bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of the Primary Kinetic Hydrogen Isotope Effects on N-dealkylation from N-alkylamine by Hemoproteins
Authors: Hata Masayuki , Hirano Yoshinori , Hoshino Tyuji , Tsuda Minoru 
Published: November 2002

Abstract
The atomic level reaction mechanism for N-dealkylation of N,N-dimethylaniline (PhNMe2) by hemoproteins, in which a kinetic hydrogen isotope effect (KHIE) was observed, was investigated by quantum mechanical theoretical calculations. Using quantum mechanical theory, one can determine the primary KHIE by the difference in zero-point vibrational energies on normal vibrational modes which are related to the reaction coordinate of H (D or T) atom abstraction from a C–H (C–D or C–T) bond. On the basis of this idea, we theoretically determined the intramolecular primary KHIE for two cases of hydrogen atom abstraction in N-dealkylation of PhNMe2; i.e., hydrogen atom abstraction from a neutral state and proton abstraction from a cation radical state. When the intramolecular primary KHIE obtained by theoretical calculation was compared with experimental results of the intramolecular KHIE on N-dealkylation of PhNMe2, which was catalyzed by some hemoproteins, it was found that four experimental values can be interpreted only from the primary KHIE. However, many other experimental values can not be interpreted only from the primary KHIE.
Stereochemistry and Stereoisomerism Characterized by the Sphericity Concept
Authors: Fujita Shinsaku 
Published: November 2002

Abstract
The sphericity concept proposed for specifying stereochemistry in a molecule (S. Fujita, J. Am. Chem. Soc., 112, 3390 (1990)) has been extended to investigate stereoisomerism among molecules. The new matter of the present approach is to characterize the global symmetries of molecules as the “local symmetries of stereoisomerism”. Thereby, stereochemistry and stereoisomerism have been discussed on a common basis. Promolecules, which have been generated as stereochemical models of molecules by placing proligands (structureless ligands with chirality/achirality) on the vertices of a tetrahedral skeleton, have been analyzed by a permutation-group approach as well as by a point-group one. The skeleton has been considered to belong to the symmetric group of degree 4 (S[4]) as well as to the isomorphic point group Td. The chirality fittingness derived from the sphericity concept has been applied to the characterization of local symmetries of promolecule, where two types of Young’s tableaus have been compared. Thus, Young’s tableaus of symmetry have been introduced to treat the ligand packing based on the chirality fittingness. These tableaus have been compared with Young’s tableaus of permutation, which have taken no account of such chirality fittingness. The two types of Young’s tableaus have been applied to the enumeration of tetrahedral isomers under the observance and the violation of chirality fittingness. This enumeration has enabled us to clarify the quantitative aspect of the sphericity concept in characterizing isomer equivalence. Thereby, equivalent isomers under a point-group symmetry have been shown to construct an orbit of stereoisomers that is ascribed to a coset representation. Homomeric, enantiomeric, and diastereomeric relationships between stereoisomers have been discussed by means of homospheric, enantiospheric and hemispheric orbits of stereoisomers. Skeleton-based and ligand-based categories for enantiomers and diastereomers have been discussed. The stereogenicity and the prostereogenicity of the Chan–Ingold–Prelog system have been related to Young’s tableaus of permutation.
Optical–Optical Double Resonance Spectroscopy of I2 through the Parity Mixed Valence States
Authors: Ishiwata Takashi , Yotsumoto Takashi , Motohiro Satoshi 
Published: November 2002

Abstract
We used the perturbation-facilitated optical–optical double resonance technique to access the ungerade ion-pair states of I2 using the (1 + 1) photo-excitation sequence through the B3Π(0u+)–c1g parity mixing states. By analyzing the second step of the double resonance to the F0u+(3P0), γ1u(3P2), and H1u(3P1) states, the g–u coupling schemes were elucidated in the intermediate B3Π(0u+)–c1g state. We were also able to populate the δ2u(3P2) state through the g–u mixing state, and to improve its molecular constants. The interference effect between the parallel γ1u(3P2)–c1g and perpendicular δ2u(3P2)–c1g transitions was used to derive the ratio of their electronic transition moments, (μ||e/μ⊥e) ∼ 5.5.
HeI Photoelectron and Ab Initio Study of Retinal Derivatives
Authors: Katsumata Shunji 
Published: November 2002

