bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between Side-Chain Pyridyl Groups of α-Helical Polypeptide and Guest Trp in the Ternary Cu2+ Ion Complex
Authors: Nagata Yoshitomo , Kanuka Satoru , Kinoshita Takatoshi , Takizawa Akira , Tsujita Yoshiharu , Yoshimizu Hiroaki 
Published: August 2006

Abstract
Interaction between the side-chain pyridyl ligands of an α-helical poly(Nω-2-pyridylmethyl-l-glutamine) (P2PG) and guest ligands such as tryptamine and d- and l-tryptophan (d- and l-Trp) within ternary Cu2+ complexes was investigated by absorption and circular dichroism (CD) spectroscopy in 2,2,2-trifluoroethanol solutions. The host complex species, Cu2+-one pyridyl-substituted side-chain (s-2PG) complexes (1 : 1 Cu2+-P2PG, [Cu2+]/[s–2PG] &gt; 1.0) and Cu2+- two s-2PGs complexes (1 : 2 Cu2+-P2PG, [Cu2+]/[s–2PG] &lt; 1.0), were prepared, using Cu2+ and P2PG depending on the Cu2+ ion concentration. All guest molecules could bind noncovalently to the 1 : 1 Cu2+-P2PG system, having the ligand sites of Cu2+ partly unfilled, to yield their ternary Cu2+ complexes. The respective ternary complexes had induced optical activities in the CD spectra and a charge-transfer band indicating ligand–ligand stacking interactions involving charge transfer between the coordinated s-2PG and the guest indole moieties around Cu2+. The CD spectral intensity was in the order tryptamine &lt; d-Trp, l-Trp, which suggests that the coordination of both amino and carboxyl groups of Trp to Cu2+ is important for the regular arrangement of the ligands on the periphery of the α-helix backbone of P2PG. The differences in the CD spectra suggest that the indole rings of d- and l-Trp face in a direction opposite to that of the pyridyl ring of P2PG. d- and l-Trp could also bind the 1 : 2 Cu2+-P2PG host system, whose Cu2+ coordination sites are filled with s-2PGs, but the 1 : 2 Cu2+-P2PG did not yield the ternary complexes with tryptamine.
Footprint Catalysis VII. Reinvestigation of the Imprinting Procedures for Molecular Footprint Catalytic Cavities: The Effects of Imprinting Procedure Temperature on the Catalytic Characteristics
Authors: Morihara Kensaku , Doi Sakurako , Takiguchi Michie , Shimada Toyoshi 
Published: August 2006

Abstract
The authors’ imprinting procedures for “molecular footprint” catalytic cavities on a silica (alumina) gel surface were reinvestigated. The increases of temperature during the incorporation of aluminum ions into the silicate matrix and during the footprint-imprinting with a template remarkably affected the catalytic characteristics of the resulting cavities. A change from room temperature to 75—80 °C increased the catalytic specificities (kcat/Km) by a factor of nearly 50. The results also provided experimental proof for the speculated mechanism of footprint formation. That is, the imprinting comprises precedent Lewis acid site generation on a silicate surface and subsequent Lewis acid–template complexation. The resulting acid–template complexes give rise to the footprint cavities upon removal of the template.
Studies on 5-8 Fused Ring Compounds. VII. The Conformations of the Eight-Membered Rings in C6–C8–C5 Fused Ring Compounds
Authors: Umehara Misao , Honnami Hiromi , Hishida Shinzaburo , Kawata Takashi , Ohba Shigeru , Zen Shonosuke 
Published: August 2006

Abstract
The five cis/trans isomers of C6–C8–C5 fused ring compound, tricyclo[9.4.0.04,8]pentadecane-2,9-dione were synthesized by photocycloaddition of decalin-1,3-dione to cyclopentene. The conformational analyses were carried out by MM2 and the results were compared with X-ray analyses. The eight-membered rings take predominantly boat-chair forms although those in C5–C8–C5 fused ring compounds exist in various conformations.
Convenient Radical α-Monoallylations of Carbonyl Compounds
Authors: Watanabe Yoshihiko , Yoneda Tetsuo , Okumura Tatsuya , Ueno Yoshio , Toru Takeshi 
Published: August 2006

