bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical Modification of Amide-Based Catenanes and Rotaxanes I. Synthesis of secondary Amine [2]Catenanes and [2]Rotaxanes by the Borane Reduction of secondary Amide [2]Catenanes and [2]Rotaxanes and Mobility of Their Components
Authors: Furusho Yoshio , Shoji Junko , Watanabe Nobuhiro , Kihara Nobuhiro , Adachi Tomohiro , Takata Toshikazu 
Published: September 2002

Abstract
Various secondary amine [2]catenanes and [2]rotaxane were prepared by borane reduction of the corresponding secondary amide [2]catenanes and [2]rotaxane. Their structures were characterized by NMR, IR, and FAB-MS spectroscopies. The mobility of the components in solution was examined by 1H NMR spectroscopy. The substituents on the isophthaloyl units of the catenanes prevented complete circumrotation of the macrocyclic components (“half rotation”). On the other hand, macrocyclic ring components bearing unsubstituted isophthaloyl units completely circumrotated through the other faster than on the 1H NMR time scale (“full rotation”). In the case of the secondary amine [2]catenanes, no hydrogen bonding interaction between the secondary amino groups was observed. A dynamic 1H NMR study showed a highly enhanced mobility of the components of the secondary amine [2]catenanes and [2]rotaxane compared with the corresponding amide compounds, even at lower temperature.
Chemical Modification of Amide-Based Catenanes and Rotaxanes II. Synthesis of tertiary Amine [2]Catenanes and [2] Rotaxanes via N-Methylation Followed by Borane Reduction of secondary Amide [2]Catenanes and [2]Rotaxanes and Mobility of Their Components
Authors: Watanabe Nobuhiro , Furusho Yoshio , Kihara Nobuhiro , Takata Toshikazu , Kinbara Kazushi , Saigo Kazuhiko 
Published: September 2002

Abstract
Secondary amide [2]catenane 1a was converted to the corresponding tertiary amide [2]catenane 1b by repetitive treatment with a methylating system of CH3I and KOH in DMSO. The amide functions of 1b were reduced with borane in refluxing THF to give the corresponding tertiary amine [2]catenane 1c. Their structures were characterized by NMR, IR, and FAB-MS spectroscopies. An X-ray crystallographic analysis of 1c showed that its solid-state structure was stabilized by a CH–π interaction between the p-xylylene and m-xylylene units, together with a π–π stacking interaction between the two m-xylylene units. A variable temperature 1H NMR study suggested that 1c had components of highly enhanced mobility in CDCl3, even at lower temperature, although a much weaker interaction, such as the CH–π interaction, existed between their components in solution. Tertiary amine [2]rotaxane 3c was obtained from the corresponding secondary amide [2]rotaxane 3a by a procedure similar to that used for 1a. The 1H NMR spectra indicated that the mobility of the components of 3c is sufficiently high even at lower temperature.
Fluorescence Properties, Induced-Fit Guest Binding and Molecular Recognition Abilities of Modified γ-Cyclodextrins Bearing Two Pyrene Moieties
Authors: Aoyagi Taiyo , Ikeda Hiroshi , Ueno Akihiko 
Published: September 2002

Abstract
γ-Cyclodextrin (γ-CD) derivatives bearing two pyrene moieties at AB, AC, AD, and AE glucose units (1–4), were prepared as chemosensors for detecting molecules by their guest-responsive excimer emission intensity. All these hosts exhibited predominant excimer emission and remarkable induced circular dichroism (ICD) in a 20% dimethyl sulfoxide aqueous solution. The excimer emission and the ICD intensities mostly decreased upon addition of a variety of organic guests. The result indicates that 1–4 undergo an induced fit conformational change upon complex formation, excluding the pyrene moieties from inside to outside the γ-CD cavity in guest binding. The guest-induced fluorescence variations were analyzed by 1 : 1 host–guest stoichiometry and the obtained binding constants were roughly correlated with the guest-induced fluorescence variations. The binding and fluorescence data revealed that 1–4 have remarkable molecular recognition abilities for bile acids and other guests.
Pd(II)-Hydrotalcite-Catalyzed Selective Oxidation of Alcohols Using Molecular Oxygen
Authors: Kakiuchi Nobuyuki , Nishimura Takahiro , Inoue Masashi , Uemura Sakae 
Published: September 2002

