bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Capacity and Glass Transition of Crystalline Pentachloronitrobenzene
Authors: Tan Zhi-Cheng , Nakazawa Yasuhiro , Saito Kazuya , Sorai Michio
Published: September 2002

The heat capacity of crystalline pentachloronitrobenzene was measured by adiabatic calorimetry between 6 and 303 K. A large step in heat capacity was detected around 185 K; this is attributed to a glass transition corresponding to freezing of structural disorder. The observed glass transition temperature was similar to that estimated from the temperature dependence of the dielectric relaxation due to molecular reorientation around the “sixfold axis” of the benzene core.
Phase Behavior of Benzyltributylphosphonium Salts in Aromatic Hydrocarbons or Aqueous Solutions
Authors: Ohtani Noritaka , Tsuchimoto Daisuke
Published: September 2002

The solubility of benzyltributylphosphonium salt (BTBPX: X = Cl, Br, or I) in aromatic hydrocarbons was examined as a function of the temperature. The solubility curve had specific features, which were characterized by critical values corresponding to the Krafft point and critical micelle concentration. A slight difference in the oil structure exerted a significant effect on the solubility behavior. The Krafft boundary as well as a liquid–liquid immiscibility gap, on the other hand, featured the solubility behavior of BTBPX in an aqueous solution. The shape of the gap was assumed to be a closed loop and the region of the gap was sharply dependent on the concentration of the added metal halide (MX). The phase behavior of the three- or four-component systems, composed of BTBPX, benzene, water, and MX, has been examined in detail. According to their constituent, composition, and temperature, the system afforded a single- to four-phase state form. There were at least three kinds of liquid phases: a BTBPX-rich phase (M), an aqueous solution phase (W), and an oil solution phase (O). When these three liquid phases coexist, the system affords an O–M–W three-liquid-phase equilibrium state. The three-liquid phase may be converted to O–M or M–W two-liquid-phase, depending on the temperature and MX concentration in the W phase. In the presence of excess MX (S), BTBPCl gave an O–M–W–S four-phase state, while BTBPBr or BTBPI never formed a four-phase state. The phase behavior of the four-component systems is discussed based on phase diagrams of fewer component systems.
Platinum-Catalyzed Bis-Germylation of Alkynes with Organodigermanes and Cyclic Oligogermanes
Authors: Mochida Kunio , Wada Tohru , Suzuki Kaoru , Hatanaka Wakako , Nishiyama Yuriko , Nanjo Masato , Sekine Akiko , Ohashi Yuji , Sakamoto Masato , Yamamoto Akio
Published: September 2002

Hexamethyldigermane, Me3GeGeMe3, reacted with various alkynes in the presence of platinum complexes at 120 °C to afford Z–1,2-bis(germyl)ethenes in moderate to good yields. Terminal alkynes exhibit higher reactivities than internal ones. [Pt(acac)2] and [Pt(dba)2] serve as efficient catalysts, while [Pt(PPh3)4], [PtCl2(PPh3)2], and [Pt(dba)2]-phosphite were found to be inactive. Four- and six-membered cyclic oligogermanes, such as dodecamethylcyclohexagermane, (Me2Ge)6, reacted with alkynes in the presence of platinum catalysts to yield 1,4-digermacyclohexa-2,5-dienes in ca. 30% yield. The reactions of phenylacetylene with 1,2-digermacyclohexa-3,5-dienes afforded the corresponding 1,4-digermacycloocta-2,5,7-trienes in 93% yield. Bis(germyl)platinum complexes having various tertiary phosphine ligands have been prepared as models of a key intermediate in the above mentioned catalytic bis-germylation of alkynes, and their structures have been established by spectroscopic methods and X-ray crystallography. Bis(germyl)platinum complexes reacted with phenylacetylene to give the corresponding insertion products, germyl(germylvinyl)platinum species, whose structures have been determined by spectroscopic and X-ray analysis. Germyl(germylvinyl)platinum complexes were found to liberate a bis-germylation product of the alkyne upon heating. The result supports a mechanism involving the oxidative addition of a digermane to a Pt(0) complex, the insertion of an alkyne into one of the two Pt-Ge bonds to give a germyl(germylvinyl)platinum species, and the reductive elimination of the bis-germylation product of the alkyne. Evidence suggesting the extrusion of a germylene unit from the bis-germylplatinum species has been obtained, accounting for the generation courses of other by-products.
Kinetics and Mechanism for the Oxidation of CS2 and COS at High Temperature
Authors: Murakami Yoshinori , Kosugi Masami , Susa Kenji , Kobayashi Takaomi , Fujii Nobuyuki
Published: September 2002

The rate constants for the thermal decompositions of CS2 and COS were investigated by measuring the time profiles of S atom using atomic resonance absorption spectroscopy behind the incident shock of CS2/Ar or COS/Ar mixtures, and the rate constants were determined to be k = (4.0 ± 0.1) × 1014 exp (−295 ± 20 kJ/RT) cm3 mol−1 s−1, T: 2200–2900 K and k = (1.4 ± 0.3) × 1015 exp (−290 ± 25 kJ/RT) cm3 mol−1 s−1, T: 2000–3200 K, respectively. The oxidation mechanism of COS was also investigated behind the incident shock of COS/O2/Ar mixtures and the rate constant for the reaction S + O2 → SO + O was obtained to be k = (9.5 ± 0.7) × 1013 exp (−41 ± 28 kJ/RT) cm3 mol−1 s−1, T: 2200–2900 K. From a numerical analysis for time profiles of S atom behind the incident shock of CS2/O2/Ar mixtures, the rate constant for the reaction O + CS → CO + S was expressed as k = (3.2 ± 1.0) × 1013 cm3 mol−1 s−1, T: 2100–3000 K. Similarly, the rate constant for the reaction CS + O2 → COS + O was also determined to be k = (6.1 ± 0.6) × 1012 exp (−51.0 ± 68 kJ/RT) cm3 mol−1 s−1, T: 2000–2900 K by measuring the time profiles of O atom behind the reflected shock of CS2/O2/Ar mixtures. Ab initio calculations were carried out and the reaction pathways of CS + O2 → COS + O and CS + O2 → CO + SO were also investigated.
Theoretical Study of a Conformational Change Occurring with Lithium Complexation to a Tetra-aza Macrocycle Containing 2,2′-Bipyridines
Authors: Furuhama Ayako , Takano Keiko , Ogawa Shojiro , Tsuchiya Shinji
Published: September 2002

