bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charge-Transfer Complexes of Benzo[b]thiophene with σ- and π-Electron Acceptors
Authors: Ayad Mohamad M 
Published: June 2006

Abstract
The spectrophotometric properties of the charge-transfer (CT) complexes of benzo[b]thiophene with iodine at 24 °C in different solvents such as cychlohexane, carbon tetrachloride, chloroform, dichloromethane, and 1,2-dichloroethane are studied. In addition the spectrophotometric and thermodynamic properties of the CT complexes of benzo[b]thiophene with tetracyanoethylene, chloranil, 2,3-dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8,-tetracyanoquinodimethane are studied. The results show that the equilibrium and the thermodynamic parameters and the wavelengths of the maximum absorption bands (λmax) of the complexes vary markedly with the solvent. The ionization potential and the donor sites of benzo[b]thiophene are also determined and discussed.
Electrochemical Reduction Behavior of Alizarin Red S at HMDE in Aqueous Solutions
Authors: Abdel-Hamid Refat , Rabia Mostafa K , El-Sagher Hussein M 
Published: June 2006

Abstract
At hanging mercury-drop electrode (HMDE) Alizarin Red S (ARS) is electrochemically reduced in aqueous buffer solutions, giving rise to a prominent wave and a pre-wave. The prominent wave is diffusion-controlled and involves two electrons and two protons. The pre-wave is attributed to a strong reversible adsorption of the reduction product at the electrode. The reduction mechanism was proposed and discussed on the basis of the cyclic voltammetric and double potential-step chrono-amperometric & coulometric results. It was concluded that the reduction pathway is an ECEC mechanism in which the chemical reactions (C) are a dimerization of the formed radical anion and protonation of the dianion dimer, respectively. The rate-determining step is the protonation reaction. The adsorption process obeys a Langmuir isotherm with maximum surface excess of 1.4 × 10−10 mol cm−2 at a bulk concentration ≥4.6 × 10−5 mol dm−3, corresponding to 1.18 nm2/molecule. This indicates that ARS is horizontally oriented and resists reorientation upon increasing its bulk concentration.
π-Conjugation in Y-Shaped Configuration. Does a Special Stability Exist?
Authors: Ohwada Tomohiko , Kagawa Hirotaka , Ichikawa Hiroshi 
Published: June 2006

Abstract
The constrained HF method was applied to the estimation of conjugation of Y-shaped molecules. This method does not include the effect of the geometrical change, and gives a direct measurement of π-conjugation energy. We conclude that the magnitude of conjugation in a trimethylen–methane dianion is around that of a hexadienediide dianion, far less than that of a neutral cyclic aromatic compound (typically that of benzene). This is consistent with the previous conclusions obtained with the different energetic criteria. The physical meaning of Y-conjugation was interpreted in terms of relaxation of the kinetic-energy pressure of the π electrons.
Syntheses, Structures, and Properties of the Dinuclear Copper(II) and Nickel(II) Complexes Bridged by an Alkoxide and a Pyridazine or a Phthalazine
Authors: Li Chunmin , Kanehisa Nobuko , Miyagi Yoshie , Nakao Yasuo , Takamizawa Satoshi , Mori Wasuke , Kai Yasushi 
Published: June 2006

Abstract
In this paper we report our recent research on the dinuclear copper(II) and nickel(II) complexes 1—10 (Chart 1) containing Schiff bases, derived from acetylacetone, benzoylacetone, or trifluoroacetylacetone, and 1,3-diaminopropane-2-ol. These complexes are bridged by an alkoxide and a pyridazine (pyd) or phthalazine (phta). The magnetic susceptibilities, visible absorption spectra, conductivities, and redox properties of the complexes were investigated and the molecular structures of 2, 4, and 5 are described. The Cu–O–Cu angles found in these complexes indicate a role of the alkoxo-bridge as one of the principal antiferromagnetic exchange pathways. At the same time, the coplanarity of two coordination planes of copper(II) ions is also shown to relate to the exchange process.
Adsorption of Lead(II) Ion on Complexane Types of Chemically Modified Chitosan
Authors: Inoue Katsutoshi , Ohto Keisuke , Yoshizuka Kazuharu , Yamaguchi Tomoo , Tanaka Takeshi 
Published: June 2006

