bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersion Interaction between Fluoranthene and Benzene in Cyclohexane
Authors: Enomoto Shigendo , Hasegawa Miki , Yoshinaga Tetsutaro , Hiratsuka Hiroshi , Kobayashi Michio , Okubo Jun , Hoshi Toshihiko 
Published: September 2002

Abstract
The electronic absorption spectra of fluoranthene (abbreviated as FA) were measured in various solvents together with the polarization spectrum with the aid of the stretched polymer film technique. The electronic structure of FA is discussed in comparison with MO calculated results. The polarization directions of the electronic transitions of FA were determined. For instance, the 404 (very weak) and 360.3 nm bands are polarized along the shorter and the longer (C2-) molecular axes, respectively. A weak van der Waals type FA–benzene complex formation was recognized in cyclohexane. The equilibrium constants for this complex formation were determined at various temperatures, e.g. K = 0.147 ± 0.03 dm3·mol-1 at 298 K. The enthalpy, entropy, and free-energy changes are estimated to be ΔH° = -5.9 ± 1.2 kJ·mol-1 (-1.4 ± 0.3 kcal·mol-1), ΔS°298 = -36 ± 1.0 J·K-1 mol-1 (-8.7 ± 0.24 cal·K-1 mol-1), and ΔG°298 = 4.7 ± 0.4 kJ·mol-1 (1.1 ± 0.1 kcal·mol-1). This ΔH° value is considerably small compared with the familiar hydrogen bonding energy, ca. -12 kJ·mol-1(-3 kcal·mol-1).
Temperature and Pressure Effects on Intermolecular Interactions in Charge Transfer Crystals of 2-(4-Methoxyphenyl)-1,4-benzoquinone and Quinhydrone
Authors: Uchida Yuki , Okabe Chie , Kishi Atsushi , Takeshita Hideyoshi , Suzuki Yoshio , Nibu Yoshinori , Shimada Ryoichi , Shimada Hiroko 
Published: September 2002

Abstract
Temperature and pressure effects on the Raman spectra due to the intramolecular vibrations of charge transfer crystals of 2-(4-methoxyphenyl)-1,4-benzoquinone and quinhydrone were studied. In quinhydrone crystals involving the intermolecular charge transfer and the intermolecular hydrogen bonding, the temperature- and pressure-induced frequency shifts of the intramolecular vibrations showed blue and red shifts with decreasing temperature and increasing pressure depending on the vibrational modes. In the yellow crystal of 2-(4-methoxyphenyl)-1,4-benzoquinone involving the intramolecular charge transfer, and in the red crystal involving both the intra- and intermolecular charge transfers, the frequencies of the intramolecular vibrations showed only blue shift with increasing pressure. This blue shift was larger in the yellow crystal than in the red crystal. It was also observed that phase transitions take place under 1.8 and 2.7 GPa in quinhydrone crystal and that the phase transitions take place under 1.5 and 2.5 GPa in the yellow and red crystals of 2-(4-methoxyphenyl)-1,4-benzoquinone, respectively.
Laser Trapping-Picosecond Fluorescence Microspectroscopy of Single Microdroplets under High Pressure: Droplet-Size and Pressure Effects
Authors: Kitagawa Fumihiko , Kitamura Noboru 
Published: September 2002

Abstract
A laser trapping picosecond fluorescence microspectroscopy system was combined with a high pressure cell to study droplet size and pressure effects on chemical phenomena in single micrometer-sized oil droplets. When a rectangular capillary tube was used as a pressure cell, single oil droplets were easily and stably trapped by a 1064-nm laser beam even under high pressure. The developed system enabled us to pressurize a sample emulsion as high as 75 MPa; such pressure was enough to induce pressure and droplet-size effects on the fluorescence dynamics of an Acridine Orange derivative (C12-AO+) in single oil droplets. In particular, droplet-size effects on the fluorescence dynamics were pronounced with an increase in static pressure. Possible origins of the pressure and droplet-size effects were discussed.
Crystalline Molecular Complexes of 1-Alkylpyridinium Bromide with Aromatic Compounds
Authors: Iimura Nahoko , Hirata Hirotaka , Ohashi Yuji 
Published: September 2002

