bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of C132-Stereochemistry on the Molecular Properties of Chlorophylls
Authors: Furukawa Hiroyasu , Oba Toru , Tamiaki Hitoshi , Watanabe Tadashi 
Published: September 2002

Abstract
To elucidate the origin of differences in the monomeric properties of chlorophyll a and a′ (Chl a/a′; C132-(R/S)-epimers of Chl a), a series of Zn-Chl derivatives possessing a variety of C134 substituents were prepared. The (S)-epimers gave absorption and emission bands at slightly longer wavelengths than the corresponding (R)-epimers. The (S)-epimers had more intense CD peaks than the (R)-epimers. In comparison with Zn-Chl a/a′ (C134-Me), Zn-Chl with a bulky 2,4-dimethyl-3-pentyl moiety at the C134-position showed a greater difference between the 13C NMR chemical shifts of the epimers. These spectral differences between the (R)- and (S)-epimers were attributed to ruffling of the chlorin macrocycle, arising from a steric repulsion between the C132 and C17 moieties. The trend of the rate constant of epimerization, isomerization at the C132 position, in the C134-substituted Zn-Chls is in line with the above interpretation. The relationship between the spectroscopic and kinetic results and the distortion of the macrocycle is schematically represented.
Infrared Spectroscopic Study on Methane Adsorption Sites on Mesoporous Silicates
Authors: Yamazaki Tatsuya , Watanabe Michimasa , Saito Hiroaki 
Published: September 2002

Abstract
Some MCM-41 materials substituted by trivalent metal ion (Met-MCM-41; Met = Al, Fe, and Ga) were prepared, and their methane adsorption sites were investigated by IR spectroscopy. Three adsorption sites on Met-MCM-41 with different strengths of electric field were observed. They were assigned to pore wall site (0 V m-1), silanol site (ca. 4×109 V m-1), and Na+ site (ca. 6×109 V m-1), respectively. The amounts of silanol site in Met-MCM-41 were estimated to 2—3 mmol g-1, while the amounts of the Na+ site were 0.1—0.2 mol g-1. Methane molecules were preferentially adsorbed on the electrostatic sites (silanols and Na+sites) at low methane pressures, but as methane pressure increased, the amount of adsorption on the pore wall site became comparable to that on the silanol sites. Since the amounts of Na+ site estimated from methane adsorption on the Met-MCM-41 samples were less than the theoretical ones calculated from the compositions of starting materials, most of the Na+ sites were thought to be inaccessible for methane molecules.
Photosensitized Luminescence of Neodymium(III) Coordinated with 8-Quinolinolates in DMSO-d6
Authors: Iwamuro Mitsunori , Adachi Tomoko , Wada Yuji , Kitamura Takayuki , Nakashima Nobuaki , Yanagida Shozo 
Published: September 2002

Abstract
Some quinolinol derivatives possessing suitable triplet state energy were examined to sensitize the luminescence of neodymium ion (Nd(III)) as coordinating ligands. Photosensitized luminescence in the near-infrared region of four neodymium(III) complexes: tris(8-quinolinolato)neodymium(III) ([Nd(q)3]), tris(5,7-dichloro-8-quinolinolato)neodymium(III) ([Nd(Clq)3]), tris(5,7-dibromo-8-quinolinolato)neodymium(III) ([Nd(Brq)3]) and tris(5,7-diiodo-8-quinolinolato)neodymium(III) ([Nd(Iq)3]), were observed by selective excitation of the ligand moieties in DMSO-d6. Highly efficient intramolecular energy transfer from the excited ligand moieties to the central Nd(III) ion was successfully achieved by using the halogenated ligands.
Structures and Magnetic Properties of [o- and p-MePyNN+]2[Cu(ox)2] (MePyNN+ = Nitronyl Nitroxyl Radical Cation)
Authors: Oshio Hiroki , Yaginuma Taira , Ito Tasuku 
Published: September 2002

