bluuebunny/crossref_metadata_2025 huggingface dataset:
Intramolecular Change Distribution and Related Properties in a Series of 3,6-Di-tert-butylbenzoquinonatocobalt Complexes Containing Piperidine
Authors: Jung Ok-Sang , Lee Young-A , Park Sung Ho , Kim Yun Ju , Yoo Kyung Ho , Kim Dong Chan
Published: September 2002

A series of cobalt-benzoquinone complexes containing piperidine derivatives as a coligand, [Co(3,6-dbq)2(N-N)], (N-N = 1,1′-methylenedipiperidine (mdp), 1,1′-methylenebis(3-methylpiperidine) (mbmp), 1-methyl-4-(methylamino)piperidine (mmap); 3,6-dbq = 3,6-di-tert-butyl-1,2-benzoquinone) have been prepared and characterized. The crystal structure of [Co(3,6-dbq)2(mmap)]•0.5Me2CO (P1-, a = 11.524(2) Å, b = 12.565(4) Å, c = 14.160(3) Å, α = 80.65(2)°, β = 82.15(2)°, γ = 87.39(2)°, V = 2003.6(8) Å3, R = 0.0763) proves that the molecule exists as low-spin [CoIII(3,6-dbsq)(3,6-dbcat)(mmap)] (3,6-dbsq = 3,6-di-tert-butyl-1,2-semiquinonato; 3,6-dbcat = 3,6-di-tert-butylcatecholato) in the solid state. According to magnetic, spectroscopic, and thermal analyses, [CoIII(3,6-dbsq)(3,6-dbcat)(mmap)] is locked up to 431 K while [CoII(3,6-dbsq)2(mdp)] and [CoII(3,6-dbsq)2(mbmp)] are changed to their corresponding low spin CoIII forms at (below) T1/2 = 215 K and 271 K, respectively. The transition temperature (T1/2) between CoIII/CoII varies as mbmp < mdp << mmap, which appears to be associated with electronic versus steric effects of the piperidine coligands. In particular, [Co(3,6-dbq)2(mdp)] reveals a two-step spin conversion centered at 208 K and 298 K with a plateau of 90 deg.
Multielement Determination of Trace Elements in Seawater by Inductively Coupled Plasma Mass Spectrometry after Tandem Preconcentration with Cooperation of Chelating Resin Adsorption and Lanthanum Coprecipitation
Authors: Yabutani Tomoki , Chiba Koichi , Haraguchi Hiroki
Published: September 2002

A tandem preconcentration method, in which chelating resin adsorption and La coprecipitation were cooperatively employed for preconcentration, was developed as a pretreatment method for simultaneous multielement determination of trace elements in seawater by ICP-MS. First, the seawater sample (250 ml) was treated with a chelating resin for preconcentration of trace elements, and then trace elements with good recoveries were determined by ICP-MS. Trace elements with the chemical properties of oxoanion- and hydride-formation, which were poorly recovered in the chelating resin preconcentration, were further subjected to preconcentration by La coprecipitation. As a result, more than 30 elements could be determined in the concentration range from 9.6 μg L-1 for Mo to 0.00018 μg L-1 for Tm, when the present tandem method was applied to the analysis of open seawater standard reference material (NASS-4). Furthermore, the analytical results for open seawater reference materials were compared with those for coastal seawater reference material as well as for coastal seawater collected in the Ise Bay. It was found that the multielement data for trace elements in these seawater samples clearly showed different elemental distributions, reflecting the different marine environments.
Stabilities in Water and Transfer Activity Coefficients between Nonaqueous Solvents and Water of 1 : 1 Complexes of 15,15-Dimethyl-16-crown-5 with Metal Ions
Authors: Katsuta Shoichi , Motoyama Takako , Takeda Yasuyuki , Ouchi Mikio
Published: September 2002

The stability constants of 1 : 1 complexes of 15,15-dimethyl-16-crown-5 (DM16C5) with Li+, Na+, K+, Ag+, Tl+, Sr2+, Ba2+, and Pb2+ and of 16-crown-5 (16C5) with Li+ have been determined by conductometry in water at 25 °C. The transfer activity coefficients (sγ  H2O) of the alkali metal ion complexes between nonaqueous solvents (s: acetonitrile, propylene carbonate, and methanol) and water have been calculated. These values have been compared with the literature values for 16C5 and 15-(2,5-dioxahexyl)-15-methyl-16-crown-5 (L16C5). In water, 16C5 and DM16C5 selectively complex Li+ over Na+ and K+. The complexing ability of DM16C5 for a given metal ion is generally lower than that of 16C5 and L16C5. The alkali metal ion complexes of all the crown ethers are much less stable in water than in s, and the selectivity and the substituent effects also depend upon the solvent. The sγ  H2O values provide the following information: the alkali metal ion and the ether oxygen atoms are greatly dehydrated upon complexation in water; the dehydration is most drastic for Na+; the dehydration for Na+ is hindered by the methyl groups of DM16C5 and facilitated by the electron-donating side arm of L16C5. The solvent effects upon complexation are explained in terms of solute-solvent interactions.
Chemical Lithiation/Delithiation of K+-β-Ferrite (K1+xFe11O17)
Authors: Ito Shigeru , Omomo Yoshitomo , Fujii Takashi
Published: September 2002

The chemical lithiation⁄delithiation of K+-β-ferrite has been performed using butyllithium, lithium naphthalide (for lithiation), and iodine (for delithiation). In lithiation using butyllithium, the lithium content (y) in K1+xLiyFe11O17 was dependent on the average grain size of K+-β-ferrite single crystals; small grains (5 μm) largely reacted with lithium to form K0.99Li1.65Fe11O17. Lithiation was performed by the reduction of Fe3+ to Fe2+. Since the same X-ray diffraction (XRD) patterns were obtained before and after lithiation, the reaction seemed to be restricted to only near the grain surfaces. In lithiation using lithium naphthalide, the lithium content (y), which attained to be 36, was independent of the average grain size of K+-β-ferrite single crystals. This lithium content was remarkably large, compared to y = ca.1.6 in lithiation using butyllithium. A large amount of Fe0 (metal) was detected in the samples. According to scanning electron microscope (SEM) and XRD studies, not only pulverization of grains, but also destruction of the β-structure, occurred upon lithiation. On the other hand, delithiation of deeply lithiated samples was achieved by using iodine as an oxidant.
Synthesis and Structural Characterization of Thiolato-Bridged Tetranuclear Palladium(II) Complexes with N,N,S-Tridentate Ligands
Authors: Kawahashi Takako , Mikuriya Masahiro , Nukada Ryoji , Lim Jong-Wan
Published: September 2002