Ab initio Hartree–Fock theory was used to determine the structures of model molecules of a dibutyl dicyano tetra-aza macrocycle (1) containing 2,2′-bipyridines and their lithium complexes. Energy profiles for the conformational inversion, which is closely related to the complexation process of a lithium cation, were also studied. Macrocycles having cyano groups on the bridge methylene carbons were found to be good macrocyclic models related to the macrocycle (1). The energy profiles of stationary points and the vibrational frequencies of macrocycles and their lithium complexes reveal that conformational inversion in the lithium complexes is plausible after lithium complexation. The difference in the vibrational frequencies corresponding to the movement of the lithium cation suggests that C2v-like skeletons in the macrocyclic moiety have a stronger interaction between the lithium cation and coordinating nitrogens than the C2h structure.
Temperature- and Pressure-Induced Phase Transitions in p-Difluorobenzene Crystals
Authors: Towata Yuji , Suzuki Yoshio , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: September 2002

The temperature and pressure effects on the Raman-active inter- and intramolecular vibrations of [1H4]- and [2H4]p-difluorobenzene crystals were studied. The observed spectral structure, and the temperature and pressure dependences on the vibrational frequencies of the inter- and intramolecular vibrations indicate the following facts: (1) The temperature-induced phase transitions take place at about 235 and 195 K under 1 atm in [1H4]- and [2H4]p-difluorobenzene crystals. (2) The pressure-induced phase transition takes place under about 2.7 and 2.8 GPa at 298 K in [1H4]- and [2H4]p-difluorobenzene crystals, respectively. (3) A weak C–H···F–C intermolecular interaction exists in crystals.
The Effect of Surfactants on Equilibria in Aluminium(III) Ion + Ofloxacin Solution and Adsorption of Ofloxacin on Aluminium-Oxide
Authors: Djurdjevic Predrag , Jelikic-Stankov Milena , Lazarevic Ivan
Published: September 2002

The protonation and complex formation equilibria in aluminium(III) + ofloxacin (Hoflo) solutions in the presence of either cetyltrimethylammonium bromide (CTAB, 5.0 mmol L−1), cetylpyridinium chloride (CPCL, 2.0 mmol L−1) or polyethylene glycol tert-octylphenyl ether (triton X-100, 1.0 mmol L−1) have been studied by glass-electrode potentiometric measurements in a 0.1 mol L−1 LiCl ionic medium at 298 K. In the concentration range 0.4 ≤ CAl ≤ 1.0 mmol L−1, with a ligand to metal ratio of 1 : 1 to 5 : 1, and 3.5 ≤ −log h ≤ 7.0, a non-linear least squares treatment of the data indicate that in all studied systems the complex Al(oflo)2+ forms as the dominating one. Its overall stability constant (log β) is in the range 10.37–11.90 (depending on the type of surfactant), which is about 1 log unit higher than in the absence of surfactants. The formation of bis(ofloxacinato) and mixed protonated or hydrolytic complexes is largely suppressed in the presence of surfactants. The adsorption of ofloxacin on aluminium oxide was studied in neutral, acidic (0.1 mol L−1 HCl) and alkaline (0.001 mol L−1 NaOH) media; in absence and presence of ionic surfactants; sodium dodecylsulfate (SDS, 10 mmol L−1); or CTAB (5.0 mmol L−1). The adsorption is of the Freundlich type and is higher in neutral media with no presence of surfactants, while in an acidic medium it is significantly enhanced in the presence of SDS. Both surfactants increase the adsorption in an alkaline medium. The observed phenomena were explained based on the hydrophilic/lipophilic properties of the surfactants.
Flotation-Separation of Chromium(VI) and Chromium(III) from Water and Leathers Tanning Waste Using Active Charcoal and Oleic Acid Surfactant
Authors: Ghazy Shaban El-Sayed , Moustafa Gamal Abdel-Hafeez
Published: September 2002

An experimental procedure is presented for the separation of Cr(VI) and Cr(III) from aqueous solutions, natural water and leather tanning waste using powdered active charcoal (PACh) as an adsorbent and oleic acid (HOL) as a surfactant. Several parameters (namely: the initial concentrations of surfactant and active charcoal, pH value, ionic strength, shaking time, temperature and foreign ions) that influence the separation process were studied. Good results were obtained, according to which more than 98% of Cr(VI) at pH 2.0 or Cr(III) at pH 7.5 were removed. The selective separation of Cr(VI) from Cr(III) was also examined, since the system Cr(III)/Cr(VI) is toxic, and occurs in industrial effluents and some surface waters. The procedure may find analytical applications for speciation studies. Moreover, a flotation mechanism is suggested.
Reversed-Phase High-Performance Liquid-Chromatographic Determination Systems Specific to Ultratrace Hard Metal Ions with Tridentate Schiff Bases and Pyridylhydrazones
Authors: Hoshino Hitoshi , Saitoh Yuzuru , Nakano Koji , Takahashi Toru , Yotsuyanagi Takao
Published: September 2002