Abstract
Reactions of [o-MePyNN+]PF6 and [p-MePyNN+]PF6 with [n-Bu4N]2[Cu(ox)2] in acetonitrile yielded dark-blue crystals of [o-MePyNN+]2[Cu(ox)2]·2CH3OH (1) and [p-MePyNN+]2[Cu(ox)2]·2H2O (2), respectively, where [o-MePyNN+] or [p-MePyNN+] represents the 2-(2 or 4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazo-1-oxyl 3-oxide radical cation. X-ray structural analyses showed that the crystals of 1 and 2 are isomorphous. The coordination geometry of the Cu2+ ions in 1 and 2 is an elongated octahedron, and the equatorial and apical coordination sites of the Cu2+ ions are occupied by two oxalato groups and two radial cations, respectively. Magnetic susceptibility measurements for 1 and 2 revealed that the copper and radical centers are ferromagnetically coupled with J = +8.2(1) and +7.8(1) cm-1 (H = -2J∑SCu·Srad), respectively.
Formation of Two, One, and Zero-Dimensional Coordination Assemblies from Cd(II) Ion and 4,4′-Bipyridine
Authors: Aoyagi Masaru , Biradha Kumar , Fujita Makoto 
Published: September 2002

Abstract
Complexation of Cd(NO3)2 with 4,4′-bipyridine (4,4′-bpy) gave, depending on the L/M ratios and concentrations, two-dimensional, one-dimensional or zero-dimensional coordination assemblies, which were characterized by X-ray crystallography. The two dimensional structure was shown to be a non-interpenetrated square grid network in which the square cavities were occupied by water and nitrate ions. The one-dimensional polymer also formed a two-dimensional network with the assistance of O-H…N hydrogen bonds. The zero-dimensional structure was composed of two Cd2+ centers, four unidentate 4,4′-bpy, and a bridging bidentate 4,4′-bpy. The networks and the packing of these structures were analyzed in terms of coordination and hydrogen bonds.
Crystal Structure and Thermal Study of the Aqua(butyl)cobaloxime/α-Cyclodextrin Inclusion Complex
Authors: Chen Ying , Luo Lai-bin , Chen Hui-lan , Hu Chun-hua , Chen Jian , Zheng Pei-ju 
Published: September 2002

Abstract
The crystal structure of the aqua(butyl)cobaloxime/α-cyclodextrin inclusion complex was determined by single X-ray diffraction. It crystallizes in the orthorhombic space group P212121 with a = 14.083(3), b = 19.237(4), c = 24.517(5) Å and Z = 4. A thermogravimetric analysis has indicated that the thermal stability of the aqua(butyl) cobaloxime was increased in its α-cyclodextrin inclusion complex.
Assingments of Tri- and Tetrapeptide Sequences in Globular Proteins to the 18 Kinds of Local Structures along Helices and Their Propensities for Specific Local Structures
Authors: Narita Mitsuaki , Mochizuki Akihiko , Ohuchi Shoukichi 
Published: September 2002

Abstract
The genetic information for local structures along helices, encoded in local sequences of protein chains, was statistically investigated for tri- and tetrapeptide sequences (3- and 4-letter words) using the 411 analyzed protein chains. The 18 kinds of local structures adopted by tri- and tetrapeptide sequences were represented 1-dimensionally by using a single helix element and pairs of helix elements in parentheses, respectively. The local sequences have propensities for none to some specific local structures along helices. A local structure (LS)-value is introduced for the evaluation of the normalized preference (NP)-value of a local sequence for a particular local structure. It should be emphasized that N-capping tetrapeptide sequences of helices do not necessarily prevent helix elongation. Local structures adopted by tetrapeptide sequences are plastic, and a particular local structure along helices is determined by the sequence context of helices.
Enzymatic Synthesis of Soluble Polyphenol
Authors: Oguchi Takahisa , Tawaki Shin-ichiro , Uyama Hiroshi , Kobayashi Shiro 
Published: September 2002