Abstract
Two kinds of complexane-type of chitosan chemically modified with EDTA and DTPA were synthesized and examined concerning the adsorption behavior for iron(III), copper(II), nickel(II), zinc(II), aluminium(III), and lead(II) from a dilute hydrochloric acid solution. Both of these adsorbents were found to adsorb lead(II) at low pH in a similar highly selective manner over zinc regardless of the kind of acid, whether it be hydrochloric acid or nitric acid, and to have a much stronger adsorption power compared with a commercial phosphonamidic acid-type chelating resin. The maximum adsorption capacities of lead were 1.8 and 1.5 mol/kg-dry gel for DTPA- and EDTA-chitosan. The breakthrough followed by elution tests demonstrated that it is achievable to concentrate a small amount of lead(II) which has been very selectively separated from a large excess of zinc by using an adsorption column packed with these adsorbents.
The Response Behavior of a Polyacrylamide–Benzo-15-C-5 Electrode to Sodium and Calcium Ions in Acetonitrile and Its Application to the Study of Their Complexing with Other Basic Aprotic Solvent Molecules
Authors: Nakamura Toshio , Mongi Hideyuki 
Published: June 2006

Abstract
The response behaviors of an ionophore-conjugated polymer-based ion sensor, which consists of a polyacrylamide (PAA) coupled to benzo-15-crown-5 (B15C5), for Na+ and Ca2+ in acetonitrile (AN) and N-methylpyrrolidinone (NMP) were studied. The PAA–B15C5 electrode showed a Nerstian response to Na+ in AN and Ca2+ in AN and NMP. The electrode was then applied to investigate the complexation of Na+ in AN with such other solvent molecules (D) as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO); the successive complex formation constants and Gibbs energies of transfer of Na+ in AN to DMF or DMSO and AN to AN–D mixtures were obtained. Reasonable responses of the electrode to an activity change of Na+ due to the solvation of the basic solvent molecules could be certified. The complex formation constant of Ca2+ in AN with such D as DMF, NMP, N,N-dimethylacetamide (DMA), DMSO and hexamethylphosphoric triamide could be obtained by the electrode. The association constants of Ca2+ with CF3SO3− in AN, propylene carbonate, DMF, and DMSO were determined conductometrically and the constant in AN (K1AN = 1.02 × 104 dm3 mol−1) was used for correcting the variation of calcium ion-activity due to a concentration change of Ca(CF3SO3)2 in AN.
Growth of Chlorapatite Crystals from a Sodium Chloride Flux
Authors: Oishi Shuji , Sugiura Isao 
Published: June 2006

Abstract
Well-formed crystals of chlorapatite [Ca5Cl(PO4)3] were first grown from a sodium chloride flux. The solubility of Ca5Cl(PO4)3 in NaCl increased with increasing temperature. At 1100 °C, Ca5Cl(PO4)3 had a solubility of about 0.15 mol%. The crystal growth of Ca5Cl(PO4)3 was conducted by heating a mixture of solute and flux at 1100 °C for 10 h, followed by cooling to 500 °C at a rate of 5 °C h−1. Colorless and transparent crystals having lengths up to 4.0 mm and widths of 1.2 mm were grown from high-temperature solutions containing small amounts of solute (0.05—0.5 mol%). The obtained crystals were divided into two distinct morphological types: prisms and needles. The most suitable solute contents for the growth of prismatic and needle crystals were 0.15 and 0.1 mol%, respectively. The crystal forms were also dependent on the solute content. The prismatic crystals were bounded by the {} and {} faces. The needle crystals elongated in the &lt;0001&gt; directions. Calcium, chlorine, phosphorus, and oxygen were almost homogeneously distributed in the crystals.
Synthesis and Structural Characterization of Manganese(II) Complexes with N,N′-Bis(2-pyridylmethylene)-1,3-diaminopropan-2-ol or N,N′-Bis(2-pyridylmethylene)-1,3-propanediamine
Authors: Mikuriya Masahiro , Hatano Yasushi , Asato Eiji 
Published: June 2006

