Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 3
Showing 1-27 articles out of 27 articles from the selected issue
  • Akihiko Ishii, Toru Akazawa, Meng-Xin Ding, Takanari Honjo, Teruo Maru ...
    1997 Volume 70 Issue 3 Pages 509-523
    Published: 1997
    Released: June 11, 2006
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    The reaction of the 6-exo-oxide of 2,2,4,4-tetramethyl-1,5-diphenyl-6,7-dithiabicyclo[3.1.1]heptane (2) with 2KHSO5·KHSO4·K2SO4 gave the first isolable dithiirane oxide, (1RS, 3SR)-3-phenyl-3-(1,1,3,3-tetramethyl-4-oxo-4-phenylbutyl)dithiirane 1-oxide (1), while the 6-endo-oxide of 2 gave both 1 and its (1RS, 3RS)-isomer 10. Under similar reaction conditions, 2 yielded the first isolable, unoxidized dithiirane, 3-phenyl-3-(1,1,3,3-tetramethyl-4-oxo-4-phenylbutyl)dithiirane (3). The dithiirane 3 was also obtained by treatment of 2 with NaOCl–NaClO4. The X-ray structure analyses were performed for 1, 3, and 10. Treatment of unsymmetrical 8,8-dimethyl-1,9-diphenyl-10,11-dithiatricyclo[7.1.1.02,7]undeca-2,4,6-triene with NaOCl–NaClO4gave 3-[1-(o-benzoylphenyl)-1-methylethyl]-3-phenyldithiirane selectively in good yield. However, 1,3-dithietanes, prepared from adamantane-2-thiones, failed to give the corresponding dithiiranes by treatment with 2KHSO5·KHSO4·K2SO4 or NaOCl–NaClO4. The dithiirane 3 thermally isomerized to 2,2,4,4-tetramethyl-1,5-diphenyl-8-oxa-6,7-dithiabicyclo[3.2.1]octane probably via 2,2,4,4-tetramethyl-1,5-diphenyl-5-thioxo-1-pentanone S-sulfide.
  • Takeshi Hasegawa, Jujiro Nishijo, Yoshihiro Kobayashi, Junzo Umemura
    1997 Volume 70 Issue 3 Pages 525-533
    Published: 1997
    Released: June 11, 2006
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    The Fourier transform infrared (FTIR) polarized external reflection (ER) spectra of 9-monolayer cadmium stearate Langmuir–Blodgett (LB) films were measured on various kinds of materials (Ge, ZnSe, and GaAs) in order to investigate whether their spectra could be used for a quantitative analysis of the molecular orientation. The FTIR ER spectra on double-side-polished substrates with LB films on both sides would not fit in, even qualitatively, with the 5-layer system (IR//air/LB/substrate/LB/air) theoretical prediction. On the other hand, the ER spectra of a single-side-deposited LB film (IR//air/substrate/LB/air) were qualitatively explained by a simple 3-layer system (IR//substrate/LB/air) in which the reflection in the substrate was treated as a single reflection. This indicated that the output rays from the substrate in the conventional 5-layer system did not interfere sufficiently with each other. A 5-layer system calculation without any interference effect qualitatively explained the ER spectra of LB films on a double-side-polished substrate. It was eventually concluded that double-side-polished materials are not suitable for a precise analysis of ER spectra, since it is almost impossible to estimate the area ratio of interferential and non-interferential rays.
  • Yoshihisa Matsui, Masaharu Ono, Shuichi Tokunaga
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 535-541
    Published: 1997
    Released: June 11, 2006
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    The addition of alkali salts of chaotropic anions such as Br, I, SCN, N3, ClO4, and NO3 to an α-cyclodextrin (α-CD) solution in D2O caused marked downfield shifts in the 1H NMR signal of the C(5)–H located in the interior of the α-CD cavity, whereas the signal showed no or only small upfield shifts upon the addition of alkali salts of antichaotropic anions such as F, HCO3, H2PO4, HPO42−, and SO42−. The effects of the inorganic salts on the chemical shifts (δ) for the other protons of α-CD were significant but smaller than that on δ for C(5)–H. These facts indicate that the chaotropic anions are included within the α-CD cavity and held in the vicinity of C(5)–H. Similar, but smaller, effects of the inorganic salts were observed for β- and γ-CD. The binding constants and thermodynamic parameters determined for complexation of CD’s with some chaotropic anions suggest that hydrophobic and van der Waals interactions, as well as a conformational change of CD macrocycles and the desolvation of CD’s and/or the anions upon complexation, play important roles in complex stabilization. The effect of inorganic salts on the spin-lattice relaxation times of α-CD protons also supports the above conclusion.