Two Schiff-base ligands derived from salicylaldehyde and two 2-pyridylhydrazones were examined for the ultratrace determination of metal ions by reversed-phase high-performance liquid chromatography (HPLC). Although these ligands have been thought to be rather unattractive in inorganic analysis, their renewal in the HPLC methodology was demonstrated in this work. In these ligand systems, certain hard metal ions such as Al(III), Ga(III), V(V), Fe(III), and Co(III) ions, were effectively separated on octadecyl- or cyanopropyl-bonded silica packing materials. A highly sensitive fluorimetric detection of Al(III) ion was achievable with N-salicylidene-2-hydroxyaniline having an O,N,O donor set; although the contamination problem actually limited the detection capability, the calculated detection limit for Al(III) ion was down to 0.1 nM (3 ppt) on a 3 σ blank basis. The chromatography of chelates with 4-N,N-diethylaminosalicylaldehyde-2-pyridylhydrazone seems to be attractive for actual analysis; Al(III), Ga(III), V(V), Fe(III), and Co(III) ions at the sub-ppb to ppb levels have been photometrically detected with a relative standard deviation of less than 5%. The fluorimetric detection using 4-hydroxysalicylaldehyde-2-pyridylhydrazone was very effective to access trace levels of Al and Ga ions, giving detection limits of 3.0 nM and 1.3 nM, respectively (M = mol dm−3).
Thermal Stability of Pyridine Base Complexes of Cadmium Chloride
Authors: Sawada Kiyoshi , Satoh Keiichi , Shirakura Yasuhiro , Masuda Yoshio
Published: September 2002

The heat of decomposition of a series of crystalline pyridine base (Rpy) complexes of cadmium chloride was determined by means of differential scanning calorimetry, where the complexes were bis(pyridine base) complexes, CdCl2·2Rpy (Rpy = pyridine and 4-methyl-, 3-methyl-, 4-acetyl- and 4-cyanopyridine) and mono(pyridine base) complexes, CdCl2·Rpy (Rpy = 2-methyl- and 2-ethylpyridine). The heats of dissolution of the pyridine base complexes, cadmium chloride CdCl2, and pyridine bases in a non-polar aprotic solvent, 1,2-dichloroethane, containing tetrabutylammonium chloride were determined by a calorimetry. The stability of the crystalline complexes is discussed in connection with the heat of dissolution and reaction of the complexes in solution. The stability of the complexes is explained by various interactions, such as the basicity and steric hindrance of the pyridine bases and the intermolecular interaction between the complexes.
Synthesis and Structure of Ln(W5O18)-Capped Mixed-Ligand Polyoxotungstolanthanoate [Ln(W5O18){Ln(H2O)2(SbW9O33)(W5O18)}]15−(Ln = Sm and Er)
Authors: Naruke Haruo , Yamase Toshihiro
Published: September 2002

Polyoxotungstolanthanoate, [Ln2(H2O)2(SbW9O33)(W5O18)2]15− (Ln = Sm and Er), possessing Ln3+, trivacant α-B-Keggin [SbW9O33]9−, and monovacant Lindqvist [W5O18]6− groups with a ratio of 2 : 1 : 2, was prepared and structurally characterized. In the anion the α-B-[SbW9O33]9− group coordinates to two [Ln(W5O18)]3− moieties through terminal- and bridging-O atoms at vacant and non-vacant sites, respectively. A 183W-NMR spectrum for Y3+-analog in aqueous solution was consistent with this anion structure.
Crystal Structures and Spectroscopic Characterization of Linear-Type S-Bridged Trinuclear Complexes ΔΛ- and ΔΔ/ΛΛ-[ReIII{RhIII(aet)3}2]3+ (aet = 2-Aminoethanethiolate)
Authors: Miyashita Yoshitaro , Mahboob Nagina , Tsuboi Satoko , Yamada Yasunori , Fujisawa Kiyoshi , Okamoto Ken-ichi
Published: September 2002

The reduction of an acidic mixture of fac(S)-[RhIII(aet)3] (aet = 2-aminoethanethiolate) and NH4ReVIIO4 gave the first linear-type S-bridged trinuclear complexes containing a d4 metal ion, [ReIII{RhIII(aet)3}2]3+. The meso (1a) and racemic (1b) isomers were selectively isolated by using HCl and HBr solutions, respectively, although both isomers were formed in each case. The crystal structures of 1aCl(ReO4)2·4H2O and 1b(ClO4)3 were determined by X-ray crystallography. Both complex cations consist of two terminal fac(S)-[RhIII(aet)3] units and a central rhenium atom, which is situated in an octahedral environment with the ReIIIS6 chromophore. 1b was optically resolved by a column chromatographic method and characterized by CD spectroscopy. 1a and 1b were fairly stable in water, even under aerobic conditions, unlike in the case of previously reported [MoIII{RhIII(aet)3}2]3+. The Re(III) ion, which is incorporated into the S-bridged polynuclear structure, indicated a lower magnetic moment (1.32 μB for 1b) at room temperature than the spin-only value for the d4 electronic configuration. The 1H and 13C NMR spectra of 1a and 1b showed paramagnetic shifts compared with those of the corresponding diamagnetic complexes, [CoIII{RhIII(aet)3}2]3+. 1a and 1b were also characterized on the basis of the IR and UV-vis absorption spectra and the molar conductivities.
Stereoselective Electron-Transfer Reactions of Myoglobin and Cytochrome c with Chiral Viologen-Radical Cations
Authors: Tsukahara Keiichi , Ueda Rie , Goda Mariko
Published: September 2002