Abstract
A novel heterogenized Pd catalyst, palladium supported by hydrotalcite [Pd(II)-hydrotalcite], has been synthesized. The catalyst is found to be effective for the oxidation of a wide range of alcohols using molecular oxygen as a sole oxidant. In this catalytic system, various alcohols are readily converted to the corresponding aldehydes or ketones selectively in high to excellent yields. It is noteworthy that the catalyst is also applicable to the oxidation of unsaturated alcohols such as geraniol and nerol without any isomerization of an alkenic part. Another characteristic property of this heterogeneous catalyst is that a shape selectivity depending on the structure of alcohols is observed in some cases. The catalyst also has advantages such as ease of handling, easy preparation, and reusability for several times.
4-(2-Aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one as a Highly Sensitive Fluorescent Labeling Reagent for Carnitine
Authors: Nakaya Ken-ichi , Tanaka Toshiyuki , Shirataki Yoshiaki , Shiozaki Hisayoshi , Funabiki Kazumasa , Shibata Katsuyoshi , Matsui Masaki 
Published: September 2002

Abstract
4-(2-Aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one, synthesized and identified by a HMBC study, can be used as a fluorescent labeling reagent for carnitine. The excitation and emission maxima in acetonitrile were observed at λ 454 and 508 nm, respectively. This reagent smoothly reacted with carnitine in the presence of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride to afford the corresponding amide under mild conditions. The detection limit (S/N &gt; 3) of carnitine was ca. 12 fmol.
Investigations into the Bromination of Substituted Phenols using Diethyl Bromomalonate and Diethyl Dibromomalonate
Authors: Coumbarides Gregory Socrates , Dingjan Marco , Eames Jason , Weerasooriya Neluka 
Published: September 2002

Abstract
Substituted 4-bromophenols can be synthesised efficiently by heating the corresponding phenol in either neat diethyl bromomalonate or diethyl dibromomalonate. We discuss the regioselectivity of such reactions and comment on the scope and limitation of this procedure.
A Novel Regioselective Desulfation Method Specific to Silyl Ester of Primary Sulfate Using Silylating Agents. Selective Preparation of Secondary Alkyl Sulfates Having a Primary Hydroxy Group
Authors: Horibe Mineko , Oshita Hiroyuki 
Published: September 2002

Abstract
The treatment of bis(trimethylsilyl)ester of 1-O-decylglycerol-2,3-disulfate with trimethylsilyl-N-trimethylsilylacetimidate (BSA) or (dimethylamino)trimethylsilane caused regioselective desulfation to afford 1-O-decyl glycerol-2-sulfate selectively in good yield. Silylating agents, having nitrogen, seems to be responsible for facilitating trimethylsiloxysulfonyl cation transfer.
Characterization of Azide-Binding Type 2 Cu(II) Site of Nitrite Reductase
Authors: Deligeer  , Kataoka Kunishige , Suzuki Shinnichiro 
Published: September 2002

Abstract
The azide-binding type 2 Cu sites of nitrite reductases (NIRs) from denitrifying bacteria, Alcaligenes xylosoxidans GIFU 1051 and Achromobacter cycloclastes IAM 1013, have been spectroscopically characterized. The titration of two NIRs with azide indicates that two monodentate azide ions are coordinated to type 2 Cu(II). The difference between azide-treated and native NIR absorption spectra shows one absorption band near 450 nm due to N3- → type 2 Cu(II) charge-transfer transitions.
Characterization of Calcium, Strontium, Barium and Lead Hydroxyapatites: X-ray Diffraction, Photoelectron, Extended X-ray Absorption Fine Structure and MAS NMR Spectroscopies
Authors: Sugiyama Shigeru , Moriga Toshihiro , Hayashi Hiromu , Moffat John B 
Published: September 2002

Abstract
Calcium, strontium, barium and lead hydroxyapatites have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (XAFS) and solid state NMR. XPS analyses showed that the binding energies of P 2s or P 2p and O 1s of all hydroxyapatites, XRD of which matched to the corresponding JCPDS data, were essentially identical and were not influenced by those divalent cations. In contrast, it was revealed that the nearest neighbour distances between divalent cations and oxygen determined by XAFS and the chemical shifts of 1H and 31P NMR were strongly influenced by each divalent cation in hydroxyapatites.
Redox and Optical Properties of Conjugated Ferrocene Oligomers
Authors: Nishihara Hiroshi 
Published: September 2002

