bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 (&gt; 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &gt; 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

Abstract
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 &gt; 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

Abstract
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

Abstract
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

Abstract
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.