Abstract
The HeI photoelectron spectra of all-trans-retinal, 13-cis-retinal and 9-cis-retinal have been observed in the gas phase by using an infrared heating device, which was developed in this laboratory. The first four ionization energies (Iobs) of all-trans-retinal have been determined to be 7.55, 8.40, 9.21, and 10.03 eV, and the ionization energies for the other two derivatives were also equal to them within the experimental error. Ab initio calculations were performed to study the optimized structures of neutral and cationic ground states of retinals and to elucidate the valence electronic structures associated with the observed ionization energies. The structural change from the neutral to the cation was considered, and the bond lengths and dihedral angles between the planes of the β-ionone ring and the polyene chain in each of retinals have been determined.
Crystal Structure and Photo-Reaction of a New Coordination Polymer: [Ni(en)2]4[Fe(CN)5NO]2[Fe(CN)6]·6H2O
Authors: Gu Zhong-Ze , Sato Osamu , Einaga Yasuaki , Kai Masahiro , Iyoda Tomokazu , Fujishima Akira , Hashimoto Kazuhito 
Published: November 2002

Abstract
A new photo-responsive coordination polymer of [Ni(en)2]4[Fe(CN)5NO]2[Fe(CN)6]·6H2O was synthesized. In this compound, Ni–CN–Fe forms one-dimensional standing-wave-like chains, onto which photo-functional groups of pentacyanonitrosylferrate(II) are appended. Photo-irradiation with blue light at less than 200 K transformed the pentacyanonitrosylferrate(II) from the ground state to a metastable state, which could be reverted to the original state by irradiation with red light.
Synthesis, Structure, and Characterization of an α-Dawson-type [S2W18O62]4− Complex
Authors: Himeno Sadayuki , Tatewaki Hideki , Hashimoto Masato 
Published: November 2002

Abstract
A yellow sulfatotungstate complex was formed by heating a 50 mM W(VI)–2 M H2SO4–40% (v/v) CH3CN system at 70 °C for 14 days, being isolated as the tetrapropylammonium (n-Pr4N+) salt. An X-ray structural analysis (ortho-rhombic, Pca21 (No. 29) a = 27.181(1), b = 14.1428(6), c = 27.7292(9) Å, and Z = 4) revealed that the structure consists of an α-Dawson-type [S2W18O62]4− anion. The α-[S2W18O62]4− complex underwent a four-step reversible one-electron reduction in CH3CN, and the presence of acid caused the one-electron waves to be converted into three two-electron waves. The formation conditions were elucidated by a combined Raman and voltammetric study.
Supercooling of Aqueous Solutions of Alkali Chlorides and Acetates
Authors: Miyata Kuniharu , Kanno Hitoshi , Tomizawa Kiyoshi , Yoshimura Yukihiro 
Published: November 2002

Abstract
Homogeneous nucleation temperatures (TH’s) of aqueous alkali chloride and acetate solutions were measured as a function of salt concentration. There is a linear relation between TH and 1/r+ (r+: ionic radius of alkali ion) for aqueous alkali chloride solutions. In the supercooling of aqueous alkali acetate solutions, the ionization constant also plays an important role in their supercooling behavior. The TH results were discussed in relation to nucleation theory.
Growth of Strontium Chlorapatite Crystals from a Sodium Chloride Flux
Authors: Oishi Shuji , Mitsuya Mai , Suzuki Takaomi , Ishizawa Nobuo , Rendon-Angeles Juan Carlos , Yanagisawa Kazumichi 
Published: November 2002

