bluuebunny/crossref_metadata_2025 huggingface dataset:
Extension of Protein Functions by the Incorporation of Nonnatural Amino Acids
Authors: Sisido Masahiko , Hohsaka Takahiro
Published: November 2004

Site-specific mutagenesis of proteins was extended to incorporate nonnatural amino acids through in vitro cell-free translation or through in vivo translation in the living cells. To this end, a variety of nonnatural amino acids were synthesized and linked to tRNA by chemical aminoacylation. Further, unique codon/anticodon pairs were derived, such as the 4-base codon/anticodon pairs that are orthogonal to the conventional 3-base codon/anticodon pairs. By the extension of amino acids and the genetic codes, site-directed incorporation of specialty amino acids into a variety of proteins has been achieved. Amino acids that carry large aromatic side groups with straight configurations, such as 2-anthrylalanine and 2-anthraquinonylalanine were successfully introduced into proteins and the CGGG or AGGU 4-base codons were used to assign their positions.

Amino acids carrying photocleavable side groups, a spin probe, fluorescent probes, and other functional groups have been introduced into proteins. The specialty proteins were shown to be powerful tools for biochemical research and are expected to be novel molecules with designed arrangements of functional groups on the protein framework.
Synthesis and Characteristics of Complex Multicomponent Oxides Prepared by Polymer Complex Method
Authors: Kakihana Masato , Yoshimura Masahiro
Published: November 2004

This account focuses on the synthesis and characteristics of ceramics prepared by the Pechini-type in-situ polymerizable complex (IPC) method. The current status of the IPC method is reviewed, and the principle and underlying chemistry of the IPC method is illustrated with a special emphasis on its intrinsic advantage over other solution-based technologies. The method has the ability to prepare complex multicomponent oxides with good homogeneity through mixing at the molecular level. The importance of “polymerization” itself in the IPC route is demonstrated by comparing with the non-polymerizable so-called amorphous citrate method, which affords less compositional homogeneity. The use of heterometallic complexes in the IPC processing is shown to be one of the most promising techniques to synthesize ceramics with exceptionally good homogeneity. It is one function of this account to describe how Raman and 13C NMR spectroscopies can be effectively used for characterizing precursors in the IPC processing. Finally, it is demonstrated that another type of polymer complex solution (PCS) method overcomes the serious drawback of the IPC method; i.e. the amount of organics required for the PCS method is less than that required for the IPC method by a factor of about 20.
Aromatic β-Silylethenylation Reactions via Organogallium Compounds
Authors: Kido Yoshiyuki , Yoshimura Satoru , Yamaguchi Masahiko , Uchimaru Tadafumi
Published: November 2004

In the presence of GaCl3, silylethyne reacted electrophilically with aromatic hydrocarbons to give β-silylethenylated arenes. The reaction proceeded via cationic species generated by the interaction of GaCl3 and silylethyne. High reactivity of the intermediate was demonstrated by the rapid reaction rate at −78 °C using close to the equimolar amount of the substrates. ipso-Substitution reaction took place with 1,2,3-trimethoxybenzene. Structures and properties of several organogallium compounds involved in the reactions are discussed.
A Theoretical Study of the Crystal HgCl2 Compound
Authors: Liao Meng-Sheng , Zhang Qian-Er
Published: November 2004

A theoretical study of the crystal HgCl2 compound has been done using a quasi-relativistic density-functional method. The crystalline environment was simulated by a cut-off type Madelung potential. Bond length, dissociation energy, force constants, and sublimation enthalpy are calculated. The calculated properties are in goon agreement with available experimental data. The calculated difference in bond length between the isolated and crystalline molecule is consistent with the data obtained by the more recent gas-phase electron diffraction and X-ray single crystal measurements. The predicted symmetrical and antisymmetrical force constants (ks, kas) and their trend (kas > ks) are in accordance with the Raman and IR data. The trend is in contrast to the free molecule case, where kas < ks. The sublimation enthalpies of hypothetical HgX2 (X = F, Cl, Br, I) compounds with the XeF2-type structure are evaluated. It is shown that the XeF2-type structures for HgX2are significantly less stable than the actual structures.
Numerical Study on the Response of a Minimal Chemical Oscillator to an External Perturbation
Authors: Sasaki Yoshihiro
Published: November 2004

The response of a sinusoidally perturbed minimal chemical oscillator was simulated over a wide range of perturbation parameters. Under a weakly perturbed condition, the system exhibited entrainment, quasiperiodicity and a Farey tree; under a more strongly perturbed condition, two types of chaos, small-amplitude oscillations and the coexistence of two oscillation modes were found. Phase-shifting of a kicked oscillator was considered in order to understand the entrainment.
Classical Dynamics of the Hydrogen Atom and Muonium Trapped in Diamond Clusters: A Direct Ab-initio Dynamics Study
Authors: Tachikawa Hiroto , Shimizu Akira
Published: November 2004

Direct ab-initio dynamics calculations have been carried out for hydrogen and muonium (Mu) trapped in a C10H16 cluster model in order to elucidate qualitatively the finite temperature effect on f-value ( = |ΦH(0)|2/|Φvac(0)|2, where |Φvac(0)|2 is the contact spin density on H nuclei in vacuum and |ΦH(0)|2 is one in the model cluster). In the dynamics calculations, a split-valence type basis set (31G) was used for the central hydrogen atom and a minimal basis set STO-3G for the cluster model. All atoms were treated as classical particles moving on the ab-initio full dimensional surface including all degrees of freedom calculated at the Hartree–Fock level. Three temperatures, 300, 600, and 1000 K, are chosen as simulation temperatures. The averaged f-values are obtained for each temperature by using MP2/3-21G* level. In addition, the f-value corresponding to 0 K is calculated by the static ab-initio MO calculation (i.e., without dynamics effect). The f-values for 0, 300, 600, and 1000 K were calculated to be 1.224, 1.211, 1.200, and 1.185, respectively, indicating that the f-value linearly decreases with increasing temperature. The f-value was simply expressed by the equation f (T) = f(T = 0 K)[1−0.325 × 10−5  T]. The present calculations indicated that the f-value is slightly affected by the thermal activation, the shift of f-value is small. This work is the first attempt to calculate the finite-temperature effect on the f-value at the ab-initio dynamics level.
Enhanced Formation of Ozone by the Addition of Chloropicrin (Trichloronitromethane) to Propene/NO/Air/Photoirradiation Systems
Authors: Hatakeyama Shiro , Imamura Takashi , Washida Nobuaki
Published: November 2004