Abstract
Manganese(II) complexes with N,N′-bis(2-pyridylmethylene)-1,3-diaminopropan-2-ol (HL1) or N,N′-bis(2-pyridylmethylene)-1,3-propanediamine (L2), [Mn(HL1)(NO3)2] (1) and [Mn(HL1)(NCS)2] (2), [Mn(HL1)(phen)](ClO4)2 (3), [Mn2(L1)(CH3COO)(phen)2](ClO4)2 (4), [Mn(L2)(NO3)2] (5), [Mn(L2)(bpy)(CH3OH)](ClO4)2 (6), [Mn(L2)(NCS)2] (7), [Mn(L2)(phen)](ClO4)2 (8), have been synthesized and characterized by measurements of the infrared, electronic, and ESR spectra, and magnetic susceptibilities. The molecular structures of these complexes were determined by the single-crystal X-ray structure analysis. The complexes 1·C2H5OH and 5 have an eight-coordinated manganese atom with a square antiprism geometry. The complex 6 is seven-coordinated in a monocapped trigonal prism. The manganese atoms of 2, 7, and 8 are six-coordinated in a trigonal prism environment. The coordination environment of 3 is disordered between the seven- and six-coordinate geometries. The complex 4·H2O is a dinuclear molecule comprising two octahedral Mn(II) atoms.
Synthesis of Macrocyclic Bis(dithiocarbonic ester)s and Bis(thiocarbamate)s from Diethylene, Triethylene, and Tetraethylene Glycols
Authors: Fukada Naoaki , Tanaka Takashi , Fukuya Tetsuo , Takeda Yasuyuki 
Published: June 2006

Abstract
The reaction of dipotassium bis(dithiocarbonate)s from diethylene, triethylene, and tetraethylene glycols with dibromoalkanes or ethereal oxygen-containing diiodides under high-dilution conditions gave 1 : 1 reaction products, 14—25-membered macrocyclic bis(dithiocarbonic ester)s. From dimethyl esters of the bis(dithiocarbonic acid)s and diaminoalkanes or ethereal oxygen-containing diamines, macrocyclic bis(thiocarbamate)s were obtained.
Novel Water-Soluble Organosilane Compounds as a Radical Reducing Agent in Aqueous Media
Authors: Yamazaki Osamu , Togo Hideo , Nogami Genki , Yokoyama Masataka 
Published: June 2006

Abstract
The development of novel water-soluble organosilane compounds and their application to radical reactions in water medium have been studied. A series of novel organosilane compounds having hydrophilic groups, such as an ether group and a hydroxy group in the side chain to bear hydrophilicity, were synthesized by the reaction of trichlorosilane or tetrachlorosilane and Grignard reagents. The reactivities of these organosilane compounds were studied in the radical reduction of 2-bromoethyl phenyl ether in ethanol in the presence of triethylborane under aerobic conditions. The results showed that diarylsilane was the most effective among them. The radical reduction of alkyl and aryl halides with diarylsilane was applied to a reaction in aqueous media, which gave the corresponding reduction product in good yields. Thus, the present organosilanes are very useful for the reduction of water-soluble substrates, such as halo sugars in water.
Oxidation of Diols and Ethers by NaBrO3/NaHSO3 Reagent
Authors: Sakaguchi Satoshi , Kikuchi Daisuke , Ishii Yasutaka 
Published: June 2006