Abstract
A surfactant, 1-alkylpyridinium salt, such as 1-hexadecylpyridinium bromide, formed complexes with aromatic compounds, such as phenolic derivatives and basic substances from an aqueous, alcohol, or acetone solution at low temperatures (&lt; 10 °C). Fifteen complex crystals were obtained, of which two well-grown crystals, 1-hexadecylpyridinium/guaiacol and 1-hexadecylpyridinium/9-anthracenecarboxylic acid, were suitable for X-ray analysis. The structures, analyzed by X-rays, were shown to be very similar to each other, and have a common packing pattern, which has been observed in crystalline molecular complexes with surfactants contained as quaternary alkylammonium salts. The void space to accommodate the aromatic compounds in the 1-alkylpyridinium bromide complexes is greater than the corresponding one in the quaternary alkylammonium bromide complexes.
Laser-Induced Fluorescence Instrument for the Detection of Tropospheric OH Radicals
Authors: Matsumi Yutaka , Kono Mitsuhiko , Ichikawa Toshio , Takahashi Kenshi , Kondo Yutaka 
Published: September 2002

Abstract
An instrument for the measurement of troposphric OH radical concentrations using a laser-induced fluorescence technique has been developed. Ambient air is expanded through a pinhole into a low-pressure fluorescence cell and irradiated by the second harmonic of a dye laser at a high repetition rate of 1 kHz. The OH radicals are electronically excited using A2Σ+(ν′ = 0) ← X2Π (ν′′ = 0) transitions around 308 nm. The fluorescence from OH radicals is collected by a lens system and detected by a photomultiplier. The photoelectron pulses from the photomultiplier are processed by a photon-counting system. The dynode gate of the photomultiplier and counting gate systems are made to minimize the detection of the chamber and Rayleigh scattering signal. The sensitivity of the developed instrument is calibrated with two methods: one is a long-path absorption technique and the other is a titration technique with simultaneous photolysis of water vapor and oxygen. It is found that the background signal is mainly produced by after-pulse effects in the photomultiplier for the fluorescence detection with a dynode gate system. The minimum detection limit is determined to be 7.0×105 molecules cm-3 for OH radicals with a signal-to-noise ratio of 2 and a signal integration time of 60 s.
NMR Chemical Shift Methods for Binding Constant Determination of an Organic Anion and α-Cyclodextrin
Authors: Funasaki Noriaki , Ishikawa Seiji , Neya Saburo 
Published: September 2002

Abstract
Internal reference compounds suitable for proton chemical shift measurements of organic anions in deuterium oxide solutions are proposed and used to determine the binding constant of sodium hexane-1-sulfonate (SHS) and α-cyclodextrin (α-CD). The chemical shift of the methyl proton of sodium methyl sulfate (MeS), referred to external sodium 4,4-dimethyl-4-silapentane-1-sulfonate (DSS), changes linearly with the α-CD concentration, because of the volume magnetic susceptibility effect. The chemical shifts of the SHS methyl proton, referred to external DSS and corrected for this magnetic susceptibility effect, as well as referred to internal MeS and methanol (MeOH), provide reliable binding constants of SHS and α-CD. Therefore, MeS and MeOH are appropriate internal standards for organic anions. The present results serve not only for choosing appropriate internal references and the internal or external standard method for chemical shift measurements but also for correcting the chemical shift referred to an external standard.
Copper-Organic Coordination Polymers with Porous Structures
Authors: Wang Rui-Hu , Hong Mao-Chun , Su Wei-Ping , Liang Yu-Cang , Cao Rong , Zhao Ying-Jun , Weng Jia-Bao 
Published: September 2002