The photolysis of chloropicrin in air at 1 atm was performed in a 6-m3 photochemical reaction chamber with a combination of Xe arc lamps and Pyrex filters as a light source. Phosgene was obtained as one of the main products with a yield of unity. No nitrosyl chloride was observed, which supports the C–N scission mechanism for the photolysis. Photochemical ozone formation was enhanced when chloropicrin was added to the propene/NO/air/photoirradiation system after the ozone concentration maximum had been reached. The ozone-formation factor for chloropicrin under the conditions employed was, however, estimated to be 0.25 mole of ozone formed per mole of the decomposed chloropicrin. This implies that the Cl atom, itself, contributes to the destruction of ozone rather than to the formation of ozone under the experimental conditions. NO2 released from chloropicrin is the source of enhanced ozone. If the amount of chloropicrin as a soil fumigant increases, it can cause an increase of the ozone concentration in suburban and/or rural areas.
Assembly of Methylene Blue on Nucleic Acid Template as Studied by Resonance Light-Scattering Technique and Determination of Nucleic Acids of Nanogram
Authors: Huang Cheng Zhi , Li Yuan Fang , Deng Shi You , Liu Shu Rong
Published: November 2004

The template role of nucleic acids in the long-range assembly of Methylene Blue (MB) was characterized with Resonance Light-Scattering (RLS) measurements, and a determination method of nucleic acids of nanogram was proposed. At the pH range 6.87—8.74 and ionic strength lower than 0.01, the interactions of MB with nucleic acids result in two characteristic RLS peaks at 355.0 and 560.0 nm. Mechanism studies show that these peaks result from the long-range assembly of MB on the molecular surface of nucleic acids. A Scatchard plot was constructed by using the RLS data, yielding an assembly number and assembly constant of 5.67 and 9.22 × 104 mol−1 dm3 for MB assembly on the molecular surface of calf thymus DNA (ctDNA), 5.79 and 4.68 × 104 mol−1 dm3 for MB assembly on that of fish sperm DNA (fsDNA). This assembly could be used for analytical purposes and 0—1.4 μg ml−1 for ctDNA, 0—1.2 μg ml−1 for fsDNA, and 0—0.24 μg ml−1 for yeast RNA could be determined if 3.0 × 10−5 mol dm−3 MB was employed. The limits of determination were 11.0 ng ml−1 for ctDNA, 4.9 ng ml−1 for fsDNA and 8.6 ng ml−1 for yeast RNA, respectively. Four synthetic samples were determined with satisfaction.
The Structure of a Meso-Type Heteropolyion of Tetrahydrogen Disodium Dodecamolybdohexaphosphonate(III) (6−) Contained in [NEt4]6[H4Na2(PH)6Mo12O54]·4H2O
Authors: Hori Toshitaka , Taniguchi Nobuko , Himeno Sadayuki , Sano Ken-ichi , Tamada Osamu
Published: November 2004

The structure of [NEt4]6[H4Na2(PH)6Mo12O54]·4H2O (1) has been determined by the single-crystal X-ray method. The crystals are monoclinic, space group of C2/c, with cell parameters a = 23.790(3), b = 16.319(2), c = 28.788(3) Å, β = 114.365(7)°, and Z = 4. The structure model was refined by full-matrix least squares to R = 0.0624 and Rw = 0.0661 for 6798 independent reflections with Fo > 3σ(F) and in 2θ < 50°. The existence of a meso-type heteropolyion [H4Na2(PH)6Mo12O54]6− (2) in the title crystals has been confirmed. It is composed of a pair of enantiomeric moieties of [H2Na(PH)3Mo6O27]3− (3 and 3i, respectively) which are linked by sharing Na+ ions; here, the superscript i denotes the symmetrical operation code of (1/2−x, 1/2−y, −z). The six MoO6-octahedra contained in the respective moieties are arranged to form Plus- and Minus-helices.
Evaluation of the Stability Constants for Alkaline-Earth Metal Complexes with Dodecaoxohexaphosphate(III) Using EDTA as a Complexation-Competing Agent
Authors: Nakashima Toshio , Waki Hirohiko , Tanaka Taichi , Sugihara Gohsuke
Published: November 2004

The stability constants for complexes of a ring oxoanion of phosphorus dodecaoxohexaphosphate(III), with magnesium, calcium, and strontium were evaluated in aqueous solutions at an ionic strength of 0.1. A new spectroscopic equilibrium analysis for a system involving complexes of very high stability was accomplished by introducing EDTA as a complexation-competing agent to the system. The logarithmic stability constant values for the magnesium, calcium, and strontium complexes were found to be 8.4, 8.8, and 7.5, respectively, whose stability order was different from that of a simple one expected from their ionic radii.
Schiff-Base Complexes of Metal(II) as New Catalysts in the High-Regioselective Conversion of Epoxides to Halo Alcohols by Means of Elemental Halogen
Authors: Sharghi Hashem , Naeimi Hossein
Published: November 2004

The ring opening of epoxides with elemental iodine and bromine in the presence of some Schiff-base complexes of the first-row transition metal(II) as new catalysts affords vicinal iodo alcohols and bromo alcohols in high yields. This new procedure occurs regioselectively under mild conditions in various aprotic solvents. The catalysts are easily recovered and can be reused several times.
Cyclodextrin Complexes of Bisepoxide and of α,ω-Diamine in Several Molar Ratios. Preparation and Characterization in the Solid State
Authors: Yamaguchi Isao , Ishii Hidetake , Osakada Kohtaro , Yamamoto Takakazu , Fukuzawa Shin-ichi
Published: November 2004