Abstract
Large and well-formed crystals of strontium chlorapatite [Sr5Cl(PO4)3] were grown for the first time from a sodium chloride flux. The obtained crystals were colorless and transparent. The crystal growth of Sr5Cl(PO4)3 was conducted by heating a mixture of solute and flux at 1100 °C for 10 h, and then cooling to 500 °C at a rate of 5 °C h−1. Hexagonal prismatic crystals with lengths of up to 8.6 mm and widths of 2.1 mm were grown from high-temperature solutions containing 0.05–0.9 mol% solute. The most suitable solute content for the growth of prismatic crystals was 0.2 mol%. The prismatic crystals were bounded by the {101-0} and {101-1} faces. The aspect ratios were in the region of 1.1 to 4.2. Hexagonal needle crystals with lengths of up to 2.6 mm and widths of 60 µm were obtained during every growth run. The needle crystals were elongated in the &lt;0001&gt; directions, with aspect ratios ranging from 33 to 66. The major constituents were almost homogeneously distributed in the prismatic and needle crystals. The solubility of Sr5Cl(PO4)3 crystals in NaCl flux increased with increasing temperature, reaching about 0.25 mol% solubility at 1100 °C.
Effect of Tris(acetylacetonato)chromium(III) as a Complex Ligand on the Extraction of Lanthanoid(III) with 2-Thenoyltrifluoroacetone
Authors: Kameta Naohiro , Imura Hisanori 
Published: November 2002

Abstract
Enhancement of the extraction of lanthanoid(III) (Ln) with 2-thenoyltrifluoroacetone (Htta) in cyclohexane or benzene has been observed by the addition of tris(acetylacetonato)chromium(III) (Cr(acac)3). The equilibrium analysis suggested that the effect of Cr(acac)3 could be ascribed to the formation of a 1 : 1 adduct of Ln(tta)3 with Cr(acac)3, i.e., a binuclear complex, in the organic phase. The formation constants (βs,1) of the adducts were determined across the Ln series. The βs,1 values decreased with decrease in the ionic radii of Ln in the light Ln, and were constant in the heavy Ln. Spectroscopic studies such as electronic absorption, IR, and 1H NMR were performed to explain the difference between the light and heavy Ln. The adduct of light Ln is mainly an inner sphere complex in which Cr(acac)3 displaces the coordinated water of the Ln chelate and directly coordinates to the Ln ion. On the other hand, the adduct of heavy Ln is an outer sphere complex formed by the hydrogen bonding between Cr(acac)3 and the coordinated water of the Ln chelate. Abilities of Cr(acac)3 as a complex ligand, i.e., the basicity and the steric factor, were evaluated by comparing with Co(acac)3 reported previously.
Spectral, Kinetics, and Redox Studies on the Transients Formed on Pulse Radiolysis of Aqueous Solution of (4-Methylthiophenyl)methanol
Authors: Mohan Hari , Mittal Jai Pal 
Published: November 2002

Abstract
Pulse radiolysis technique has been employed to investigate the nature and the redox properties of the transient species generated on radiolysis of aqueous solution of (4-methylthiophenyl)methanol (MTPM). Pulse radiolysis in 1,2-dichloroethane, reaction with specific one-electron oxidants (Cl2•−, SO4•−, Tl2+, Br•) and reaction of •OH radicals in acidic solution showed absorption bands at 320 and 545 nm; these are assigned to solute radical cation with positive charge on the benzene ring. OH-adduct was observed in neutral solution. The oxidation potential for MTPM/MTPM•+ couple is determined to be 1.55 ± 0.04 V vs NHE. eaq− reacts with a bimolecular rate constant of 1.5 × 109 dm3 mol−1 s−1 and the transient absorption bands (λmax = 320, 470 nm) are assigned to the solute radical anion. E0 value for MTPM/MTPM•− couple is determined to be −1.84 ± 0.04 V vs NHE. The redox properties of the transient species formed on reaction with •OH, •H, and O•− have been evaluated.
Synthesis and Biological Activity of 3,7-Anhydro-2,4-dideoxy-4-[(R)-3-hydroxytetradecanoylamino]-6-O-phosphono-5-O-[(R)-3-(tetradecanoyloxy)tetradecanoyl]-d-glycero-d-ido-octonic Acid Derivatives
Authors: Wakabayashi Takanori , Shiozaki Masao , Kanai Saori , Kurakata Shin-ichi 
Published: November 2002