Palladium(II) complexes with 2-[(2-aminoethyl)amino]ethanethiol (HL1), 2-[(3-aminopropyl)amino]ethanethiol (HL2), 2-[(2-pyridylmethyl)amino]ethanethiol (HL3), and 2-{[2-(2-pyridyl)ethyl]amino}ethanethiol (HL4), [Pd4(L1)4]Cl4 (1), [Pd4(L2)4]Cl4 (2), [Pd4(L3)4](ClO4)3Cl (3), [Pd4(L4)4][Pd(SCN)4]Cl2 (4), and [Pd4(L4)4](ClO4)4 (5), were synthesized and characterized by measurements of the infrared, electronic, and NMR spectra. X-ray crystal structure analyses of 1, 2, 3, and 4 show that these complexes have a thiolato-bridged tetranuclear structure, where each palladium(II) center takes a square-planar N2S2 coordination environment.
Synthesis and Dimeric Structure of a Palladium(II) Complex with Bis(benzoylacetoneimine)-1,3-propan-2-ol
Authors: Mikuriya Masahiro , Minowa Kenichi , Lim Jong-Wan
Published: September 2002

A palladium(II) complex with 2-hydroxy-N,N′-bis(1-methyl-3-hydroxy-3-phenol-2-propene-1-ylidene)-1,3-propanediamine (H3L), [Pd(HL)]2, was synthesized and characterized by measurements of the magnetic moment and the electronic spectra. The X-ray crystal structure shows that the compound has a dimeric structure with two planar N2O2 coordination environments, which is formed by hydrogen-bonds between the alkoxy groups and the coordinating keto groups.
Fluorescent Monitoring of Complexation of Phthalimide-Fused Crown Ethers with Alkali Metal Ions
Authors: Otsuki Joe , Yamagata Toshihiro , Ohmuro Koji , Araki Koji , Takido Toshio , Seno Manabu
Published: September 2002

Phthalimide-fused mono(crown ether)s (1 and 2) and bis(crown ether)s (3 and 4) were prepared. These imide derivatives strongly fluoresce in methanol, and the fluorescence intensity is affected by alkali metal ions due to crown-ion interactions. While fluorescence increases upon complexation involving a single macrocycle, it decreases when the fluorophores take a face-to-face arrangement. This property was used to monitor the process of ion complexation and concomitant conformation changes. With the incremental addition of cesium ions (M) to the bis(crown ether)s (L), a folded sandwich complex (LM) initially formed, which subsequently transformed into a more extended LM2-type complex. This behavior, which was independently confirmed by 1H NMR spectroscopy, is clearly manifested in the fluorescence intensity.
Regioselectivity on Electroreductive Transannular Reaction of 7-Methylenebicyclo[3.3.1]nonan-3-one
Authors: Itoh Hiroki , Kato Ichiro , Unoura Kei , Senda Yasuhisa
Published: September 2002

A competitive transannular reaction occurred to give 7-methyltricyclo[3.3.1.03,7]nonan-3-ol (5) and 1-adamantanol (6) in the non-mediated electroreduction of 7-methylenebicyclo[3.3.1]nonan-3-one (1) in N,N-dimethylformamide. The apparent temperature dependence of the regioselectivity of the reaction may be attributed to the competitive operation of both kinetic and thermodynamic controls in the cyclization of the ketyl radical anion. The differences in the parameter of activation between the 5-exo- and 6-endocyclizations of 1•-, ΔΔH‡(5-exo - 6-endo) and ΔΔS‡(5-exo - 6-endo), were evaluated to be -3.1 kcal mol-1 and -11 cal mol-1 K-1, respectively. Semiempirical PM3 (RHF and UHF) calculations were also carried out to elucidate the reaction mechanism.
36-Membered Macrocyclic Diether Lipid is Advantageous for Archaea to Thrive under the Extreme Thermal Environments
Authors: Arakawa Kenji , Eguchi Tadashi , Kakinuma Katsumi
Published: September 2002

Described in this paper is the biophysical significance of the archaeal 36-membered macrocyclic diether phospholipid 36MPC as a function of temperature, which was studied by measuring of membrane fluidity, liposomal proton permeability, and liposomal thermostability in comparison with its acyclic counterpart, DPhyPC, their glycolipid derivatives, 36MGen and DPhyGen, egg yolk lecithin eggPC, and a mixed lipid of DMPC–cholesterol (2 : 1). Fluorescence anisotropy measurements indicated that the macrocyclic structure led to a decrease in the fluidity in the inter-membrane hydrophobic part more than in the membrane surface by limiting the motional freedom of the alkyl chains. The proton permeability was also significantly reduced by introducing a macrocyclic structure. Liposomal thermostability measurements using 6-carboxyfluorescein (CF) suggested that 36MPC formed liposomes with greater thermal stability than these of DPhyPC. The presence of glycolipids to the corresponding phospholipids greatly reduced the CF leakage from liposomes. Most importantly, DMPC-cholesterol liposome showed less leakage than 36MPC at 40 °C. However, by raising the temperature, this situation was completely reversed. This suggested that the cyclic structure contributed to the formation of stable liposomes, especially at higher temperatures. These findings clearly demonstrate that the 36-membered macrocyclic lipid membrane plays an important role for the thermophilic archaea to adapt to extreme environments.
Restricted Rotation Involving the Tetrahedral Carbon. LXIV. Barriers to Rotation of s-Alkyl Groups in 9-s-Alkyl-8,13-difluoro-1,4-dimethyl- and 1,2,3,4-tetrachloro-triptycenes
Authors: Oki Michinori , Nishino Masahiro , Kaieda Kazuihiro , Nakashima Takafumi , Toyota Shinji
Published: September 2002