Addition of 1,4-butanediol diglycidyl ether (glycidyl = 2,3-epoxypropyl) to aqueous solutions of α-cyclodextrin (CD) leads to separation of the 2 : 1 complex from the solution. The 13C CP/MAS NMR spectrum of the complex indicates the presence of diastereomeric oxirane groups formed via the complexation. 1,4-Butanediol diglycidyl ether forms the 1 : 1 or 2 : 2 complex with γ-CD similarly from the aqueous reactions of the two compounds. 2,2-Dimethyltrimethylene glycol diglycidyl ether also forms water-insoluble host–guest complexes with α-CD (2 : 1) and with γ-CD (1 : 1 or 2 : 2). Poly(propylene glycol diglycidyl ether) with an Mn of 640 reacts with β-CD to give the 1 : 4 complex. Poly(tetrahydrofuran) terminated with NH2 groups at both ends also forms the 1 : 4 complexes both with α-CD and with γ-CD.
Sequence-Specific Hybridization between Two Different Types of Peptide Nucleic Acids
Authors: Kuwahara Masayasu , Arimitsu Miki , Sisido Masahiko
Published: November 2004

Nielsen’s-type peptide nucleic acids (PNA) and the oxy-PNA (OPNA), both carrying thymine or adenine bases, were prepared. Hybridizations were observed not only between the complementary pairs of PNA(A12)–DNA(T12) and OPNA(A12)–DNA(T12), but also between the complementary pairs of the artificial nucleic acid analogues, OPNA(A12)–PNA(T12). In the three-component mixture of PNA(T12)–DNA(T12)–OPNA(A12), OPNA(A12) was found to hybridize preferentially with DNA(T12). Addition of DNA(T12) to a preformed duplex of OPNA(A12)–PNA(T12) gave rise to a strand displacement to form a OPNA(A12)–DNA(T12) duplex. No triplex formation was detected in the three-component mixture.
Total Synthesis of a Macrocyclic Antibiotic, Micrococcin P
Authors: Okumura Kazuo , Nakamura Yutaka , Shin Chung-gi
Published: November 2004

The first total synthesis of a macrocyclic antibiotic, micrococcin P (1), was accomplished. After constructing the central 2,3,6-tristhiazolyl-substituted pyridine skeleton [Fragment A—C segment] (21) from ethyl 2-(2-bromoacetyl-6-dimethoxymethyl-3-pyridyl)thiazole-4-carboxylate (15) in 11 steps, successive fragment condensations of 21 with ethyl 2-[(Z)-1-(O-t-butyldiphenylsilyl-l-threonylamino)-1-propenyl]thiazole-4-carboxylate (29) and (S)-1-(O-methoxymethyl-l-threonylamino)-2-(O-methoxymethyl)-2-propanol (25) [the protected Fragments B and D moieties, respectively] gave the protected Fragment A–B–C–D segment 34. Subsequent deprotection of all the protecting groups of 34 with trifluoroacetic acid and then cyclization by using BOP as condensing agent under high dilution conditions gave the expected micrococcin P (1). The synthetic 1 was identical with the natural 1 with respect to the chemical and physical properties.
Highly Efficient Photoinduced DNA Cleavage by Naphthopyrone Hydroperoxides
Authors: Tao Zhi-Fu , Qian Xuhong , Fan Mingcai
Published: November 2004

A variety of naphthopyrone hydroperoxides as novel photochemical DNA cleavers were synthesized and evaluated. Their photochemical DNA-cleaving abilities depend on skeleton arrangement of the naphthopyrone core and are much more efficient than those of the reported 1,8-naphthalenedicarboximide analog. The DNA-cleaving mechanism by these new hydroperoxides probably mainly involves hydroxyl radicals, indicating that naphthopyrone hydroperoxides may be able to serve as a new class of intercalating photo-Fenton reagents.
Significance of the 72-Membered Macrocyclic Structure Found in Archaeal Membrane Lipids: Model Studies of the Macrocyclic Tetraether Diphospholipids by Calorimetric, 31P NMR, and Electron Microscopic Analyses
Authors: Arakawa Kenji , Kano Hiroki , Eguchi Tadashi , Nishiyama Yayoi , Kakinuma Katsumi
Published: November 2004

Described in this paper are the characterizations of the synthetic 72-membered macrocyclic tetraether phospholipids (7, 8) and their acyclic congeners (9, 10), the hydrocarbon chains of which are unbranched straight chains instead of isoprenoid chains such as found in those of archaea. Thermal analyses by differential scanning calorimetry (DSC) clearly showed that the phase transition temperature (Tc) of the cyclic tetraether lipids 7 and 8 was rather lower than those of the corresponding acyclic counterparts 9 and 10. This trend was opposite to that of the diether lipids. The findings from 31P NMR and electron microscopic analyses suggested that the lipid polymorphism of 7 and 8 was quite different from that of 9 and 10. These results revealed that the cyclic structure in 7 and 8 contributed not only to the limitation of motional freedom at the hydrophobic region but also to the change of the lipid polymorphism in comparison with 9 and 10. Furthermore, it was found that these physicochemical as well as polymorphic properties were indistinguishable between the regioisomers 7 and 8 (or 9 and 10).
Proto- and Iodo-lactonization Reaction of Substituted α,β : γ,δ-Unsaturated Carboxylic Acid
Authors: Kuroda Chiaki , Tang Chen Ying , Tanabe Makoto , Funakoshi Masabumi
Published: November 2004

Iodolactonization of 4,5-disubstituted 2-(trimethylsilylmethyl)- and 2-methyl-penta-2,4-dienoic acids was studied. The latter afforded the corresponding iodolactone in good yield by treatment with I2 in MeCN. Iodolactone was also obtained by treatment with I2/NaHCO3/CHCl3/H2O in the presence of cerium(IV) salt as an additive. It was found that protolactonization proceeds by the aid of the trimethylsilyl group, while it prevents iodolactonization.
Thiocrown Ether Additive Effects on Diastereoselectivity of the Lipase-Catalyzed Reaction: Preparation of Optically Active 3-Hydroxy-2-methylalkanenitriles through a Double Enzymatic Reaction Strategy
Authors: Mitsukura Koichi , Choraku Hiroko , Da San Thi , Itoh Toshiyuki
Published: November 2004