Abstract
Internuclear electronic interactions in conjugated ferrocene oligomers display unique redox and optical properties. I describe here recent research on the dependence of such properties on the number of ferrocene nuclei and on the structure of conjugated spacers. The neighboring-site interaction model explains the redox properties of oligo(ferrocene-1,1′-diyl)s. The infrared (IR) spectra of carbonyl complex-bound biferrocene and terferrocene enlighten the electronic structure in the mixed-valence states. Energy shifts of intervalence transfer (IT) in the mixed-valence states of oligo(ferrocene-1,1′-diyl)s resulting from changes in the oxidation state are rationalized by taking into account the change in neighboring-site combination by photo-electron transfer, which delivers extra energy due to the strain in internuclear distance. Oligo- and poly-(ferrocene-1,1′-diyl)s oxidized partially by tetracycanoethylene (TCNE) exhibit near-IR photoconductivity. Conjugated spacer groups between ferrocene nuclei involving metal complex moieties affect the redox properties of ferrocene dimers significantly. The azo group acts as a distinctive spacer of which conjugation ability is changeable photochemically.
Crystal Structure of Long Alkyl 3-(Thymin-1-yl)propionates: Style of Hydrogen Bonding and Dependence on the Alkyl Chain Length
Authors: Mochizuki Eiko , Yasui Nobuyoshi , Kai Yasushi , Inaki Yoshiaki , Yuhua Wang , Saito Takao , Tohnai Norimitsu , Miyata Mikiji 
Published: September 2002

Abstract
Crystal structures of the ester derivatives of thymine having long alkyl chains are described. The crystal structure of the thymine derivative was found to be affected particularly by the carbon number of the alkyl chain. The thymine derivatives having even-numbered alkyl chains formed unusual hydrogen bonds between N3-H and O2 of the thymine base. The interactions between the methyl group and the oxygen were found to play an important role in the crystal structure. The thymine base of the even-numbered alkyl derivatives was surrounded by neighboring molecules with the interactions between the methyl group and the oxygen. Therefore, usual hydrogen bonds between N3-H and O4 were inhibited by steric effects from forming the hydrogen bonds between N3-H and O2.
Theoretical and Computational Study of Thermoreversible Gelation
Authors: Tanaka Fumihiko , Koga Tsuyoshi 
Published: September 2002

Abstract
This paper reviews recent theoretical and computational studies of thermoreversible gelation with multiple cross-link junctions in associating polymers. Paying special attention to the multiplicity and sequence length of the network junctions, we derive phase diagrams with coexisting gelation and phase separation. Local and global structures of the gel networks are studied. The conventional Eldridge–Ferry method is extended to allow for simultaneous evaluation of multiplicity and sequence length (or enthalpy of the cross-links), and applied to the experimental gel melting curves of poly(vinylalcohol) in water. On the basis of the Scanlan–Case criterion, we calculate the number of elastically effective chains and of dangling ends in the network as functions of polymer concentration and temperature. The effect of added surfactants on the formation of thermoreversible gels (surfactant-mediated gelation) in hydrophobically modified associating polymer solutions is also studied under the assumption of the existence of a minimum multiplicity required for stable cross-links. Competition between intramolecular micellization and intermolecular cross-linking is also studied with special attention to the formation of flower micelles.
Highly Sensitive Probe for Gene Analysis by Electrochemical Approach
Authors: Takenaka Shigeori 
Published: September 2002

Abstract
Electrochemically active DNA ligands, including ferrocenyl DNA oligonucleotides and ferrocenyl naphthalene bis(carboximide), are reviewed in connection with development of an electrochemical DNA sensor. Ferrocenyl oligonucleotides are used as an electrochemical probe DNA detectable by high performance liquid chromatography with the electrochemical detector (HPLC-ECD) system and they enable the target DNA analysis at femto mole level. Ferrocenyl oligonucelotides are useful also as a polymerase chain reaction (PCR) primer to realize quantitative PCR. Ferrocenyl naphthalene bis(carboximide) is a general DNA detecting ligand. When coupled with a probe DNA immobilized on an electrode, the target DNA from plasmid, chromosomal DNA, and total RNA extracted from several sources can be analyzed with very high sensitivity. Ferrocenyl naphthalene bis(carboximide) bound to the DNA duplex serves as a pseudo-polyferrocene array and this unique architecture leads to enhanced electron transfer between reduced glucose oxidase and the electrode. Unpaired base(s) present on the mismatched base(s) of the DNA duplex can be detected by observation of a decrease in the amount of ferrocenyl naphthalene bis(carboximide) bound to such a mismatched DNA duplex. Hybridized DNA on the DNA microarray was visualized electrochemically in the aqueous solution by the scanning electrochemical microscope (SECM) coupled with the ferrocenyl naphthalene bis(carboximide).
Radical Reaction by a Combination of Phosphinic Acid and a Base in Aqueous Media
Authors: Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro 
Published: September 2002