Abstract
NaBrO3 combined with NaHSO3 was found to be an excellent oxidizing reagent of alcohols, diols, and ethers under mild conditions. A variety of aliphatic and cyclic diols were selectively oxidized with satisfactory yields to the corresponding hydroxy ketones and/or diketones, which are difficult to selectively prepare due to a concomitant formation of cleaved products. For example, 2-hydroxycyclohexanone and 1,2-cyclohexanedione were selectively formed by allowing 1,2-cyclohexanediol to react with NaBrO3/NaHSO3 reagent in a selected solvent. On the other hand, an alkyl ether, such as dioctyl ether, reacted with NaBrO3/NaHSO3 in water at room temperature to give octyl octanoate in 82% yield. The same oxidation at higher temperature (60 °C) produced the α-brominated ester, octyl 2-bromooctanoate, which is considered to be formed through an alkenyl alkyl ether as the intermediate. The treatment of 1-ethoxy-1-heptene with NaBrO3/NaHSO3 afforded ethyl 2-bromoheptanoate and 2-bromoheptanoic acid as the major products.
Preparation of Inorganic–Organic Nanocomposites through Intercalation of Organoammonium Ions into Layered Silicates
Authors: Ogawa Makoto , Kuroda Kazuyuki 
Published: June 2006

Abstract
Recent developments in the study of the intercalation of organoammonium ions into layered silicates are reviewed. The new developments of the applications of the organoammonium-exchanged layered silicates include the selective adsorption of toxic compounds from water, the immobilization of photo and electroactive species to construct novel photo and electrofunctional materials, and the complexation with organic polymers for the enhancement of the mechanical properties. The conversion of the layered solids to three dimensional nanoporous solids with novel microstructures and adsorptive properties has also been successfully done. The novel controlled properties achieved by the modification with the adsorption of organoammonium ions open new opportunities to tailor the properties of the inorganic-organic nanostructured materials.
Study on the Photolysis Quantum Yield of Diphenyl Disulfide by the Transient Grating Method
Authors: Kimura Yoshifumi , Sugihara Kohei , Terazima Masahide , Hirota Noboru 
Published: June 2006

Abstract
Transient grating (TG) spectroscopy, photoaccoustic spectroscopy, and transient adsorption spectroscopy have been applied to studying the nongeminate recombination of photodissociated diphenyl disulfide (DPDS) in liquids. The photolysis quantum yield can be easily determined by an analysis of the time profile of the thermal grating signal, if the contribution of the population grating can be neglected. The quantum yield of the photodissociation for DPDS in isooctane has been determined to be 0.43 ± 0.02, which coincides with the values evaluated from the acoustic strength in the TG signal and the acoustic intensity in an ordinary photoacoustic measurement. This result is compared with a pico-second transient absorption measurement (T. W. Scott and S. N. Liu, J. Phys. Chem., 93, 1393 (1989)).
Charge Recombination via Electron Tunneling after Two-Photon Ionization of Dopant Chromophore in Poly(butyl methacrylate) Film at 20 K
Authors: Ohkita Hideo , Sakai Wataru , Tsuchida Akira , Yamamoto Masahide 
Published: June 2006

Abstract
The charge recombination of electron–cation pairs produced in a poly(butyl methacrylate) film through two-photon ionization was examined at 20 K by emission spectroscopy and absorption spectroscopy. Both the isothermal luminescence (ITL) decay and the absorbance decay of the radical cation obeyed the same kinetics at 20 K: the t−m law, I(t) ∝ t−m with m ≈ 1. The temperature dependence of the ITL decay kinetics remained the same from 20 to 200 K far below the glass-transition temperature (293 K). These findings show that the ITL decay at low temperatures can be explained in terms of a long-range electron transfer by electron tunneling. Multi-shot photoirradiation was found to cause a deviation of the ITL decay from the t−m law. Multi-shot photoirradiation probably induces a larger separation of a photoejected electron from the parent cation and/or a deepening of the trap depth.
Synthesis of 2,3-Dimethylbutenes by Dimerization of Propene Using Highly Active Nickel-Phosphine Catalysts in the Presence of Sulfonic Acids and/or Dialkyl Sulfates
Authors: Nomura Kotohiro , Ishino Masaru , Suzukamo Gohfu 
Published: June 2006