The additive effect on diastereoselectivity towards the lipase-catalyzed hydrolysis of acetates of 3-hydroxy-2-methyl- or 3-hydroxy-2-ethylalkanenitriles has been investigated. Diastereoselectivity was not influenced by thiocrown ether additives, although a significant modification of enantioselectivity was observed. Origin of the diastereoselectivity of the lipase-catalyzed reaction was thus evidently different from that of enantioselectivity. Based on these results, an easy preparation of optically active 3-hydroxy-2-methylpentanenitrile and 3-hydroxy-2-methylbutanenitrile have been demonstrated through lipase-catalyzed reaction by a double enzymatic reaction strategy.
Neighboring Group Participation by Heteroaromatic Rings: The Wagner–Meerwein Type Skeletal Rearrangement in the Electrophilic Addition Reactions of Norbornadiene-Fused Furans, Pyrroles, and Thiophenes
Authors: Kobayashi Tomoshige , Tsuzuki Takeo , Saitoh Mayu
Published: November 2004

The electrophilic addition reactions of norbornadiene-fused furans, pyrroles, and thiophenes with bromine, arenesulfenyl chlorides, or a triazoledione generally afforded skeletally rearranged adducts except for a dibenzoyl-substituted thiophene. The formations of the adducts are attributable to the neighboring group participation by five-membered heteroaromatic rings, accompanied by the formations of bridged heteroarenium ions and the subsequent Wagner–Meewein type skeletal rearrangement.
Effect of a Catalyst on the Formation of SiC Whiskers from Polycarbosilane. Nickel Ferrite as a Catalyst
Authors: Otoishi Shinji , Tange Yoshihiro
Published: November 2004

The effect of a catalyst, nickel ferrite, on the formation of SiC whiskers from porous bodies containing polycarbosilane and milled carbon fibers was studied. SiC whiskers were deposited at above 1373 K from porous bodies having a catalyst, while noodle-like SiC products were obtained at above 1473 K from porous bodies having no catalyst. A scanning electron-microscopic analysis and an energy-dispersive X-ray analysis revealed that SiC whiskers were formed via a vapor–liquid–solid process. An X-ray diffraction measurement revealed that the whiskers consisted of β-SiC, and that their crystallinity was significantly high in spite of the heating temperature (1373 to 1623 K). Based on changes in the infrared absorption spectra and gas-evolution curves during the heating process, it was presumed that the pyrolyzing process of polycarbosilane in the two kinds of porous bodies, one with a catalyst, and the other without a catalyst, remarkably resembled each other. SiC whiskers were proved to grow remarkably with decreasing the Si–O bondings by infrared spectroscopy and a chemical analysis. It could therefore be presumed that the formation mechanism of the SiC whiskers was analogous to that of silica–carbothermal reduction.
Effects of Mordenite Support on Photodegradation of Gaseous Organic Compounds over TiO2 Photocatalyst
Authors: Takeda Norihiko , Torimoto Tsukasa , Yoneyama Hiroshi
Published: November 2004

Effects of mordenite as a support material for TiO2 on photodegradation rates of gaseous propionaldehyde, acetone, and propane were investigated using TiO2 (50 wt%)-loaded mordenite as a photocatalyst in reference to unsupported TiO2. The supported photocatalyst allowed adsorption of all the substrates several times greater than the unsupported photocatalyst, resulting in higher photooxidation rates for them. Detailed analysis suggests that the enhancement of the decomposition rate caused by the use of mordenite support is more remarkable for lower amounts of adsorption of the substrates on the support. The concentration of oxygen was found to have little influence on the photodegradation rates, suggesting that the rate of degradation of the organic substrates was not decided by photogenerated electron transfer processes but by the consumption of photogenerated holes by adsorbed organic substrates.
Photochromic Reactions of Two Azobenzene Chromophores in a Chiral Cyclohexane Moiety
Authors: Yamaguchi Tadatsugu , Nakazumi Hiroyuki , Irie Masahiro
Published: November 2004

A chiral cyclohexane containing two photochromic azobenzene units, (1R,2R)-N,N′-bis[4-(phenylazo)benzylidene]-1,2-cyclohexanediamine, was synthesized in an attempt to construct a molecule which shows a large optical rotation change due to photoirradiation. The CD spectrum dramatically changed depending on the configuration of the two azobenzene units. The specific rotations of (E,E)-, (E,Z)- and (Z,Z)-isomers were −1400°, −940°, and −670°, respectivly, while that of the monosubstituted chiral cyclohexane, (1R, 2R)-N-[(4-phenylazo)benzylidene]-N′-benzylidene-1,2-cyclohexanediamine ((E)-isomer), was only −470°. There was no difference in the photoisomerization rates of the azobenzene chromophores attached to chiral and nonchiral cyclohexanes.
Liquid-Crystalline Properties of Dissymmetric Molecules Part 3: Smectic Properties of 4-[2-(Perfluoroalkyl)ethoxy]-Substituted Nitrobenzenes and Benzonitriles
Authors: Duan Meili , Okamoto Hiroaki , Petrov Vladimir F , Takenaka Shunsuke
Published: November 2004

This paper describes the thermal properties of some homologs of 4- and 3-[2-(perfluoroalkyl)ethoxy]-substituted nitrobenzenes and benzonitriles. Many of the homologs show notable smectic properties involving smectic A and B phases. The smectic structures were characterized by an X-ray diffraction examination. The smectic A phase has a partially interdigitated bilayer arrangement where the layer spacing is 1.2—1.8 times the calculated molecular length. Interestingly, some homologs show a smectic B phase with a layer spacing of 2 times the calculated molecular length. Both fluorophilic and polar interactions are supposed to play important roles for the molecular arrangements.
Microvoltammetric Study of Electrochemical Hydrogenation of a Surface-Treated Mg2Ni Alloy Single Particle
Authors: Kim Ho-Sung , Nisizawa Matsuhiko , Itoh Takashi , Uchida Isamu
Published: November 2004