Abstract
Three copper coordination polymers containing organosulfur ligands ({[CuI2(bpsb)3(ClO4)](ClO4)}n (1), {[CuI2(bpsb)3Cl](ClO4)}n (2), and {[CuII(bpb)2Br](ClO4)·3dmf·MeCN}n (3) (bpsb = 1,2-bis[(2-pyrimidinyl)sulfanylmethyl]benzene, bpb = 1,2-bis[(4-pyridyl)sulfanylmethyl]benzene, dmf = N, N-dimethylformamide)) were synthesized and characterized by X-ray structural analysis. Complexes 1 and 2 have similar structures. In both, each bpsb molecule exhibits an exo-bidentate coordination fashion and bridges 3-coordinated copper(I) and 4-coordinated copper(I) through pyrimidinyl rings. Thus, six copper(I) centers, three 3-coordinated and three 4-coordinated located at two different planes alternatively, are linked by six bpsb molecules forming a crown-like nanocavity; such nanocavities make up a 2-D lamellar structure. In complex 3, each copper(II) center adopts a distorted square pyramidal coordination mode; each bpb molecule acts as an exo-bidentate ligand through coordinating to copper(II) atoms in two different directions to form a square unit with solvent molecule guests. Such square units share copper atoms and generate a single-stranded infinite 1-D chain structure.
Hydration of Polymer Complexes with Iminodiacetate-Type Chelating Resin
Authors: Yuchi Akio , Sotomura Yuka , Ueda Kaoru 
Published: September 2002

Abstract
Hydration of polymer complexes of divalent and trivalent metal ions with an iminodiacetate (IDA)-type chelating resin (-LNa2) was studied. The hydration numbers of [(-LH)2MII] for Ca2+ and [(-LH)3MIII] for Y3+ and La3+, which are practically the same as those of the respective aqua ions, indicate simple electrostatic interactions between the carboxylates of monoprotonated species of iminodiacetate, (-LH)-, and hydrated metal ions. In contrast, an appreciably smaller hydration number of [(-LH)3MIII] for Sc3+ than that of the aqua ion suggests involvement of the carboxylates in the coordination sphere. The difference in their interaction modes is discussed.
Crystal Structures and 166Er Mössbauer Spectra for Some β -Diketonatoerbium(III) Complexes
Authors: Wang Junhu , Takahashi Masashi , Takeda Masuo 
Published: September 2002

Abstract
The crystal structures and 166Er Mössbauer spectra for some β -diketonatoerbium(III) complexes have been investigated. The geometries around the Er(III) ions in [Er(dpm)3(H2O)] (1; Hdpm = 2,2,6,6-tetramethyl-3,5-heptanedione), [Er(pta)3(H2O)] (2; Hpta = 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione) and [Er2(pta)6] (3) are distorted monocapped trigonal prisms. 3 is a dimeric structure in which one of the chelating oxygen atoms of the pta ligand bridges between the Er(pta)3 fragments. The 166Er Mössbauer spectra for those β -diketonatoerbium(III) complexes show paramagnetic relaxation patterns at 12 K. The estimated relaxation time (τ) is spread out from 0.1 to 1 ns. For the seven-coordinated complexes, τ decrease among with a decrease in the Er(III)–Er(III) distance. τ for the six-coordinated complex of [Er(dpm)3] is as short as 0.4 ns in spite of having a rather long distance of Er(III)–Er(III) ions, suggesting that the τ also depends on the coordination number.
Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)
Authors: Yoshimura Yasuki 
Published: September 2002