Abstract
Free radical allylations of α-seleno carbonyl compounds with tributyl-substituted 2,4-pentadienyltin, 2-methyl-2-propenyltin, 2-butenyltin, and 3-methyl-2-butenyltin, are described. Such successful C–C bond formations, in particular with the 2-butenyltin and the 3-methyl-2-butenyltin, are owing to the high reactivity of the α-carbon radical, generated from α-seleno carbonyl compounds, toward allylic tin compounds.
The Synthesis of Salvinolone, Saprorthoquinone, and 4-Hydroxysapriparaquinone from (+)-Dehydroabietic Acid
Authors: Matsumoto Takashi , Tanaka Yasutaka , Terao Hiromitsu , Takeda Yoshio , Wada Makoto 
Published: August 2006

Abstract
Salvinolone, saprorthoquinone, and 4-hydroxysapriparaquinone isolated from the roots of Salvia prionitis Hance. were synthesized starting from (+)-dehydroabietic acid via 11,12-dimethoxyabieta-8,11,13-trien-7-one and 12-methoxyabieta-8, 11,13-triene.
Energy Transfer in β-Turned Peptide-Bridged Porphyrin Dimers
Authors: Tamiaki Hitoshi , Nomura Kimiatsu , Maruyama Kazuhiro 
Published: August 2006

Abstract
β-Turned peptide-bridged diporphyrinyl compounds were prepared. Each isomeric monozinc complexes were easily available; metal-free porphyrin–peptide–zinc porphyrin and zinc porphyrin–peptide–metal-free porphyrin. In the isomers, the intramolecular energy transfer efficiencies from zinc porphyrin moiety to metal-free porphyrin moiety were the same from analysis of the steady-state fluorescence spectra, indicating that the efficiencies should be independent upon the linked peptide spacer and dependent upon the distance between the porphyrin moieties in the molecule. Singlet energy might migrate intramolecularly from zinc porphyrin moiety to metal-free one mainly by through-space mechanism.
Crystal and Molecular Structure of (1R,6S)-3,6,14,16-Tetrahydroxyspiro[1,5]grayanotoxin-5-one
Authors: Sato Mamoru , Katsube Yukiteru , Terai Tadamasa , Katakawa Jun’ichi , Tetsumi Tadahiro 
Published: August 2006

Abstract
The three-dimensional structure of a grayanotoxin II derivative, (1R,6S)-3,6,14,16-tetrahydroxyspiro[1,5]grayanotoxin-5-one, has been determined by X-ray diffraction at room temperature. The structure was solved by direct methods and refined by the full matrix least-squares method to a final R = 0.043 for 1436 independent reflections with Fo ≥ 3σ(Fo). The molecule is based on a tetracyclic structure and consists of two six-membered and two five-membered rings. The absolute configuration at C(1) atom (spiro atom) was determined as R on the basis of internal comparison with the absolute structure of grayanotoxin II.
Novel Biradical Cyclization via Remote-Hydrogen Transfer in Photochemistry of 2-Dialylaminoethyl 3-Benzoylacrylates
Authors: Hasegawa Tadashi , Yamazaki Yuko , Yoshioka Michikazu 
Published: August 2006

Abstract
Upon irradiation, 2-(N,N-dibenzylamino)ethyl and 2-(N-benzyl-N-methylamino)ethyl 3-benzoylacrylate underwent photocyclization via remote-proton transfer from their (Z)-forms competing with (E)–(Z) isomerization. The quantum yield for the cyclization under the conditions where both (E)- and (Z)-isomers absorb the irradiation light was estimated to be 0.05 by applying the steady-state approximation.
Electronic Structure of the 1-(Benzoyloxy)ethyl Radical
Authors: Uchida Nozomu , Shiomi Tomoo , Imai Kiyokazu , Tatewaki Hiroshi 
Published: August 2006