Abstract
d-Glucosaminylacetic acid derivatives (10, 11 and 12) of GLA-60 were synthesized to investigate the LPS-antagonistic activity toward human monoblastic U937 cells. Compounds 10 and 11 show weak LPS-antagonistic activity, but 12 shows both LPS-antagonistic and -agonistic activities, depending on the concentration.
Asymmetric Synthesis of β-Amino-α-Hydroxy Acids through Lewis Acid-Mediated Addition of Ketene Acetal to Imines
Authors: Ha Hyun-Joon , Ahn Young-Gil , Woo Jun-Sik , Lee Gwan Sun , Lee Won Koo 
Published: November 2002

Abstract
Asymmetric synthesis of β-amino-α-hydroxy acids, key components of medicinally important molecules including Paclitaxel, KRI-1314, amastatin, and microginin, has been attained from the aldimine coupling of chiral imines N-alkylidene-(S)- or (R)-α-methylbenzylamine with (Z)-α-methoxyketene methyltrimethylsilyl acetal, followed by demethylation, hydrogenolysis, and hydrolysis.
Trifluoromethyl-Substituted Donor–Acceptor Norbornadiene, Useful Solar Energy Material
Authors: Nagai Takabumi , Fujii Kazuhisa , Takahashi Ikuko , Shimada Miwa 
Published: November 2002

Abstract
Trifluoromethyl (CF3)-substituted donor–acceptor norbornadiene (NBD) derivatives were synthesized. The photoisomerization of CF3-NBD derivatives proceeded smoothly. The thermal stability of quadricyclane (QC) derivatives obtained from CF3-NBD derivatives was examined, and it was found that the CF3 group increased the thermal stability of the QC derivatives. Furthermore, CF3-NBD derivatives exhibited efficient fatigue resistance.
O2-Binding Properties of Double-Sided Porphinatoiron(II)s with Polar Substituents and Their Human Serum Albumin Hybrids
Authors: Komatsu Teruyuki , Okada Tomoyuki , Moritake Miho , Tsuchida Eishun 
Published: November 2002

Abstract
Double-sided porphinatoiron(II)s with polar substituents [R; hydroxy (FeDP(OH)), methoxy (FeDP(OMe)), and acetoxy (FeDP(OAc))] on the 2,2-dimethylpropanoyloxy-fence groups have been synthesized. FeDP(OMe) and FeDP(OAc) formed five-N-coordinated high-spin Fe2+ complexes with an intramolecularly bound axial imidazole in toluene (or CH2Cl2) under an N2 atmosphere. Upon the addition of O2, they produced stable O2 adducts at 25 °C; their half-lives in water-saturated toluene (50–77 h) are 2–3 fold longer compared to that of the single-face encumbered porphinatoiron(II) (FeP). Their O2-binding parameters are almost identical to that of FeDP(H), which has nonpolar substituents on the fences. In contrast, FeDP(OH) showed a significantly low O2-binding affinity and was immediately oxidized to the Fe3+ state after contact with bubbling O2 gas. The incorporation of these FeDPs into the human serum albumin (HSA) provided artificial hemoproteins, which can reversibly bind and release O2 under physiological conditions (in aqueous media, pH 7.3, 37 °C) like hemoglobin and myoglobin. The half-life of the dioxygenated HSA–FeDP(H) reached 5 h (37 °C). This corresponded to a 2.5-fold increase compared to that of HSA–FeP. The time dependences of the absorption changes accompanying the O2- and CO-rebindings to the HSA–FeDPs after laser flash photolysis were composed of two phases. These observations indicate that the recombination of O2 and CO to the central Fe2+ ion is affected by the microenvironments around the FeDPs in the HSA structure, e.g. a steric hindrance of the amino acid residue and a difference in polarity. Furthermore, FeDP(H) incorporated into HSA showed a high stability against H2O2.
Iron(II) Complex of Octopus-Porphyrin with a Covalently Linked Proximal Imidazole; Self-Assembly and O2-Coordination in Aqueous Media
Authors: Komatsu Teruyuki , Hayakawa Shoichi , Yanagimoto Tetsuya , Kobayakawa Makiko , Nakagawa Akito , Tsuchida Eishun 
Published: November 2002