Electron-transfer (ET) reactions of metmyoglobin (metMb) and the oxidized form of cytochrome c (cyt c(III)) with chiral viologen-radical cations containing (1-phenyl- and 1-cyclohexylethyl)carbamoylmethyl groups were examined at pH 7.0 (10 mM phosphate buffer), ionic strengths (I) of 0.040–0.50 M, and temperatures of 10–35 °C. In the metMb system, the pseudo first-order rate constant of the decay of the viologen-radical cation was saturated with increasing concentrations of metMb, indicating that metMb interacts with the viologen-radical cation to form a complex followed by an intramolecular ET reaction. The stereoselectivity was observed in both the complex formation and the intramolecular ET processes for the (S,S)-isomers of chiral viologens. The ratios of the association constants and the intramolecular ET rate constants of the (S,S)-isomer with those of the (R,R)-isomer were 1.1–1.3 and 1.1–1.5, respectively. The saturation kinetics was not observed for the ET reaction between metMb and the achiral benzylviologen-radical cation, which has no CONH bond, suggesting that the hydrogen bonding of the CONH group of the chiral viologen with the side chain of the polypeptide in metMb plays an important role in the stereoselectivity. No appreciable complex formation was observed in the ET reaction between cyt c(III) and viologen-radical cations, although the stereoselectivity was observed. The ratios of the second-order rate constants of the (S,S)-isomer with those of the (R,R)-isomer were 1.1–1.4. The stereoselectivity is discussed based on the activation parameters.
Organization of Nucleosides Supported by Boronic-Acid-Appended Poly(l-lysine): Creation of a Novel RNA Mimic
Authors: Kobayashi Hideki , Amaike Masato , Koumoto Kazuya , Shinkai Seiji
Published: September 2002

Boronic-acid-appended poly(l-lysine) (1) can form anionic boronate esters with diol derivatives in aqueous solution. One can thus expect that when nucleosides are mixed with 1, the resultant complexes will satisfy the basic structural characteristics of RNA, viz., one-dimensionally organized nucleic bases and anionic charges. To obtain insights into this novel RNA mimic, the solution properties of adenosine (Ad) were estimated in the absence and the presence of 1. The large absorption and CD spectral changes were observed at pH 6–10 where the poly(l-lysine) main chain tends to adopt an α-helix-rich conformation. On the basis of the fact that the magnitude of the spectral changes is much larger than the fraction of complexed Ad molecules, the polymer-supported organization mode was proposed: that is, Ad molecules complexed by covalent bonds with 1 act as clusters to induce further organization of uncomplexed Ad molecules by noncovalent interactions. The proposal was further confirmed by 1H NMR spectroscopy and dynamic light scattering. On the other hand, none of these spectral changes were observed for 2′-deoxyadenosine. The 1–Ad complex thus formed can interact with complementary poly(U) but not with noncomplementary poly(C), indicating that it can act as a novel RNA mimic.
Practical Synthesis of 13-Substituted Milbemycin
Authors: Sugiyama Yoko , Saito Akio
Published: September 2002

A novel and practical method to synthesize 13-alkoxy derivatives from milbemycin A4 was studied and an efficient approach via the 15-hydroxymilbemycin derivative was established. During the study, a novel conversion of the 15-alkoxy derivative into the 13-alkoxy derivative via allyl cation and a new method for the conversion of allyl iodide into allyl ether using copper(I) trifluoromethanesulfonate as a catalyst were also found.
Adamantane-2,4-bis(p-quinone methide) and -2,6-bis(p-quinone methide) as New Models for Intramolecular Interactions between Spatially Separated Redox Systems
Authors: Kurata Hiroyuki , Shimoyama Takushi , Matsumoto Kouzou , Kawase Takeshi , Oda Masaji
Published: September 2002

Adamantane-2,4-bis(p-quinone methide) and -2,6-bis(p-quinone methide) were synthesized by the reaction of adamantane-2,4-dione and -2,6-dione, respectively, with lithium 4-lithio-2,6-di-t-butylphenoxide, followed by dehydration. Their structures were established by spectroscopic and X-ray crystallographic analyses. Having a distance (2.47 Å) between C2 and C4 longer than that (ca. 1.9 Å) between C1 and C3 of cyclobutane-1,3-bis(p-quinone methide)s, adamantane-2,4-bis(p-quinone methide) was found to show a clear through-space interaction (homoconjugation) and to form a σ-bond at its bis(anion radical) stage upon both chemical and electrochemical reduction. On the other hand, adamantane-2,6-bis(p-quinone methide), which has a long distance and near orthogonal arrangement between the quinone methide chromophores, shows a through-bond interaction, though it is weak.
Highly Active 3-Oxobutylideneaminatocobalt Complex Catalysts for an Enantioselective Hetero Diels–Alder Reaction
Authors: Kezuka Satoko , Mita Tsuyoshi , Ohtsuki Natsuki , Ikeno Taketo , Yamada Tohru
Published: September 2002

Optically active 3-oxobutylideneaminatocobalt(III) complexes were developed as effective catalysts for the enantioselective hetero Diels–Alder reaction of aromatic and aliphatic aldehydes with 3-(t-butyldimethylsilyloxy)-1-methoxy-1,3-butadiene. In the presence of the highly active cationic cobalt(III) complex, the hetero Diels–Alder reactions proceeded to afford the corresponding dihydropyran-4-ones with high performance and high enantioselectivities. The reaction with aromatic aldehydes substituted by a coordinating group at the ortho position proceeded more smoothly.
Palladium(II)- and Rhodium(III)-Catalyzed Carbonylation Reaction of Aryltin Compounds
Authors: Ohe Toshiyuki , Motofusa Shin-ichi , Ohe Kouichi , Uemura Sakae
Published: September 2002

A variety of aryltin compounds can be employed for carbonylation reactions in the presence of a catalytic amount of palladium(II) salt with reoxidant in acetonitrile or acetic acid under an atmospheric pressure of carbon monoxide (CO) to afford arenecarboxylic acids and diaryl ketones. Similar reactions also proceed by using rhodium(III) salt as a catalyst, where the presence of reoxidant is sometimes not necessary. More than one of two, three, or four aryl groups of aryltin compounds, and almost all of them in some cases, can be transferred to the products in this catalytic carbonylation.
Size Control of Metastable ZnS Particles in W/O Microemulsion
Authors: Hanaoka Toshiaki , Tago Teruoki , Kishida Masahiro , Wakabayashi Katsuhiko
Published: September 2002