Abstract
In the polymerization of vinyl benzoate, the tacticity of the obtained polymer is changed toward less isotactic by UV irradiation. To explain this phenomenon, it was assumed that the growing terminal of the polymer was excited by UV irradiation and that the coplanarity of the vinyl benzoates was broken. It was thus naturally concluded that the existence of a twisted radical reduced the isotacticity. To examine the above assumption, the electronic structures of the ground and excited states of 1-(benzoyloxy)ethyl radical () were studied as a model of the growing terminal of the polymer by ab initio SCF and CI calculations. The present calculation, however, showed that the planer structure was stable in both the ground and excited states.
Optical Properties and Thermochromism of the Crystals of Chloranil-Hexamethyl Benzene and Fluoranil-Perylene Charge-Transfer Complexes
Authors: Tanaka Masashi 
Published: August 2006

Abstract
The reflection spectra of the crystal of chloranil-hexamethyl benzene and fluoranil-perylene charge-transfer complexes were measured, and the charge-transfer degrees in these complexes were estimated. Furthermore, the polarized IR absorption spectra of these crystals were measured and compared with those of the powders of the complexes and the component compounds in the KBr disks. The thermochromism of these CT complex crystals was studied by differential scanning calorimetry and the IR spectra.
Quasi-Action Variable for Chaos in Chemical Dynamics
Authors: Takatsuka Kazuo 
Published: August 2006

Abstract
Is proposed quasi-action variable as a means to analyze the onset of classical chaos in molecular vibrational systems. The basic idea rests on a symplectic area generated by a classical trajectory in phase space, from which the geometrical information of a torus and its breakdown in extracted. The Fourier spectrum of the time derivative of this symplectic area centers on the following definition and findings: (1) in an integrable system, the action variables can be simply calculated in terms of the above Fourier amplitudes, (2) the quasi-action variable is also defined in a similar way and is a good approximation to the corresponding action variable, but (3) the construction of the quasi-action variable does not depend on the integrability and hence it it defined as well even for a chaotic system, and (4) the characteristics of chaos can be analyzed in the continuous spectrum of the quasi-action variable. Some numerical examples of the quasi-action variable are presented for a system of what we call phase-space large amplitude motion. As a byproduct, a simple method has been devised to calculate very accurate frequencies and amplitudes from the so-called Fast-Fourier-Transform (FFT) spectra without resorting to the so-called window technique.
Theoretical Study of Metal NMR Chemical Shifts. Selenium Compounds
Authors: Nakatsuji Hiroshi , Higashioji Takuji , Sugimoto Manabu 
Published: August 2006

Abstract
The 77Se chemical shifts of nine selenium compounds, SeRR′ (R, R′ = H, Me, Et, Ph, SiH3, GeH3), are theoretically investigated by ab initio Hartree–Fock/finite perturbation method. The calculated values agree well with the experimental values. The Se chemical shift is dominated by the Se valence 4p AO contribution to the paramagnetic term, and shows a parallelism with the 4p-hole population and the net charge of the central Se atom. The Se chemical shift moves downfield as an increase of the hole in the 4p orbitals, and therefore, as an increase in the electron-withdrawing ability of the ligands attached to the selenium atom.
Metallaboranes with Group 8 and 9 Transition Metals. Is Accurate ab initio Molecular Orbital Calculation of Structure, Stability, and NMR Chemical Shifts Possible?
Authors: Mebel Alexander M , Musaev Djamaladdin G , Koga Nobuaki , Morokuma Keiji 
Published: August 2006