Abstract
A nickel-phosphine catalyst system consisting of nickel naphthenate, P(cyclo-C6H11)3, AlEt3, and 2,4,6-trichlorophenol (TCP) in the presence of sulfonic acids (CF3SO3H and MeSO3H) or dialkyl sulfates (Me2SO4 and Et2SO4) exhibits remarkable catalytic activity for the dimerization of propene. The catalytic activity (turnover number (TON) for the formation of C6 olefins or 2,3-dimethylbutenes) was enhanced when the catalyst was combined with effective additives, such as Et2SO4 and MeSO3H. The reaction products consisted of 2,3-dimethyl-1-butene (DMB-1) and/or 2,3-dimethyl-2-butene (DMB-2) in high yields (selectivity of dimers based on the reacted propene = 70—80%: selectivity of 2,3-dimethylbutenes in C6 olefins = 78—80%). The ratio of DMB-1/DMB-2 could be controlled by varying the molar ratios of the catalyst ingredients without decreasing in the turnover numbers. Although CF3SO3H was found to be the best additive as far as the catalytic activity and the selectivity of dimers (94—99%) are concerned, the selectivity of 2,3-dimethylbutenes in C6 olefins decreased. The addition of a small amount of water was also effective to enhance the catalytic activity: The turnover number for the formation of 2,3-dimethylbutenes was raised from 7050 to 30360.
A Novel Reaction of HCrO4− with PH2O2−, Induced by Molecular Oxygen, Forming Peroxodiphosphate Ions in an Aqueous Solution
Authors: Kimura Masaru , Takahashi Aki , Kayanoki Hiroko , Sakata Tomomi , Tsukahara Keiichi 
Published: June 2006

Abstract
The chromate (VI) ion HCrO4− at pH 2—4 was not appreciablly reduced by the phosphinate ion PH2O2− in the absence of molecular oxygen (O2), but was reduced in the presence of O2, forming peroxodiphosphate ions (denoted by PDP and meaning all forms of P2O84−, HP2O83− etc.) in much higher concentrations than those of the added chromate(VI). Both the rates of the chromate decay and the PDP formation increased with decreasing pH. When the chromate(VI) ion disappeared completely, PDP formation stopped and its concentration remained constant. However, such PDP once formed in the presence of O2 began to decompose after the solution was saturated with N2 gas; its decomposition ceased again when the solution was again saturated with air. Such behaviors are discussed while presenting the reaction mechanisms.
Mixed-Valence Ruthenium Diphosphates with a Tunnel Structure: ARu2(P2O7)2 (A = Li, Na, Ag, and Cu) and Ru2(P2O7)2
Authors: Fukuoka Hiroshi , Imoto Hideo 
Published: June 2006

Abstract
Mixed-valence ruthenium diphosphates with a tunnel structure, ARu2(P2O7)2 (A = Li, Na, Ag, and Cu), were prepared by the reaction of an amorphous ruthenium phosphate, H2RuP3O10, with Li2CO3, NaNO3, AgNO3, and Cu3(PO4)2·3H2O, respectively. The structure has a three-dimensional network constructed with RuO6 and P2O7 groups, and has large tunnels where A cations reside. In the sodium system, two isotypic compounds were obtained. One was obtained as single crystals and the X-ray structure analysis showed ruthenium and sodium vacancies. Another was obtained as powder and Rietveld analysis did not indicate ruthenium vacancies. It is paramagnetic and shows an antiferromagnetic transition at around 5.5 K. The phosphate with no cation in the tunnel, Ru2(P2O7)2, was obtained as a powder upon heating amorphous ruthenium phosphate (atomic ratio P/Ru is 4).
Roles of 2′-Hydroxyls of Leadzyme on an RNA Cleavage
Authors: Ohmichi Tatsuo , Sugimoto Naoki 
Published: June 2006