The effect of various factors on the metastable size of ZnS particles was investigated in order to widely and precisely control the size of ultrafine particles synthesized in a microemulsion. The metastable size of the ZnS particles could be more widely changed by changing the microemulsion system, the specific permittivity of the organic solvent, the pH, and the synthesis temperature than the previously reported factors. We proposed a stabilization model of the ZnS ultrafine particles by surfactants and a new method for controlling the size of ultrafine particles synthesized in the microemulsion.
Non-specific and Specific Adsorption of Proteins on Langmuir–Blodgett Films of Amino Acid Derivative Polymers
Authors: Ide Makoto , Mitamura Akihiro , Miyashita Tokuji
Published: September 2002

Polymer LB films consisting of lysine and alanine derivative polymers were prepared to investigate the interfacial recognition between protein and ligand on the LB film. The surface of lysine derivative polymer LB film was modified by the biotin molecule that is the ligand for avidin. The biotinylation was carried out without inducing non-specific adsorption of proteins; avidin specifically adsorbed onto the biotinylated surfaces. Moreover, it was found that there is an optimum molar ratio of biotinylation for the adsorption of avidin onto the surface.
Chemical Modification of Amide-Based Catenanes and Rotaxanes I. Synthesis of secondary Amine [2]Catenanes and [2]Rotaxanes by the Borane Reduction of secondary Amide [2]Catenanes and [2]Rotaxanes and Mobility of Their Components
Authors: Furusho Yoshio , Shoji Junko , Watanabe Nobuhiro , Kihara Nobuhiro , Adachi Tomohiro , Takata Toshikazu
Published: September 2002

Various secondary amine [2]catenanes and [2]rotaxane were prepared by borane reduction of the corresponding secondary amide [2]catenanes and [2]rotaxane. Their structures were characterized by NMR, IR, and FAB-MS spectroscopies. The mobility of the components in solution was examined by 1H NMR spectroscopy. The substituents on the isophthaloyl units of the catenanes prevented complete circumrotation of the macrocyclic components (“half rotation”). On the other hand, macrocyclic ring components bearing unsubstituted isophthaloyl units completely circumrotated through the other faster than on the 1H NMR time scale (“full rotation”). In the case of the secondary amine [2]catenanes, no hydrogen bonding interaction between the secondary amino groups was observed. A dynamic 1H NMR study showed a highly enhanced mobility of the components of the secondary amine [2]catenanes and [2]rotaxane compared with the corresponding amide compounds, even at lower temperature.
Chemical Modification of Amide-Based Catenanes and Rotaxanes II. Synthesis of tertiary Amine [2]Catenanes and [2] Rotaxanes via N-Methylation Followed by Borane Reduction of secondary Amide [2]Catenanes and [2]Rotaxanes and Mobility of Their Components
Authors: Watanabe Nobuhiro , Furusho Yoshio , Kihara Nobuhiro , Takata Toshikazu , Kinbara Kazushi , Saigo Kazuhiko
Published: September 2002

Secondary amide [2]catenane 1a was converted to the corresponding tertiary amide [2]catenane 1b by repetitive treatment with a methylating system of CH3I and KOH in DMSO. The amide functions of 1b were reduced with borane in refluxing THF to give the corresponding tertiary amine [2]catenane 1c. Their structures were characterized by NMR, IR, and FAB-MS spectroscopies. An X-ray crystallographic analysis of 1c showed that its solid-state structure was stabilized by a CH–π interaction between the p-xylylene and m-xylylene units, together with a π–π stacking interaction between the two m-xylylene units. A variable temperature 1H NMR study suggested that 1c had components of highly enhanced mobility in CDCl3, even at lower temperature, although a much weaker interaction, such as the CH–π interaction, existed between their components in solution. Tertiary amine [2]rotaxane 3c was obtained from the corresponding secondary amide [2]rotaxane 3a by a procedure similar to that used for 1a. The 1H NMR spectra indicated that the mobility of the components of 3c is sufficiently high even at lower temperature.
Fluorescence Properties, Induced-Fit Guest Binding and Molecular Recognition Abilities of Modified γ-Cyclodextrins Bearing Two Pyrene Moieties
Authors: Aoyagi Taiyo , Ikeda Hiroshi , Ueno Akihiko
Published: September 2002

γ-Cyclodextrin (γ-CD) derivatives bearing two pyrene moieties at AB, AC, AD, and AE glucose units (1–4), were prepared as chemosensors for detecting molecules by their guest-responsive excimer emission intensity. All these hosts exhibited predominant excimer emission and remarkable induced circular dichroism (ICD) in a 20% dimethyl sulfoxide aqueous solution. The excimer emission and the ICD intensities mostly decreased upon addition of a variety of organic guests. The result indicates that 1–4 undergo an induced fit conformational change upon complex formation, excluding the pyrene moieties from inside to outside the γ-CD cavity in guest binding. The guest-induced fluorescence variations were analyzed by 1 : 1 host–guest stoichiometry and the obtained binding constants were roughly correlated with the guest-induced fluorescence variations. The binding and fluorescence data revealed that 1–4 have remarkable molecular recognition abilities for bile acids and other guests.
Pd(II)-Hydrotalcite-Catalyzed Selective Oxidation of Alcohols Using Molecular Oxygen
Authors: Kakiuchi Nobuyuki , Nishimura Takahiro , Inoue Masashi , Uemura Sakae
Published: September 2002

A novel heterogenized Pd catalyst, palladium supported by hydrotalcite [Pd(II)-hydrotalcite], has been synthesized. The catalyst is found to be effective for the oxidation of a wide range of alcohols using molecular oxygen as a sole oxidant. In this catalytic system, various alcohols are readily converted to the corresponding aldehydes or ketones selectively in high to excellent yields. It is noteworthy that the catalyst is also applicable to the oxidation of unsaturated alcohols such as geraniol and nerol without any isomerization of an alkenic part. Another characteristic property of this heterogeneous catalyst is that a shape selectivity depending on the structure of alcohols is observed in some cases. The catalyst also has advantages such as ease of handling, easy preparation, and reusability for several times.
4-(2-Aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one as a Highly Sensitive Fluorescent Labeling Reagent for Carnitine
Authors: Nakaya Ken-ichi , Tanaka Toshiyuki , Shirataki Yoshiaki , Shiozaki Hisayoshi , Funabiki Kazumasa , Shibata Katsuyoshi , Matsui Masaki
Published: September 2002

