bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass-Spectrometric Study of Ion-Molecule Reactions of CH5+, C2H5+, and C3H5+ with C8–C18 Alcohols in an Ion Trap
Authors: Tanaka Yuki , Tsuji Masaharu 
Published: September 2002

Abstract
Chemical ionization of n-alkyl alcohols (n-CxH2x+1–OH = M; x=8–18) by the CH5+, C2H5+, and C3H5+ ions has been studied under a reactant-ion selective mode of an ion-trap type of GC/MS. In all reactions, [M – H]+, alkyl CyH2y+1+ (y = 3−x), and alkenyl CyH2y−1+ (y = 4−x) ions were observed. On the basis of observed initial distributions and calculated thermochemical data, it was concluded that the major reactions for the formation of CyH2y+1+ were proton transfer to a hydroxy group in the CH5+ reactions, proton transfer and/or hydroxide-ion abstraction in the C2H5+ reactions, and CzH2zOH−-ion (z &lt; x) abstraction in the C3H5+ reactions, while the major reactions for the formation of CyH2y−1+ ions were proton transfer to alkyl chain in the CH5+ reactions, hydride-ion abstraction in the C2H5+ reactions, and alkanide-ion abstraction in the C3H5+ reactions.
Application of 57Fe Mössbauer Spectroscopy to a Study of the Difference in Interactions between Guest and Host Molecules among (R), (S) and Racemic Isomers for (2-Methylbutyl)-, (2-Phenylpropyl)- and (2-Phenylbutyl)ferrocenes Enclathrated in Deoxycholic Acid
Authors: Nakashima Satoru , Ichikawa Naoki , Okuda Tsutomu 
Published: September 2002

Abstract
57Fe Mössbauer spectroscopy was applied to determine the difference, if any, in the interactions between host and guest molecules among the (R)-, (S)- and racemic isomers for (2-methylbutyl)-, (2-phenylpropyl)- and (2-phenylbutyl)ferrocene-deoxycholic acid (DCA) clathrates. The (S) isomer is included into DCA, while the (R) isomer is not in the case of (2-phenylpropyl)ferrocene. There is no significant difference in the temperature dependences of the 57Fe Mössbauer spectra between the (S) and racemic isomers-DCA for (2-phenylpropyl)ferrocene. For 2-methylbutyl and 2-phenylbutyl derivatives, all isomers form DCA clathrates. 57Fe Mössbauer spectroscopy revealed a difference in the molecular motion of guest molecules in the DCA lattice among them. For the 2-phenylbutyl derivative, the (S) isomer-DCA clathrate has one solvated molecule per guest molecule, a racemic isomer-DCA 0.7 solvated molecule, while the (R) isomer includes no solvated molecule. There was a difference in the powder X-ray diffraction patterns among them. An interesting phase transition was observed in (S)- and racemic (2-phenylbutyl)ferrocenes-DCA, which was accompanied by a desolvation, and then a change of crystal structure to that of (R) isomer-DCA heated up to the same temperature. Such a phase transition was not observed in (R) isomer-DCA. 57Fe Mössbauer spectroscopy revealed that (R) isomer-DCA changes in lattice vibration around 160 K, while (S) isomer-DCA does not.
Acid Dissociation of (5,10,15,20-Tetraphenylporphyrinato)zinc(II) in Cetyltrimethylammonium Chloride Reversed Micellar Solutions
Authors: Nakashima Toshiyuki , Nishida Ikuko , Fujiwara Terufumi 
Published: September 2002