Abstract
Ab initio MO study of structure, stability and rearrangements of nido-metallaboranes with Ir, Co, and Fe transition metals has been performed at HF and correlated MP2 levels. Reasonable agreement with experiment has been found for RHF optimized geometry of [(IrB5H8)(CO)(PH3)2] iridaborane, and the MP2 optimization improves the agreement to the maximum error of 0.035 Å. Two geometric isomers, 2- with basal Ir and 1- with apical Ir are close in energy for [(IrB5H8)(CO)(PH3)2]. NMR 11B and 1H chemical shifts calculated by the IGLO method qualitatively reproduce experimental spectra. Methods more sophisticated than MP2 would be necessary for accurate calculations of metallaboranes with first row transition metals.
The Random Graph Model of Hydrogen Bond Network
Authors: Sasai Masaki 
Published: August 2006

Abstract
A new lattice model of liquid water is developed. The hydrogen bond network is represented by the Ising variables with the method similar to the one used in combinatorial problems in random graph. Thermodynamic properties of the model are studies with the mean-field approximation. Phase diagram, density maximum, and anomalies of supercooled water are discussed. Dynamical properties are also investigated by using the coupled-map-dynamics method. Energy fluctuation is shown to have 1/f like long time correlation. The network structural rearrangement takes place collectively in localized regions.
Reinvestigation of the Electrochemical Reduction of KMnO4
Authors: Lin San-Chung , Wang Yung-Yun , Wan Chi-Chao , Chang J -Cheng 
Published: August 2006

Abstract
Investigating the electrochemical reduction behavior of MnO4−, we determined the consecutive reduction/oxidation potentials of MnO4− by the cyclic voltammetric method. We have also confirmed that MnO42− is reduced into MnO43−. We then investigated the cause of the generation of MnO2 on the electrode surface with the rotating ring-disk electrode method. The reversibility of the reduction of MnO4− depends on the concentration of KMnO4 and KOH. Reversibility increases when the concentration of KOH increases, but the reversibility decreases when the concentration of KMnO4 increases. The reaction rate of MnO4−/MnO42− follows the law:
Complexation Equilibria and Fluorescent Properties of Chelating Reagents Derived from Ethylene Glycol Bis(β-aminoethylether)-N,N,N′,N′-tetraacetic Acid
Authors: Yuchi Akio , Tanaka Atsushi , Hirai Manabu , Yasui Takashi , Wada Hiroko , Nakagawa Genkichi 
Published: August 2006

Abstract
The complexation equilibria of divalent and lanthanoid metal ions with 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) and 2-[(2-amino-5-methylphenoxy)methyl]-6-methoxy-8-aminoquinoline-N,N,N′,N′-tetraacetic acid (quin2) were studied by pH titration. In lanthanoids, BAPTA shows a maximum stability for Pr3+, whereas quin2 has higher affinities for heavier ones. These trends are discussed in terms of the rigidity and donor atoms of these ligands. Intense fluorescence was observed for quin2 complexes of Group-2 and -3 elements. Among the lanthanoids, only Sc, Y, La, Gd, and Lu enhance the fluorescence at around 380 nm.
Determination of Silicate by Ion-Exclusion Chromatography with Luminol Chemiluminescence Detection
Authors: Sakai Hiroyuki , Fujiwara Terufumi , Kumamaru Takahiro 
Published: August 2006

Abstract
An increased chemiluminescence (CL) emission was produced upon mixing an acidified solution of silicate with a basic solution of luminol and hydrogen peroxide. The new CL reaction was used to develop a simple and rapid post-column detection system for selective determination of silicate after separation by ion-exclusion chromatography (ICE). Separation of silicate from other anions like phosphate, nitrite, sulfide or carbonate ion was achieved using a low-capacity cation-exchange column and a dilute perchloric acid solution as an eluent. Also, the present method has an advantage of eliminating interferences from ionic metal species. The detection limit of 50 ng cm−3 and a linear calibration graph with a dynamic range from 100 ng cm−3 to 30 μg cm−3 was obtained for silicon(IV). The proposed ICE-CL method was applied to the determination of silicate in tap and river water samples.
Synthetic Studies of Venturicidins. Synthesis of the C1–C14 Segment of Venturicidins
Authors: Nakata Masaya , Ohashi Junji , Ohsawa Kunihiko , Nishimura Toru , Kinoshita Mitsuhiro , Tatsuta Kuniaki 
Published: August 2006