Abstract
Treatment of various organic halides with phosphinic acid (hypophosphorous acid) in aqueous ethanol in the presence of a radical initiator and a base gave the corresponding reduced products in high yields. Addition of a base is indispensable for the reduction of halides by phosphinic acid. Allylic ether of o-iodophenol or 2-haloalkanal allylic acetal underwent radical cyclization under the same conditions to afford the corresponding cyclic product in excellent yield. Deuterated phosphinic acid was found to be an efficient chain carrier for the radical deuteration of organic halides. For example, a deuterium oxide solution of deuterated phosphinic acid, potassium carbonate, 2,2′-azobis(isobutyramidine) dihydrochloride as an initiator, and p-iodobenzoic acid was heated at reflux to give p-deuteriobenzoic acid in 94% yield. A mixed dioxane/D2O solvent system combined with DBU and potassium peroxodisulfate was crucial to deuterate hydrophobic substrates in high yields and with high deuterium incorporation. Complete deuterium incorporation was accomplished only by the reaction in D2O without an organic cosolvent and an organic base.
Microviscosity Dependence of Magnetic Isotope Effect on Radical Pair Decay Rates in SDS Micellar Solution
Authors: Fujiwara Yoshihisa , Taga Yoshito , Tomonari Taro , Akimoto Yukimi , Aoki Takeshi , Tanimoto Yoshifumi 
Published: September 2002

Abstract
The microviscosity dependences of the magnetic field and magnetic isotope effects on disappearance of radical pairs (RPs) comprising benzophenone ketyl and alkyl radicals were investigated in sodium dodecyl sulfate (SDS) micellar solutions. The increase in microviscosity of the SDS micelle by adding MgCl2 caused not only a deceleration in the escape rate of the component radicals from the micelle but also a small magnetic isotope effect on the RP decay rate. The small magnetic isotope effect was explained by an increase in the correlation time of the radical motion, which is coupled with the anisotropic hyperfine interaction modulating the spin-lattice relaxation of RP.
Structures and Reactions of Alkoxymethyl(alkali metals). Ethylation by Methyl Ethers in the Presence of Organometallic Bases
Authors: Naruse Yuji , Hayashi Akihiro , Sou Shin-ichiro , Ikeda Hirotaka , Inagaki Satoshi 
Published: September 2002

Abstract
Structures and reactions of CH3OCH2M (M = Li, Na, K) were investigated in a theoretical manner. CH3OCH2M has the acute bond angle of ∠M-C-O due to a strong coordination of the oxygen to the alkali metals. The nucleophilic substitution reaction of the substrate CH3OCH2Li by the nucleophile CH3OCH2Li is more preferred than the carbene generation by α-elimination and a nucleophilic substitution of CH3OCH2Li by CH3Li. The resulting 2-methoxyethyllithium readily liberated lithium methoxide to afford ethylene, which added to the anion species to give an ethylated product. Among the CH3OCH2M (M = Li, Na, K), CH3OCH2K is the most nucleophilic, due to the high σC–K level, while CH3OCH2Li is the most nucleophilic because of the lowest σ*C–O level. This supports a previously proposed mechanism for the ethylation of indole derivatives by methyl ethers in the presence of BuLi - t-BuOK.
Temporal Analysis of Products (TAP) Study of the Adsorption of CO, O2, and CO2 on a Au/Ti(OH)4* Catalyst
Authors: Olea Maria , Kunitake Maki , Shido Takafumi , Asakura Kiyotaka , Iwasawa Yasuhiro 
Published: September 2002

Abstract
The adsorption kinetics on Au/Ti(OH)4* (a newly developed Au catalyst, active for low-temperature CO oxidation) for CO, O2, and CO2 in the temperature range 298–473 K was determined by temporal analysis of products (TAP) technique. The response signals from the single-pulse TAP experiments were analyzed using a statistical approach, and they were fitted to analytical models in order to establish the adsorption/desorption parameters. The pulse response of a non-adsorbing gas (argon) was used as a “reference”. The experiments revealed that: CO molecules reversibly adsorbed on the catalyst surface; O2 molecularly adsorbed , irreversibly for high pulse intensities and reversibly for low pulse ones; CO2 molecules irreversibly adsorbed on the surface, probably as carbonates. This catalyst exhibited an apparent negative activation energy for irreversible adsorption of O2.
Negative Chemical Ionization Mass Spectrometric Study on the Electron-Attachment Process of Nitric Carbons
Authors: Nakagawa Seiko , Shimokawa Toshinari 
Published: September 2002