Abstract
Enzymatic oxidative polymerization of phenol using peroxidase as catalyst has been carried out in a mixture of alcohol and buffer. Hydrogen peroxide (oxidizing agent) was added dropwise to the reaction mixture. Effects of the reaction parameters have been systematically investigated. The polymer solubility strongly depended on the buffer pH and content, and a polymer soluble in N,N-dimethylformamide (DMF) was obtained in good yields under appropriate reaction conditions. The solvent composition also affected the regioselectivity of the polymer. Purity and amount of the enzyme also affected the polymerization behaviors. By changing the concentration and addition rate of hydrogen peroxide, the molecular weight and solubility of the polymer could be controlled. Some solid properties of the resulting polyphenol were evaluated. From thermal analysis, the polymer was found to possess relatively high thermal stability.
Antibacterial Activity of Arg/Pro-Rich Bactenecin 5 Model Peptides and Their Interaction with Phospholipid Membranes
Authors: Niidome Takuro , Tsuiki Masashi , Tokunaga Yoko , Hatakeyama Tomomitsu , Aoyagi Haruhiko 
Published: September 2002

Abstract
H-Arg-Phe-Arg-Pro-Pro-Ile-Arg-(Arg-Pro-Pro-Phe)n-NH2 (n = 2—5 and 7), models of antibacterial bactenecin 5, were synthesized. The CD measurement showed that they took polyproline II-like conformations in neutral lipid vesicles at 25 and 50 °C, and in acidic ones at 25 °C. However, their conformations changed in acidic lipid vesicles at 50 °C. The membrane perturbation activity of the peptides was also found only for acidic lipid vesicles at 50 °C. The perturbation activity increased with increasing in the peptide chain length. All peptides exhibited negligible hemolytic activity for rabbit erythocytes, whereas they, except for the shortest peptide, had moderate or strong antibacterial activity against Gram-positive and Gram-negative bacteria. Together with the previous results, the N-terminal cationic portion and a certain peptide chain length were found to be important for antibacterial activity.
Structures and Ionization Energies of Some Bis- and Tris(3,4-dimetala-1-butyne-1,4-diyl)s Containing Group 14 Elements as Key Metal Atoms: Tetragermacycloocta-1,5-diyne, Hexasilacyclododeca-1,5,9-triyne, Hexagermacyclododeca-1,5,9-triyne, and Related Compounds
Authors: Nakadaira Yasuhiro , Komoriya Haruhiko , Kakuma Seiji , Kako Masahiro , Mochida Kunio , Yasui Masanori , Iwasaki Fujiko , Shimoda Masakatsu , Matsumoto Fuyuhiko , Yashikawa Masao 
Published: September 2002

Abstract
By X-ray crystallographic analysis, the molecular structure of 3,4,7,8-tetragermacycloocta-1,5-diyne 1b has been established to be planar and quite similar to that of silicon analog 3,4,7,8-tetrasilacycloocta-1,5-diyne 1a. The detailed comparison of structures of cyclic acetylene analogs including a group 14 element shows that ring strain induced by the ethynylene units may be released in a different manner by the carbocycle and by its group 14 metalloid analogs. In contrast to cycloocta-1,5-diynes, structures of the higher homologs, 3,4,7,8,11,12-hexasilacyclododeca-1,5,9-triyne 2a and 3,4,7,8,11,12-hexagermacyclododeca-1,5,9-triyne 2b were determined by X-ray crystallographic analyses to adopt a chair-like conformation. Ionization energies of these 3,4-dimetala-1-butyne-1,4-diyls in condensed phase were obtained by photoelectron spectroscopic methods.
Novel Carbon-Carbon Bond Formation through Mizoroki-Heck Type Reaction of Silanols and Organotin Compounds
Authors: Hirabayashi Kazunori , Ando Jun-ichi , Kawashima Jun , Nishihara Yasushi , Mori Atsunori , Hiyama Tamejiro 
Published: September 2002

Abstract
The reaction of dimethyl(phenyl)silanol with butyl acrylate in the presence of a stoichiometric amount of Pd(OAc)2 or by a combined use of 0.1 molar amount of Pd(OAc)2 and Cu(OAc)2/LiOAc (molar ratio 3/2) gave butyl cinnamate in 76% or 57% yield, respectively. The similar reaction with tributyl(phenyl)tin also proceeded in 77% yield. The organotin compound was shown to react faster than the silanol, although the tin reagent sometimes induced undesirable homo-coupling, while the reaction with silanol did not give such by-product.
Synthesis of Some New Sol-Gel Derived Metal-Organic Compounds and Their Hydrolysis-Condensation Reactions
Authors: Sener Sadiye , Sayilkan Hikmet , Sener Engin 
Published: September 2002

