bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of C60 Monolayer Based on Structural Relaxation on the Water Surface
Authors: Yanagida Masami , Takahara Atsushi , Kajiyama Tisato
Published: September 2002

A C60 monolayer was constructed by a multi-step creep method for the first time. In the case that a dilute C60 benzene solution of 1×10-5 M (1 M = 1 mol dm-3) was spread on the water surface, C60 molecules formed into highly organized 2-dimensional crystalline domains. On the other hand, in the case of the conventional continuous compression method up to a low surface pressure below 15 mN m-1, the C60 monolayer-like aggregates were formed with a lot of vacancies. Each monolayer-like C60 aggregate was easily collapsed into small fragments and changed into 3-dimensional aggregates at a high surface pressure above 20 mN m-1. The C60 film could not full up the vacancies during continuous compression, since the C60 molecules formed rigid aggregates. These results clearly indicate that structural relaxation at a low surface pressure was required to construct the defect-diminished C60 monolayer. The occupied area of a C60 molecule in the monolayer prepared by the multi-step creep method was in good agreement with that of a 2-dimensional C60 crystal calculated from lattice constants of a 3-dimensional C60 crystal. The surface morphology of the C60 monolayer prepared by the multi-step creep method was homogeneous, and C60 molecules in the monolayer were closely and regularly packed in a hexagonal array. The hexagonal packing of the C60 molecules was confirmed on the basis of atomic force microscopic and electron diffraction observations.
A New Parameter for Maturity Determination of Organic Matter in Sediments Based on the Clay-Catalyzed Thermal Isomerization of Monomethylphenanthrenes
Authors: Nomoto Shinya , Hagiwara Masayosi , Nakano Yoshinobu , Shimoyama Akira
Published: September 2002

Monomethylphenanthrenes (MPs) were isomerized by heating in the presence of Na-montmorillonite at 250—400 °C. Isomerization between 1- and 2-MP was found to proceed faster than those between the other sets of MPs. On the basis of this facile interconversion, the molar ratio of 1- to 2-MP was suggested to be a useful new parameter for the maturity assessment of sedimentary organic matter. This parameter was tested in a geochemical study on Miocene to Pliocene sediments in the Shinjo basin of Yamagata Prefecture. We determined the molar ratio in 12 depth-differing sediments, and found an almost linearly decreasing trend in the ratio with increasing depth, showing a good correlation of this parameter to the maturity of the sedimentary organic matter.
Gold Valence Transition and Phase Diagram in the Mixed-Valence Complexes, M2[AuIX2][AuIIIX4] (M = Rb, Cs; X = Cl, Br, and I)
Authors: Kojima Norimichi
Published: September 2002

In this paper, I review the structural and physical properties of the gold mixed-valence complexes, M2[AuIX2][AuIIIX4] (M = Rb, Cs; X = Cl, Br, and I), having perovskite-type structure. In spite of the three dimensional perovskite-type structure, the charge transfer interaction between AuI and AuIII in these complexes is two-dimensional. These complexes undergo the pressure-induced Au valence transition from the mixed valence state of AuI,III to the single valence state of AuII, which is coupled with a structural phase transition. In the pressure region below the Au valence transition, these complexes show a metallic behavior, which would be attributed to a dynamic two-electron exchange between the AuI and AuIII states (i.e. highly mobile bipolarons). The metallic cubic phase appearing commonly for these complexes under high pressure and high temperature can be obtained as a metastable phase even at ambient pressure and room temperature. Moreover, as a recent topic, I report the photo-induced Au valence transition for Cs2[AuIBr2][AuIIIBr4].
A Novel Tetralithium Salt of a Tetraanion and a Dilithium Salt of a Dianion, Formed by the Reduction of the Tetrasilylethylene Moiety. Synthesis, Characterization, and Observation of an Si-H···Li+ Interaction
Authors: Matsuo Tsukasa , Watanabe Hidetoshi , Sekiguchi Akira
Published: September 2002

2,3,6,7-Tetrakis(trimethylsilyl)-1,1,4,4,5,5,8,8-octamethyl-1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene (3) was prepared starting from 2,3,6,7-tetrakis(dimethylsilyl)-1,1,4,4,5,5,8,8-octamethyl-1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene (1). The molecular structures of 1 and 3 have been determined by X-ray crystallography. Compound 1 has an almost planar structure, whereas compound 3 exhibits a highly folded structure due to the steric repulsion of the trimethylsilyl groups. Treatment of 1 and 3 with lithium metal yielded the corresponding tetralithium salts of the tetraanions 4 and 5, in which the two tetrasilylethylene units were subjected to two-electron reduction. 2,3-Bis(dimethylsilyl)-1,1,4,4-tetramethyl-1,4-disila-1,4-dihydronaphthalene (6), which has a half unit of 1, was reacted with lithium metal to give the dilithium salt of the dianion (7). Evidence for an interaction between the Si-H and the Li+ ion of 4 and 7 in both solid state and solution is also given.
A Thermodynamic Theory of Suspension I. Thermodynamic Theory
Authors: Furukawa Junji
Published: September 2002

The stability of a colloid has been treated in terms of repulsion by electric charge and attraction by cohesion of particles, but colloid particles are v-times larger in volume-size than the solvent molecules. v is as large as 103-6 and the molar energy of cohesion H/v is negligibly small compared with the electric repulsion energy Wel/v. Cohesion acts over the distance of 1—5 Å or only at the contact point. H does not increase with v, contrary to the DLVO theory. The molar energy of sedimentation Wsed/v is taken as an influential factor for the stability of a colloid of large particles. It is calculated from Stokes law as Wsed/v = Δρ u2, where Δρ is the density difference and u is the stationary velocity of sedimentation equal to (Δρ/η)(2/9)gr2, where η, r, and g are viscosity of solvent, radius of particle, and acceleration constant of gravity, respectively. Sedimentation occurs when Wsed/v is equal to kT/3, i.e., the perpendicular component of the energy of Brownian motion. The critical radius rc is rc = 30C nm, where C = 10 (η2/Δρ3)1/4 and k is Boltzmann's constant. rc is 10—100 nm for inorganic sol, above 100 nm for organosol and aerosol. A theory of colloidal solution is proposed by using a lattice model of size v. Molar free energy of mixing ΔG of the volume fraction of particles φ is ΔG = [(1-φ) ln (1-φ) + (φ/v) ln (φ/v)] R T + (φ Wsed-φ2Wel + φ2H)/v. Solubility is φ = [1- (r/rc)]/[1 + (1/v2) + (H-Wel)/v RT]. Wsed is absorbed internally in the dispersion system. When r > rc, sedimentation takes place to form muddy mixtures including agglomerates of particles. Cohesion acts only at a contact point and is negligibly small.
Energy Transfer and Guest Responsive Fluorescence Spectra of Polyrotaxane Consisting of α-Cyclodextrins Bearing Naphthyl Moieties
Authors: Tamura Makio , Ueno Akihiko
Published: September 2002