Abstract
The iron complex of tetrakis[2,6-di(alkanoyloxy)phenyl]porphyrin derivative with seven phosphocholine head groups and an N-alkylimidazole side-chain as the proximal base (octopus-porphyrin) has been synthesized. The ferrous complex (7b) was easily dispersed in water to provide a stable colloid. Transmission electron microscopy and scanning force microscopy of the evaporated solution showed spherical micelles with a diameter of 8 nm, which probably consists of a dimer of 7b. These micellar aggregates could reversibly coordinate O2 at 25 °C; and the O2-binding parameters are also given.
Solid-State and Solution Structures of Calix[4]arene Tetramethyl Ether Containing Four Diphenylphosphino Moieties at the Upper Rim
Authors: Takenaka Kazuhiro , Obora Yasushi , Jiang Li Hong , Tsuji Yasushi 
Published: November 2002

Abstract
X-ray crystallographic analysis and CPMAS solid-state NMR measurements of tetrakis(diphenylphosphino)calix[4]arene tetramethyl ether (1) elucidated that in the solid-state 1 adopts a flattened partial cone conformation having C1 symmetry. In solution, on the other hand, the 1H, 13C, and 31P NMR spectra measured at −20 °C indicated that 1 has a partial cone conformation with a mirror plane. Two-dimensional 31P EXSY and variable-temperature 31P NMR spectra reveal a fluxional behavior of 1 in solution on the NMR time scale due to annulus rotation from the methoxy side. Concerning the energetics for the four conformers of 1, an ab initio molecular orbital calculation showed that the partial cone conformation is the most stable form, while the cone and the 1,3-alternate conformers are only slightly less stable.
Silyl-Substituted Dithioles as Candidates for New Electron Donors
Authors: Li Hongqi , Nishiwaki Keiji , Itami Kenichiro , Yoshida Jun-ichi 
Published: November 2002

Abstract
Molecular orbital calculations revealed that the introduction of a silyl group onto the 2-position of 1,3-dithiole caused significant decrease of the ionization potential and that 2-silyl-1,3-dithioles served as a pseudo π-electron system. The silyl group could also be utilized as a bridge for linking π-electron systems to achieve artificial stacking. These concepts led us to the design and synthesis of silyl-substituted 1,3-benzodithioles as candidates for new electron donors. The oxidation potential of monosilyl-substituted 1,3-benzodithiole was found to be significantly less positive than that of the parent 1,3-benzodithiole. The introduction of the second silyl group caused further decrease of the oxidation potential. Compounds composed of two 1,3-benzodithiole units linked by a silyl group were also synthesized. These showed comparable oxidation potentials to those of the corresponding monomeric compounds. The effect of stannyl-substitution onto the 2-position of 1,3-dithiole was found to be larger than that of silyl-substitution. The effects of silyl- and stannyl-substitution for related systems such as thioanisole and 1,3-dithiane were also studied.
Iridium-Catalyzed Reaction of 1-Naphthols, N-(1-Naphthyl)benzenesulfonamides, and Salicylaldehyde with Internal Alkynes
Authors: Nishinaka Yuko , Satoh Tetsuya , Miura Masahiro , Morisaka Hideaki , Nomura Masakatsu , Matsui Hisaji , Yamaguchi Chiharu 
Published: November 2002

Abstract
1-Naphthols efficiently couple with internal alkynes via cleavage of the C–H bond at the peri-position in the presence of a catalyst system of [IrCl(cod)]2/PBut3 to selectively afford the corresponding 8-vinyl-1-naphthol derivatives. N-(1-Naphthyl)benzenesulfonamides can similarly react with the alkynes. The reaction of salicylaldehyde with the alkynes using the catalyst system gives 2-hydroxyphenyl vinyl ketones via cleavage of the aldehyde C–H bond.
Oxidation of Ferrocenyl End-Substituted Oligothiophenes
Authors: Sato Masa-aki , Sakamoto Mune-aki , Kashiwagi Shin-ichiro , Suzuki Tomohiro , Hiroi Masao 
Published: November 2002