Abstract
Acid dissociation of (5,10,15,20-tetraphenylporphyrinato)zinc(II), Zn(tpp) dispersed in reversed micellar media of cetyltrimethylammonium chloride (CTAC) in chloroform/water and chloroform–cyclohexane/water has been investigated using a stopped-flow spectrophotometer. When Zn(tpp) is mixed with the reversed micellar solution containing a concentrated acid, spectral data reveal that its dissociation, following immediate formation of the chloro-coordinated complex Zn(tpp)Cl− in the interfacial phase of the reverse micelle, occurs rapidly to produce the diacid salt of 5,10,15,20-tetraphenylporphyrin, H4(tpp)2+(Cl−)2. The dissociation rate increases with an increase of acid concentration in the reversed micellar aqueous pool. At higher acid concentrations (&gt; 3 mol dm−3 in the pool), the rate constant and the fraction of Zn(tpp)Cl− formed increase in the order: HNO3 &lt; HCl ≤ H2SO4 &lt; HBr &lt; HClO4, and decrease with an increase in volume fraction of cyclohexane in the reversed micellar bulk solvent. These observations may be explained by assuming selective distribution of the Cl− ion to the interfacial surfactant and bulk organic phases, which is affected by affinities of the acid anions for the surfactant head group and by the Cl− solvation.
Synthesis of 4-Alkoxy-2-substituted-benzenethiols and Their Application to Thermotropic Liquid Crystals
Authors: Okamoto Hiroaki , Wu Jianwei , Morita Yuki , Takenaka Shunsuke 
Published: September 2002

Abstract
A new synthetic method of 4-alkoxy-2-X-benzenethiols (X = H, halogens, CH3) has been established. In order to confirm the validity as a component of liquid crystal materials, some derivatives of S-(4-alkoxy-2-X-phenyl) 4-R-thiobenzoates (R = CnH2n+1O, CN, NO2, X = halogens, CH3) were prepared. Most of the thioesters exhibit a nematic phase, while the lateral substituents (X) tend to reduce the mesophase thermal stability as well as the melting point. The effect of lateral substituents on the mesomorphic properties is discussed.
Polymer Complexes of Rhodium(II) Trifluoroacetamidate with Pyrazine, 4,4′-Bipyridine, and 1,4-Diazabicyclo[2.2.2]octane
Authors: Handa Makoto , Muraki Yasuhiro , Mikuriya Masahiro , Azuma Hiroshi , Kasuga Kuninobu 
Published: September 2002

Abstract
Polymer complexes of rhodium(II) trifluoroacetamidate dimers bridged by bidentate ligands [{Rh2(HNOCCF3)4(L)}n], L = pyrazine (pyz), 4,4′-bipyridine (4,4′-bpy), and 1,4-diazabicyclo[2.2.2]octane (dabco), have been prepared and characterized.
O-Alkylation of Dihydroxo(tetraarylporphyrinato)phosphorus(V) and Antimony(V) Complexes with Alkyl Halides
Authors: Andou Yoshito , Ishikawa Kazuki , Shima Kensuke , Shiragami Tsutomu , Yasuda Masahide , Inoue Haruo 
Published: September 2002

Abstract
The O-alkylation of dihydroxo(tetraarylporphyrinato)phosphorus(V) complexes with several kinds of alkyl bromide in MeCN in the presence of K2CO3 and 18-crown-6 ether produced dialkoxo(tetraarylporphyrinato)phosphorus(V) complexes in-moderate-good yields. Similar O-alkylation was applied to dihydroxo(tetraarylporphyrinato)antimony(V) complexes. The O-alkylation proceeded by the occurrence of an SN2 attack of the alkoxide anion of the complexes at the carbon substituted with halides.
Efficient Reductive Deoximation by Tungsten(VI) Chloride (WCl6) or Molybdenum(V) Chloride (MoCl5) in the Presence of Zn Powder in CH3CN
Authors: Firouzabadi Habib , Jamalian Arezu , Karimi Babak 
Published: September 2002

Abstract
Tungsten(VI) chloride (WCl6) or molybdenum(V) chloride (MoCl5) in the presence of zinc powder in CH3CN provides an efficient and facile procedure for the deprotection of oximes to their corresponding aldehydes and ketones in high yields.
Synthesis and Complexing Ability of a C-Pivot Type of Double-Armed 15-Crown-5 Ethers toward Alkali Metal Cations
Authors: Nakatsuji Yohji , Muraoka Masahiro , Kajiya Hiroyuki , Zhang Wanbin , Kida Toshiyuki , Ikeda Isao 
Published: September 2002