We constructed a polyrotaxane (1) composed of about 15 α-cyclodextrins, each bearing roughly two naphthalene units and a polyethylene glycol (PEG) as a threading chain with adamantane groups at both ends. The product was characterized by 1H NMR, 13C NMR, and absorption spectroscopies. We observed that photoenergy transfer occurs from the naphthalene units of 1 to 5-dimethylamino-1-naphthalenesulfonyl (dansyl) of dansyl modified β-cyclodextrin (Dnsβ-CD) when Dnsβ-CD forms a complex with each terminal adamantane moiety of the polyrotaxane. This energy transfer was reduced by the addition of adamantanol, which acts as a competitive binder for Dnsβ-CD.
Preparation and Spectroscopic Characterization of 2 : 1 Molecular Complexes of Tetracyanoethylene and meso-Tetraphenylporphyrins
Authors: Mohajer Daryoush , Dehghani Hossein
Published: September 2002

Different para-substituted meso-tetraphenylporphyrins (H2T(4-X)PP, X = H, Cl, CH3, CH(CH3)2, OCH3) react with various molar ratios of tetracyanoethylene (TCNE) in dichloromethane or benzene and produce only the 1 : 2 molecular complex, (TCNE)2H2T(4-X)PP. The remarkable agreement between the corresponding 1H, 13C solution (CDCl3) NMR resonances of the porphyrin moiety in these complexes with those of tetraphenylporphyrin dication, H4TPP2+, and also the strong resemblance between their UV-vis spectra and the spectra of the related diprotonated porphyrins indicates similar out-of-plane distorted porphyrin core structure in all of them. Based on these close spectral correspondences among the various molecular complexes and the related diprotonated porphyrins, and also consideration of the known structure of H4TPP2+Cl2- species, it is proposed that the two TCNEs in (TCNE)2H2T(4-X)PP complexes are bonded from above and below the mean porphyrin plane to the lone electron pairs of the pyrrolenine nitrogens of the porphyrins.Spectral data (13C, IR) of the bonded TCNEs in the molecular complexes seem to be most consistent with the interaction of an acceptor π* orbital centered at a CN group of the TCNEs with the porphyrin core nitrogen donors.
Evaluation of Novel Local Structural Parameters of Acids and Bases for 1 : 1 Hydrogen-Bond Complexation I. OH-, NH-Acids and Phosphorus Bases in Carbon Tetrachloride
Authors: Mishima Shozi , Nakajima Tsuyoshi , Fujii Tsuneo
Published: September 2002

Novel local structural parameters, η° and ω°, representing the nature of the functional group and the residual moiety (supporting group) of acid and base molecules, respectively, have been evaluated for the first time for the 1 : 1 hydrogen-bond complexation of nine OH- or NH-acids and five phosphorus bases in CCl4. An evaluation of η° and ω° was carried out by making use of convergent linear relationships among the log K values and by introducing three numerical criteria. For acid-base complexation, all of the 180 log K values at 288.15—318.15 K and 45 ΔHf° values were reproduced from the η and ω values within the experimental error. The reversals in the order of log K and ΔHf° observed in the system could be reasonably explained by applying the η° and ω° scales.
Negative Chemical Ionization Mass Spectrometric Studies on Dissociative Electron Attachment Processes of Chloroethylenes and Bromoethylenes
Authors: Nakagawa Seiko , Shimokawa Toshinari
Published: September 2002

The temperature dependence of the formation of negative ions from chloroethylenes (cis-1,2-C2H2Cl2, trans-1,2-C2H2Cl2, C2HCl3, C2Cl3F, C2Cl4) and bromoethylenes (cis-1,2-C2H2Br2, trans-1,2-C2H2Br2, C2HBr3, 1,1-C2Br2F2) was studied using negative chemical ionization mass spectrometry. The halide ion was observed for all samples. Other fragment anions, (M-X)- (parent molecule, M, less one halogen atom, X)- and X2- were produced for some samples. The former was observed for trans-1,2-C2H2X2 and C2HBr3, and the latter for 1,2-C2H2Cl2, cis-1,2-C2H2Br2, and C2HBr3. The branching ratio of X2- and (M-X)- decreases with increasing the temperature. The branching ratio of X2- is considerably different for chloroethylenes and for bromoethylenes.
A Thermodynamic Theory of Suspension II. Kinetic Theory for Viscosity of Suspension
Authors: Furukawa Junji
Published: September 2002

A dispersion is prepared by vigorous agitation for large particles of radius r or volume v larger than its critical rc or vc. The viscosity η is several Pa s and will be large compared with the viscosity of the solvent η0 of 10-3 Pa s. As a typical case, cement paste was studied by Hattori-Izumi who showed a gradual increase in η with time t. It was explained by collisions followed by cohesion, but gradual sedimentation seems more likely to be the origin. The author proposes a dynamic theory of viscosity.

The static viscosity is proportional to the energy of sedimentation Wsed, whereas dynamic viscosity η is expressed as exponential functions of Wsed. Molar concentration Wsed/v increases with the density of particles ρ, but decreases with the viscosity of solvent. The η value decreases by addition of water and fly ash. ζ-potential promotes dispersion. Contrary to an ordinary concept, cohesion heat may not act except in the coagulated state.