9-(3-Acetoxy-1-methylpropyl)-8,13-difluoro-1,4-dimethyltriptycene and 9-(1-methyl-2-propenyl)-8,13-difluoro-1,4-dimethyl- and 1,2,3,4-tetrachloro-triptycenes were prepared. Their barriers to internal rotation around the C(9)–C(alkyl) bonds were measured by the classical kinetics. The barrier was affected a little by the substituent, being ca. 25–26 kcal mol-1. Rotamer distributions in these compounds and possible causes for these indifferent barriers to rotation are discussed.
Solvent Effects and Steric Course in the Solvolysis of 1,3,3-Trimethyl-2-oxocyclopentyl Mesylate in Comparison with 1,1,3,3-Tetramethyl-2-oxobutyl System
Authors: Takeuchi Ken’ichi , Ushino Takuhiro , Okazaki Takao , Kitagawa Toshikazu , Kinoshita Tomomi , Ohga Yasushi , Tanaka Koichi , Toda Fumio
Published: September 2002

The rates of solvolysis in various solvents were determined for 1,1,3,3-tetramethyl-2-oxobutyl tosylate (1OTs) and 1,3,3-trimethyl-2-oxocyclopentyl mesylate (4OMs). The rate data for 1OTs reinforced that the linear Grunwald-Winstein (GW) relationship of 1OMs previously reported by Creary for non-aqueous solvents must also hold for aqueous organic solvents. 4OMs showed a markedly dispersed GW relationship that is, on the other hand, well correlated with an extended GW equation involving a nucleophilicity parameter. Such solvent dependence, such marked effects of added sodium azide on rates, and the 100% inversion of configuration of the solvolysis product showed that the solvolysis of 4OMs would be categorized to SN2(intermediate), whereas 1OMs and 1OTs solvolyze via limiting SN1. The negligible susceptibility of 1OTs toward nucleophilicity of solvent and azide probe indicates that the nucleofuge leaves along the C=O axis in such a manner that the back-strain (B-strain) in the ground state is efficiently relieved in the transition state. Comparison of solvolysis rates of 1OMs and 4OMs with those of the corresponding parent substrates suggests that the transition states of these substrates would not be stabilized by carbonyl π conjugation. The origin of the unexpectedly fast rates of solvolysis of 1OMs has been discussed.
Synthesis of Trifluoromethyl Ketones by Palladium-Catalyzed Cross-Coupling Reaction of Phenyl Trifluoroacetate with Organoboron Compounds
Authors: Kakino Ryuki , Shimizu Isao , Yamamoto Akio
Published: September 2002

Cross-coupling reaction of aryl trifluoroacetates with organoboron compounds catalyzed by palladium complexes gives trifluoromethyl ketones in moderate to excellent yields under mild conditions. The catalytic process has been designed on the basis of fundamental studies dealing with oxidative addition of phenyl trifluoroacetate to a Pd(0) complex to give a (phenoxo)(trifluoroacetyl)palladium(II) complex and its subsequent reaction with phenylboronic acid to liberate phenyl trifluoromethyl ketone. The catalytic cycle is proposed to be composed of (a) oxidative addition of the ester to give acyl(aryloxo)palladium intermediate, (b) the subsequent transmetallation with arylboron compounds, and (c) reductive elimination. Palladium(0) complexes, as well as catalysts prepared in situ from palladium acetate and 3 molar amounts of tributylphosphine or phosphite at room temperature, serve as convenient and effective catalysts. The process is applicable to a wide range of phenyl- and naphthylboronic acids to give various aryl trifluoromethyl ketones under mild conditions. Aryl perfluoroalkyl ketone derivatives can be similarly prepared in high yields from various phenyl perfluoroalkanecarboxylates and arylboronic acids.
Regioselective Substitution of Phenols with Trifluoroacetaldehyde Ethyl Hemiacetal
Authors: Gong Yuefa , Kato Katsuya , Kimoto Hiroshi
Published: September 2002

Phenol did not react directly with trifluoroacetaldehyde ethyl hemiacetal. In the presence of catalytic amounts of anhydrous potassium carbonate, however, the reaction readily occurred. The p-substituted product 4-(2,2,2-trifluoro-1-hydroxyethyl)phenol predominated. In contrast, the reaction catalyzed by zinc halide predominantly produced the o-substituted product. Corresponding reactions of several phenols were studied under the same catalytic conditions.
2,2′-(1,3-Phenylene)bis(4-t-butyl-6-phenylphenylnitrene): An ESR Study of a Quintet Dinitrene Coupled with 1,3-Phenylene
Authors: Miura Yozo , Oka Hiroyuki , Teki Yoshio
Published: September 2002

4-t-Butyl-2,6-diphenylphenylnitrene and 2,2′-(1,3-phenylene)bis(4-t-butyl-6-phenylphenylnitrene) were generated by the phyolysis of the corresponding mono- and diazides and studied by ESR spectroscopy.
Fabrication of Solid-State Dye-Sensitized TiO2 Solar Cell Using Polymer Electrolyte
Authors: Matsumoto Masamitsu , Wada Yuji , Kitamura Takayuki , Shigaki Kouichiro , Inoue Teruhisa , Ikeda Masaaki , Yanagida Shozo
Published: September 2002

A solid-state dye-sensitized TiO2 solar cell has been fabricated with a polymer electrolyte constructed with α-methacryloyl-ω-methoxyocta(oxyethylene) or 2-(2-methoxyethoxy)ethyl acrylate as a base polymer, α-acryloyl-ω-acryloyloxyocta(oxyethylene)octa(ethylene glycol) dimethacrylate as a cross-linking agent and 3-methoxypropiononitrile as a plasticizer. The polymer is in-situ polymerized at the porous TiO2 film by photo-irradiation and the resulting film is immersed into the liquid electrolyte in order to introduce the electrolyte to the polymer phase. The conductivity of the polymer electrolyte reached 2.67 mS cm-1. The energy conversion efficiency of the solid-state cell was 2.62% under irradiation of simulated sunlight (AM 1.5, 1 kW m-2), achieving 86.4% of the cell efficiency using the liquid electrolyte.
The C60-Photosensitized Reduction of Methyl Viologen Through the Intermediary of O2
Authors: Konishi Toshifumi , Fujitsuka Mamoru , Ito Osamu , Toba Yasumasa , Usui Yoshiharu
Published: September 2002