  • Kazuyasu Ibuki, Masakatsu Ueno
    1997 Volume 70 Issue 3 Pages 543-553
    Published: 1997
    Released: June 11, 2006
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    The inertia and non-Markovian effects on the short-time dynamics of a diffusion-controlled reaction were studied using a generalized Fokker–Planck equation with a boundary condition suitable for a collision-induced reaction. The approximation of half-range Maxwellian velocity distributions was employed to calculate the time-dependent rate constant. At time zero, the rate constant obtained analytically exhibits a limiting value which is independent of the friction kernels, and is smaller than that of the Smoluchowski–Collins–Kimball (SCK) theory. At finite times, the rate constant is obtained numerically, and its initial decay is slower than that of the SCK theory even when only the inertia effect is taken into account. When a non-Markovian effect is also taken into account, the initial slow decay becomes more pronounced. We have also found that the theoretical rate constant is sensitive to the boundary condition for the velocity distribution at the reaction radius. In order to test the results, we carried out a computer simulation of an encounter reaction between a test particle and hard-sphere reactants in a hard-sphere fluid, and obtained the survival probabilities of the test particle. Our results agree excellently with the simulation results.
  • Masayasu Tasaka, Ryotaro Kiyono, Masud Shamsul Huda
    1997 Volume 70 Issue 3 Pages 555-559
    Published: 1997
    Released: June 11, 2006
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    Theoretical equations for the thermoosmosis and thermal membrane potential across a charged membrane were derived using a set comprising the energy flux and the coupled logarithmic temperature-difference force as a dissipation function of irreversible processes. In order to obtain phenomenological equations in discontinuous systems by integrating phenomenological equations in continuous systems, it was assumed that temperature and total chemical potential are continuous at the interface between the membrane and the external solution. The new equations were compared with approximate equations derived previously from a set comprising the entropy flux and the coupled temperature-difference force as the dissipation function. Moreover, an equation for the thermal membrane potential was also derived using an alternative method by summing two parts: the equilibrium potential differences between the membrane and the external solutions on both sides of the membrane (two Donnan potentials) and the thermal-diffusion potential in the membrane.
  • Mark A. Young, Gary DeBoer, Akira Fujimoto, Naoya Iwasaki, Hassime Tra ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 561-569
    Published: 1997
    Released: June 11, 2006
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    The laser-induced fluorescence spectra and the fluorescence lifetimes of 1-methyl-2(1H)-pyridinimine and its deuterated analog were measured in a supersonic jet. The spectral results reveal a number of low frequency modes which are assigned to torsional motions involving the methyl group. The two major groups of peaks observed are ascribed to the presence of cis/trans conformers in the supersonic expansion.
  • Kohjiro Hara, Tadayoshi Sakata
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 571-576
    Published: 1997
    Released: June 11, 2006
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    Electrochemical reduction of CO2 was studied under high pressure on Co, Rh, Ni, Pd, Pt, Ag, and Cu electrocatalysts supported in the gas diffusion electrode (GDE). CO was produced on Pd and Ag catalysts at faradaic efficiencies of 58 and 86%, respectively, at 300 mA cm−2 under CO2 20 atm. In the case of Cu-GDE, CO and formic acid were produced as the main reduction products. Hydrogen was the predominant reduction product in the electrolyses using other GDEs. Effects of the CO2 pressure, the current density, and the passed charge in the electrochemical reduction of CO2 using Pd and Ag-GDEs were investigated in detail. The maximum partial current density of CO formed on the Pd-GDE under CO220 atm was 450 mA cm−2. A very large partial current density of CO formation of 3.05 A cm−2 was achieved in the electrolysis under 30 atm on the Ag-GDE.