Abstract
The C1–C14 segment of venturicidins, (2R,6R)-3,6-dihydro-6-[(E)-7-(dimethoxyphosphinyl)-1-methyl-6-oxo-1-heptenyl]-2-methoxy-5-methyl-2H-pyran-2-acetic acid (1), has been synthesized. The C8–C13 segment of venturicidins, (E)-2-bromo-7-(4,4′-dimethoxytriphenylmethoxy)-2-heptene (2), was lithiated with t-butyllithium and the resulting vinyllithium compound was coupled with the C1–C7 segment, (2Z,7S)-7-(t-butyldimethylsilyloxy)-8-(t-butyldiphenylsilyloxy)-2-methyl-5,5-(trimethylenedithio)-2-octenal (4), to afford the alcohol. A subsequent seven-step conversion of this alcohol furnished the synthesis of the C1–C13 segment, (2R,6R)-3,6-dihydro-6-[(E)-6-hydroxy-1-methyl-1-hexenyl]-2-methoxy-5-methyl-2H-pyran-2-acetate (9). Finally, the known four-step transformation led 9 to the target compound 1.
Preparation of New Nitrogen-Bridged Heterocycles. 35. Smooth Synthesis of 10aH-Pyrido[1,2-d][1,4]thiazepine Derivatives
Authors: Kakehi Akikazu , Ito Suketaka , Hakui Jun-ichi 
Published: August 2006

Abstract
Various 1-pyridinio(thiocarbonyl)methylides and 2-isoquinolinio(thiocarbonyl)methylides react smoothly with dimethyl acetylenedicarboxylate at room temperature or at the reflux temperature in chloroform to give new heterocycles, dimethyl 10aH-pyrido[1,2-d][1,4]thiazepine-1,2-dicarboxylate derivatives, in moderate yields. Similarly, the reactions of some 3-(1-pyridinio)thiophene-2-thiolates with the same reagent afforded the corresponding dimethyl 6aH-pyrido[1,2-d]thieno[2′,3′-b][1,4]thiazepine-5,6-dicarboxylates. The structures of these 1,4-thiazepine derivatives were mainly assigned based on physical and spectral inspections, and were finally confirmed by X-ray analyses of three compounds.
The Addition Effect of Hydrogen Bromide on Methane Ignition behind Reflected Shock Waves
Authors: Takahashi Kazuo , Inomata Tadaaki , Jinno Hiroshi 
Published: August 2006

Abstract
Ignition delay times were measured in a CH4–O2–HBr–Ar mixture behind reflected shock waves. Hydrogen bromide retarded methane ignition, though methyl bromide accelerated it. Model calculations showed that two different chain cycles, promotion and inhibition cycles, were formed for bromine-containing species. The inhibition cycle was predominant in the HBr addition.
Determination of Trace Impurities in Corrosive Gases by Gas-Phase FTIR
Authors: Miyazaki Keiji , Kimura Takako 
Published: August 2006

Abstract
Trace moisture and other potential impurities (CO2, CH4, C2H6, and alkyl halides) in HCl and in HBr gases were analyzed by gas-phase FTIR spectroscopic technique. The detection limit was estimated to be 100 ppb with 2 cm−1 spectral resolution for 5-min measurement time at 1.2 kg cm−2 pressure, using an MCT detector and an 8-m-pathlength gas cell with BaF2 windows.
The Structure of Nickel Oxide Clusters inside the Supercage in Y-Zeolite by XAFS
Authors: Sano Mitsuru , Suzuki Minoru , Niwa Miki 
Published: August 2006

Abstract
XAFS has been measured for the nickel oxide cluster in the Y-zeolite. The atomic distances in the cluster are close to those in the crystallite NiO. However, the weak intensity of Ni-fourth neighbor Ni and the coordination numbers give a model of the cluster in the supercage.
Solvent Extraction of Scandium(III) with Hexafluoroacetylacetone into Chloroform in the Absence and Presence of Tetrabutylammonium Ions or Trioctylphosphine Oxide
Authors: Noro Junji , Sekine Tatsuya 
Published: August 2006