C60-photosensitized reduction system of methyl viologen (1,1′-dimethyl-4,4′-bipyridinium) electron-mediated by O2 in organic solvents was demonstrated. By steady-state photoirradiation of C60 in the presence of electron donors such as triethanolamine (2,2′,2′′-nitrilotriethanol) and tetraphenylborate (-BPh4), the absorption-band of C60•- increased with irradiation time, and persisted for a long time. On introduction of O2, followed by the irradiation, C60•- disappeared and superoxide anion (O2•-) was generated. The photochemical reaction mechanisms were investigated by the transient-absorption method. The rate constant for electron transfer from C60•- to O2 was estimated to be (3.7 ± 0.2) × 102 mol-1 dm3 s-1. On addition of MV2+, electron transfer from O2•- to MV2+ was observed in aprotic solvents such as benzonitrile, yielding blue methyl viologen cation radical (MV•+). By irradiation of the system of C60/electron donor/O2/MV2+, MV•+ was also generated. In these systems, MV•+ accumulated and remained even in air-saturated solution for more than 1 h, because electron transfer from O2•- to MV2+ is an exothermic process in aprotic solvents.
Laser Flash Photolysis in High Speed Photopolymer Coating Layers III: Sensitization Mechanisms of Aminochalcone-Type Dyes with a Radical-Generating Reagent
Authors: Itoh Hiroki , Ishikawa Masayo , Takada Akiomi , Kudo Hideaki , Senda Yasuhisa , Urano Toshiyuki
Published: September 2002

In order to get insight into the effect of the different fixations of the conjugated systems of the aminochalcone-dyes on both the photophysical behavior and the quenching scheme of photoinitiation systems in a film, photophysical behavior of 2-benzoyl-6-(dimethylamino)benzo[b]furan (A) on 355 nm excitation with or without a radical-generating reagent, 2,4,6-tris(trichloromethyl)-1,3,5-triazine (TRI), in poly(methyl methacrylate) (PMMA) film has been investigated by laser flash photolysis using a total reflection cell. Dye A showed characteristic dual fluorescences of which the lifetimes, τSs, of shorter- and longer-wavelength components were evaluated to be 3.2 and 5.4 ns, respectively. The fluorescences were quenched by TRI with different static quenching distances, (Rs)Ss, of 1.3 and 1.5 nm for Ashort and Along, respectively. The static quenching distance of the initial triplet absorption of A, (Rs)T, was evaluated to be 1.5 nm. In addition, deconvolution analysis of the lifetimes of fluorescent dyes has been carried out to clarify the property of nonstatic quenching of the dyes: A, 10-benzoyl-2,3,6,7-tetrahydro-1H,5H-furo[3,2-g]pyrido[3,2,1-i,j]quinoline (B), 4′-(dimethylamino)chalcone (C), and (E)-3-(9-julolidinyl)-1-phenyl-2-propen-1-one (D), with TRI in the film.
Cyclic π-Conjugated Systems Annelated with Bicyclo[2.2.2]octene: Synthesis, Structures, and Properties
Authors: Komatsu Koichi
Published: September 2002

This article presents an account of studies on the synthesis and properties of the cyclic π-conjugated systems annelated with bicyclic σ-frameworks. Particular emphasis is placed on π-systems carrying a positive charge, which are remarkably stabilized by complete annelation with bicyclo[2.2.2]octene. In such systems, not only the kinetic effects but also electronic effects due to σ-π conjugation strongly affect the properties of the π-systems. The thermodynamic properties, redox behavior, and the X-ray crystal structures are discussed. The cyclic π-systems studied include hydrocarbon molecules such as benzene and a series of benzenoid condensed aromatics, seven-membered ring non-benzenoid aromatic cation, i.e. tropylium ion, cyclooctatetraene, a spiro-connected cyclopentadiene, and dehydroannulenes. The study is further extended to systems containing heteroatoms such as 1,4-dithiin, metallacycloheptatrienes, and silatropylium ion.
Control of Molecular Orientation of α-Helix in the Monolayer at Air–Water Interface
Authors: Doi Tomokiyo , Kinoshita Takatoshi , Tsujita Yoshiharu , Yoshimizu Hiroaki
Published: September 2002

Amphiphilic block copolymers of poly(L-leucine-co-ethylene glycol) (PLeum-PEGn) having three different compositions, m : n = 80 : 23, 57 : 46, and 66 : 114, were prepared and spread at an air-water interface to form a stable monolayer. The α-helical conformation of PLeu segment in the monolayers was confirmed by FT-IR and circular dichroism measurements. The molecular orientation of PLeu helix rods in the monolayer was estimated by surface pressure-area isotherm and FT-IR reflection absorption spectroscopy measurements. As a result, we confirmed that α-helix rod of PLeu segment oriented slightly normal to the membrane plane. Furthermore, it was indicated that each α-helical rod in the PLeu57–PEG46 monolayer is effectively oriented normal to the interface compared to that in the PLeu80–PEG23 and PLeu66–PEG114 monolayers.
Ground and Excited Singlet (S1) State Interactions of 2,2′- and 4,4′-Biphenyldiols with Proton Acceptors
Authors: Mohanty Jyotirmayee , Pal Haridas , Sapre Avinash V
Published: September 2002

Proton-transfer interactions of 2,2′- and 4,4′-biphenyldiols with urea (U), N-methylurea (MU), and triethylamine (TEA) have been investigated in methanol solutions using optical absorption as well as steady-state and time-resolved fluorescence measurements. In the ground state, both 2,2′- and 4,4′-biphenyldiols do not interact with weak proton acceptors, like U and MU. In the excited singlet (S1) state, only the 2,2′-biphenyldiol is seen to transfer a proton to U and MU, via the formation of intermolecular hydrogen-bonded exciplexes as intermediates. With TEA, a strong proton acceptor, both 2,2′- and 4,4′-biphenyldiols undergo an efficient proton-transfer reaction in their S1 state. In the ground-state, however, only 2,2′-analogue is seen to transfer a proton to TEA. The differences in the proton-transfer behavior of 2,2′- and 4,4′-biphenyldiols with different proton acceptors have been rationalized in terms of the presence and absence of intramolecular hydrogen bonding in the two diols.
Density Inhomogeneity in Amorphous Chlorobenzene Vapor-Deposited on Cold Substrates
Authors: Ishii Kikujiro , Yoshida Morihiko , Suzuki Katsunori , Sakurai Hidekazu , Shimayama Tsutomu , Nakayama Hideyuki
Published: September 2002