The effects of surface treatments on the hydrogen storage properties of a Mg2Ni alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle placed in a KOH aqueous solution. It was found that the hydrogen storage properties of Mg2Ni at room temperature were improved by the surface treatments with a nickel plating solution. The sodium salts (sodium phosphinate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen absorption/desorption capacity at room temperature as high as about 150 mA h g−1 from the original value of 17 mA h g−1.
Interaction of Aminopyridines with Metal Hexacyanoferrates(II)
Authors: Alam Tanveer , Kamaluddin
Published: November 2004

Copper(II) and zinc(II) hexacyanoferrates(II) have been found to be effective adsorbents for aminopyridines, such as 2-amino-, 3-amino-, and 4-aminopyridines. The maximum adsorption was found at neutral pH (pH = 7.0). The adsorption trend followed a Langmuir adsorption isotherm. The Langmuir constants, KL and XM, were determined. The overall adsorption trend was found to be in the order 3-amino- > 4-amino- > 2-aminopyridine. Infrared spectral studies of the adsorption adducts indicate that adsorption takes place through an interaction between the adsorbate molecule and the outer divalent metal ion of metal hexacyanoferrates(II). The results of the present study suggest the importance of metal hexacyanoferrates(II) and metal ions in the stabilization of biomolecules from degradation on primitive earth.
High Magnetic Field Effects on the Lifetimes of Radical Pairs Generated by the Photoreduction of Anthraquinone and n-Alkyl Anthraquinone-2-carboxylates in Micellar Solutions
Authors: Fujiwara Yoshihisa , Yoda Kohji , Tomonari Taro , Aoki Takeshi , Akimoto Yukimi , Tanimoto Yoshifumi
Published: November 2004

The magnetic field effects on the lifetimes of radical pairs (RPs) comprising anthrasemiquinone (AQH·) and alkyl radicals generated in Brij35, HDTCl, and SDS micellar solutions of anthraquinone (AQ) and n-alkyl anthraquinone-2-carboxylates (AQ-n) were studied by laser flash photolysis in high magnetic fields up to 13 T. The RP lifetimes of AQ and AQ-n in the three surfactants increased along with increasing the magnetic field from 0 to about 2 T. The RP lifetimes of AQ in Brij35 and HDTCl drastically decreased in a magnetic field from 3 to 13 T, whereas the RP lifetimes of AQ in SDS were almost constant in the same range of the magnetic field. The increase in the three surfactants was explained by spin-lattice relaxation (SLR) modulated by anisotropic hyperfine and electron dipole–dipole interactions. The drastic decrease in Brij35 and HDTCl was interpreted by SLR modulated by an anisotropic Zeeman interaction. The parameters of the anisotropic g-value and the rotational correlation time for an anisotropic Zeeman interaction were obtained. The constant RP lifetimes in SDS at a high magnetic field were interpreted referring to an escape process of AQH· from the micelle core.
Interpretation of ‘π Energy’ and Its Linear Additivity in Polyenes
Authors: Ichikawa Hiroshi , Yoshida Atsushi , Kagawa Hirotaka , Aihara Jun’ichi
Published: November 2004

The kinetic energy of electrons in a one-dimensional box has the property of a linear additivity with respect to the unit length. This property coincides with that of the π electrons of linear polyenes. Both properties lead to an understanding of why the ‘π energy’ or the Hückel energy includes information about the nuclear configuration based on the molecular virial theorem. This article shows that the linear additivity is a property of the kinetic energy of particles that move in a one-dimensional box, and thus assures that the Hückel energy is another expression of the kinetic energy of π electrons. The reason for the coincidence of both methods is interpreted as meaning that they seek the same stationary wave functions. Thus, we may fairly say that the so-called Hückel energy, ‘π energy’, or the empirical π energy is a quantitative quantity of the kinetic energy of π electrons.

If the interpretation that the ‘π energy’ is the kinetic energy of π electrons is adopted, the explanation for a regular hexagon structure of benzene made by Shaik et al. is reversed.
Isotope Effect in Proton-Transfer and Association–Dissociation Reactions for Butylamine by Ultrasonic Relaxation Methods
Authors: Huang Hua , Nishikawa Sadakatsu , Dong Shaojun
Published: November 2004

Ultrasonic absorption coefficients were measured for butylamine in heavy water (D2O) in the frequency range from 0.8 to 220 MHz and at concentrations from 0.0278 to 2.5170 mol dm−3 at 25 °C; two kinds of relaxation processes were observed. One was found in relatively dilute solutions (up to 0.5 mol dm−3), which was attributed to the hydrolysis of butylamine. In order to compare the results, absorption measurements were also carried out in light water (H2O). The rate and thermodynamic parameters were determined from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. The isotope effects on the diffusion-controlled reaction were estimated and the stability of the intermediate of the hydrolysis was considered while comparing it with the results for propylamine in H2O and D2O. Another relaxation process was observed at concentrations greater than 1 mol dm−3 in D2O. In order to examine the solution characteristics, proton NMR measurements for butylamine were also carried out in D2O. The chemical shifts for the γ- and δ-proton in butylamine molecule indicate the existence of an aggregate. From profiles of the concentration dependence of the relaxation frequency and the maximum absorption per wavelength of sound absorption, the source of the relaxation was attributed to an association–dissociation reaction, perhaps, associated with a hydrophobic interaction. The aggregation number, the forward and reverse rate constants and the standard volume change of the reaction were determined. It was concluded from a comparison with the results in H2O that the hydrophobic interaction of butylamine in D2O is stronger than that in H2O. Also, the isotope effect on this reaction was interpreted in terms of the solvent structure.
Calorimetric Studies on Antiferromagnetic and Structural Phase Transitions of the Metal-Assembled Complex MnCu(obbz)·5H2O
Authors: Asano Kaori , Inoue Kazuhiro , Nakano Motohiro , Miyazaki Yuji , Sorai Michio , Nakatani Keitaro , Kahn Olivier
Published: November 2004