4-(2-Aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one, synthesized and identified by a HMBC study, can be used as a fluorescent labeling reagent for carnitine. The excitation and emission maxima in acetonitrile were observed at λ 454 and 508 nm, respectively. This reagent smoothly reacted with carnitine in the presence of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride to afford the corresponding amide under mild conditions. The detection limit (S/N > 3) of carnitine was ca. 12 fmol.
Investigations into the Bromination of Substituted Phenols using Diethyl Bromomalonate and Diethyl Dibromomalonate
Authors: Coumbarides Gregory Socrates , Dingjan Marco , Eames Jason , Weerasooriya Neluka
Published: September 2002

Substituted 4-bromophenols can be synthesised efficiently by heating the corresponding phenol in either neat diethyl bromomalonate or diethyl dibromomalonate. We discuss the regioselectivity of such reactions and comment on the scope and limitation of this procedure.
A Novel Regioselective Desulfation Method Specific to Silyl Ester of Primary Sulfate Using Silylating Agents. Selective Preparation of Secondary Alkyl Sulfates Having a Primary Hydroxy Group
Authors: Horibe Mineko , Oshita Hiroyuki
Published: September 2002

The treatment of bis(trimethylsilyl)ester of 1-O-decylglycerol-2,3-disulfate with trimethylsilyl-N-trimethylsilylacetimidate (BSA) or (dimethylamino)trimethylsilane caused regioselective desulfation to afford 1-O-decyl glycerol-2-sulfate selectively in good yield. Silylating agents, having nitrogen, seems to be responsible for facilitating trimethylsiloxysulfonyl cation transfer.
Characterization of Azide-Binding Type 2 Cu(II) Site of Nitrite Reductase
Authors: Deligeer  , Kataoka Kunishige , Suzuki Shinnichiro
Published: September 2002

The azide-binding type 2 Cu sites of nitrite reductases (NIRs) from denitrifying bacteria, Alcaligenes xylosoxidans GIFU 1051 and Achromobacter cycloclastes IAM 1013, have been spectroscopically characterized. The titration of two NIRs with azide indicates that two monodentate azide ions are coordinated to type 2 Cu(II). The difference between azide-treated and native NIR absorption spectra shows one absorption band near 450 nm due to N3- → type 2 Cu(II) charge-transfer transitions.
Solvent-Free Addition of Ethynylbenzene to Ketones
Authors: Miyamoto Hisakazu , Yasaka Shunpei , Tanaka Koichi
Published: September 2002

The addition of ethynylbenzene to ketones proceeded efficiently in the absence of a solvent to give tertiary alkynols in good yields.
Characterization of Calcium, Strontium, Barium and Lead Hydroxyapatites: X-ray Diffraction, Photoelectron, Extended X-ray Absorption Fine Structure and MAS NMR Spectroscopies
Authors: Sugiyama Shigeru , Moriga Toshihiro , Hayashi Hiromu , Moffat John B
Published: September 2002

Calcium, strontium, barium and lead hydroxyapatites have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (XAFS) and solid state NMR. XPS analyses showed that the binding energies of P 2s or P 2p and O 1s of all hydroxyapatites, XRD of which matched to the corresponding JCPDS data, were essentially identical and were not influenced by those divalent cations. In contrast, it was revealed that the nearest neighbour distances between divalent cations and oxygen determined by XAFS and the chemical shifts of 1H and 31P NMR were strongly influenced by each divalent cation in hydroxyapatites.
Redox and Optical Properties of Conjugated Ferrocene Oligomers
Authors: Nishihara Hiroshi
Published: September 2002

Internuclear electronic interactions in conjugated ferrocene oligomers display unique redox and optical properties. I describe here recent research on the dependence of such properties on the number of ferrocene nuclei and on the structure of conjugated spacers. The neighboring-site interaction model explains the redox properties of oligo(ferrocene-1,1′-diyl)s. The infrared (IR) spectra of carbonyl complex-bound biferrocene and terferrocene enlighten the electronic structure in the mixed-valence states. Energy shifts of intervalence transfer (IT) in the mixed-valence states of oligo(ferrocene-1,1′-diyl)s resulting from changes in the oxidation state are rationalized by taking into account the change in neighboring-site combination by photo-electron transfer, which delivers extra energy due to the strain in internuclear distance. Oligo- and poly-(ferrocene-1,1′-diyl)s oxidized partially by tetracycanoethylene (TCNE) exhibit near-IR photoconductivity. Conjugated spacer groups between ferrocene nuclei involving metal complex moieties affect the redox properties of ferrocene dimers significantly. The azo group acts as a distinctive spacer of which conjugation ability is changeable photochemically.
Crystal Structure of Long Alkyl 3-(Thymin-1-yl)propionates: Style of Hydrogen Bonding and Dependence on the Alkyl Chain Length
Authors: Mochizuki Eiko , Yasui Nobuyoshi , Kai Yasushi , Inaki Yoshiaki , Yuhua Wang , Saito Takao , Tohnai Norimitsu , Miyata Mikiji
Published: September 2002

Crystal structures of the ester derivatives of thymine having long alkyl chains are described. The crystal structure of the thymine derivative was found to be affected particularly by the carbon number of the alkyl chain. The thymine derivatives having even-numbered alkyl chains formed unusual hydrogen bonds between N3-H and O2 of the thymine base. The interactions between the methyl group and the oxygen were found to play an important role in the crystal structure. The thymine base of the even-numbered alkyl derivatives was surrounded by neighboring molecules with the interactions between the methyl group and the oxygen. Therefore, usual hydrogen bonds between N3-H and O4 were inhibited by steric effects from forming the hydrogen bonds between N3-H and O2.
Theoretical and Computational Study of Thermoreversible Gelation
Authors: Tanaka Fumihiko , Koga Tsuyoshi
Published: September 2002