Light transmission through amorphous chlorobenzene was studied during the vacuum deposition of the vapor onto cold substrates. It was found that samples prepared at 78 K were transparent, but those prepared at 15 K were slightly opaque. Raman and X-ray studies indicated that both kinds of samples were amorphous, but they showed different behavior against annealing. The transparent samples needed some induction period to start crystallization when the temperature was raised for annealing, while the slightly opaque samples underwent crystallization by annealing almost without any induction period. Samples prepared at very-low temperatures are considered to incorporate density inhomogeneity, and the resultant free space around molecular aggregates may allow the samples to start crystallization easily.
Electronic Structure of N, N′-Bis(2-aminobenzylidene)ethylenediaminatocopper(II)
Authors: Kumagai Ken-ichi , Hasegawa Miki , Enomoto Shigendo , Hoshi Toshihiko
Published: September 2002

The electronic absorption spectra of N,N′-bis(2-aminobenzylidene)ethylenediaminatocopper(II) (abbreviated to [Cu(amben)]) were measured in ethanol and in a KBr disk. From these spectral data together with the polarization spectrum in a stretched PVA film, the X-ray photoelectron spectra, and a VESCF-MO-CI calculation, the electronic structure of [Cu(amben)] has been clarified. The reduced polarization spectrum shows that [Cu(amben)] has longer-molecular axis (y) polarized bands at 438, 300, 280, 257.7 and 222 nm, and shorter ones (z) at 418, 280, 260, 242.5 and 224 nm. The 300 nm band is assigned to an overlap of the calculated ππ*3 and ππ*4 transitions, which are charge transfer transitions between the two π-electronic systems localized almost independently on the 2-aminobenzylideneimino groups. The solid-state electronic absorption bands, measured in a KBr disk, of [Cu(amben)] are red-shifted by 2-16 nm, and considerably broadened compared with those in ethanol, indicating that the [Cu(amben)] molecules interact significantly in the solid state. The mechanism of the intermolecular interactions is discussed using the concept of the exciton model. XPS measurements show that the degree of the charge transfer from the ligand to the metal ion in [Cu(amben)] is less than that in N,N′-disalicylideneethylenediaminatocopper(II) in the ground state.
Thermodynamic Study of the Discrimination between Uridine and Thymidine Derivatives by Hydrophobic, Stacking, and Intercalating Interactions
Authors: Rekharsky Mikhail V , Nakamura Asao , Hembury Guy A , Inoue Yoshihisa
Published: September 2002

Thermodynamic parameters for the complexation reactions of uridine/thymidine nucleobases and related compounds, with hosts of differing binding modes and properties (natural cyclodextrins, 5,10,15,20-tetrakis (1-methlpyridinium-4-yl) porphyrin tetrachloride and bis-intercaland macrocycle) have been determined by titration microcalorimetry and/or fluorometry, in an aqueous buffer. For each of these hosts the effect of the 5-methyl group on the binding affinities was investigated. Although the affinities of uridine and thymidine towards cyclodextrins and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetrachloride are very similar, the intercalation of these compounds into the bis-intercaland macrocycle has been shown to result in a high degree of discrimination of approximately 10 times. On the basis of thermodynamic data, the obtained contribution made by the 5-methyl group of thymidine to the structural characteristics of DNA and RNA is discussed.
Magnetic Properties of Mixed Triangle-Based Ladder Magnets (C1TET-TTF)(FeBr4)1 - x(FeCl4)x (C1TET-TTF: 4,5-Ethylenedithio-4′,5′-bis(methylthio)tetrathiafulvalene)
Authors: Enomoto Masaya , Miyazaki Akira , Enoki Toshiaki
Published: September 2002

Isostructural magnets (C1TET-TTF)FeX4 (X = Br, Cl) are featured with a triangle-based ladder lattice comprised of an Fe3+ zigzag chain where a donor dimer bridges between next nearest neighboring Fe3+ sites. The FeCl4- salt is an antiferromagnet with its easy axis tilted from the ladder sheet, the FeBr4- salt shows weak ferromagnetism, with the easy axis of its antiferromagnetic behavior lying on the sheet. We investigate the magnetic properties of mixed crystal (C1TET-TTF)(FeBr4)1 - x (FeCl4)x in order to reveal the origin of the differences in magnetism. The strengths of the exchange interactions varying with x can be understood on the basis of the inter-anion/donor atomic contact lengths in the crystal. Weak ferromagnetism survives with its easy axis tilted from the sheet in the concentration region x ≈ 0.2. Then weak ferromagnetism disappears above x ≥ 0.42. In the high concentration range x ∼ 0.4-0.8, the ordered state deviates from an ordinary antiferromagnet, due to the competition between two constituent exchange interactions. However, the possibility of a spiral spin which configuration theory predicts is not conclusive. The magnetic anisotropy, whose direction varies depending on x, is a consequence of the competition between the dipole-dipole interaction and the single-ion anisotropy.
New Predictive Equations for the Specific and Apparent Molar Heat Capacities of Multicomponent Aqueous Solutions Conforming to the Linear Isopiestic Relation
Authors: Hu Yu-Feng
Published: September 2002

The linear isopiestic relation has been used together with well-known thermodynamic equations to establish new simple predictive equations for the specific and apparent molar heat capacities. These equations can provide predictions for multicomponent solutions conforming to the linear isopiestic relation using only information on the corresponding binary subsystems. No additional empirical parameters are involved. The predictive capabilities of the equations have been tested by comparing with the experimental specific or apparent molar heat capacities for the ternary systems (NaCl-NaNO3-H2O, NaCl-NaClO4-H2O, NaCl-KBr-H2O, NaCl-CaCl2-H2O, NaCl-MgCl2-H2O, and CaCl2-MgCl2-H2O) at 298.15 K and the reciprocal system (K-Na-Cl-SO4-H2O) at 373.15 K. The agreement is excellent over the entire experimental composition ranges.
Interpretation of the Solid-State Spectra of Tetrathiabenzoquinone Derivatives from the Standpoint of Intermolecular Interactions
Authors: Matsumoto Shinya , Tokunaga Wataru , Miura Hisashi , Mizuguchi Jin
Published: September 2002