Abstract
Three kinds of positional isomers of the C-pivot type of double-armed 15-crown-5 ethers (cis and trans isomers for each positional isomer) bearing two 8-quinolyloxy moieties as part of the electron-donating sidearms were prepared, and their complexation properties were evaluated by measuring the stability constant in THF, the extractability, and passive transport velocity. Cis isomers were found to be much better host compounds toward alkali metal cations than trans isomers possibly because of the potential cooperative coordination of two electron-donating sidearms. All trans isomers showed almost the same stability constants toward Na+ and K+. On the other hand, in the case of cis isomers, the difference in the position of the two sidearms on the crown ring was found to remarkably affect the complexation properties toward alkali metal cations.
Dimethyl 3-Hydroxy-4-hydroxymethylcyclopentane-1,1-dicarboxylate: an Optically Pure Precursor of Spiro Carbocylic Deoxyribonucleosides
Authors: Renard Annabelle , Lhomme Jean , Kotera Mitsuharu 
Published: September 2002

Abstract
A concise, two-step preparation of dimethyl 3-hydroxy-4-hydroxymethylcyclopentane-1,1-dicarboxylate, an optically pure precursor of spiro carbocyclic nucleosides is described.
The Conformation of 2-Phenylpropionaldehyde and Alkyl 1-Phenylethyl Ketones as Evidenced by Ab Initio Calculations. Relevance of the CH/π and CH/O Interactions in Stereochemistry
Authors: Takahashi Osamu , Yasunaga Kenji , Gondoh Yoshinobu , Kohno Yuji , Saito Ko , Nishio Motohiro 
Published: September 2002

Abstract
Ab initio MO calculations were carried out for the conformation of 2-phenylpropionaldehyde 1 and related ketones CH3CH(C6H5)–CO–R (R = CH3 2, C2H5 3, i-C3H7 4, and t-C4H9 5) at the MP2/6-311G(d,p)//MP2/6-31G(d) level. The conformation whereby the alkyl group R is synclinal to the phenyl group (rotamer a, C6H5–C–CO–R torsion angle φ 64–93°) has been found to be the most stable. The second most favorable one has been shown to have R flanked by the benzylic methyl group and C6H5 (rotamer b: φ 282–297°). The difference in the enthalpy between a and b has been calculated to be 1.58, 2.16, 2.19, 2.08, and 4.89 kcal mol−1, respectively, for 1, 2, 3, 4, and 5. The C6H5/R antiperiplanar conformation (rotamer c) has been shown to be the least stable for 1 (φ 171°) and is not at an energy minimum for 2–5. In rotamers a and b, short interatomic distances have been shown between one of the alkyl hydrogens and the phenyl group. In rotamer a, a short distance has been calculated between one of the hydrogens of the benzylic methyl group and the carbonyl oxygen. The ab initio results are compatible with those obtained by NMR measurements. Contributions of the CH/π and CH/O interactions to the conformational equilibria have been invoked to accommodate the above results. Instability of rotamer c may be due to the unfavorable electrostatic interaction of the C=O dipole vs the quadrupole of the phenyl group. Conformational energies of methyl formate 6, N-methylformamide 7, and propionaldehyde 8 were also calculated to examine the effect of the CH/O interaction in carbonyl compounds. The results are consistent with the notion that the CH/O interaction is important in stabilizing the CH3/O eclipsed conformation.
Theoretical Study of Dimethyl Maleate and Its Complexes with Lewis Acids: Effect of the Interaction between Two Methoxycarbonyl Groups on Equilibrium Structures
Authors: Akakura Matsujiro , Koga Nobuaki 
Published: September 2002

Abstract
The five equilibrium structures of dimethyl maleate were theoretically determined using the RHF and B3LYP methods. In all of the structures, one of the O=C–O planes is nearly perpendicular to, and the other is coplanar with, the C–C=C–C plane. It is well known that maleic acid diester has peculiar reactivity compared with other conjugated esters, which can be ascribed to the characteristics of the conformations. Calculations of complexes of dimethyl maleate and Lewis acids were performed, and the binding energies for the complexes were analyzed by decomposing them into the deformation energy and the interaction energy. For a comparison, the conformational properties of methyl acrylate and its Lewis acid complexes were also investigated.
Synthesis, Structures, and Properties of Two Isomeric Naphthodithiophenes and Their Methyl, Methylthio, and 2-Thienyl Derivatives; Application to Conductive Charge-Transfer Complexes and Low-Bandgap Polymers
Authors: Takimiya Kazuo , Kato Ken-ichi , Aso Yoshio , Ogura Fumio , Otsubo Tetsuo 
Published: September 2002

