted C2=C2′ double bond of the 1,1′-disubstituted dimers.
Catalytic Oxidation of Alcohols to Carbonyl Compounds Mediated by N-(Arylseleno)-4-chlorobenzenesulfonamide
Authors: Onami Tetsuo , Ikeda Masanori , Woodard Scott S 
Published: June 2006

Abstract
Most secondary alcohols and β,γ-unsaturated primary alcohols have been catalytically oxidized with N-chloro-4-chlorobenzenesulfonamide sodium salt to the corresponding carbonyl compounds by the addition of a 0.01—0.03 molar amount of dimethyl 2,2′-diselenodibenzoate in good-to-excellent yields, and a catalytic species, methyl 2-[N-(4-chlorophenylsulfonyl)aminoseleno]benzoate (8), was isolated from the reaction mixture. The catalytic oxidation cycle for this reaction is proposed; the decomposition of esters, which are produced by the reaction of alcohols with oxidized 8, was found to be the rate-determining step.
Two New Quassinoids, Ailantinols C and D, from Ailanthus Altissima
Authors: Kubota Kengo , Fukamiya Narihiko , Okano Masayoshi , Tagahara Kiyoshi , Lee Kuo-Hsiung 
Published: June 2006

Abstract
Two new quassinoids, ailantinol C and ailantinol D, were isolated from Ailanthus altissima, and their structures were elucidated from spectral evidence.
Control of the Molecular Packing in Guanidinium Monolayers through Binding with Aqueous Polycarboxylates
Authors: Kamino Ayumi , Koyano Hiroshi , Ariga Katsuhiko , Kunitake Toyoki 
Published: June 2006

Abstract
By using newly developed guanylating agents, octadecyl- and dioctadecylguanidinium amphiphiles were synthesized. The interaction between each guanidinium monolayer and polycarboxylates in the subphase was investigated on the basis of the π–A isotherm, FT-IR spectroscopy, and XPS measurements. When linear dicarboxylates were used, the molecular areas of the monolayer increased, as the length of the methylene chain between the carboxylate groups increased. The expansion of the molecular area was greater for the octadecylguanidinium monolayers than for the dioctadecylguanidinium monolayers. The molecular packing was affected by the shape of polycarboxylate molecules in the case of phthalate, cis-1,2-cyclohexanedicarboxylate, and 1,1-cyclohexanediacetate. It is clear that, the molecular packing in the complexed monolayers is governed by the distance and relative orientation of the two carboxylate groups in a polycarboxylate. With all of the dicarboxylates, excluding oxalate, FT-IR and XPS measurements of the LB films indicated the formation of 1 : 1 guanidinium/carboxylate pairs with hydrogen bonding interactions. Oxalate produced an asymmetric complex where one guanidinium was bound to oxalate through hydrogen bonding, and the other guanidinium existed as a non-hydrogen bonded counter ion. These results are useful for the development of two-dimensional molecular patterns.
Characterization of 9-(p-Substituted Benzylidenehydrazono)fluorenes
Authors: Minabe Masahiro , Takabayashi Yutaka , Setta Yuji , Nakamura Hidenao , Kimura Takao , Tsubota Motohiro 
Published: June 2006

Abstract
The title azine was obtained by a reaction of the corresponding fluorenone hydrazone and p-substituted benzaldehyde. The hydrazone formed from the unsymmetrical fluorenone afforded configurational isomers; the E-isomer was thermodynamically more stable than the Z-isomer. The structure of the title azines, derived from symmetrical fluorenone, was assigned to be (s-trans/E) form. The azines from unsymmetrical fluorenone gave isomeric mixtures due to the 9-iminofluorene moiety. The electronic spectra of these azines show an intramolecular charge transfer; the red shift beyond 250 nm is observed in the case of 9-[p-(diethylamino)benzylidenehydrazono]-2,4,7-trinitrofluorene, compared to the mother azine. 9-[p-(Pentyloxy)benzylidenehydrazono]-2,7-dinitrofluorene and some of the homologs possess a liquid-crystalline property; the phase-transition temperature of the dinitro compound is K (172 °C) M1 (185) M2 (187) I between the crystalline and liquid phases.
Asymmetric Synthesis of Functionalized Secondary Alcohols by Catalytic Ring-Cleavage Reactions of Cyclic Acetals Derived from (R)-1,3-Butanediol
Authors: Kinugasa Motoharu , Harada Toshiro , Egusa Takayuki , Fujita Katsuhiro , Oku Akira 
Published: June 2006

Abstract
In the presence of a catalytic amount (0.1—0.2 molar amount) of a 2-phenyl-1,3,2-oxazaborolidin-5-one, prepared by the reaction of dichlorophenylborane and N-(trifluoromethylsulfonyl)-l-phenylalanine, and enol silyl ethers ((R2)2C=C(R3)OTMS; R3 = t-BuS, EtS, EtO, Ph) (1.1-1.5 molar amount), chiral cyclic acetals 6 derived from (R)-1,3-butanediol and aldehydes undergo an efficient ring-cleavage reaction with the inversion of the stereochemistry at the acetal carbon to give the anti isomer of the corresponding products with high stereoselectivity. The reaction is applicable to acetals derived from aromatic, aliphatic, and α,β-unsaturated aldehydes. Not only enol silyl ethers, but also methallyltrimethylsilane and allyltributyltin, can be employed as nucleophiles, leading to the selective formation of the anti isomer of the corresponding allylated ring-cleavage products. Removal of the chiral auxiliary from these ring-cleavage products by a two-step sequence ((i) PCC (ii) Bn2NH2(CF3CO2)) furnishes enantiomerically enriched β-hydroxy carbonyl compounds and homoallyl alcohols. A modest level of kinetic resolution is observed in the ring cleavage of a racemic acetal catalyzed by a phenylboron compound derived from N-mesyl-l-phenylalanine.
O/W-Emulsion Stabilized by Hydrophobized Polysaccharide
Authors: Fukui Hiroki , Akiyoshi Kazunari , Sunamoto Junzo 
Published: June 2006

Abstract
Colloidal stability of oil-in-water (o/w)-emulsion of α-linolenic acid (ALA) with or without trioctanoylglycerol (TriC8) was investigated in the presence of a hydrophobized polysaccharide, cholesteryl-bearing pullulan (CHP). The addition of ALA made the CHP/TriC8-emulsion more colloidally stable. A smaller and more colloidally stable o/w-emulsion was formed with an ALA/TriC8/CHP mixture. Electrophoretic light scattering measurements showed that the surface potential of the CHP/ALA/TriC8-emulsion was approximately zero. Fluorescence depolarization measurement using fluorescein isothiocyanate (FITC)-labeled CHP revealed that CHP adsorbs onto the surface of oil droplets and stabilizes the emulsion by a steric repulsion mechanism.