Abstract
The solubilities of soluble mer-(-)-isomers of various tris(amino acidato)cobalt(III) ([Co(aa)3]) in water were determined over the temperature range 5 to 50 °C. From these data the standard free energy (ΔdisG°), enthalpy (ΔdisH°), and entropy of dissolution (ΔdisS°) at 25 °C were estimated and compared with the values reported for mer-(+)-, fac-(-)-, and fac-(+)-isomers of [Co(aa)3]. The solubilities of these isomers increase in the order fac-(+)- &lt; fac-(-)- &lt; mer-(+)- &lt; mer-(-)-isomers for [Co(aa)3] synthesized from amino acids with longer side chains than 2-aminobutyric acid. On the other hand, the increasing sequence of the solubilities for tris(L-alaninato)cobalt(III) ([Co(L-ala)3]) and tris(L-serinato)cobalt(III) ([Co(L-ser)3]) is fac-(+)- &lt; mer-(+)- &lt; fac-(-)- &lt; mer-(-)-isomers. The solubility differences between the mer- and fac-isomers and between the (-)- and (+)-isomers are discussed based on the differences of ΔdisH° and TΔdisS° among these isomers. Furthermore, the influence of introducing hydroxyl and methyl groups into the side chains of the amino acids on the dissolution behavior of [Co(aa)3] is discussed.
Interfacial Solubilization of (5,10,15,20-Tetraphenylporphyrinato)zinc(II) in Cetyltrimethylammonium Chloride Reversed Micellar Solutions
Authors: Nakashima Toshiyuki , Fujiwara Terufumi , Kumamaru Takahiro 
Published: September 2002

Abstract
The interaction between the zinc(II) complex of 5,10,15,20-tetraphenylporphyrin (Zn(tpp)) and cetyltrimethylammonium chloride (CTAC) at the interface of a CTAC reverse micelle in chloroform and 6 : 5 (v/v) chloroform–cyclohexane has been investigated spectrophotometrically. The spectra of Zn(tpp) in the CTAC reversed micellar solutions provide evidence of formation of the associated species Zn(tpp)CTAC; its Soret band is not influenced by solvent polarity. At a fixed molar ratio of water to surfactant (Rw = [H2O]/[CTAC]), the absorbance at the maximum of the Zn(tpp)CTAC band increases with an increase in the CTAC concentration. In the slope of the plot a discontinuity was found, due to formation of reverse micelles at this CTAC concentration, taken as the critical micelle concentration (cmc). The variations of the spectral data were interpreted quantitatively by applying the pseudophase model. Increasing Rw causes a decrease in the Zn(tpp)-solubilizing ability of reverse micelles, implying that the nucleophilicity of Cl- ion to the central zinc of the complex is dropped by the Cl- hydration at the interface. Furthermore, the standard free energy of micellization, calculated from the cmc data, indicates that the micellization is promoted by the Cl- hydration and by decreasing the chloroform fraction in the bulk organic phase.
Controlling Factors of Weak Acid and Base Concentrations in Urban Dewwater—Comparison of Dew Chemistry with Rain and Fog Chemistry—
Authors: Takeuchi Masaki , Okochi Hiroshi , Igawa Manabu 
Published: September 2002

Abstract
Dewwater was collected from January 1993 to December 2000 in Yokohama, Japan, and analyzed for weak acid anions with other major chemical components. The volume-weighted average and medium pH of the dewwater were 4.88 and 6.08, respectively, at our sampling site. Weak acids (carbonate, nitrite, sulfite, formate, and acetate ions) were the major species in the dewwater and were several times higher than those in the rain- and fogwater. The concentrations of these species and ammonium ion can be estimated by the resistance model. The estimated values of N(III) correlate relatively well with the measured values, which shows the origin of N(III) in dewwater is nitrous acid in the ambient air. On the other hand, ammonium ion in the dewwater originated from not only gaseous ammonia but also aerosol ammonium ions. Hydrogensulfite ions in the dewwater which originated from sulfur dioxide are an important species as the precursor of the sulfate and they were stabilized by forming hydroxyalkanesulfonate (HASA). Formic acid and acetic acid in the dewwater originated mainly from gas, while the oxalic acid is from aerosol.
High Axial Coordination in a cis-Coordinated Succinimidatocopper(II) Complex
Authors: Akitsu Takashiro , Komorita Seiko 
Published: September 2002