Abstract
Two isomeric naphthodithiophenes (syn-NDT and anti-NDT), isoelectronic with pyrene, as well as their dimethyl, bis(methylthio), and di(2-thienyl) derivatives have been successfully synthesized as novel peri-fused heteroaromatics. Among them, the parent syn-NDT and the di(2-thienyl) derivative of anti-NDT were examined by X-ray crystallographic analyses, revealing that the molecular structures comprise fairly planar, but considerably strained skeletal rings, and their crystal structures are characterized by a herringbone arrangement of uniform stacking columns. The UV/vis spectra of these heteroaromatics show considerable red-shifts of the π–π* transitions as compared to that of pyrene, making them chromogens ranging from yellow to purple. Cyclic voltammetry indicates that they have much stronger electron donating abilities than pyrene. Consequently, all of them, except for the methyl derivatives, can form highly conductive molecular complexes with iodine and DDQ. In addition, the electrochemical oxidation of the parent naphthodithiophenes and the di(2-thienyl) derivatives leads to the formation of conductive polymers, which show low HOMO–LUMO bandgaps upon undoping. In particular, both polymers of syn-NDT and anti-NDT have very low bandgaps of ca. 0.8 eV (77 kJ mol−1).
Addition Reactions of Polyhalides to Ketene Silyl Acetals and Silyl Enol Ethers under Thermal or Photo-Irradiated Conditions without a Promoter
Authors: Mitani Michiharu , Sakata Hideo , Tabei Hisayuki 
Published: September 2002

Abstract
The reactions of ketene silyl acetals and silyl enol ethers in a CCl4 solution containing no promoter under ambient temperature, reflux, or photo-irradiation conditions afforded products via the addition of a trichloromethyl group to those silyl substrates. Polyhalides other than CCl4 were subjected to photoreactions in a hexane solution, resulting in the formation of carbonyl derivatives based on the addition of polyhalogenated alkyl groups.
Oxidative Dehydrogenation of Propane on Magnesium Vanadates in the Presence of Tetrachloromethane
Authors: Sugiyama Shigeru , Iizuka Yutaka , Konishi Yukinori , Hayashi Hiromu 
Published: September 2002

Abstract
The oxidative dehydrogenation of propane to propene on active catalysts such as magnesium vanadates (MgV2O6, Mg2V2O7, and Mg3V2O8) has been investigated in the presence and absence of tetrachloromethane (TCM) at 723 K. The introduction of a small amount of TCM into the feedstream did not influence the selectivity to propene while the conversion of propane was improved on those catalysts. The conversion was enhanced by approximately twice on Mg2V2O7 upon addition of TCM. It has been shown that the effects of TCM on lattice oxygen in those catalysts mainly control the enhancement. The formation of an excess amount of the chlorinated species on the surface of the catalysts resulted in a decrease of the conversion.
Density Functional Studies on Kinetic Reactivity of “Higher Order” Lipshutz Cuprate in Addition Reaction to Acetylene
Authors: Yamanaka Masahiro , Mori Seiji , Nakamura Eiichi 
Published: September 2002

Abstract
There is a frequently used organocuprate species that was introduced by Lipshutz and possesses a molecular structure written as CuLi2R2(CN). This species was previously called “higher order cuprate”, but is now considered to exist as an equilibrating mixture of various isomers of R2CuLi·LiCN and R(CN)CuLi·LiR, among which R2Cu−·Li2CN+ is known to be dominant in solution. The present studies on the kinetic reactivity of these species in the addition reaction to acetylene suggest that the minor species R(CN)CuLi·LiR may be more reactive than the major species, thereby making it equally possible that addition reaction products may arise through both the major and the minor reactive species. The reason for the high reactivity of the minor species has been ascribed to the anisotropic and multi-coordination capability of the cyanide ligand to metals; such capability is not available for a halide or alkyl anion ligand.
Iminomalonate as a Convenient Electrophilic Amination Reagent for Grignard Reagents
Authors: Niwa Yasuki , Takayama Kazuki , Shimizu Makoto 
Published: September 2002