This paper reviews recent theoretical and computational studies of thermoreversible gelation with multiple cross-link junctions in associating polymers. Paying special attention to the multiplicity and sequence length of the network junctions, we derive phase diagrams with coexisting gelation and phase separation. Local and global structures of the gel networks are studied. The conventional Eldridge–Ferry method is extended to allow for simultaneous evaluation of multiplicity and sequence length (or enthalpy of the cross-links), and applied to the experimental gel melting curves of poly(vinylalcohol) in water. On the basis of the Scanlan–Case criterion, we calculate the number of elastically effective chains and of dangling ends in the network as functions of polymer concentration and temperature. The effect of added surfactants on the formation of thermoreversible gels (surfactant-mediated gelation) in hydrophobically modified associating polymer solutions is also studied under the assumption of the existence of a minimum multiplicity required for stable cross-links. Competition between intramolecular micellization and intermolecular cross-linking is also studied with special attention to the formation of flower micelles.
Highly Sensitive Probe for Gene Analysis by Electrochemical Approach
Authors: Takenaka Shigeori
Published: September 2002

Electrochemically active DNA ligands, including ferrocenyl DNA oligonucleotides and ferrocenyl naphthalene bis(carboximide), are reviewed in connection with development of an electrochemical DNA sensor. Ferrocenyl oligonucleotides are used as an electrochemical probe DNA detectable by high performance liquid chromatography with the electrochemical detector (HPLC-ECD) system and they enable the target DNA analysis at femto mole level. Ferrocenyl oligonucelotides are useful also as a polymerase chain reaction (PCR) primer to realize quantitative PCR. Ferrocenyl naphthalene bis(carboximide) is a general DNA detecting ligand. When coupled with a probe DNA immobilized on an electrode, the target DNA from plasmid, chromosomal DNA, and total RNA extracted from several sources can be analyzed with very high sensitivity. Ferrocenyl naphthalene bis(carboximide) bound to the DNA duplex serves as a pseudo-polyferrocene array and this unique architecture leads to enhanced electron transfer between reduced glucose oxidase and the electrode. Unpaired base(s) present on the mismatched base(s) of the DNA duplex can be detected by observation of a decrease in the amount of ferrocenyl naphthalene bis(carboximide) bound to such a mismatched DNA duplex. Hybridized DNA on the DNA microarray was visualized electrochemically in the aqueous solution by the scanning electrochemical microscope (SECM) coupled with the ferrocenyl naphthalene bis(carboximide).
Radical Reaction by a Combination of Phosphinic Acid and a Base in Aqueous Media
Authors: Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro
Published: September 2002

Treatment of various organic halides with phosphinic acid (hypophosphorous acid) in aqueous ethanol in the presence of a radical initiator and a base gave the corresponding reduced products in high yields. Addition of a base is indispensable for the reduction of halides by phosphinic acid. Allylic ether of o-iodophenol or 2-haloalkanal allylic acetal underwent radical cyclization under the same conditions to afford the corresponding cyclic product in excellent yield. Deuterated phosphinic acid was found to be an efficient chain carrier for the radical deuteration of organic halides. For example, a deuterium oxide solution of deuterated phosphinic acid, potassium carbonate, 2,2′-azobis(isobutyramidine) dihydrochloride as an initiator, and p-iodobenzoic acid was heated at reflux to give p-deuteriobenzoic acid in 94% yield. A mixed dioxane/D2O solvent system combined with DBU and potassium peroxodisulfate was crucial to deuterate hydrophobic substrates in high yields and with high deuterium incorporation. Complete deuterium incorporation was accomplished only by the reaction in D2O without an organic cosolvent and an organic base.
Microviscosity Dependence of Magnetic Isotope Effect on Radical Pair Decay Rates in SDS Micellar Solution
Authors: Fujiwara Yoshihisa , Taga Yoshito , Tomonari Taro , Akimoto Yukimi , Aoki Takeshi , Tanimoto Yoshifumi
Published: September 2002

The microviscosity dependences of the magnetic field and magnetic isotope effects on disappearance of radical pairs (RPs) comprising benzophenone ketyl and alkyl radicals were investigated in sodium dodecyl sulfate (SDS) micellar solutions. The increase in microviscosity of the SDS micelle by adding MgCl2 caused not only a deceleration in the escape rate of the component radicals from the micelle but also a small magnetic isotope effect on the RP decay rate. The small magnetic isotope effect was explained by an increase in the correlation time of the radical motion, which is coupled with the anisotropic hyperfine interaction modulating the spin-lattice relaxation of RP.
Structures and Reactions of Alkoxymethyl(alkali metals). Ethylation by Methyl Ethers in the Presence of Organometallic Bases
Authors: Naruse Yuji , Hayashi Akihiro , Sou Shin-ichiro , Ikeda Hirotaka , Inagaki Satoshi
Published: September 2002

Structures and reactions of CH3OCH2M (M = Li, Na, K) were investigated in a theoretical manner. CH3OCH2M has the acute bond angle of ∠M-C-O due to a strong coordination of the oxygen to the alkali metals. The nucleophilic substitution reaction of the substrate CH3OCH2Li by the nucleophile CH3OCH2Li is more preferred than the carbene generation by α-elimination and a nucleophilic substitution of CH3OCH2Li by CH3Li. The resulting 2-methoxyethyllithium readily liberated lithium methoxide to afford ethylene, which added to the anion species to give an ethylated product. Among the CH3OCH2M (M = Li, Na, K), CH3OCH2K is the most nucleophilic, due to the high σC–K level, while CH3OCH2Li is the most nucleophilic because of the lowest σ*C–O level. This supports a previously proposed mechanism for the ethylation of indole derivatives by methyl ethers in the presence of BuLi - t-BuOK.
Temporal Analysis of Products (TAP) Study of the Adsorption of CO, O2, and CO2 on a Au/Ti(OH)4* Catalyst
Authors: Olea Maria , Kunitake Maki , Shido Takafumi , Asakura Kiyotaka , Iwasawa Yasuhiro
Published: September 2002