Abstract
A copper(II) complex [Cu(succim)2(N-Eten)(H2O)2] (succim = succinimidate and N-Eten = N-ethylethylenediamine) was prepared and characterized by X-ray crystallography and polarized crystal electronic spectra. The complex has a distorted octahedral [CuN4O2] chromophore. The π-donor succim ligands on cis-positions raise the potential of axial coordination up to six-coordination to maintain electroneutrality of the complex.
Photochemical Reactions of Hydroarenes with N-Bromosuccinimide
Authors: Zong Zhi-Min , Zhang Wei-Hong , Jiang Qun , Lu Jin , Wei Xian-Yong 
Published: September 2002

Abstract
The photochemical reactions of 1,2,3,4-tetrahydronaphthalene (THN), 9,10-dihydrophenanthrene (DHP), 9,10-dihydroanthracene (DHA), and acenaphthene (AN) with N-bromosuccinimide (NBS) were investigated under N2 atmosphere at room temperature. The results show that the relative reactivities of the hydroarenes toward a photochemical reaction with NBS are THN &lt; DHP &lt; AN &lt;&lt; DHA, which is consistent with the stabilities of the radicals produced by benzylic hydrogen abstraction from the hydroarenes. Photochemical reactions of THN and DHP mainly afforded dehydrogenated products, while the photobrominations of the dehydrogenated products from AN and DHA with NBS proceeded readily.
Inclusion Complexes of Cyclodextrins with Methylene Blue and α-Naphthol Orange and Temperature Dependence of the Inclusion Complexation in Aqueous Solutions
Authors: Hamai Sanyo , Satou Hideyuki 
Published: September 2002

Abstract
Methylene Blue (MB) has been found to form a complex with α-Naphthol Orange (αNO) in aqueous solution. From a simulation concerning the fluorescence quenching of MB by αNO, an equilibrium constant for the formation of the 1 : 1 MB–αNO complex has been estimated to be 79900 mol-1 dm3. Upon the addition of γ-CD to MB solution containing αNO, the absorption of the MB monomer band is enhanced in intensity without an appearance of the MB dimer band, indicating the formation of a ternary γ-CD–MB–αNO inclusion complex. To determine a stoichiometry of the ternary inclusion complex, a continuous variation method using the fluorescence intensities has been performed under the condition that the sum of the initial concentrations of γ-CD and αNO has been kept constant. The result of the continuous variation method indicates the formation of a 2 : 1 : 1 γ-CD–MB–αNO inclusion complex. The equilibrium constant for the formation of the γ-CD–MB–αNO inclusion complex from γ-CD and the 1 : 1 MB–αNO complex has been evaluated to be 1.86 × 109 mol-2 dm6 from a simulation concerning the absorbance change. From the temperature dependence of the equilibrium constants, ΔH and ΔS values have been evaluated for the γ-CD–MB–αNO and γ-CD–MB–Acid Orange 7 systems. The ΔH and ΔS values for the formation of the γ-CD–MB–αNO inclusion complex have been positive in sign, in contrast to those for the formation of the MB–αNO and γ-CD–αNO complexes.
Preparation and Rearrangement of Arylhydroxymethano[3]orthocyclo[5](1,8)naphthalenophanes.
Authors: Isobe Shin-ichiro , Kubo Kanji , Thiemann Thies , Sawada Tsuyoshi , Yonemitsu Tadashi , Mataka Shuntaro 
Published: September 2002