Abstract
Diethyl 2-[N-(p-methoxyphenyl)imino]malonate underwent amination reactions with alkyl Grignard reagents to give N-aklylation products in good yields. The obtained N-alkylation products were readily converted into N-alkyl-p-anisidines by the oxidative removal of the malonate moiety. The p-methoxyphenyl group was subsequently deprotected to give primary amines.
A Novel Synthetic Route to Redox-Active Oligo(thio-1,4-phenylene) Derivatives via a Michael-Type Addition
Authors: Yamamoto Kimihisa , Higuchi Masayoshi , Nishiumi Toyohiko , Takai Hirokazu 
Published: September 2002

Abstract
N,N′-Diphenyl-1,4-benzoquinone diimine (PBI), which is the minimum redox-active unit of polyaniline, was reduced to N,N′-diphenyl-1,4-phenylenediamine (PDA) derivatives through Michael-type additions of some nucleophiles. The addition of thiophenol to PBI proceeded very rapidly. The polyaddition of PBI-endcapped monomers (P-2PBI, B-2PBI, and TB-2PBI) with thiobisbenzenethiol (TB) produced the novel thermostable oligo(thio-1,4-phenylene)s (OTP) having PDA units as a redox-active site (OTP-P-PDA, OTP-B-PDA, and OTP-PDA). This polymerization proceeded at room temperature without catalysts. OTP-P-PDA, one of the oligomers obtained, was found to have a moderate molecular weight (Mw 8400) and to possess good thermostability (Td10% 400 °C). The polymerization based on Michael-type additions was also confirmed by NMR measurements. The oligomers obtained behaved as good electro-responsive materials. The redox process was determined by the slope of the Nernst plot that involved two electrons and two protons per PDA unit.
Oxygenative Perfluoroalkylation of Olefinic Compounds Using Perfluoroalkyl Iodide in the Presence of Oxygen
Authors: Yoshida Masato , Ohkoshi Masanori , Muraoka Tsunehiro , Matsuyama Haruo , Iyoda Masahiko 
Published: September 2002

Abstract
Reactions of perfluoroalkyl iodides with styrene and its derivatives were investigated under radical conditions in the presence of oxygen. The photochemical reaction of styrene with CF3(CF2)5I in the presence of tributyltin hydride or tris(trimethylsilyl)silane under an oxygen atmosphere afforded the corresponding perfluoroalkylated alcohols in moderate yields together with CF3(CF2)5H. However, the photochemical reactions of styrene and its derivatives with CF3(CF2)nI (n = 3, 5) in the presence of hexabutylditin under oxygen produced the perfluoroalkylated alcohols in good yields. Furthermore, the reactions of styrenes with CF3(CF2)nI (n = 3, 5, 9) and Na2S2O4 in the presence of a base under air formed the same alcohols in good yields. The alcohols were found to provide a novel type of α-fluoroalkylated styrenes by acidic dehydration. Perfluoroalkylated α,β-unsaturated ketones were synthesized by oxygenative perfluoroalkylations of α-chlorostyrene and its derivatives using CF3(CF2)nI (n = 3, 5) under radical reaction conditions. The ketones were found to be good synthetic building blocks for perfluoroalkylated heterocycles, such as pyrazoles, dihydrodiazepines, pyrimidines, and isoxazoles.
Effect of Alkaline Earth Metal Ions on the Phosphodiester Hydrolysis of RNA
Authors: Yashiro Morio , Higuchi Maiko , Washizu Yusuke , Komiyama Makoto 
Published: September 2002

Abstract
Hydrolyses of di- and triribonucleotides assisted by alkaline earth metal ions were investigated at pH 7.3 and 50 °C. Mg2+ was the most effective for the phosphodiester hydrolysis, and the rate exibited first-order dependence on the concentration of Mg2+ in a range of 0.1–1.0 mol dm−3.
Calix[4]arenes Bearing Four Redox-Active π-Conjugated Pendant Groups for a Dimensionally Oriented Redox System
Authors: Saito Kaori , Hirao Toshikazu 
Published: September 2002