Abstract
This work comprised the following parts: a) hydrolysis of Ti(OEt)4 and Zr(OPr)4 with different amounts of water, b) complexation of the same alkoxides with varying amounts of 2-methylbutanoic and 3-methylbutanoic acids, and c) hydrolysis of complexation products with varying amounts of water.
All reactions were carried out at room temperature. The complex products were [Ti(OEt)3.2(2-MBA)0.8], [Ti(OEt)3.2(3-MBA)0.8], [Zr(OPr)2.5(2-MBA)1.5], and [Zr(OPr)3.3(3-MBA)0.7] (2-MBA: 2-methylbutanoate, 3-MBA: 3-methylbutanoate). The products were characterized by 1H NMR, FT-IR, and elemental analysis. While Ti(OEt)4, [Ti(OEt)3.2(2-MBA)0.8], and [Ti(OEt)3.2(3-MBA)0.8] were hydrolyzed with 1.30, 1.28, and 1.30 mol of water, Zr(OPr)4, [Zr(OPr)2.5(2-MBA)1.5], and [Zr(OPr)3.3(3-MBA)0.7] were hydrolyzed with 2.0, 0.96, and 1.10 mol of water, respectively. These products were characterized by gas chromatography (GC), Karl-Fischer coulometric titrations, and thermal analysis.
Chemoselective Transfer Hydrogenation Reactions over Calcined-Layered Double Hydroxides
Authors: Jyothi Thundi Madathil , Raja Thirumalaiswamy , Talawar Mahadev B , Sreekumar Kurungot , Rajagopal R , Rao Bollapragada S 
Published: September 2002

Abstract
The transfer hydrogenation of aromatics containing various reducible groups has been carried out employing isopropanol as a hydrogen donor in the presence of different calcined LDHs. It was found that the NiII-AlIII (mol ratio 3) catalyst is highly active in bringing about chemoselective reduction compared to other calcined LDHs.
Construction of C60 Monolayer Based on Structural Relaxation on the Water Surface
Authors: Yanagida Masami , Takahara Atsushi , Kajiyama Tisato 
Published: September 2002

Abstract
A C60 monolayer was constructed by a multi-step creep method for the first time. In the case that a dilute C60 benzene solution of 1×10-5 M (1 M = 1 mol dm-3) was spread on the water surface, C60 molecules formed into highly organized 2-dimensional crystalline domains. On the other hand, in the case of the conventional continuous compression method up to a low surface pressure below 15 mN m-1, the C60 monolayer-like aggregates were formed with a lot of vacancies. Each monolayer-like C60 aggregate was easily collapsed into small fragments and changed into 3-dimensional aggregates at a high surface pressure above 20 mN m-1. The C60 film could not full up the vacancies during continuous compression, since the C60 molecules formed rigid aggregates. These results clearly indicate that structural relaxation at a low surface pressure was required to construct the defect-diminished C60 monolayer. The occupied area of a C60 molecule in the monolayer prepared by the multi-step creep method was in good agreement with that of a 2-dimensional C60 crystal calculated from lattice constants of a 3-dimensional C60 crystal. The surface morphology of the C60 monolayer prepared by the multi-step creep method was homogeneous, and C60 molecules in the monolayer were closely and regularly packed in a hexagonal array. The hexagonal packing of the C60 molecules was confirmed on the basis of atomic force microscopic and electron diffraction observations.
A New Parameter for Maturity Determination of Organic Matter in Sediments Based on the Clay-Catalyzed Thermal Isomerization of Monomethylphenanthrenes
Authors: Nomoto Shinya , Hagiwara Masayosi , Nakano Yoshinobu , Shimoyama Akira 
Published: September 2002