Time-dependent viscosity is caused by the relaxation of agitation energy Wag through three stages: rapid stage relaxation by collision of particles, slow stage relaxation by the consumption of Wc i.e., internal sedimentation energy due to viscous resistance and finally relaxation by coagulation. The second stage is expressed as ln η ≈ φ (Wc/vcRT)(t/τ), where Wc/vcRT = 1, vc = (rc/r)3, rc = 30 nm, r = 1 μm, τ = C0.5 (rc/r)2, C = η00.5/Δρ3/4 and τ is about 1 h.

For the case of very large particles e.g., fluidized bed, the relative volume v of the bed expands with the velocity of gas stream u0 like thermal expansion with a coefficient β and η is expressed as η = A exp (Wsed/β u0RT). This type of equation for polymeric material is known as Doolittle's equation, η = A exp (B/vf), vf being a free volume fraction.
Fluorescence Quenching of 1-Pyrenemethanol by Serotonin on the Surface of Polystyrene Latex Particles
Authors: Nakashima Kenichi , Koide Daigo , Gong Yong-Kuan
Published: September 2002

The fluorescence quenching of 1-pyrenemethanol (PyM) by serotonin (Ser) in polystyrene latex dispersions has been studied by steady-state and time-resolved fluorescence spectroscopy. From steady state fluorescence measurements, it is found that the quenching is remarkably enhanced on going from an aqueous homogeneous solution to a latex dispersion. This is attributed to that both PyM and Ser are effectively adsorbed onto the latex particles, as evidenced by measurements of the adsorption isotherms. Fluorescence decay curves of PyM in polystyrene latex dispersions have been successfully analyzed in terms of double exponential functions. The analysis reveals that the quenching of PyM fluorescence by Ser on polystyrene latex surfaces is mainly operated by a static mechanism, although the contribution of a dynamic mechanism is not negligible.
Further Insights into the Electrooxidation of N-Methyluric Acids and Correlation of Oxidation Potentials with Frontier MO Energies
Authors: Goyal Rajendra N , Thankachan P P , Jain Neena
Published: September 2002

The electrochemical oxidation of various N-methylated uric acids has been studied at a pyrolytic graphite electrode at physiological pH 7.2. The observed behavior was compared with uric acid to evaluate the effect of a methyl group. The Ep value was found to shift to less positive potentials when a methyl group is present at the N-1 position and to more positive potentials when substitution is at the N-3 position or at nitrogens of the imidazole ring. The values of ΔEp followed the additivity of the substituents effect only when two methyl groups are present in different rings. The methyl groups were also found to increase the electron density at N atoms of uric acids, and an excellent correlation between the oxidation potential and energy of the highest occupied molecular orbital was observed. On the basis of these studies it is concluded that the presence of a methyl group in the pyrimidine ring restricts the formation of allantoin. The peroxidase-catalysed oxidation of the N-methylated derivatives of uric acid was found to follow a pathway similar to that observed during electrochemical oxidation.
Electronic Spectra of Push-Pull 4-Phenylaminoazobenzene Derivatives
Authors: Makita Shohei , Saito Ayako , Hayashi Makoto , Yamada Shohei , Yoda Koji , Otsuki Joe , Takido Toshio , Seno Manabu
Published: September 2002

A series of push-pull type 4-phenylaminoazobenzene derivatives bearing an electron-withdrawing 4′-substituent were probed by electronic spectra in solution. The visible absorption maxima of these azobenzenes were correlated with the solvent parameters through the McRae theory as well as the solvent donor numbers. While the absorption spectra of these neutral species were solvent-dependent, those of protonated species were almost solvent independent. On the other hand, the absorption maxima and the rates of thermal cis-to-trans isomerization in a given solvent were correlated with Hammett constants. These results are discussed with the help of semi-empirical molecular-orbital calculations and compared with previously published data on related compounds.
Spectroscopic Study on Direction and Inclination of Helical Peptides in Monolayers Formed at the Air/Water Interface and on a Gold Substrate
Authors: Morita Tomoyuki , Kimura Shunsaku , Kobayashi Shiro , Imanishi Yukio
Published: September 2002

Monolayers at the air/water interface and self-assembled monolayers (SAMs) on a gold substrate were prepared from helical peptide derivatives carrying a 9-ethyl-3-carbazolyl group and a disulfide group. π-A Isotherms and circular dichroism spectra of Langmuir-Blodgett monolayers on a quartz substrate showed that the helical peptides were lying at the air/water interface. The molecular arrangement in the monolayer was analyzed by fluorescence quenching using in situ fluorescence spectroscopy. Computer simulations for the quenching experiment under the assumption of the mixed arrangement of parallel and antiparallel orientations explain the experimental data. On the other hand, the helical peptides in the SAMs were found to take standing orientation and a parallel arrangement by Fourier transform infrared reflection-absorption spectroscopy and fluorescence spectroscopy.
Studies of the Lowest Excited Triplet State of 3,3′-Biisoquinoline(dicyano)platinum(II) [Pt(CN)2(i-biq)] by Means of Time-Resolved Electron Paramagnetic Resonance and Optical Spectroscopy
Authors: Funayama Tomoyo , Kato Masako , Kosugi Hiroshi , Yagi Mikio , Higuchi Jiro , Yamauchi Seigo
Published: September 2002

The lowest excited triplet (T1) state of 3,3′-biisoquinoline(dicyano)platinum(II), [Pt(CN)2(i-biq)] was examined by time-resolved electron paramagnetic resonance (TREPR) and optical techniques in comparison with that of a ligand 3,3′-biisoquinoline (i-biq). Trans and cis  i-biqs were assigned from obtained and calculated zero-field splittings (zfs') in the T1 state. The zfs parameter D increased with complex formation from 2.66 to 4.66 GHz in a rigid dimethylformamide solution; the polarization pattern of the spectrum was very different between the ligand and the complex. The triplet lifetime (ca. 1 s) of i-biq is also remarkably shortened in the complex (ca. 2 ms). These facts were analyzed in terms of the spin-orbit coupling (soc) between T1 (ππ*) and 1,3dπ*. From the analyses, the soc matrix element and the magnitude of delocalization of π* electrons over the Pt atom are obtained as 65 cm-1 and 0.02, respectively. The solvent dependences of the D value and the triplet lifetime also support the importance of the 1,3dπ* states for the T1 (ππ*) properties of the complex.
Reaction of Electronically Stabilized Thiones with Benzyne. The Isolation of Thiobenzophenone-Benzyne and Thiopivalophenone-Benzyne Adducts
Authors: Okuma Kentaro , Shiki Kyoko , Sonoda Shinya , Koga Yuji , Shioji Kosei , Kitamura Tsugio , Fujiwara Yuzo , Yokomori Yoshinobu
Published: September 2002