Abstract
A p-t-butylcalix[4]arene bearing four redox-active phenylenediamine pendant groups on the lower rim was synthesized and characterized spectroscopically and electrochemically. The interconversion of the oxidation states of the pendant groups was demonstrated both chemically and electrochemically.
Symmetric, Asymmetric Charge Transfer Process of Substituted Stilbene or Its Analogues and the One-Photon-/Two-Photons-Excited Emission
Authors: Wang Xiaomei , Zhou Yufang , Zhou Guangyong , Jiang Wanli , Jiang Minhua 
Published: September 2002

Abstract
The luminescence behaviors of a series of symmetrically and asymmetrically substituted stilbene or its analogues on one-photon excitation (OPE) and two-photons excitation (TPE) have been investigated and compared. To understand the influence of intramolecular charge transfer upon the fluorescence properties, steady-state and time-resolved fluorescence spectra on one-photon-/two-photons-excitation, the solvent effect and the linear absorption spectra as well as the relative fluorescence quantum yields were examined. Based on the quantum chemical calculations of the charge density and the twisted intramolecular charge transfer (TICT) model, the luminescence properties have been interpreted. The results obtained have shown that the OPE and the TPE fluorescence behaviors are both strongly influenced by the intramolecular charge transfer process and by the planarity of effective fluorophore under the excited state. On the other hand, for a given dye, its luminescence behaviors on one-photon- and two-photons-excitation are very much alike, which means that the knowledge of two-photon fluorescence properties can be obtained by understanding the one-photon fluorescence behaviors.
Corrosion of Iron Coexisting with Molten Sodium Hydroxide and Sodium Peroxide
Authors: Ota Ken-ichiro , Mitsushima Shigenori , Hattori Naotaka , Kamiya Nobuyuki 
Published: September 2002

Abstract
Liquid sodium is used in new energy conversion systems such as fast breeder reactors and sodium-sulfur batteries. Liquid sodium forms high-temperature molten salts once it is exposed to air by reactions with oxygen or moisture. These molten salts might cause the severe corrosion of metals. In this study, the high-temperature corrosion of iron was studied in the presence of sodium salt using thermogravimetry in an air-simulated atmosphere. The corrosion reaction with coexisting NaOH obeyed a parabolic rate law. On the other hand, severe corrosion occurred with coexisting Na2O2. The corrosion reaction changed from a parabolic rate law to a linear rate law as the amount of melt increased, because the dissolution on the corrosion of the corrosion layer would increase with the amount of melt. Since the oxidation ability of Na2O2 is not as high as that of O2, dissolution of an oxide scale on iron would be the main reason for severe corrosion.
Formation of the Copper(II) Nitrosyl Cation, [CuNO]2+, in Strong Acids
Authors: Tsumori Nobuko , Xu Qiang 
Published: September 2002

Abstract
In strong acids, the reaction of Cu0, CuI or CuII compounds with atmospheric NO at room temperature results in the formation of the copper(II) nitrosyl cation, [CuNO]2+, during which the oxidation of Cu0 to CuII is accompanied by the formation of N2 and N2O, whereas the oxidation of CuI to CuII results in the formation of N2O without a significant amount of N2.
Design and Application of Ion-Channel Sensors Based on Biological and Artificial Receptors
Authors: Sugawara Masao , Hirano Ayumi , Bühlmann Philippe , Umezawa Yoshio 
Published: September 2002

Abstract
This paper reviews approaches to chemical sensing with receptor-modified electrodes that mimic the function of natural membranes containing biological and synthetic receptor channels. We highlight different types of ion-channel sensors, focusing on the working principle and the fundamental aspects, such as sensitivity and selectivity. It is demonstrated that biological receptors such as glutamate receptor ion channels and gramicidin, embedded in bilayer lipid membranes, have the potential as sensing elements for ion channel sensors with excellent sensitivity and selectivity. In addition, higher selectivities by improved receptor desigh, taking into account the particular advantages of interfacial analyte recognition at LB membranes and SAMs, are also shown with ion-channel sensors for antibodies, protamine, heparin, abasic DNA sites, and oligonucleotides.