Abstract
Arylhydroxymethano[3]orthocyclo[5](1,8)naphthalenophanes 11, which possess a rigid boat-chair conformation, were prepared by the reaction of 9,10-benzo-3,4,5-[1,8]naphthobicyclo[5.4.1]dodecan-3,9-dien-12-one 8c with aryllithium reagents and treated with hydrobromic acid in dioxane. The intermediary cation generated from 11 rearranged either to a benzo[cd]azulene system of type 12 or to a tricyclic system containing a cyclopropane-unit of type 13, depending on the nature of the aryl substituent on the bridging carbon atom.
Synthesis, Solution Chemistry, X-ray Structure and Biological Activity of Novel Pyridoxal Thiosemicarbazone Derivatives
Authors: Ferrari Marisa Belicchi , Bisceglie Franco , Leporati Enrico , Pelosi Giorgio , Tarasconi Pieralberto 
Published: September 2002

Abstract
Novel ligands were obtained by condensation of pyridoxal with thiosemicarbazides substituted with alkyl and aryl moieties on the aminic and/or hydrazinic nitrogen. The spectrophotometric characteristics of the various species are reported. The X-ray structure of two different dimethylthiosemicarbazones of pyridoxal — pyridoxal N1,N2-dimethylthiosemicarbazone monohydrate and pyridoxal N1,N1-dimethylthiosemicarbazone monohydrate — was determined. The change of methyl group position determines in the solid state strong differences which affect the ligand behavior of these compounds. In the first ligand, characterized by X-ray diffraction, the pyridoxal ring is in a zwitterion form, with the phenolic oxygen and the sulfur atoms in trans position to the iminic N atom. The second compound, with both methyl groups on the aminic nitrogen, shows the donor atoms SNO on the same side, making it potentially suitable for coordination to the metal. Biological studies have involved both inhibition of cell proliferation and apoptosis tests on human leukemia cell lines U937. Both ligands inhibited cell growth, but neither of them induced apoptosis. On the basis of the pKa values, the second ligand is more easily dissociable and this allows us to predict the formation of neutral complexes with it.
A Product Analytical Study of the Thermal and Photolytic Decomposition of Some Arenediazonium Salts in Solution
Authors: Canning Peter S J , Maskill Howard , McCrudden Katharine , Sexton Brian 
Published: September 2002

Abstract
Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
Construction of Fused Cyclooctanoid Ring Systems via Seven-Membered Ring Carbonyl Ylides
Authors: Muthusamy Sengodagounder , Babu Srinivasarao Arulananda , Gunanathan Chidambaram , Suresh Eringathodi , Dastidar Parthasarathi 
Published: September 2002

Abstract
A series of α-diazo carbonyl compounds tethered to cyclopentanone/cyclohexanone/1-tetralone units have been synthesized using a diazomethane solution to construct various fused cyclooctane ring systems via rhodium-generated carbonyl ylides. The reaction of rhodium(II) acetate dimer with various α-diazo carbonyl compounds generated transient cyclic seven-membered ring carbonyl ylides, which underwent facile 1,3-dipolar cycloadditions with dipolarophiles, like N-phenylmaleimide, p-benzoquinone, and DMAD to furnish a variety of fused epoxy-bridged cyclooctane ring systems in a tandem manner. Interestingly, an oxepine ring system was generated via an intramolecular proton transfer of a seven-membered ring carbonyl ylide. A tri-oxa polycyclic compound was obtained in the case of p-benzoquinone as dipolarophile. A single-crystal X-ray analysis of a fused cyclootanoid derivative is reported to decisively establish the structure and stereochemistry of the fused epoxy-bridged cyclooctane ring systems; a further analysis revealed the existence of a unique intermolecular C–H···π interaction motif in the solid-state architecture.
A Novel Reductase Participating in the Hydrogenation of an Exocyclic C–C Double Bond of Enones from Nicotiana tabacum
Authors: Shimoda Kei , Izumi Shunsuke , Hirata Toshifumi 
Published: September 2002

Abstract
A novel 74 kDa enone reductase which catalyzes the reduction of the exocyclic C–C double bond of enones was isolated from cultured cells of Nicotiana tabacum. The reductase was found to catalyze the enantiofacially selective reduction of the C–C double bond of 2-alkylidenecyclohexanone to give optically active (S)-2-alkylcyclohexanone.