The reaction of thiobenzophenones (1) with phenyl[2-(trimethylsilyl)phenyl]iodonium trifluoromethanesulfonate (4) in the presence of tetrabutylammonium fluoride afforded the corresponding [4+2] cycloadducts, which are the first examples of thiobenzophenone-benzyne adducts. The reaction of thiopivalophenone (6) with benzyne prepared from 4 and tetrabutylammonium fluoride at room temperature gave [2+2] cycloadducts (7). When the reaction was carried out in refluxing dichloromethane, a mixture of 7 and [4+2] cycloadducts (13) was obtained.
Effect of High Magnetic Field on the Lifetime of Biradicals Generated from Benzophenone and Diphenylamine Bifunctional Chain Molecules
Authors: Duan Wenyong , Hashimoto Akihiko , Fujiwara Yoshihisa , Tanimoto Yoshifumi
Published: September 2002

The effect of high magnetic fields (≤ 13 T) on the lifetime of triplet biradicals (BPH·-O-(CH2)n-O-DPA·, n = 2, 4, 8, 16) composed of a protonated diphenylketyl radical (BPH·) and a diphenylaminyl radical (DPA·) is studied in N,N-dimethylformamide at room temperature by laser flash photolysis. On increasing the magnetic field from zero to ca. 2 T, the lifetime of BPH·-O-(CH2)n-O-DPA· (n = 4, 8, 16) increases steeply, and then decreases gradually in higher magnetic fields. The lifetime of BPH·-O-(CH2)2-O-DPA· decreases gradually with increasing the magnetic field with a shallow dip at ca. 2 T. The reversal of the effect observed in the lifetime of BPH·-O-(CH2)n-O-DPA·, n = 4, 8, 16 is interpreted in terms of spin-lattice relaxation which is induced by the anisotropic Zeeman interaction. The dip observed in the magnetic field dependence of the lifetime of BPH·-O-(CH2)2-O-DPA· is attributable to the S-T_ level crossing.
Charge-Density and Ring-Size Dependent Dimerization of 1-Arylcycloalkene Cation Radicals
Authors: Kojima Masanobu , Ishida Akito , Kuriyama Yasunao , Oishi Shigero
Published: September 2002

The γ-radiolysis of 1-arylcyclopentenes [Ar = Ph (1a); 4-ClC6H4 (1b); 4-MeC6H4 (1c); 4-MeOC6H4 (1d)] at 77 K initially gave transient absorption bands attributable to their monomer cation radicals (1a·+—1d·+), with λmax around 400 and 650—730 nm. In the case of 1a, 1b, and 1c, simultaneous formation of new absorption bands with λmax around 480—500 nm, attributable to the dimer cation radicals, was clearly observed upon warming along with a decrease in the monomer cation radical absorption bands. Using 355-nm laser photolysis at room temperature and an N-methylquinolinium salt as an electron acceptor, the rate constants for the formation of the dimer cation radicals (kdimer) and the reaction-rate constants for 1·+ with methanol (kMeOH) were determined. The reactivities of 1·+ with 1 and with methanol are discussed on the basis of the results obtained by a semiempirical molecular orbital calculation using the PM3 method. The results indicate that the reactivities of 1·+ depend not on its structure but on the charge density of the ethylene bond. In addition, dimerization of the cycloalkene cation radicals with larger ring size than 1, such as 1-phenylcyclohexene, 1-phenylcycloheptene, and 1-phenylcyclooctene cation radicals, was found to be remarkably dependent on the ring size.
Molecular States of 2-Naphthoic Acid in Solid Dispersions with Porous Crystalline Cellulose, as Investigated by Fluorescence Spectroscopy
Authors: Tozuka Yuichi , Yonemochi Etsuo , Oguchi Toshio , Yamamoto Keiji
Published: September 2002

2-Naphthoic acid (2-NPA) crystals were mixed with porous crystalline cellulose (PCC). After a heat-treatment of the mixture, no diffraction peaks due to 2-NPA crystals were observed on the XRD pattern. Fluorescence spectral data indicated that the molecular state of 2-NPA was modified by heating with PCC. The results of a fluorescence analysis also seemed to support the molecular state change of 2-NPA. When 2-NPA formed an inclusion complex by co-grinding with γ-cyclodextrin (γ-CD), the emission spectra of 2-NPA in this sample was similar to that in the heat-treated sample with PCC. Since γ-CD could be assumed to include two naphthyl moieties into the cavity, the fluorescence properties of 2-NPA after a heat treatment with PCC could be characterized by the excimer of 2-NPA on the PCC surface.
Magnetic Field Effect on the Intramolecular Exciplex Fluorescence of Chain-Linked Pyrene/N,N-Dimethylaniline Systems
Authors: De Rina , Fujiwara Yoshihisa , Zhang Baowen , Tanimoto Yoshifumi
Published: September 2002

The magnetic field effect (MFE) (≤ 13 T) on the intramolecular exciplex fluorescence of chain-linked pyrene/N,N-dimethylaniline systems is studied. In the case of pyrenyl-(CH2)2-O-(CH2)10-N(CH3)-phenyl, the exciplex fluorescence lifetimes are 34.2 (0 T), 50.6 (1 T), and 36.1 ns (13 T) in tetrahydrofuran/N,N-dimethylformamide (1 : 1) mixed solvent at room temperature. The lifetime decrease above 1 T is explained in terms of a Δg mechanism. Solvent dependence of the MFE maximum is discussed in terms of stabilization energy of the intramolecular radical ion pair, which is in fast dynamic equilibrium with the singlet exciplex. Influences of chain length and temperature are also discussed.
Site-Selective X-Ray Absorption Fine Structure (XAFS) Spectroscopy (2). XAFS Spectra Tuned to Surface Active Sites of Cu/ZnO and Cr/SiO2 Catalysts
Authors: Izumi Yasuo , Nagamori Hiroyasu
Published: September 2002