The solid-state spectra of two tetrathiabenzoquinone derivatives have been investigated from the standpoint of intermolecular interactions, while focusing on the bathochromic shift upon crystallization. These derivatives form a characteristic molecular arrangement consisting of a one-dimensional molecular column and a two-dimensional molecular sheet. Interactions in the excited state which depend on the molecular arrangement, exciton coupling effects (interactions between transition dipoles), were found to be small in both compounds. A small bathochromic shift of the trimethylenedithio derivative is attributed to these effects. The temperature dependence of the solid-state spectra is also in good agreement with the calculated result. However, an extremely large bathochromic shift of the ethylenedithio derivative cannot be explained in terms of the exciton coupling effects. Intermolecular interactions caused by the close atomic contacts between intermolecular sulfur atoms in single crystals were found to play an important role in the solid-state spectra of the ethylenedithio derivative.
Effects of Trace Lanthanum Ion on the Stability of Vaterite and Transformation from Vaterite to Calcite in an Aquatic System
Authors: Tsuno Hiroshi , Kagi Hiroyuki , Akagi Tasuku
Published: September 2002

The effect of lanthanum ion on the crystallization of calcium carbonate was investigated using CaCl2–NaHCO3 solutions. A sampling vessel enabling us to sample a small aliquot of a solution at any time almost under a closed condition was invented for the experiments. The abundance of the crystallographic polymorphs in the precipitate was determined by powder X-ray diffraction. The formation of calcium carbonate from lanthanum-doped solutions can be featured by three stages: a spontaneous and rapid precipitation of vaterite, a transitive static stage and a delayed formation of calcite. Almost all lanthanum (> 95%) in the solution system (dissolved + suspended solid phases) was proved to be incorporated in the initially formed vaterite, and lanthanum in the vaterite seemed to be immobilized throughout the experiment. The presence of lanthanum in the starting solution (10-4 of calcium in mole) stabilized the initial vaterite crystal, preserved it much longer than one month and increased the solubility of CaCO3 to the level of vaterite. It is suggested that the lanthanum ion prohibited either the transformation initially formed vaterite to calcite or the overgrowth of calcite.
Stability and Structure of Ethylenedinitrilopoly(methylphosphonate) Complexes of the Divalent Transition Metal Ions in Aqueous Solution
Authors: Duan Wubiao , Satoh Keiichi , Sawada Kiyoshi
Published: September 2002

The formation and protonation of the complexes of a series of ethylenedinitrilopoly(methylphosphonic acids) (EDMP) [(Me)2 - p(H2O3PCH2)pNC2H4N(Me)2 - q(CH2PO3H2)q, p = 0–2, q = 1–2] with divalent transition metal ions (M = Mn2+, Co2+, Ni2+, Cu2+, Zn2+ or Cd2+) were investigated by means of potentiometry and 31P NMR spectroscopy at 25.0 °C. The complex formation constants and protonation constants of these complexes were determined by pH titration. The 31P NMR spectra of zinc and cadmium complexes were measured as a function of the pH, and the 31P NMR chemical shifts of each chemical species were evaluated by using the equilibrium constants determined by pH titration. The results for EDMP complexes were compared with those of aminopoly(methylphosphonate) (NMP) [(CH3)3 - rN(CH2PO3H2)r, r = 1 – 3] complexes and alkaline earth metal EDMP complexes. The stability constants of the metal complexes increase upon increasing the number of the phosphonate groups and are around the same between the EDMP and NMP complexes of a given metal ion having the same total number of coordinating atoms. The stabilities of the edtmp (p = q = 2) complexes are around the same as those of the medtmp (p = 1, q = 2) complexes. These results reveal the structures in which two nitrogen atoms of the ethylenedinitrilopoly(methylphosphonate) co-ordinate to the transition metal ion in any complex. These structures are different from those of the corresponding alkaline earth metal complexes. The structures of the protonated complexes were estimated from the results of the protonation constants and the 31P chemical shifts of the complexes.
Template Synthesis of Macrocyclic Dinuclear CuII Complexes and Conversion into Mononuclear Complexes by Site-Selective Copper Elimination
Authors: Hori Akiko , Yonemura Masami , Ohba Masaaki , Okawa Hisashi
Published: September 2002

The acyclic dinucleating ligand, N,N′-dimethyl-N,N′-trimethylenedi-(3-formyl-2-hydroxy-5-methylbenzylamine) (H2L), has been prepared. It combines two CuII ions with its N(amine)2O2 and O4 metal-binding sites to form a dinuclear complex [Cu2(L)](ClO4)2. The [1 : 1] condensation of [Cu2(L)](ClO4)2 with an aliphatic or aromatic diamine has provided macrocyclic dinuclear CuII complexes [Cu2(Li)](ClO4)2 (Li = L1 for the diamine = ethylenediamine, L2 for trimethylenediamine, L3 for tetramethylenediamine, L4 for o-phenylenediamine and L5 for 1,8-diaminonaphthalene). X-ray crystallographic studies for [Cu2(L1)(H2O)](ClO4)2•MeCN and [Cu2(L5)](ClO4)2•2MeOH demonstrate a macrocyclic dinuclear core structure with the two CuII ions in the N(amine)2O2 and N(imine)2O2 sites, in the Cu-Cu separation of ca. 3.0 Å. The dinuclear complexes are studied in magnetic, electronic spectral and electrochemical properties. The treatment of the dinuclear complexes with Na2S in acetonitrile resulted in the elimination of one Cu to afford the mononuclear complexes [Cu(Li)]•xNaClO4. The X-ray crystallography for [Cu(L2)], [Cu(L3)]•NaClO4 and [Cu(L4)] has demonstrated that the Cu in the N(amine)2O2 site is selectively eliminated. In the latter complex, the NaI ion is accommodated in the aminic site.
Association of n-Alcohol with p-Sulfonato Calixarenes in an Aqueous Medium Determined by Headspace Gas Chromatography
Authors: Zheng Jin-Zi , Wu Ji-Shi , Toda Kei , Sanemasa Isao
Published: September 2002

The associations of n-alcohols (C4 to C9) with water-soluble p-sulfonato calix[4, 6, and 8]arenes have been determined in aqueous solutions at 25 °C. In contrast to the case of cyclodextrins, the alkyl chain length does not contribute to the stability of the associated complex.
A Novel Five-Coordinated Sodium Ion Captured in Na2[Ni(succim)4]•2H2O (succim = succinimidate) Complex: Crystal Structure and Crystal Polarized Electronic Spectra.
Authors: Akitsu Takashiro , Hiroshima Yukiko , Komorita Seiko , Kushi Yoshihiko
Published: September 2002