The adsorption kinetics on Au/Ti(OH)4* (a newly developed Au catalyst, active for low-temperature CO oxidation) for CO, O2, and CO2 in the temperature range 298–473 K was determined by temporal analysis of products (TAP) technique. The response signals from the single-pulse TAP experiments were analyzed using a statistical approach, and they were fitted to analytical models in order to establish the adsorption/desorption parameters. The pulse response of a non-adsorbing gas (argon) was used as a “reference”. The experiments revealed that: CO molecules reversibly adsorbed on the catalyst surface; O2 molecularly adsorbed , irreversibly for high pulse intensities and reversibly for low pulse ones; CO2 molecules irreversibly adsorbed on the surface, probably as carbonates. This catalyst exhibited an apparent negative activation energy for irreversible adsorption of O2.
Negative Chemical Ionization Mass Spectrometric Study on the Electron-Attachment Process of Nitric Carbons
Authors: Nakagawa Seiko , Shimokawa Toshinari
Published: September 2002

The formation of negative ions from halogenated acetonitriles XCH2CN (X = F, Cl, Br, I) and C6F4(CN)2 was studied using negative chemical ionization mass spectrometry. The halide ion was observed for XCH2CN (X = Cl, Br, I). While the intensity of the ion increased with increasing temperature for ICH2CN, the temperature dependence for the production of ions was only slightly observed over the temperature range of 393–537 K for ClCH2CN and BrCH2CN. The parent anions were observed for C6F4(CN)2. The intensity of the parent anions increased in the order 1,3-C6F4(CN)2- < 1,2-C6F4(CN)2- < 1,4-C6F4(CN)2-. A temperature dependence for the parent anions was not observed. The difference in the intensity can be explained by a recombination reaction with the positive ions.
Relative Stabilites of the Crossed vs. Linear σ-Conjugated Group 14 Triplet Diradicals E4H8 and E5H10 (E = C, Si, Ge, Sn): Orbital Phase Predictions
Authors: Ma Jing , Ikeda Hirotaka , Inagaki Satoshi
Published: September 2002

Orbital phase theory was applied to predict that the cross σ-conjugated isomers of acyclic Group 14 triplet diradicals E4H8  1 and E5H10  3 (E = C, Si, Ge, Sn) are more stable than the linear ones, 2 and 4, respectively. This prediction was confirmed by ab initio molecular orbital (MO) and density functional theory (DFT) calculations. It was also found that the radicals are preferentially in conjugation with the C-H bond for E = C (1a and 2a), but with the E-E bond for E = Si, Ge, Sn.
Investigation of Two-Dimensional Vibrational Spectrum by a Diagrammatic Approach
Authors: Tominaga Keisuke , Maekawa Hiroaki
Published: September 2002

We have theoretically investigated two-dimensional vibrational spectra for a two-mode system in terms of a diagrammatic approach. The two vibrational modes are anharmonically coupled. The perturbed stationary states are obtained by treating the cubic anharmonicity as a perturbation, and expressions for the third order response functions are derived. A physical origin of cross peaks in the spectrum is discussed. It is found that the vibrational dephasing time as well as the anharmonicity is important for the appearance of cross peaks.
Successive Crystalline-State Photoisomerization of the 4-Cyanobutyl Group in a Cobaloxime Complex
Authors: Vithana Champika , Uekusa Hidehiro , Ohashi Yuji
Published: September 2002

The 4-cyanobutyl group bonded to the cobalt atom in a cobaloxime complex crystal was isomerized to the 2-cyanobutyl group through the 3-cyanobutyl group on exposure to a xenon lamp with retention of the single crystal form. The X-ray crystal structure analysis of the initial crystal, (I), and the crystal after 66 hours exposure, (II), revealed that the produced 3-cyanobutyl group at one site in (II) is not disordered racemates but one enantiomer. The occupancy factors of the 4-cyanobutyl and the produced 3-cyanobutyl group were 0.786(7) and 0.214(7), respectively in (II). Although the structure of the produced 2-cyanobutyl group was not located on the difference electron density map, the NMR measurement clearly indicated that a small amount of the 2-cyanobutyl complex (ca. 6%) was produced.
Spin Chemical Approach towards Long-Lived Charge-Separated States Generated by Photoinduced Intramolecular Electron Transfer in a Donor–Bridge–Acceptor System
Authors: Mori Yukie , Sakaguchi Yoshio , Hayashi Hisaharu
Published: September 2002

Photo-induced intramolecular electron transfer (ET) and subsequent back ET have been studied for phenothiazine-bridge-pyromellitdiimide (D-B-A) and phenothiazine-bridge-pyromellitdiimide-nitroxide radical (D-B-A-R•) in various solvents by nano-second transient absorption spectroscopy. Upon excitation of the phenothiazine (D) moiety in these compounds, ET from 1D* to A took place at a rate of ca. 5 × 109 s-1 to give charge-separated (CS) states, 1[D•+-B-A•-] or 2[D•+-B-A•--R•], in high quantum yields. The decay dynamics of the CS states was determined by the interplay between the spin conversion and the back ET to the ground state. The efficiency of the interconversion between states with different spin multiplicities was strongly affected by the presence of R• and external magnetic fields. A faster spin conversion of [D•+-B-A•--R•] resulted in a slower initial decay of the CS state generated from the excited singlet state of D compared with [D•+-B-A•- ]. Such a spin effect manifested most markedly in dioxane. On the other hand, the back ET rate (kBET) varied by more than two orders of magnitude with the solvent polarity. In dimethyl sulfoxide, the back ET was predicted to be almost barrierless, kBET ≥ 109 s-1, while in benzene, this process fell in the inverted region, kBET = 6.5 × 106 s-1.