Site-selective XAFS spectra were measured by tuning the Rowland-type fluorescence spectrometer to each site of Cu/ZnO and Cr/SiO2 catalysts. The chemical shifts between Cu0 and CuI sites and between CrIII and CrVI sites were relatively large for model compounds (ΔE = 1.6 eV), and were utilized as the tune energies of site-selective XAFS. Site-selective XANES tuned to Cu0, CuI, and CrIII sites were successfully obtained. Based on the correlation between the chemical shift and the peak width (energy resolution of the fluorescence spectrometer), site-selective XANES spectra were analyzed. The population ratio of Cu metal, Cu2O, and CuI atomically dispersed on ZnO was estimated to be 70(±23) : 22(±14) : 8(±5). The contribution of the CrIII site to site-selective XANES tuned to the CrIII site was 94(±3)%.
1H NMR Spectra of Ternary Platinum(II) Complexes with N-Ethyl- or N-Benzyl-1,2-ethanediamine and 2,2′-Bipyridine or 1,10-Phenanthroline: Intramolecular Aromatic-Aromatic Interaction in Coordination Sphere, and It's Solvent and Temperature Effects
Authors: Goto Masafumi , Sumimoto Masamitsu , Matsumoto Takashi , Iwasaki Maki , Tanaka Yoshitomo , Kurosaki Hiromasa , Yuto Koji , Yoshikawa Yuzo
Published: September 2002

Square-planar complexes with the formula [Pt(L1) (L2)]X2, where L1 is di(ammine) or 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) and L2 is N-ethyl-1,2-ethanediamine (Eten) or N-benzyl-1,2-ethanediamine (Been), and X = NO3- or Cl-, were prepared. NMR measurements of D2O solutions of these complexes showed that the N-ethyl and N-benzyl groups are forced to take a pseudo axial disposition due to an intramolecular repulsion from hydrogen atoms of aromatic diamines for complexes where L1 = bpy or phen and significant upfield shifts due to the ring current effect were observed for the Been complexes. An analysis of coupling with N-H and 195Pt showed that the major rotamer due to rotation around CH2-NH is (-)-syn for the Been with a significant intramolecular stacking between aromatic rings of L1 and L2, but anti- for the Eten complexes. The solvent and temperature dependency of the upfield shift of the Been complexes are described; the protein denaturants, guanidinium chloride, and urea, act to reduce stacking as dioxane.
Production of Sb(IV) Chloro Complex by Flash Photolysis of the Corresponding Sb(III) and Sb(V) Complexes in CH3CN and CHCl3
Authors: Shinohara Nobuyoshi , Ohshima Masaaki
Published: September 2002

[SbCl6]2- was formed in the flash photolysis of [SbCl6]3- or [SbCl6]- in both solutions of CH3CN and CHCl3 in the presence of an excess of chloride. [SbCl6]2- had absorption maxima at 293, 328, and 390 nm in CH3CN. A similar absorption spectrum of [SbCl6]2- was also obtained in CHCl3. The lifetime of [SbCl6]2- was much shorter in CHCl3 than in CH3CN. [SbCl6]- was easily reduced to [SbCl6]3- upon continuous UV-irradiation in CH3CN as well as in CHCl3. On the other hand, [SbCl6]3- was oxidized to [SbCl6]- in CHCl3 in the presence of oxygen, but was not in CH3CN. The spectrum and the decay rate of [SbCl6]2- were not essentially affected by oxygen in both solutions of CH3CN and CHCl3.
A New and Convenient Method for the Synthesis of Dehydroamino Acids Starting from Ethyl N-Boc- and N-Z-α-Tosylglycinates and Various Nitro Compounds
Authors: Nagano Tanemasa , Kinoshita Hideki
Published: September 2002

Ethyl N-Boc- and N-Z-α-tosylglycinates, which were readily available from t-butyl or benzyl carbamate, ethyl glyoxylate, and sodium p-toluenesulfinate in formic acid, were reacted with a variety of nitro compounds in the presence of a base to afford the corresponding α,β-didehydroamino acid derivatives in good yields. Eventually, it was found that the (Z)-isomer was predominantly formed in the present method.
Langmuir Films of Amphiphilic [60]Fullerene Derivatives
Authors: Nakamura Yosuke , Taki Masumi , Asami Aya , Inokuma Seiichi , Hiratani Kazuhisa , Taguchi Kazuhiro , Higuchi Masahiro , Nishimura Jun
Published: September 2002

The stability of Langmuir films of [60]fullerene bisphenols 1—3, monophenols 4 and 5, and monocatechol 6 was investigated on the basis of surface pressure-area (π-A) isotherms. The films of 1—3 were found to be more stable than those of 4—6. Among bisphenols 1—3, cis-3-isomer 2 forms less stable Langmuir films than cis-2- (1) or e-isomer (3). This is ascribable to the lower hydrophilicity due to the intramolecular hydrogen bonding between the OH groups in 2, as demonstrated by the 1H NMR and IR spectroscopies. The contribution of intramolecular hydrogen bonding was also observed in monocatechol 6.
Effect of the N6-Methyl Group of the Adenine Ring on the Stacking Interaction
Authors: Itahara Toshio
Published: September 2002

In an effort to determine the effects of N6-methylation of the adenine ring on stacking, the molecular aggregation of 9,9′-(α,ω-alkanediyl)bis[6-(dimethylamino)purine] (1) and of 9,9′-(α,ω-alkanediyl)bis[6-(methylamino)purine] (2) were compared with that of 9,9′-(α,ω-alkanediyl)bis[adenine] (3) by NMR spectroscopy. The obtained concentration effects indicate that N6-methylation resulted in an increase in the population of intermolecular aggregates in the buffer solution at pD 7.0, and had an additive effect on the aggregation. It can be interpreted as a hydrophobic effect of the N6-methyl groups. The aggregation of 1 and 2 depended on the length of the polymethylene chains in a similar manner as that of 3, when the measurements were made on the solution of low concentrations. This suggests that the aggregates of 1, 2, and 3 were similar to each other through stacking between two adenine rings. Furthermore, the chemical shifts of the N6-methyl groups were slightly influenced by the length of the polymethylene chains and the changes of temperature. The N6-methyl group may be located outside the stacking. On the basis of these data, it may be concluded that the N6-methylation enhanced the stacking, but had little influence on the conformation of the stacking.
Synthesis of Amphiphilic Chitopentaose and Chitoheptaose Derivatives Using a Common Disaccharidic Synthon as the Chain Elongation Unit
Authors: Hinou Hiroshi , Umino Atsusi , Matsuoka Koji , Terunuma Daiyo , Takahashi Shunya , Esumi Yasuaki , Kuzuhara Hiroyoshi
Published: September 2002