Heat capacities of the molecule-based antiferromagnet MnCu(obbz)·5H2O (obbz = oxamidobis(benzoato)) have been measured at temperatures from 0.1 to 300 K by means of adiabatic calorimetry. A phase transition due to three-dimensional antiferromagnetic ordering was observed at 2.18 K, above which a heat capacity hump appeared, arising from the short-range ordering characteristic of a low-dimensional magnet. The enthalpy and entropy gained at the magnetic phase transition were evaluated to be 48.6 J mol−1 and 12.1 J K−1 mol−1, respectively. This entropy gain is close to the value R ln 5 ( = 13.4J K−1 mol−1) expected for the spin-manifold of the S = 2 ground state. The heat capacity hump above the magnetic transition temperature is explained well by the S = 2 one-dimensional ferromagnetic Heisenberg model with the exchange interaction J/kB = 0.75 K, where kB is the Boltzmann constant. These results confirm that the present complex behaves as a one-dimensional ferrimagnet, in which strong antiferromagnetic coupling exists between a pair of spins of Mn(II) (S = 5/2) and Cu(II) (S = 1/2) but the magnetic interaction is very weak between the pairs. A first-order phase transition was also found at 268.4 K. This transition may arise from orientational order–disorder mechanism of the crystalline water molecules in the complex.
Group-Theoretical Framework for Characterizing the Ring Flipping and N-Inversion of Piperidine Derivatives. Extended Pseudo-Point Groups and Subsymmetry-Itemized Enumeration
Authors: Fujita Shinsaku
Published: November 2004

The ring flipping (F) and the N-inversion (I) of piperidine are discussed by presuming a quadruplet of conformers as a model. After an extended pseudo-point group is defined, the concept of FI-energeticity is proposed. The flexible piperidine derivatives are enumerated on the basis of the model by the unit-subduced-cycle-index approach. The enumerated derivatives are classified into FI-isoenergetic (Types I, I′, and II) and FI-anisoenergetic (Types III and IV) by means of their extended pseudo-point groups.
Kinetics and Mechanism of Tris(pyridine-2-carboxylato)manganese(III) Reduction by Azide Ion in Sodium Pyridine-2-carboxylate–Pyridine-2-carboxylic Acid Buffer Media
Authors: Sen Gupta Kalyan Kali , Pal Biswajit , Bhattacharjee Nandini , Ghosh Saktiprosad
Published: November 2004

The kinetics and mechanism of the reduction of tris(pyridine-2-carboxylato)manganese(III) by azide ion in Na(pic)–picH [where Na(pic) = sodium salt of pyridine-2-carboxylic acid and picH = pyridine-2-carboxylic acid] have been studied. The reaction appears to proceed through the intermediate formation of a hepta-coordinated 1 : 1 complex between [MnIII(pic)3] and N3− ion, which then decomposes to give the free radical () and diaquabis(pyridine-2-carboxylato)manganese(II). The free radical further reacts with [MnIII(pic)3] to give nitrogen as the product of oxidation. During the reduction, pyridine-2-carboxylate ion is generated and the coordination sphere of the parent complex is altered, thereby indicating that the reaction takes place by an inner-sphere mechanism. The enthalpy change (ΔH°) and change in entropy (ΔS°) associated with the equilibrium step are −61 ± 4 kJ mol−1 and −169 ± 14 J K−1 mol−1, whereas the enthalpy of activation (ΔH≠) and the entropy of activation (ΔS≠) associated with the slowest step are found to be 91 ± 4 kJ mol−1 and 11 ± 14 J K−1 mol−1, respectively.
X-Ray Structural Characterization of [Eu(H2O)8]2[V10O28]·8H2O
Authors: Naruke Haruo , Yamase Toshihiro , Kaneko Masahiko
Published: November 2004

Europium decavanadate, [Eu(H2O)8]2[V10O28]·8H2O, crystallizes in triclinic, , a = 9.413(1), b = 9.885(1), c = 23.556(4)Å, α = 81.31(2), β = 82.08(2), γ = 89.51(2)°, V = 2145.8(5)Å3, Z = 2. There are two crystallographically independent [Eu(H2O)8]3+ cations and two centrosymmetric [V10O28]6− anions in a unit cell. Each [Eu(H2O)8]3+ cation achieves eight-fold coordination by aqua-ligands with an approximately square-antiprismatic configuration. The Eu–O distances for the [Eu(H2O)8]3+ cations were found to be 2.38(1)—2.54(1) Å (mean 2.44 ± 0.02 Å). The crystal structure consists of two crystallographically inequivalent [Eu(H2O)8]2[V10O28] layers and interstitial water molecules, the former being piled up alternately along the c-direction, and the latter linking the two adjacent layers with hydrogen-bonds.
Molecular Structure of a μ-Oxo Chromium–Iron Complex: Rare Example of a Crystallographically Characterized μ-Oxo Heterometallic Porphyrin
Authors: Oyaizu Kenichi , Haryono Agus , Nishimura Yukio , Yamamoto Kimihisa , Tsuchida Eishun
Published: November 2004

The crystal structure of a μ-oxo heterometallic porphyrin [(pip)(tpp)CrIIIOFeIII(tpp)] (pip = piperidine) not only confirmed the proposed oxidation state of chromium and iron atoms, but also revealed a unique coordination environment around chromium(III), which is substantially protruded from the porphyrin plane.
Ion Association of Primary Ammonium Ions with Aromatic Anions by Capillary Zone Electrophoresis
Authors: Takayanagi Toshio , Wada Eiko , Oshima Mitsuko , Motomizu Shoji
Published: November 2004

