bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &gt; 2 1. This tendency was understood by the average Sn-N(Tp* ligand) bond distance being longer in the order 3 &gt; 2 &gt; 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Thermodynamics of the Adsolubilization Equilibrium of Rhodamine B by Surfactant-Modified Zeolites
Authors: Hayakawa Katumitu , Miyamoto Yukihiko , Kurawaki Junichi , Kusumoto Yoshifumi , Satake Iwao , Sakai Masashi 
Published: September 2002

Abstract
The adsolubilization of the cationic dye rhodamine B (RB) into the adsorbed layers of dodecyl- (DTAB) and tetradecyltrimethylammonium bromide (TTAB) on high silica mordenites (HSZ-1, HSZ-3) and P-type zeolite (PZ) was examined quantitatively. The adsolubilization constant for the HSZ-1/TTAB system was determined at temperatures from 10 to 40 °C. As the surfactant adsorption increased, the adsolubilization of RB by the zeolite/surfactant complexes was enhanced. Adsolubilization of RB by HSZ-3/surfactant complexes required a critical quantity of adsorbed surfactant, whereas the PZ/TTAB complex needed only a very small quantity of adsorbed TTAB to adsolubilize RB. Both the adsolubilization constant and the maximum capacity were calculated using a Langmuir-type equation, and the enthalpy and entropy changes were determined for the HSZ-1/TTAB mixed system. The difference in the adsolubilization mode of the three zeolite/surfactant complexes is discussed in relation to the aggregation mode of the cationic surfactant.
Hydrogen Bond Formations of 1-Aminoanthracene in the Ground and Excited Electronic States with Protic Solvent Molecules
Authors: Watanabe Satoshi , Kumagai Ken-ichi , Hasegawa Miki , Kobayashi Michio , Okubo Jun , Yoshinaga Tetsutaro , Hiratsuka Hiroshi , Hoshi Toshihiko 
Published: September 2002

Abstract
The absorption and fluorescence spectra of 1-aminoanthracene (AA) in various solvents have been compared with those of 1-dimethylaminoanthracene (DMAA). This comparison has demonstrated that the amino group of AA in the ground electronic state acts as a proton-acceptor to form the A-type hydrogen bond with alcohol, while that of AA in the excited electronic state acts as a proton-donor to form the B-type one. In the cyclohexane-ethanol mixed solvent, the solute-solvent configuration for the fluorescing excited state of AA changes with the ethanol concentration; it keeps the same type of hydrogen bond with ethanol as that (A-type) in the ground electronic state in the lower ethanol concentrations up to 0.2% and exhibits an intramolecular-like rearrangement of the A-type hydrogen bond into the B-type one in the ethanol concentration range of 0.2—1%. This hydrogen bond rearrangement occurs in cooperation with a bulk reorientation of solvent molecules in the range of 1—100%. AA forms the hydrogen-donor-acceptor-type excimer in the nonpolar fluid matrix of MP (a 1 : 1 mixed solvent of methylcyclohexane and isopentane) at low temperature.
Kinetic Stability of Azaborafullerene C58BN as Predicted by the Bond Resonance Energy Model
Authors: Aihara Jun-ichi , Ishida Toshimasa 
Published: September 2002

Abstract
The kinetic stability of a polyatomic molecule is very hard to judge. We utilized the bond resonance energy (BRE) model to estimate the kinetic stability of azaborafullerenes C58BN. In marked contrast to C58B2 and C58N2, all truncated icosahedron-shaped isomers of C58BN were found to lack chemically reactive substructures. On this theoretical basis, these isomers are presumed to be kinetically fairly stable even under harsh reactor conditions. This explains well why C58BN can be detected by mass spectrometry. At least some of the isomers will be isolated in macroscopic amounts in the near future.
Mononuclear Copper(II) Hydroxo Complex: Structural Effect of a 3-Position of Tris(pyrazolyl)borates
Authors: Fujisawa Kiyoshi , Kobayashi Takako , Fujita Kouyu , Kitajima Nobumasa , Moro-oka Yoshihiko , Miyashita Yoshitaro , Yamada Yasunori , Okamoto Ken-ichi 
Published: September 2002

Abstract
New mononuclear nitratocopper(II) complexes ([Cu(NO3){HB(3,5-iPr2pz)3}] (1) and [Cu(NO3){HB(3-tBu-5-iPrpz)3}] (3)) and a novel mononuclear hydroxocopper(II) complex ([Cu(OH){HB(3-tBu-5-iPrpz)3}] (4)) have been prepared. These complexes were characterized by X-ray analysis and IR, UV-vis, and EPR spectroscopies. Except for the dinuclear complex ([{Cu[HB(3,5-iPr2pz)3]}2(μ-OH)2] (2)), the complexes are mononuclear structures having square-pyramidal (1), trigonal-pyramidal (3), and distorted tetrahedral (4) geometry. In comparison with these structures and their physicochemical properties, the structural effects on the alkyl substitutions at the close 3-position in hydrotris(pyrazolyl)borates play an important role in modifying the coordination environment about a copper(II) center and their physicochemical properties.
Monitoring Hydrothermal Reactions on the Millisecond Time Scale Using a Micro-Tube Flow Reactor and Kinetics of ATP Hydrolysis for the RNA World Hypothesis
Authors: Kawamura Kunio 
Published: September 2002