With interest in clustering bioactive chitooligosaccharides, a pair of amphiphilic derivatives of around DP (degree of polymerization) 6, which has been considered to be the minimum molecular length for some kinds of bioactivity, was synthesized. Homologous derivatives of chitopentaose and chitoheptaose carrying tetradecanoyl and tetradecyloxy groups at the NH and C-1 of the reducing ends, respectively, were actually obtained using a 1,6-anhydro-2-azido-2-deoxy-β-D-glucopyranose derivative as the terminal precursor and a chitobiose derivative as the elongation unit. Micelle formation of both derivatives was assumed from the results obtained by dye solubilization tests.
A Facile Transformation of Terminal Olefins to vic-Difluoro Olefins: Electro-optical Properties of Liquid Crystalline Materials Having a vic-Difluoro Olefinic Moiety
Authors: Kanie Kiyoshi , Tanaka Yoichiro , Takehara Sadao , Hiyama Tamejiro
Published: September 2002

A facile synthetic method of vic-difluoro olefins from the corresponding olefins is explored and applied to the synthesis of liquid crystals (LCs) having a terminal vic-difluoro olefinic moiety. The physical and electro-optical properties of these LCs are compared with those of the corresponding parent olefinic LCs.
Photo-Cleavage of Carbon-Carbon Bond of α-Iodocycloalkanones Giving ω,ω-Dialkoxyalkanoic Ester in Alcohol
Authors: Ji Shun-Jun , Horiuchi C Akira
Published: September 2002

The irradiation at λ > 300 nm of α-iodocycloalkanones with a high-pressure mercury lamp in alcohols containing a small amount of water afforded the corresponding ω,ω-dialkoxyalkanoic ester (65—88%) by photochemical cleavage of the C(I)-C=O bond at room temperature. In the case of a commercial fluorescent lamp as the irradiating light source, photochemical ring-opening products were also obtained. The irradiation of 2α-iodo-5α- and 4β-iodo-5β-cholestan-3-ones in methanol gave methyl 2,2-dimethoxy-2,3-seco-5α-cholestan-3-oate and methyl 4,4-dimethoxy-3,4-seco-5β-cholestan-3-oate in 78 and 62% yields, respectively. The photochemical behavior of the cleavage reaction of α-iodocycloalkanones is also discussed on the basis of 2-hydroxycycloalkanone as an intermediate.
Design of Optically Active Hydroxamic Acids as Ligands in Vanadium-Catalyzed Asymmetric Epoxidation
Authors: Hoshino Yujiro , Murase Noriaki , Oishi Masataka , Yamamoto Hisashi
Published: September 2002

New optically active hydroxamic acids bearing a 1,1′-binaphthyl group were prepared as ligands in a vanadium-catalyzed asymmetric epoxidation. The feature of these hydroxamic acids is a sterically hindered ligand. The asymmetric epoxidation with good selectivity and reactivity can be established by using VO(O-i-Pr)3 (5 mol%) and a small excess amount of ligand (7.5 mol%) with triphenylmethyl hydroperoxide (TrOOH) in toluene at -20 °C. Disubstituted allyl alcohols were epoxidized more rapidly than mono- or tri-substituted allyl alcohols, and were obtained in good to high enantioselectivities (48—94%ee). The transition state based on X-ray crystal structure of 1e is discussed.
A Convenient Synthetic Method for Preparing 2,5-Disubstituted 1,6-Methano[10]annulenes from 1,6-Diacetylcyclohepta-1,3,5-triene
Authors: Kuroda Shigeyasu , Zuo Shengli , Oda Mitsunori , Fukuta Atsushi , Kajioka Takanori , Saito Toyohiko , Furuta Shinji , Tsukumo Hitoshi , Sano Kenji , Miyatake Ryuta , Tomoda Shozo , Hayakawa Chiharu , Nozawa Haruna
Published: September 2002

The reaction of 1,6-diacetylcyclohepta-1,3,5-triene with various Grignard reagents gave high yields of addition products 5, which were treated with a catalytic amount of p-toluenesulfonic acid or pyridinium p-toluenesulfonate to afford 2,5-disubstituted 2,3-dihydro-1,6-methano[10]annulenes 6 via 1,6-bis(1-substituted vinyl)cyclohepta-1,3,5-trienes 8 and 2,5-disubstituted 3,4-dihydro-1,6-methano[10]annulenes 9. On the other hand, reactions under more forcing conditions gave the rearrangement products: 4,7-disubstituted 1,2-benzocyclohepta-1,3-dienes 7. The oxidation of 6 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone gave the 2,5-disubstituted 1,6-methano[10]annulens 4 in moderate-to-good yields. Conversion from 5 into 4 can be achieved by a one-flask procedure, providing a convenient synthetic method for preparing the title annulenes, particularly 2,5-diaryl ones. The reaction mechanism from 8 to 6, 7, and 9 is discussed on the basis of semiempirical molecular orbital calculations.
Mass-Spectrometric Study on Ion-Molecule Reactions of CH5+, C2H5+, and C3H5+ with Benzoic Acid and Benzoates
Authors: Tsuji Masaharu , Arikawa Takeshi , Tanaka Yuki , Nishimura Yukio
Published: September 2002