Ion associability of some alkylammonium-type ion association reagents with the positional isomers of aromatic anions has been examined in an aqueous solution through electrophoretic mobility changes of the corresponding anions in capillary zone electrophoresis. Ion associability of the alkylammonium ions was investigated for monovalent and divalent cationic groups, considering the hydrophilicity and hydrophobicity of cationic groups and the hydration of the ionic sites. When such monovalent cationic reagents as hexylmethylammonium, hexyltrimethylammonium, and hexyltriethylammonium ions were used, the ion associability increased with an increase in the number and bulkiness of alkyl groups of the cations. On the other hand, hexylammonium ion, a primary ammonium ion, showed different behavior: Higher ion associability was obtained with aromatic anions possessing two carboxylate groups at adjacent positions. Also ion associability of the primary diammonium ions with phthalate and naphthalene-2,3-dicarboxylate ions was the highest among their positional isomers, which was the reverse behavior from that obtained with quaternary diammonium ions. Such characteristic ion associability in the primary ammonium ions could be explained from the hydrophilicity of the ionic groups of the pairing ions: A primary ammonium group is more ion associable with hydrophilic anionic groups.
Synthesis of Tetracyano(S-2-aminomethylpyrrolidine) and Tetracyano(2-aminomethylpiperidine) Complexes of Fe(II) and Co(III): Stereochemistry and Comparison of Spectroscopic Properties of Isoelectronic Structures
Authors: Goto Masafumi , Tsuruda Nobuhiro , Fujioka Sachiko , Kurosaki Hiromasa
Published: November 2004

Sodium tetracyano((S)-2-aminomethylpyrrolidine = S-pyrda)ferrate(II) and -cobaltate(III) and tetracyano(2-aminomethylpiperidine = pipda)ferrate(II) and -cobaltate(III) were prepared. These complexes afforded well-separated 1H NMR spectra sufficient to delineate their structures in solution. The major conformation of the coordinated pyrda and pipda differs in the condensation mode of the five-membered chelate ring and the heterocycles, i.e. cis- and trans-, respectively, this leads to the different orientation of the heterocycle of the diamines. The comparison of the 1H and 13C chemical shifts and the electronic structure is described from the viewpoint of the isoelectronic structures with different electric charges.
Single Amino Acid Preferences for Specific Locations at Type-I α-Turns in Globular Proteins
Authors: Narita Mitsuaki , Sode Koji , Ohuchi Shokichi
Published: November 2004

Using both dihedral angles and hydrogen-bond definitions, 225 type-I α-turns were extracted from 125 analyzed proteins. The extracted α-turns were built up from 5% (1125) of the total amino acid residues (23286) found in the proteins. The type-I α-turn is an independent kind of secondary structural unit, although it has been frequently classified as (i, i+1) double β-turns. Both the nucleation of a helix with the type-I β-turn and its propagation with the repetitive addition of the type-I β-turn suggest that the origin of the helix in a globular protein might be the type-I β-turn. Single amino acid preferences for specific locations at type-I α-turns were compared to those at type-I β-turns and the ends of helices. The result indicates that the type-I α-turn, the type-I β-turn, and the helix are of similar kin. Similarities in the structure and amino acid preferences for specific locations among them suggest that the amino acid residues on defined positions along both turns could be properly assigned to the corresponding helix elements.
Synthesis of Two Possible Disulfide Bonds Containing Peptide Fragments (Cys6–Cys47, Cys48–Cys52 (Type I), and Cys6–Cys48, Cys47–Cys52(Type II) of h-IGF-I) for the Identification of Disulfide Bond Linkage in Recombinantly Produced h-IGF-I
Authors: Iwai Michio , Yamada Hisashi , Ishii Yoshinori , Tamura Kouichi , Niwa Mineo , Kobayashi Masakazu
Published: November 2004

The primary structure of human IGF-I, except for the disulfide bond system, has been reported by Rinderknecht and Humbel. IGF-I afforded the corresponding characteristic peptide fragments on V8 protease digestion, which contained Cys6, Cys47, Cys48, and Cys52. Two possible fragments, Type I with Cys6–Cys47 and Cys48–Cys52 and Type II with Cys6–Cys48 and Cys47–Cys52 of h-IGF-I(4-9,47-53), were chemically synthesized. The disulfide bond system of IGF-I was unequivocally determined to be the Type-II form along with Cys18–Cys61. Interestingly, the Type-I system was included in the disulfide bond isomer produced as the main by-product in the refolding step on IGF-I synthesis by the recombinant DNA method.
Palladium(II)-Catalyzed Aryl Coupling of Triarylbismuthines under Air
Authors: Ohe Toshiyuki , Tanaka Takumi , Kuroda Masashi , Cho Chan Sik , Ohe Kouichi , Uemura Sakae
Published: November 2004

Triarylbismuthines readily reacted with a catalytic amount of palladium(II) acetate in methanol under air to give the corresponding biaryls in high yields. The presence of oxygen was indispensable for this catalytic coupling, biaryl formation being quite slow under nitrogen. Oxygen absorption was observed during the reaction and a Pd-oxygen complex prepared separately worked effectively as a reagent for this coupling even under inert gas.
Effect of Benzylic Methyl Groups on Kinetic Basicity of Amine Ligand in o-Boron Substituted N,N-Dimethylbenzylamines
Authors: Toyota Shinji , Asakura Mitsuhiro , Futawaka Tadahiro , Oki Michinori
Published: November 2004

Rates of the dissociation of the intramolecular B–N coordination bond in two series of phenylborane derivatives, the boronate and diethylborane complexes, with –CHMeNMe2 or –CMe2NMe2 group at the o-position were determined by the NMR lineshape analysis or saturation transfer method. The new organoboron compounds were synthesized from the corresponding organolithium compounds with appropriate boron reagents. Comparison of the kinetic data with those of the –CH2NMe2 compounds reveals that the barrier height to the dissociation, namely the kinetic basicity of the amine ligand, is increased as the molecule possesses more methyl groups at the benzylic position for both of the series of boron compounds. The X-ray structure of one of the boronate complexes and the NMR titration measurements of model amines indicate that the basicity of the amine ligand is not affected much by the methyl substitution in the coordinated form. Therefore, the substituent effect on the kinetic basicity is mainly ascribed to the destabilization of the transition state by the geminal dimethyl groups rather than to any inductive or steric effects at the initial state, especially for the –CMe2NMe2 compounds.
Synthesis and Electronic Properties of d8 Transition-Metal Complexes of Vinylene-Bridged Bis- and Tris(octaethylporphyrin)s
Authors: Higuchi Hiroyuki , Shinbo Masatoshi , Usuki Masanobu , Takeuchi Makoto , Hasegawa Yutaka , Tani Keita , Ojima Juro
Published: November 2004