  • Masayuki Someya, Kohsuke Fukushima, Ryosuke Shimozawa
    1997 Volume 70 Issue 3 Pages 577-582
    Published: 1997
    Released: June 11, 2006
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    We measured the binding of local anesthetic tetracaine to phosphatidylinositol (PI), dipalmitoylphoshpatidylcholine (DPPC) and PI/DPPC mixed vesicles by an equilibrium dialysis method at different pH (5.5, 7.0, 8.0) at 35 °C. The results obtained for the pure phospholipid vesicles show that tetracaine binds to PI with the polyhydroxy headgroup, rather than to twitter ionic DPPC. For mixed vesicles, the higher is the ratio of the PI in mixed vesicles, the higher is the binding number. The change in pH slightly influences the binding to PI, while it strongly influences the binding to DPPC. We calculated the binding parameters which characterize the binding isotherms based on Langmuir-type and Hill equations. The binding parameters for pure PI and DPPC vesicles well reproduce the binding isotherms for PI/DPPC mixed vesicles with different mixing ratios. The results for pure PI were compared with those previously obtained for dilauroylphosphatidic acid (DLPA) in order to examine the influence of inositol in the head group of PI on the binding of tetracaine to phospholipid vesicles.
  • Midori Kato, Masaaki Okunaka, Nami Sugita, Masashi Kiguchi, Yoshio Tan ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 583-585
    Published: 1997
    Released: June 11, 2006
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    We have synthesized a series of 2-alkylcarboxamido-4′-methoxy-4-nitrotolan derivatives and studied the second-order nonlinear optical properties using the total reflection technique. We measured the infrared absorption spectra of the derivatives and examined the absorption peak of the N–H stretching vibration around 3300 cm−1, which is sensitive to hydrogen bonding. We observed that the peak frequencies of the nonlinear optical active materials were lower than those of the inactive ones, and thus found that for 2-alkylcarboxamido-4′-methoxy-4-nitrotolan derivatives the hydrogen bond plays an important role in activating the second-order optical nonlinearity of the material.
  • Kazuki Nakanishi, Naohiro Soga
    1997 Volume 70 Issue 3 Pages 587-592
    Published: 1997
    Released: June 11, 2006
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    Phase separation and gelation behaviors have been studied for acid-catalyzed, alkoxide-based silica systems containing poly(ethylene oxide), PEO. In order to clarify the role of PEO in a phase-separating sol–gel system, the effects of the molecular weight of PEO and the reaction temperature were investigated in detail. The PEO concentration of the highest phase-separation tendency slightly increased along with a decrease in the molecular weight, suggesting that the phase-separation behavior is mainly governed by an interaction between PEO and the solvent mixture. The reaction temperature affected the morphology-composition relationship mainly by its effect on the sol–gel transition kinetics.
  • Chong-Liang Zhang, Yoshio Narusawa
    1997 Volume 70 Issue 3 Pages 593-600
    Published: 1997
    Released: June 11, 2006
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    A new titration method based on concentration-variable patterns is presented. Since this titration method is characterized by a non-dilution and a non-gradient operation, no volume correction is necessary, and the influence of the matrix is indifferent. The proposed method is applied to acid–base and redox titrations. In addition, a new approach for equivalence-point detection is established, where the equivalence point can be mathematically determined by solving simultaneous linear equations before and after the equivalence point. Indicators or first-derivative and second-derivative treatments are no longer necessary, and the accuracy and precision in the equivalence point have been improved, compared with the traditional titration method. The titration error has been decreased to such levels as 0.1 pH for acid–base titrations, and of 0.01 V unit for redox titrations.