The gas-phase ion-molecule reactions of CH5+, C2H5+, and C3H5+ with PhCOOX = M (X = H, CH3, C2H5, and Ph) have been studied under a reactant-ion selective chemical ionization mode of an ion-trap type of GC/MS. The major product channel is non-dissociative proton transfer leading to (M+H)+ in most cases. Dissociative proton transfer leading to (M+H-CO2)+ and/or (M+H-XOH)+ competes with the above channels. In the C3H5+/PhCOOX (X = H, CH3, and C2H5) reactions, initial (M+C3H5)+ adduct ions and/or their decomposition products are found. The reaction mechanism is discussed based on the reaction-time dependence of product-ion distributions and semi-empirical calculations of the energies of intermediates and products.
Novel C1 Building Blocks for Fluoro Olefin Synthesis: FC(SiMe3)3 and FC(SiMe3)2SnBu3
Authors: Shimizu Masaki , Hata Takeshi , Hiyama Tamejiro
Published: September 2002

Fluorotris(trimethylsilyl)methane reacted with 2 mol of aromatic aldehydes in the presence of KF/18-crown-6 to give 1,3-disubstituted 2-fluoro-2-propen-1-ols in one pot. On the other hand, treatment of fluoro(tributylstannyl)bis(trimethylsilyl)methane with BuLi, followed by addition of an aldehyde, produced (1-fluoroalkenyl)trimethylsilanes in moderate to good yields.
Chemoselective Aldehyde Addition of Zinc Carbenoid Generated from Tribromofluoromethane
Authors: Hata Takeshi , Kitagawa Hirotaka , Shimizu Masaki , Hiyama Tamejiro
Published: September 2002

Treatment of tribromofluoromethane with diethylzinc in DMF at -60 °C generated a zinc carbenoid reagent, which reacted with aldehydes RCHO chemoselectively to give RCH(OH)CFBr2 in moderate-to-good yields.
Properties of 2-Acetyl-7-nonylfluorene and Its O-Analogs in the Alkyl Chain
Authors: Takabayashi Yutaka , Fukami Toshiyuki , Yamamoto Atsushi , Kimura Takao , Minabe Masahiro
Published: September 2002

The O-analog in the alkyl chain of 2-acetyl-7-nonylfluorene is less stable than the parent compound concerning the mesophase as a liquid crystal, except for 2-acetyl-7-(octyloxy)fluorene.
Cause of the Memory Effect Observed in Alkaline Secondary Batteries Using Nickel Electrode
Authors: Sato Yuichi , Takeuchi Shigeo , Magaino Shin'ichi , Kobayakawa Koichi
Published: September 2002

By repeating shallow discharging and overcharging of alkaline secondary batteries using nickel electrode, a lowering of working voltage is observed on the discharge curve, which is called a memory effect. The X-ray diffraction pattern of the charged-state of the normal nickel electrode contained only diffraction peaks due to β-NiOOH. A charged-state nickel electrode showing lowered discharge voltage had diffraction peaks due to γ-NiOOH in addition to those due to β-NiOOH. The formation of γ-NiOOH can be attributed to be the main cause for the memory effect commonly observed in alkaline secondary batteries such as nickel cadmium and nickel hydrogen batteries. By XRD analysis and AC impedance study, γ-NiOOH was found to be initially formed at the current collector side; it grows to the solution side in the course of shallow discharge-charge cycling. Therefore, if the amount of γ-NiOOH formed is small, only β-NiOOH can be detected, even when the memory effect is observed. In this case, γ-NiOOH can be detected by shaving the surface of the electrode using a piece of emery paper to remove covering β-NiOOH. This γ-NiOOH disappears within a few cycles of the normal charge-discharge cycling, resulting in the elimination of the memory effect. It may be concluded that the cause of the memory effect is mainly due to the formation of γ-NiOOH.
Photochemical Modulation of Alignment in Liquid Crystals
Authors: Ikeda Tomiki , Kanazawa Akihiko
Published: September 2002

Liquid crystals (LCs) show an anisotropic nature in various aspects of optical and electronic properties. This anisotropy enables LC materials to be used as active media in display devices. Birefringence, an anisotropy in optical properties of LCs, is especially useful from the viewpoint of changing refractive indices of LC materials. If alignment of LCs can be changed by light, a large change in refractive index can be induced by light. This is the principle of LC photonics, in which optical signals are processed with the aid of LC materials. In this article, various approaches are described to change the alignment of the LC molecules: 1) photochemically induced phase transition of LCs by photochromic reactions is an order to disorder transition and can be brought about in a time scale of micro- to nanosecond; 2) reorientation of LC molecules by means of linearly polarized light is a change in alignment of LC molecules that occurs within the LC phases and induces a large change in refractive index, but needs more time. Applications of LC systems as photonic materials are also discussed.
Benzyl Derivatives of N-2,4-Dinitrophenyl-D-glucosamine and Their Use for Oligosaccharide Synthesis
Authors: Koto Shinkiti , Hirooka Motoko , Yago Kazuo , Komiya Mitsuo , Shimizu Toshio , Kato Kumi , Takehara Tsunehiko , Ikefuji Ayami , Iwasa Ayako , Hagino Saho , Sekiya Michiyo , Nakase Yozo , Zen Shonosuke , Tomonaga Fumiya , Shimada Shigehiko
Published: September 2002

Four tri-O-benzyl derivatives of 2-deoxy-2-(2,4-dinitroanilino)-D-glucopyranose were synthesized. Glycosylation using 3,4,6-tri-O-benzyl-2-deoxy-2-(2,4-dinitroanilino)-D-glucopyranose as glycosyl donor and a reagent mixture of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine produced β-glycosides with complete selectivity. Starting from benzyl 3,6-di-O-benzyl-2-deoxy-2-(2,4-dinitroanilino)-β-D-glucopyranoside as acceptor, O-α-D-galactopyranosyl-(1→4)-O-β-D-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-D-glucopyranose, the human blood-group P1-antigenic determinant, was synthesized.
Substituent Effect on Organotin Tp* Compounds as the Tp* Reagent for the Preparation of Mono Tp* Complexes of Group 4—6 Metals (Tp* = Tris(3,5-dimethylpyrazol-1-yl)hydroborate)
Authors: Oshiki Toshiyuki , Mashima Kazushi , Kawamura Shin-ichi , Tani Kazuhide , Kitaura Kazuo
Published: September 2002