Complexes of vinylene-bridged bis- and tris(octaethylporphyrin)s (bis(OEP)–M and tris(OEP)–M) with d8 transition-metal ions (M = Ni(II), Pd(II), and Pt(II)) were synthesized. Metalation of (E)-bis(OEP)–H2 was carried out under the same conditions as for the corresponding octaethylporphyrin complex (OEP–M), to afford a mixture of complexes bearing the vinylene-linkages with (E)- and (Z)-configurations. On the other hand, metalation of tris(OEP)–H2 afforded the single product of which two vinylene-linkages remained holding the same (E,E)-configuration as that in the free-base. 1H NMR spectra varied more drastically for (Z)-bis(OEP)–M, with respect to those of OEP–M, while electronic absorption spectra did more drastically for the (E)-isomers. Their electronic properties at the ground state were examined, proving that the interaction between the constituent OEP rings through the vinylene-linkages is more intensive for tris(OEP)–M than for bis(OEP)–M and more intensive for the Ni complex than for the Pd and Pt ones.
Syntheses of Dialkali Metal Complexes of Tetrakis(dimethylsilyl)ethylene: [(HMe2Si)2C=C(SiMe2H)2]2−[M+(ligand)n]2. Evidence for SiH–Alkali Metal Agostic Interactions
Authors: Ichinohe Masaaki , Sekiguchi Akira , Takahashi Masae , Sakurai Hideki
Published: November 2004

A series of dialkali metal complexes, [(HMe2Si)2C=C(SiMe2H)2]2−[M+(ligand)n]2 (M = Li, Na, K, Rb, Cs), were prepared by the reaction of tetrakis(dimethylsilylethylene) with alkali metals. These complexes exhibit Si–H alkali metal agostic interactions and have been characterized by spectroscopic and structural methods. Spectroscopic evidence for the interaction of the hydrogen on the silicon atom with alkali metals include (1) an unusually small value of the silicon-hydrogen coupling constant (1JSi–H) in NMR spectra and (2) low-energy Si–H stretching frequency in the infrared spectra. The smallest cation, Li+, can interact with SiH most strongly.
Thiophene 1,1-Dioxide: Synthesis, Isolation, and Properties
Authors: Nagasawa Hidehiro , Sugihara Yoshiaki , Ishii Akihiko , Nakayama Juzo
Published: November 2004

Oxidation of thiophene with dimethyldioxirane at −20 °C and removal of the solvent and volatile materials below −40 °C allowed the isolation of the parent thiophene 1,1-dioxide (1) as colorless crystals in pure form. The 1,1-dioxide 1, which had eluded isolation for a long time despite many efforts, melted at about 6 °C and the melt solidified at room temperature because of the dimeric and trimeric products formation. The structure of 1 was fully characterized by 1H- and 13C NMR, IR, Raman, UV/vis, and Mass spectroscopies. The decomposition of 1 in solution provided the dimer (7) as the principal product along with the trimer (9), whereas the decomposition of a neat sample furnished 7 and 9 in comparable amounts. The half-life of 1 is dependent upon the concentration of 1; 137 and 747 min at 25 °C in 0.12 and 0.025 M CDCl3 solutions (1 M = 1 mol dm−3), respectively. Kinetics of the dimerization of 1 in a dilute solution provided the activation parameters of Ea = 64.4 (±0.3) kJ mol−1, ΔH≠ = 62.0 (±0.3) kJ mol−1, and ΔS≠ = −59.8 (±1.0) J K−1 mol−1. Attempted reactions of 1 with a series of dienophiles and dienes all failed because the dimerization of 1 is much faster than reactions with these additives. An exception is the reaction with cyclopentadiene which gave the Diels–Alder adduct in good yield. The adduct of the dimer 7 with dimethyl acetylenedicarboxylate was found to undergo a retro Diels–Alder reaction to regenerate 1.
The Kinetics and Mechanism of Interaction of Fe40Ni40B20 Amorphous Metallic Alloys with Mineral Acid Media
Authors: Košturiak Adam , Valko Ladislav , Polavka Jirí , Brutovsky Milan , Morris Harry
Published: November 2004

The paper emphasizes the importance of amorphous metallic alloys thin films for magnetic coatings as well as their characterisation with respect to the mineral acid medium in a more qualitative way. The kinetics and mechanism of the interaction of Fe–Ni–B amorphous alloys films with various concentrations of mineral acids (o-phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid,) were studied. On the basis of the weighing method used we deduced that the overall physically and chemically complicated process consists of simultaneous formation of oxides on the surface of the thin films, their dissolution and moreover dissolution of the metal (Fe, Ni) and metalloid (B) elements through a tendency of all of them to react with hydrogen ions. It should be stressed that dissolution of the two-dimensional amorphous metallic alloys-ribbons significantly differs from such dissolution of the metal bulk systems.
Liquid Crystalline Phase Transition in Organophosphazenes with 4-Octyloxybiphenyl Mesogenic Groups
Authors: Moriya Keiichi , Suzuki Toshiya , Mizusaki Hiroshi , Yano Shinichi , Kajiwara Meisetsu
Published: November 2004

Cyclotriphosphazenes with the same 4-octyloxybiphenyl mesogenic side groups have been synthesized and were studied their phase transition and liquid crystallinity using DSC measurements and polarizing microscope observations. We found an enantiotropic smectic C phase in hexakis(4-(4′-octyloxy)biphenoxy)cyclotriphosphazene but no liquid crystalline phase was observed in octakis(4-(4′-octyloxy)biphenoxy)cyclotetraphosphazene. These may originate from each of the three side chains of the cyclotriphosphazene molecules pointed upwards and downwards perpendicularly from the cyclotriphosphazene ring, which helps the formation of the liquid crystalline layer structure. However, in the cyclotetraphosphazene, the eight side chains orient relatively at random and this prevents the formation of the mesogenic layer structure.