Abstract
Monomethylphenanthrenes (MPs) were isomerized by heating in the presence of Na-montmorillonite at 250—400 °C. Isomerization between 1- and 2-MP was found to proceed faster than those between the other sets of MPs. On the basis of this facile interconversion, the molar ratio of 1- to 2-MP was suggested to be a useful new parameter for the maturity assessment of sedimentary organic matter. This parameter was tested in a geochemical study on Miocene to Pliocene sediments in the Shinjo basin of Yamagata Prefecture. We determined the molar ratio in 12 depth-differing sediments, and found an almost linearly decreasing trend in the ratio with increasing depth, showing a good correlation of this parameter to the maturity of the sedimentary organic matter.
Gold Valence Transition and Phase Diagram in the Mixed-Valence Complexes, M2[AuIX2][AuIIIX4] (M = Rb, Cs; X = Cl, Br, and I)
Authors: Kojima Norimichi 
Published: September 2002

Abstract
In this paper, I review the structural and physical properties of the gold mixed-valence complexes, M2[AuIX2][AuIIIX4] (M = Rb, Cs; X = Cl, Br, and I), having perovskite-type structure. In spite of the three dimensional perovskite-type structure, the charge transfer interaction between AuI and AuIII in these complexes is two-dimensional. These complexes undergo the pressure-induced Au valence transition from the mixed valence state of AuI,III to the single valence state of AuII, which is coupled with a structural phase transition. In the pressure region below the Au valence transition, these complexes show a metallic behavior, which would be attributed to a dynamic two-electron exchange between the AuI and AuIII states (i.e. highly mobile bipolarons). The metallic cubic phase appearing commonly for these complexes under high pressure and high temperature can be obtained as a metastable phase even at ambient pressure and room temperature. Moreover, as a recent topic, I report the photo-induced Au valence transition for Cs2[AuIBr2][AuIIIBr4].
A Novel Tetralithium Salt of a Tetraanion and a Dilithium Salt of a Dianion, Formed by the Reduction of the Tetrasilylethylene Moiety. Synthesis, Characterization, and Observation of an Si-H···Li+ Interaction
Authors: Matsuo Tsukasa , Watanabe Hidetoshi , Sekiguchi Akira 
Published: September 2002

Abstract
2,3,6,7-Tetrakis(trimethylsilyl)-1,1,4,4,5,5,8,8-octamethyl-1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene (3) was prepared starting from 2,3,6,7-tetrakis(dimethylsilyl)-1,1,4,4,5,5,8,8-octamethyl-1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene (1). The molecular structures of 1 and 3 have been determined by X-ray crystallography. Compound 1 has an almost planar structure, whereas compound 3 exhibits a highly folded structure due to the steric repulsion of the trimethylsilyl groups. Treatment of 1 and 3 with lithium metal yielded the corresponding tetralithium salts of the tetraanions 4 and 5, in which the two tetrasilylethylene units were subjected to two-electron reduction. 2,3-Bis(dimethylsilyl)-1,1,4,4-tetramethyl-1,4-disila-1,4-dihydronaphthalene (6), which has a half unit of 1, was reacted with lithium metal to give the dilithium salt of the dianion (7). Evidence for an interaction between the Si-H and the Li+ ion of 4 and 7 in both solid state and solution is also given.
A Thermodynamic Theory of Suspension I. Thermodynamic Theory
Authors: Furukawa Junji 
Published: September 2002

Abstract
The stability of a colloid has been treated in terms of repulsion by electric charge and attraction by cohesion of particles, but colloid particles are v-times larger in volume-size than the solvent molecules. v is as large as 103-6 and the molar energy of cohesion H/v is negligibly small compared with the electric repulsion energy Wel/v. Cohesion acts over the distance of 1—5 Å or only at the contact point. H does not increase with v, contrary to the DLVO theory. The molar energy of sedimentation Wsed/v is taken as an influential factor for the stability of a colloid of large particles. It is calculated from Stokes law as Wsed/v = Δρ u2, where Δρ is the density difference and u is the stationary velocity of sedimentation equal to (Δρ/η)(2/9)gr2, where η, r, and g are viscosity of solvent, radius of particle, and acceleration constant of gravity, respectively. Sedimentation occurs when Wsed/v is equal to kT/3, i.e., the perpendicular component of the energy of Brownian motion. The critical radius rc is rc = 30C nm, where C = 10 (η2/Δρ3)1/4 and k is Boltzmann's constant. rc is 10—100 nm for inorganic sol, above 100 nm for organosol and aerosol. A theory of colloidal solution is proposed by using a lattice model of size v. Molar free energy of mixing ΔG of the volume fraction of particles φ is ΔG = [(1-φ) ln (1-φ) + (φ/v) ln (φ/v)] R T + (φ Wsed-φ2Wel + φ2H)/v. Solubility is φ = [1- (r/rc)]/[1 + (1/v2) + (H-Wel)/v RT]. Wsed is absorbed internally in the dispersion system. When r &gt; rc, sedimentation takes place to form muddy mixtures including agglomerates of particles. Cohesion acts only at a contact point and is negligibly small.
Energy Transfer and Guest Responsive Fluorescence Spectra of Polyrotaxane Consisting of α-Cyclodextrins Bearing Naphthyl Moieties
Authors: Tamura Makio , Ueno Akihiko 
Published: September 2002