Abstract
The anionic chelate of scandium(III) with hexafluoroacetylacetone (Hhfa) was extracted into chloroform in the presence of the tetrabutylammonium ion (tba+), though such an anionic chelate was not extracted when the chelating extractant was 2-thenoyltrifluoroacetone (Htta). The extraction was also studied in the same systems in the presence of trioctylphosphine oxide (TOPO); the extraction of the anionic complex, Sc(hfa)4−tba+, was compared with that of the adducts with TOPO, Sc(hfa)3(TOPO)n.
Synthesis of cis-Olefins via Palladium-Catalyzed Coupling of Organic Halides, Norbornadiene, and Organotin Compounds
Authors: Kosugi Masanori , Kimura Tomoyuki , Oda Hiroshi , Migita Toshihiko 
Published: August 2006

Abstract
Palladium-catalyzed cross-coupling of organic halides with organotin compounds in the presence of norbornadiene gave 5,6-disubstituted norbornene, which was treated by a retro Diels–Alder reaction yielding cis-ethene and cyclopentadiene.
Effect of the Molecular Orientation on the Stability of Hydrogen-Bonded Benzoic Acid Dimers. Infrared Study of Liquid-Crystalline 4-Alkylbenzoic Acids
Authors: Kato Takashi , Jin Chihiro , Kaneuchi Fumiko , Uryu Toshiyuki 
Published: August 2006

Abstract
Liquid-crystalline benzoic acid derivatives, 4-pentylbenzoic acid and 4-hexylbenzoic acid, have been examined by infrared spectroscopy. These benzoic acids show nematic phases. In the crystalline state, only the dimeric form is observed. However, the monomeric non-hydrogen-bonded benzoic acid appears once the temperature reaches the crystal-nematic transition (melting) point. The fraction of the monomeric moiety increases upon heating and an abrupt increase is observed at the isotropization temperature. These results suggest that the stability of the hydrogen bonds is not simply a function of the temperature, but greatly depends on the molecular orientation.
Diamagnetic Susceptibilities of Ionic Functional Groups
Authors: Takahashi Fujio , Sakai Yasuzo , Tsuchida Satoru 
Published: August 2006

Abstract
The diamagnetic susceptibilities of various series of organic compounds containing one or two ionic functional groups were measured by Guoy’s method. The diamagnetic susceptibilities of ionic functional groups in organic compounds were determined by calculations according to an additive property of the magnetic susceptibility in a combination of Pascal’s method with the diamagnetic susceptibilities of Na+, K+, Cl−, and Br−, which are given by Pascal. The results showed that the diamagnetic susceptibilities of ·COO−, ·SO3−, ·NH3+, and ·N(CH3)3+ are −12.3 × 10−6, −29.2 × 10−6, −13.0 × 10−6, and −39.8 × 10−6 cm3 mol−1, respectively. It became possible to estimate the diamagnetic susceptibilities of organic compounds containing ionic bonds consisting of the above-mentioned ionic functional groups.
Revision of the Dual Scaling Method for Successive Categories Data and Its Application to Quantitative Structure–Activity Relationships (QSAR)
Authors: Takagi Tatsuya , Tange Koichi , Jikihara Takahiro , Onozawa Norihisa , Sakashita Kazumi , Fujiwara Hideaki , Sasaki Yoshio 
Published: August 2006

Abstract
Nishisato’s Dual Scaling Method for successive categories data has been revised in order to apply it to quantitative structure–activity relationships. The revised version can give category values of successive categories, even though the original one can give only boundary values between two adjacent successive categories. The new version can be applied to an analysis of the antimicrobial activities of polymethylene bi(pyridineamine) derivatives, which are potential agents for controlling and/or preventing the formation of dental plaque. The results show that the proper molecular length of the agents leads to the maximum antimicrobial activity.