Abstract
The roles of two different 2′-hydroxyls near to a catalytic site of a leadzyme (Pb2+ ribozyme), CUGGGAGUCC, have been investigated kinetically. These roles of two different 2′-hydroxyls were clearly distinguished upon a cleavage reaction of an RNA substrate. One 2′-hydroxyl of G of the leadzyme in an asymmetry internal loop contributed to only the binding constant for the leadzyme with the substrates. The other 2′-hydroxyl of A in the asymmetry loop contributed to only the cleavage rate constant. On the basis of the results, we propose the possibility of the formation of a hydrogen bond between the 2′-hydroxyl of G of the leadzyme and the substrate and the binding between Pb2+ ion and the 2′-hydroxyl of A.
13C NMR and Electronic Absorption Spectroscopic Studies on the Equilibrium between the Colorless Lactone and the Colored Zwitterion Forms of a Fluoran-Based Black Color Former
Authors: Yanagita Mitsuhiro , Aoki Izuo , Tokita Sumio 
Published: June 2006

Abstract
The equilibrium between the colorless lactone (L) and the colored zwitterion (Z) forms of the fluoran compound 1, which has been widely used as a typical black color former in data-recording systems, has been studied by 13C NMR and electronic absorption spectroscopies. Fluoran 1 showed no visible absorption in aprotic solvents, while a black color appeared in phenolic solvents. The 13C NMR and signal of the spiro carbon of 1 in CDCl3 appeared at 84.2 ppm, indicating that 1 exists substantially as L in aprotic solvents. In phenol d6 at 50 °C, the signal of the spiro carbon in 1 shifted to a lower magnetic field and appeared in the sp2-hybridization region (δ = 162.7), suggesting that in phenol-d6 a cleavage of the C(spiro)–O bond in the lactone ring occurs and that the ring-opened Z form is produced. The equilibrium between L and Z depended strongly on the temperature and solvents. The high temperature and inhibition of the solute (1)–solvent interaction by steric hindrance, self-association and intramolecular chelation of the solvent shifted the L–Z equilibrium toward L. The thermodynamic parameters for the equilibrium reaction in phenolic solvents were also estimated.
Ring Expansion and Ring Contraction Observed in Isopropenyldihydrofuran Derivatives
Authors: Yamaguchi Seiji , Sugioka Yoshihiko , Kitagawa Yuzoh , Matsumoto Yoshinori , Yokoyama Hajime , Hirai Yoshiro 
Published: June 2006

Abstract
An intramolecular anhydride formation in 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic acid caused a new ring expansion to give 4,7-dihydro-6-methyloxepin-2,3-dicarboxylic anhydride (2b). An aminolysis of 2b with benzylamine gave a mixture of two isomeric carboxamides, N-benzyl-4,7-dihydro-6-methyloxepin-2-carboxamide and trans-1-(benzyloxamoyl)-2-isopropenylcyclopropane. Also, the ring expansion and ring contraction are discussed.
Effects of Solvent Molecular Size on Rates of Topomerization in Organolithium Compounds
Authors: Oki Michinori , Ikeda Hiroshi , Kodama Kazuya , Toyota Shinji 
Published: June 2006

Abstract
Rates of topomerization of substituted 9-fluorenyllithiums and α-(benzylthio)benzyllithium were determined in various ether-type solvents by the dynamic NMR technique. The rates are small in solvents of bulky molecules in comparison with those of less-bulky molecules. UV-vis spectra of these compounds in the solvents indicate that the compounds tend to exist as solvent-separated ion pairs in solvents of small molecular size, whereas they exist as contact ion pairs in solvents of bulky molecules. 1H NMR spectra did not show signals attributable to two species at the lowest temperature of study. From these results, it is concluded that the observed process is the tumbling of the anion in solvent-separated ion pairs with a rapid pre-equilibrium between contact ion pairs and solvent-separated ion pairs, further intervention of solvent molecule(s) into the observed solvent-separated ion pairs being the rate-limiting step. A term, dimensiosolvatic effect, is proposed for the effects where the solvent molecular size plays important roles in determining rates of reaction or equilibria.