Abstract
The formation of negative ions from halogenated acetonitriles XCH2CN (X = F, Cl, Br, I) and C6F4(CN)2 was studied using negative chemical ionization mass spectrometry. The halide ion was observed for XCH2CN (X = Cl, Br, I). While the intensity of the ion increased with increasing temperature for ICH2CN, the temperature dependence for the production of ions was only slightly observed over the temperature range of 393–537 K for ClCH2CN and BrCH2CN. The parent anions were observed for C6F4(CN)2. The intensity of the parent anions increased in the order 1,3-C6F4(CN)2- &lt; 1,2-C6F4(CN)2- &lt; 1,4-C6F4(CN)2-. A temperature dependence for the parent anions was not observed. The difference in the intensity can be explained by a recombination reaction with the positive ions.
Relative Stabilites of the Crossed vs. Linear σ-Conjugated Group 14 Triplet Diradicals E4H8 and E5H10 (E = C, Si, Ge, Sn): Orbital Phase Predictions
Authors: Ma Jing , Ikeda Hirotaka , Inagaki Satoshi 
Published: September 2002

Abstract
Orbital phase theory was applied to predict that the cross σ-conjugated isomers of acyclic Group 14 triplet diradicals E4H8 1 and E5H10 3 (E = C, Si, Ge, Sn) are more stable than the linear ones, 2 and 4, respectively. This prediction was confirmed by ab initio molecular orbital (MO) and density functional theory (DFT) calculations. It was also found that the radicals are preferentially in conjugation with the C-H bond for E = C (1a and 2a), but with the E-E bond for E = Si, Ge, Sn.
Investigation of Two-Dimensional Vibrational Spectrum by a Diagrammatic Approach
Authors: Tominaga Keisuke , Maekawa Hiroaki 
Published: September 2002

Abstract
We have theoretically investigated two-dimensional vibrational spectra for a two-mode system in terms of a diagrammatic approach. The two vibrational modes are anharmonically coupled. The perturbed stationary states are obtained by treating the cubic anharmonicity as a perturbation, and expressions for the third order response functions are derived. A physical origin of cross peaks in the spectrum is discussed. It is found that the vibrational dephasing time as well as the anharmonicity is important for the appearance of cross peaks.
Successive Crystalline-State Photoisomerization of the 4-Cyanobutyl Group in a Cobaloxime Complex
Authors: Vithana Champika , Uekusa Hidehiro , Ohashi Yuji 
Published: September 2002

Abstract
The 4-cyanobutyl group bonded to the cobalt atom in a cobaloxime complex crystal was isomerized to the 2-cyanobutyl group through the 3-cyanobutyl group on exposure to a xenon lamp with retention of the single crystal form. The X-ray crystal structure analysis of the initial crystal, (I), and the crystal after 66 hours exposure, (II), revealed that the produced 3-cyanobutyl group at one site in (II) is not disordered racemates but one enantiomer. The occupancy factors of the 4-cyanobutyl and the produced 3-cyanobutyl group were 0.786(7) and 0.214(7), respectively in (II). Although the structure of the produced 2-cyanobutyl group was not located on the difference electron density map, the NMR measurement clearly indicated that a small amount of the 2-cyanobutyl complex (ca. 6%) was produced.
Spin Chemical Approach towards Long-Lived Charge-Separated States Generated by Photoinduced Intramolecular Electron Transfer in a Donor–Bridge–Acceptor System
Authors: Mori Yukie , Sakaguchi Yoshio , Hayashi Hisaharu 
Published: September 2002

Abstract
Photo-induced intramolecular electron transfer (ET) and subsequent back ET have been studied for phenothiazine-bridge-pyromellitdiimide (D-B-A) and phenothiazine-bridge-pyromellitdiimide-nitroxide radical (D-B-A-R•) in various solvents by nano-second transient absorption spectroscopy. Upon excitation of the phenothiazine (D) moiety in these compounds, ET from 1D* to A took place at a rate of ca. 5 × 109 s-1 to give charge-separated (CS) states, 1[D•+-B-A•-] or 2[D•+-B-A•--R•], in high quantum yields. The decay dynamics of the CS states was determined by the interplay between the spin conversion and the back ET to the ground state. The efficiency of the interconversion between states with different spin multiplicities was strongly affected by the presence of R• and external magnetic fields. A faster spin conversion of [D•+-B-A•--R•] resulted in a slower initial decay of the CS state generated from the excited singlet state of D compared with [D•+-B-A•- ]. Such a spin effect manifested most markedly in dioxane. On the other hand, the back ET rate (kBET) varied by more than two orders of magnitude with the solvent polarity. In dimethyl sulfoxide, the back ET was predicted to be almost barrierless, kBET ≥ 109 s-1, while in benzene, this process fell in the inverted region, kBET = 6.5 × 106 s-1.