The crystal structure of Na2[Ni(succim)4]•2H2O complex having four monodentate succinimidate (succim) ligands was determined by X-ray structural analysis. The host complex captures five-coordinated guest sodium ion, which is the first example of a podand complex formed in a crystal. Polarized crystal electronic spectra of the complex were measured with parallel and perpendicular to b axis polarization.
Substituent and Solvent Effects on the Reactions of Organoboronic Acids with Fluoride
Authors: Yuchi Akio , Tatebe Atsushi , Kani Shinpei , James Tony D
Published: September 2002

The introduction of an electron-withdrawing substituent or a substituent protonated to be positively charged and potentially involved in hydrogen bonding enhances the reactivities of phenylboronic acids with fluoride. The use of a 60% aqueous MeOH medium suppresses the formation of the negatively charged species, irrespective of whether their structures are trigonal or tetrahedral, but enhances the overall reactivity because of less solvation of fluoride.
Generation of 1,3-Chalcogenaza-1,3-butadienes by Thermal Cycloreversion of 2,4,6-Trisubstituted 6H-1,3,5-Oxachalcogenazines
Authors: Shimada Kazuaki , Aikawa Kei , Fujita Takuji , Sato Masanobu , Goto Kurara , Aoyagi Shigenobu , Takikawa Yuji , Kabuto Chizuko
Published: September 2002

1,3-Thiaza- and 1,3-selenaza-1,3-butadienes bearing several substituents at the C-2 and C-4 positions were generated through thermal cycloreversion of 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines, respectively, and the heterodienes were efficiently trapped by using acetylenic dienophiles. When 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines were heated in the presence of nucleophiles, such as alcohols or thiols, the corresponding 1,4-adducts of the heterodienes with the nucleophiles were obtained in good yields. On the other hand, heating of 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines in the absence of trapping agents afforded several products which originated from the in situ generated 1,3-chalcogenaza-1,3-butadienes; also the heterodienes were not isolated or observed directly as the monomeric forms at all.
Synthesis and Properties of Planar-Chiral (η6-Benzene)(η5-cyclopentadienyl)ruthenium(II) Complexes in an Optically Pure Form
Authors: Matsushima Yuji , Komatsuzaki Nobuko , Ajioka Yoshiki , Yamamoto Mari , Kikuchi Hidetomo , Takata Yasuyuki , Dodo Noriko , Onitsuka Kiyotaka , Uno Mitsunari , Takahashi Shigetoshi
Published: September 2002

Planar-chiral cyclopentadienylruthenium complexes [Ru(η5-1-CO2R*-2-Me-4-R1C5H2)(η6-C6H6)][X] (4 and 8) (R* = (l)- or (d)-menthyl; R1 = Me, Ph, t-Bu, 2-Naphthyl, or 4-BrC6H4; X = PF6 or BPh4) were synthesized in a diastereomerically pure form. The absolute configuration of 8b and 4c (R1 = Ph, t-Bu) were determined by an X-ray crystallographic analysis and those of the others were assigned on the basis of their optical properties including their CD spectra. Enantiopure complexes (SC1)-[Ru(η5-1-CONHBut-2-Me-4-R1C5H2)(η6-C6H6)][PF6] 9 and -[Ru(η5-1-CONHBut-2-Me-4-R1C5H2)(η6-C6H6)] [BPh4] 10, and (RC1)-9 and -10 were prepared from direct hydrolysis of diastereomeric complexes, followed by the reaction of amines. Replacement reactions of the bromo group in 9e (R1 = 4-BrC6H4) gave alkyl, phenyl, and ethynyl derivatives. Complexes [Ru(η5-1-CO2Et-2-Me-4-R1C5H2)(η6-C6H6)][PF6] 6 were also transformed to planar-chiral [Ru(η5-1-CO2Et-2-Me-4-R1C5H2)(CH3CN)3][X], which underwent ligand exchange reactions to afford carbonyl, phosphine, and π-arene complexes.
Charge-Transfer Complexes of PXX (PXX = 6, 12-Dioxaanthanthrene). The Formal Charge and Molecular Geometry
Authors: Asari Takehiro , Kobayashi Norihito , Naito Toshio , Inabe Tamotsu
Published: September 2002

Three kinds of charge-transfer (CT) complexes of PXX (PXX = 6, 12-dioxaanthanthrene) have been newly prepared and structurally characterized. In the 1 : 2 CT complex with TNP (TNP = 2,4,6-trinitrophenol), PXX is practically neutral. In the semiconducting partially oxidized salt with I3, the PXX molecules form a trimer and each PXX is formally oxidized by e/3. In the 3 : 2 salt with [Ni(mnt)2]- (mnt = maleonitriledithiolate), the PXX molecules again form a trimer unit and each PXX is formally oxidized by 2e/3. Together with the structural data obtained from the PXX single component crystal, the molecular geometry change by the formal charge on PXX has been examined. A noticeable change has been found in the aromatic ring framework, which is consistent with the distribution of the HOMO coefficients obtained from the extended Hückel calculation.
Diastereoselective Formation of Disaccharides from (RS)-1-Phenylethanol by Cultured Cells of Catharanthus roseus
Authors: Hirata Toshifumi , Shimoda Kei , Fujino Takeshi , Yamane Shin-ya , Ohta Shinji
Published: September 2002

The biotransformation of (RS)-1-phenylethanol with cultured cells of Catharanthus roseus gave its vicianoside [α-L-arabinopyranosyl-(1-6)-β-D-glucopyranoside], primeveroside [β-D-xylopyranosyl-(1-6)-β-D-glucopyranoside] and gentiobioside [β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside] via the corresponding glucoside. It was found that primeveroside and gentiobioside were enantioselectively composed of only (R)-1-phenylethanol as its aglycone moiety.
Solvolysis of 1-Decenyl(phenyl)iodonium Tetrafluoroborate: Mechanisms of Nucleophilic Substitution and Elimination
Authors: Okuyama Tadashi , Imamura Shohei , Ishida Yoshimi
Published: September 2002