Abstract
We constructed a polyrotaxane (1) composed of about 15 α-cyclodextrins, each bearing roughly two naphthalene units and a polyethylene glycol (PEG) as a threading chain with adamantane groups at both ends. The product was characterized by 1H NMR, 13C NMR, and absorption spectroscopies. We observed that photoenergy transfer occurs from the naphthalene units of 1 to 5-dimethylamino-1-naphthalenesulfonyl (dansyl) of dansyl modified β-cyclodextrin (Dnsβ-CD) when Dnsβ-CD forms a complex with each terminal adamantane moiety of the polyrotaxane. This energy transfer was reduced by the addition of adamantanol, which acts as a competitive binder for Dnsβ-CD.
Preparation and Spectroscopic Characterization of 2 : 1 Molecular Complexes of Tetracyanoethylene and meso-Tetraphenylporphyrins
Authors: Mohajer Daryoush , Dehghani Hossein 
Published: September 2002

Abstract
Different para-substituted meso-tetraphenylporphyrins (H2T(4-X)PP, X = H, Cl, CH3, CH(CH3)2, OCH3) react with various molar ratios of tetracyanoethylene (TCNE) in dichloromethane or benzene and produce only the 1 : 2 molecular complex, (TCNE)2H2T(4-X)PP. The remarkable agreement between the corresponding 1H, 13C solution (CDCl3) NMR resonances of the porphyrin moiety in these complexes with those of tetraphenylporphyrin dication, H4TPP2+, and also the strong resemblance between their UV-vis spectra and the spectra of the related diprotonated porphyrins indicates similar out-of-plane distorted porphyrin core structure in all of them. Based on these close spectral correspondences among the various molecular complexes and the related diprotonated porphyrins, and also consideration of the known structure of H4TPP2+Cl2- species, it is proposed that the two TCNEs in (TCNE)2H2T(4-X)PP complexes are bonded from above and below the mean porphyrin plane to the lone electron pairs of the pyrrolenine nitrogens of the porphyrins.Spectral data (13C, IR) of the bonded TCNEs in the molecular complexes seem to be most consistent with the interaction of an acceptor π* orbital centered at a CN group of the TCNEs with the porphyrin core nitrogen donors.
Evaluation of Novel Local Structural Parameters of Acids and Bases for 1 : 1 Hydrogen-Bond Complexation I. OH-, NH-Acids and Phosphorus Bases in Carbon Tetrachloride
Authors: Mishima Shozi , Nakajima Tsuyoshi , Fujii Tsuneo 
Published: September 2002

Abstract
Novel local structural parameters, η° and ω°, representing the nature of the functional group and the residual moiety (supporting group) of acid and base molecules, respectively, have been evaluated for the first time for the 1 : 1 hydrogen-bond complexation of nine OH- or NH-acids and five phosphorus bases in CCl4. An evaluation of η° and ω° was carried out by making use of convergent linear relationships among the log K values and by introducing three numerical criteria. For acid-base complexation, all of the 180 log K values at 288.15—318.15 K and 45 ΔHf° values were reproduced from the η and ω values within the experimental error. The reversals in the order of log K and ΔHf° observed in the system could be reasonably explained by applying the η° and ω° scales.