Organotin compounds [Tp*SnCl3-nBun] (2: n = 1; 3: n = 2) having a Tp* ligand (Tp* = tris(3,5-dimethylpyrazol-1-yl)hydroborate) are useful reagents for introducing a Tp* ligand on Group 4 and 5 metals and chromium. The test reactions of these organotin compounds along with [Tp*SnCl3] (1) with ZrCl4, affording a known complex [Tp*ZrCl3] (4), were examined. The reaction rates were in the order 3 > 2  1. This tendency was understood by the average Sn-N(Tp* ligand) bond distance being longer in the order 3 > 2 > 1 as revealed by the crystallographic studies and the orbital interactions between the Tp* ligand and the SnCl3-nBun fragments estimated by the ab initio calculations for 1—3. On the basis of the above findings, we applied the compound 3 to prepare Tp* complexes of Group 4—6 metals. Reactions of TiCl4 with an equimolar amount of 3 afforded [Tp*TiCl3] (7) in good yields after a simple rinse to remove the resulting tin compound, SnBu2Cl2. [Tp*HfCl3] (8) was prepared in moderate yield by reaction of [HfCl4(THF)2] with 3 under severe conditions. Similarly, the reactions of 3 with a stoichiometric amount of [NbCl4(THF)2] or [NbCl5(OEt)2] and TaCl5 in toluene gave [Tp*NbCl3] (9) and [Tp*TaCl3][TaCl6] (10), respectively. We also applied our synthetic method to prepare Tp* complexes of vanadium, [Tp*VCl2(THF)] (11), [Tp*VCl2(DNAP)] (12) (DMAP = 4-dimethylaminopyridine), and [Tp*VCl2(=NC6H3Me2-2,6)] (13) and those of chromium, [Tp*CrCl2(L)] (14: L = THF; 15: L = H2O; 16: L = DMAP). Some of these Tp* complexes, 4, 8, 12, 13, 15, and 16 were crystallographically characterized to have discrete octahedral geometry containing the facial coordination of the Tp* ligand.
pH-Dependent Luminescence of Ruthenium(II) Polypyridine Complexes
Authors: Jing Bingwen , Wu Tao , Tian Chunhong , Zhang Manhua , Shen Tao
Published: September 2002

The changes in the absorption and emission of three new complexes, [Ru(bpy)2L]2+(1—3), upon a pH variation are considered and the mechanism of the changes is discussed. The luminescence quantum yields of complexes 2 and 3 are strongly influenced by the pH due to intramolecular photoinduced electron transfer, which depends on the pH of the environment.
An Optical Absorption Investigation of Cross-Linking of Gold Colloidal Particles with a Small Dithiol Molecule
Authors: Mayya K Subramanya , Patil Vijaya , Sastry Murali
Published: September 2002

The controlled aggregation of colloidal metal particles is a problem of technological importance in the generation of, for example, quantum wires. In this communication, we present results of an optical absorption spectroscopy investigation of the flocculation of gold colloidal particles capped with a small bifunctional molecule (1,3-propanedithiol). The self-assembly of the dithiol molecule on the gold surface leads to thiol surface functionalization of the colloidal particles, which may thereafter be used to chemically cross-link the gold clusters. Optical absorption measurements performed immediately after capping the gold colloidal particle surface with the dithiol molecules clearly show the growth of a long-wavelength component, indicating that the clusters aggregate in open string-like structures. Increasing the surface coverage of the dithiol molecules on the clusters leads to a greater flocculation rate, but prevents the formation of large gold clusters in direct contact, as indicated by X-ray diffraction measurements of the aggregates. This approach of controlled cross-linking of colloidal particles may have important applications in the generation of metal cluster networks.
Phosphorescence Spectra and Excited States Dynamics of Chlorotoluenes in a Rigid Glass Matrix
Authors: Okutsu Tetsuo , Kounose Naomi , Tsuchiya Jun , Suzuki Tadashi , Ichimura Teijiro , Hiratsuka Hiroshi
Published: September 2002

The excited-state dynamics of chlorobenzene (CB), o-chlorotoluene (o-CT), m-chlorotoluene (m-CT) and p-chlorotoluene (p-CT) have been investigated in 3-methylpentane at 77 K. The phosphorescence spectra of CB and o-CT show a maximum at around 510 nm, while the maxima of m-CT and p-CT are 450 and 420 nm, respectively. These phosphorescence spectra are divided into dual phosphorescence spectra: namely 3ππ* and 3πσ* phosphorescence. The large phosphorescence peak-shifts among the chlorotoluenes are ascribable to a lowering of the low-lying 3ππ* state. The intersystem-crossing (ISC) quantum yields from S1 to 3ππ* (φISCππ*) depend on the samples, whereas φISCπσ* from S1 to 3πσ* are independent of the sample. These results have been explained in terms of the vibrational Franck-Condon overlap between the S1 state and triplet manifolds.
Fluorescence Quenching of Pyrene by Chromium Complexes in Sodium Dodecyl Sulfate Micelles
Authors: Kanthimathi Mookandi , Deepa Kannamvelly , Nair Balachandran Unni , Mandal Asit Baran
Published: September 2002

The aggregation number of sodium dodecylsulfate (SDS) is known to vary with its concentration. Keeping the SDS concentration fixed at 15, 50, and 100 mM, the effect of various Cr(III) quenchers on the aggregation behavior of SDS was studied using pyrene as a probe during static and time-resolved fluorescence measurements. Cr(III) compounds, such as [Cr(en)3]Cl3, [Cr(salprn)(H2O)2]+, [Cr(phen)3](ClO4)3, and [Cr(bpy)3](ClO4)3 were used as quenchers in this investigation. Cetylpyridinium chloride (CPC) was also used as a quencher to keep the Cr(III) complexes fixed at 0.05 and 0.1 mM in order to further confirm the aggregation behavior of SDS micelles in the presence of various ligands. The aggregation numbers of SDS are very low (2 to 32) when the ligand is aliphatic, whereas they are surprisingly high (75—860) in the presence of Schiff-base and aromatic ligand environments. The aliphatic ligand acts as a structure breaker, whereas Schiff-base and aromatic ligands act as structure makers for aggregated SDS micelles, which have been further substantiated by lower and higher counterion association values, respectively, obtained from conductivity experiments.