Solvolysis of (E)-1-decenyl(phenyl)iodonium tetrafluoroborate 1 was carried out in some alcohols, acetic acid, and mixed aqueous alcoholic solvents at 50–60 °C and the effects of added carboxylates and other salts were also examined in methanol. Reaction products include enol derivatives (substitution) and 1-decyne (elimination) as well as iodobenzene. Rates for the solvolysis increase with increasing nucleophilicity of the solvent but have no correlation with the solvent ionizing power. The substitution occurs mostly via inversion of configuration, and is concluded to follow the in-plane SN2 mechanism with a minor concomitant out-of-plane SN2 pathway. The reactions with the deuterated substrates show that stronger bases of pKa of the conjugate acid > 3 induce exclusively α-elimination of 1 in methanol. However, both α- and β-elimination occur in neutral methanol in a ratio of about 3/1 besides the substitution. Mechanisms for these reactions are proposed.
Chiral N-Substituted Perylene-3,4-dicarboximides as Fluorescent Labeling Reagents
Authors: Nakaya Ken-ichi , Funabiki Kazumasa , Shibata Katsuyoshi , Matsui Masaki
Published: September 2002

Chiral N-substituted perylene-3,4-dicarboximides have been synthesized. These optically pure compounds were sufficiently soluble in acetonitrile used as fluorescent labeling reagents. Their excitation and emission maxima were observed at λ 500 and 550 nm in acetonitrile, respectively. Enantiomers in a racemic mixture could be analyzed by these reagents. Racemic Ibuprofen and alanine methyl ester were nicely separated by (R)-N-(2-hydroxy-1-phenylethyl)- and (R)-N-(α-carboxyphenethyl)perylene-3,4-dicarboximides in HPLC, respectively. The detection limits (S/N > 3) of Ibuprofen and alanine methyl ester were 1 and 13 pmol, respectively.
Formation and Structures of Dimeric Compounds from an (E)-5,5′-Diphenyl-2,2′,3,3′-tetrahydro-3,3′-bipyrrolylidene-2,2′-dione
Authors: Irikawa Hajime , Shiratori Kimiaki , Adachi Norihide , Adachi Keiichi , Kawata Satoshi
Published: September 2002

Dimeric fluorescent compounds were formed from an (E)-5,5′-diphenyl-2,2′,3,3′-tetrahydro-3,3′-bipyrrolylidene-2,2′-dione by a treatment with acid anhydride and TFA. The structures of these compounds were clarified by X-ray analysis and spectral (UV-vis, 1H and 13C NMR) comparisons.
Preparation of Mo and W Complexes Containing a New Linear Tetradentate Phosphine Ligand meso-o-C6H4(PPhCH2CH2PPh2)2 from Dinitrogen Complexes trans-[M(N2)2(Ph2PCH2CH2PPh2)2] (M = Mo, W)
Authors: Arita Chirima , Seino Hidetake , Mizobe Yasushi , Hidai Masanobu
Published: September 2002

A benzene solution of trans-[Mo(N2)2(dppe)2] (1a; dppe = Ph2PCH2CH2PPh2) and an equimolar amount of dppe was heated at reflux for 2 h under Ar to give [Mo(P4)(dppe)] (2a; P4 = meso-o-C6H4(PPhCH2CH2PPh2)2), where the new linear tetraphosphine P4 is presumed to form through condensation of two dppe ligands in the coordination sphere of Mo. The W complex [W(P4)(dppe)] (2b) and its dppm analogue [W(P4)(dppm)] (dppm = Ph2PCH2PPh2) were also prepared from the reactions of trans-[W(N2)2(dppe)2] with one equiv of dppe or dppm in toluene at reflux for 2 h under Ar. Detailed structures of 2a and 2b were determined by X-ray crystallography. In contrast, when the reaction mixtures obtained by treatment of 1a with excess PR3 (R = Bun, Et) in place of dppe were cooled down to room temperature under N2, novel dinitrogen complexes containing the P4 ligand [Mo(N2)(P4)(PR3)] formed; these were characterized spectroscopically and by elemental analyses.
Tin(II) Trifluoromethanesulfonate-Catalyzed Highly Selective Synthesis of 2-Substituted 4-Methylenetetrahydropyrans from Trimethyl{2-[2-(trimethylsiloxy)ethyl]allyl}silane and Acetals
Authors: Oriyama Takeshi , Ishiwata Akihiro , Suzuki Takeshi
Published: September 2002

A variety of 2-substituted 4-methylenetetrahydropyrans are easily produced by the reaction of acetals with trimethyl{2-[2-(trimethylsiloxy)ethyl]allyl}silane under the influence of a catalytic amount of tin(II) trifluoromethanesulfonate.
Synthesis of Soluble Complexan Polymers in Organic Solvents for Using as a Polymer–Chelate Precursor to YBa2Cu3O7-x Thin Films
Authors: Naka Kensuke , Tanaka Yasuyuki , Yamasaki Kunitoshi , Ohki Akira , Chujo Yoshiki , Maeda Shigeru
Published: September 2002

A soluble complexan polymer in organic solvents, derived from 1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA), was synthesized and used as a polymer chelate precursor to YBa2Cu3O7-x thin films. Five complexan polymers (3) were prepared by a ring-opening polyaddition of CyDTA dianhydride (1) with several diamines (2). The polymer (3e) prepared with 1,2-diaminocyclohexane (2e) was soluble in water, dimethyl sulfoxide (DMSO), methanol, and ethanol. A clear aqueous solution (pH 8) containing 3e and 1/2 equivalent molar amount of metal nitrates of Y, Ba, and Cu (1 : 2 : 3 in molar ratio) was poured into tetrahydrofurane (THF) to precipitate a polymer–metal chelate. The chelate formations of each metal were confirmed by C=O stretching bonds. The polymer chelate precursor was soluble in methanol, DMSO, and water, and partially soluble in ethanol. The polymer–metal chelate was dissolved in methanol, of which the metal concentration was adjusted to 3 wt%. This solution was spin-coated onto SrTiO3 (100) and MgO (001) substrates for preparing YBa2Cu3O7-x thin films. According to an X-ray diffraction analysis, YBa2Cu3O7-x film with a c-axis orientation was formed on a SrTiO3 substrate; even the precursor film was sintered at 780 °C for 1 h under air. Superconducting YBa2Cu3O7-x films with a c-axis orientation were also prepared on a MgO (001) substrate.