Abstract
A ferrocenyl end-substituted terthiophenes derivative and a sexithiophene derivative were prepared as model compounds for a molecular wire. Electrochemical measurements and absorption spectroscopy were performed to elucidate the oxidation process and the oxidized states of those model compounds. The first oxidation of the model compounds took place in the ferrocene moieties (terminals). The resultant oxidized species in the ferrocene moieties seeped into the oligothiophene moieties (wires) and spread over two or three thiophene rings. Further oxidation of the ferrocenyl-terthiophene derivative did not occur, whereas that of the ferrocenyl-sexithiophene derivative produced an oxidized species, such as a cation radical in the sexithiophene moiety.
Total Synthesis of the Novel Spider Toxin NPTX-594 from Nephila madagascariencis
Authors: Wakamiya Tateaki , Yamamoto Akinori , Kawaguchi Keita , Kinoshita Tomohiko , Yamaguchi Yoshihiro , Itagaki Yasuhiro , Naoki Hideo , Nakajima Terumi 
Published: November 2002

Abstract
A novel spider toxin, NPTX-594, comprised of four constituents: i.e., 2,4-dihydroxyphenylacetic acid (Dhpa), asparagine, 4,8-diaza-1,12-dodecanediamine (Dada), and lysine, was chemically synthesized. The synthetic compound was completely identical with the natural product as regards 1H NMR and mass spectra. The structure of NPTX-594 was thus determined synthetically to be N12-(Dhpa-Asn)-N1-Lys-Dada, as proposed by spectrometric elucidation.
Chemical Composition Distribution of Biosynthesized Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Determined by Temperature Rising Elution Fractionation
Authors: Kawai Tadatomo , Teramachi Shinya , Yokoyama Takamitsu 
Published: November 2002

Abstract
The chemical composition distributions (CCDs) of biosynthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), samples with different average compositions were determined by temperature rising elution fractionation (TREF). P(3HB-co-3HV) samples were supplied by Sigma–Aldrich Co. Inc. According to catalog data, the 3HV contents were about 8, 14, and 24 mol%, respectively. The TREF condition was as follows: the sample concentration was 0.3% dissolved in acetonitrile at 75 °C; the column temperature was slowly (2 °C/h) decreased from 75 °C to 0 °C to crystallize the sample. The fractions were eluted with acetonitrile by stepwise increasing the temperature by 5 °C.
The chemical compositions of the original samples and the fractions were determined by 1H NMR. Cumulative CCD curves were constructed from the fractionation data for the respective samples. It became clear that these samples had bimodal CCDs with two discrete peaks, that is, one part in the wide composition range around 10–15 mol% of 3HV contents and another part at different compositions.
Positive-Tone Imaging of Photo-Decomposable Polymer LB Films
Authors: Li Tiesheng , Mitsuishi Masaya , Miyashita Tokuji 
Published: November 2002

Abstract
We describe the lithographic properties of poly(N-isopentylmethacrylamide-co-t-butyl 4-vinylphenyl carbonate) [p(iPMA-tBVPC)] which has a structure that is subject to the main chain scission and to deprotection of t-butoxycarbonyloxy group by deep UV irradiation. The positive-tone patterns of the p(iPMA-tBVPC) LB film with 60 layers could be obtained by deep UV light irradiation, followed by development with alkaline aqueous solution. The resolution of the pattern was 0.75 μm, which is the resolution limit of the photomask employed. The photopattern formation with the copolymer [p(iPMA-tBVPC)] LB film was more sensitive than the homopolymer poly(N-isopentylmethacrylamide) [p(iPMA)] LB film. The etching resistance of the p(iPMA-tBVPC) LB film deposited for the pattern of the gold film is also investigated.