Abstract
A new method for monitoring hydrothermal reactions on the millisecond time scale has been developed using a micro-tube flow reactor. The system was designed based on a high-pressure pump, a sample-loop injector, a narrow-bore size capillary, a cooling bath, back-pressure tubing, and a sampling port. Samples were analyzed using high-performance liquid chromatography. Kinetic analyses of the hydrolyses of adenosine 5′–triphosphate (ATP) and adenosine 5′–monophosphate (AMP) on the millisecond time range at 250—315 °C were demonstrated so as to evaluate the performance of the method. In conclusion, monitoring was successful for the hydrolysis of ATP and AMP in 2—50 ms using fused-silica capillary tubing with 0.015 and 0.025 mm inner diameter (ID). The method enables real-time monitoring of hydrothermal reactions in about 100-times shorter time range than other techniques. This paper proposes apparent rate constants and activation energy for the consecutive hydrolysis of ATP to adenine at high temperatures that were difficult to determine by a conventional batch method. On the basis of the rate constants, kinetics and mechanistic analyses of the step-wise decomposition of ATP were investigated from the viewpoint of the RNA world hypothesis under hydrothermal environments.
The Development of Carbon Nanotubes/RuO2·xH2O Electrodes for Electrochemical Capacitors
Authors: Ma Renzhi , Wei Bingqing , Xu Cailu , Liang Ji , Wu Dehai 
Published: September 2002

Abstract
Carbon nanotubes were refluxed with nitric acid to create acid sites on the surface. After such treatment, amorphous or nano-scale crystalline RuO2·xH2O can be adhered to the surfaces of carbon nanotubes by a simple method. RuO2·xH2O became more amorphous with decreasing the fraction of carbon nanotubes. The capacitance can be enhanced significantly by the adherence. When the weight fraction of RuO2·xH2O in the composite electrodes reached 75%, a specific capacitance of 560 F g-1 was achieved. On the other hand, carbon nanotubes/RuO2·xH2O capacitors exhibit excellent power delivery behavior. So the processing of carbon nanotubes/RuO2·xH2O composite electrodes is a new attempt to fabricate supercapacitors with both high energy and high power density.
Highly Sensitive Energy-Transfer Luminescence of the N,N′-Bis(2-hydroxybenzyl)-ethylenediamine-N,N′-diacetatoterbium(III) Complex in Aqueous Solution
Authors: Saito Shingo , Hoshino Hitoshi , Yotsuyanagi Takao 
Published: September 2002

Abstract
The luminescent properties of a terbium complex with a hexadentate ligand of N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED) having a phenolate functional group as antenna moiety, have been investigated. The complex exhibits a high emission quantum yield (φ = 0.222, ex. 288 nm, em. 546 nm) with a long decay lifetime (τH2O = 1.2 ms) in aqueous solution, which indicates energy-transfer type emission. The number of metal-bound water molecules in the complex was determined to be q = 1.8. The triplet energy level was estimated based on the data of its low-temperature phosphorescence. The calibration graph for Tb(III) was linear over the range from 3 × 10-11 to 1 × 10-8 mol dm-3. A 3σ-blank detection limit of 3 ppt was achieved.
Highly Selective Solvent Extraction of Uranyl Ion Using Super Uranophiles in the Presence of Methyltrioctylammonium Chloride
Authors: Nishida Masashi , Kondo Hirotomo , Sonoda Miwako , Ishii Daido , Yoshida Isao 
Published: September 2002

Abstract
A highly selective solvent extraction of uranyl ion, UO22+, was carried out by using superuranophiles, i.e., hydroxycalix[n]arene-p-sulfonates, Hj1nn- (n = 6, j = 2; n = 8, j = 4), in aqueous solution in the presence of methyltrioctylammonium chloride, MTA+Cl-, in chloroform. In the present extraction, UO22+ in the aqueous phase reacted first selectively and quantitatively with Hj1nn- to form a complex, (UO216H-3)9- or ((UO2)218H-3)11-, respectively. Then, the resultant complexes combined with MTA+ to form hydrophobic and electrically neutral ionic associates, (MTA+)9 (UO216H-3)9- or (MTA+)11 ((UO2)218H-3)11-, and were extracted quantitatively into chloroform. No interference by the coexisting-metal ions was observed. The presence of a large amount of chloride and carbonate ions decreased the extractability of UO22+. The extracted UO22+ was recovered by the stripping method using 2 M sulfuric acid, retaining Hj1nn- in the chloroform phase as a MTA+ associates. The organic phase could be repeatedly used for subsequent extractions.