  • Didarul A. Chowdhury, Satsuo Kamata
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 601-607
    Published: 1997
    Released: June 11, 2006
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    A series of new bis-type derivatives of O,O-diisobutyl phosphorodithioate, namely, the alkane-1,ω-diyl bis(O,O-diisobutyl phosphorodithioate)s (ADBDiBPDT), were synthesized for use in the solvent extraction of precious metals. These compounds having the general formula (i-BuO)2P(S)S(CH2)nS(S)P(Oi-Bu)2, have considerable selectivity for extraction of Pd(II) over Au(III), Ag(I), and Pt(IV) when extracted from 0.1 M (1 M = 1 mol dm−3) perchlorate, nitrate, and chloride media. The extractability of individual metal ions increases with the increase in the length of the alkane-1,ω-diyl chain (n = 1—4), joining the two phosphorodithioate groups in the bis-structure. The extraction of palladium(II) from 1.0 M chloride solution at pH 3 in 1,2-dichloroethane (DCE) proceeds through the formation of either a 1 : 2 (n = 1) or a 1 : 1 (n = 2,3,4) palladium-ligand complex involving ligand displacement in PdCl42− species. When compared with the monofunctional triisobutylphosphine sulfide (TIBPS) and dihexyl sulfide (DHS), the new reagents were found to provide higher Pd(II) extraction and better extraction selectivity, under identical conditions. The higher members of the ADBDiBPDT series acting as bidentate ligands are also characterized by better stripping properties compared with those of the monodentate sulfur ligands. The metal loading capability, the extraction constants, and the kinetic properties of palladium extraction using these reagents are discussed.
  • Noriyuki Takahashi, Masanori Tanaka, Teiji Satoh, Tadashi Endo
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 609-614
    Published: 1997
    Released: June 11, 2006
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    A novel porous adsorbent was prepared by adding an aqueous solution having Zn, Al, and Si components into a suspension of silica hydrogel at 40 °C. According to the results of XRD, NMR, TEM etc., the adsorbent was identified as being a new composite consisting of lamellar fraipontite and silica. The layer structure of the resulting fraipontite was not stratified three-dimensionally. NMR data also verified that the structural framework consisted of a single ZnO6 octahedral sheet with Aloct and a single SiO4 tetrahedral sheet with Altet, which bonded with silica. The formation process of this porous adsorbent, incorporated by silica particles, was systematically examined in some detail.
  • Tomohide Tanaka, Keiko Tsurutani, Atsushi Komatsu, Toyofumi Ito, Kazum ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 615-629
    Published: 1997
    Released: June 11, 2006
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    A series of cationic salen-type Schiff base complexes of copper(II), the general formula of which is [Cu{R3N+–CH2–C6H3(O)–CH=N–}2X]Br2 (R: CH3, C2H5, C3H7, C4H9; X: C2H4, C3H6, C6H10, C6H4, C10H6), was newly prepared, and the molecular structure of complex 1 (R = CH3, X = C2H4) was determined by an X-ray crystal structure analysis. The binding mode and binding constants (Kb) of all the complexes with calf thymus DNA were investigated at an ionic strength of I = 0.05(NaCl + HEPES buffer, pH = 7.2) using induced CD and the UV-vis spectra. Those complexes with aliphatic X group selectively bound to the groove of DNA, and the Kb’s were in the range of 102—103 mol dm−3 (site size base pairs n = 7.2—7.4). However, those with aromatic X group selectivity intercalated to the base pairs, and the Kb’s were in the range of 104—105mol dm−3 (n = 2.8—4.0). These binding modes were confirmed based on the salt dependence of Kb’s. In addition, 1 and 10 (R = CH3, X = C6H4) were found to exhibit AT-sequence affinity from the induced CD spectra and Kb’s for poly(dA-dT)–poly(dA-dT), poly(dG-dC)–poly(dG-dC), and poly(dA-dC)–poly(dT-dG).
  • Sadayuki Himeno, Hirotaka Niiya, Tadaharu Ueda
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 631-637
    Published: 1997
    Released: June 11, 2006
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    Molybdenum(VI) solutions were investigated in detail by Raman spectroscopy with a view to establishing the speciation of the predominant polynuclear species (isopolymolybdates) formed in aqueous solution. The most intense Raman frequencies due to asymmetric stretching vibration of Mo=O were very sensitive to even small changes of the structure of the isopolymolybdates. As the pH was lowered, the major Raman line showed no gradual shift but exhibited a discrete change. Evidence was obtained for the existence of Mo7O246− (pH 4—6), Mo3O102− (pH 3.5—5), α-Mo8O264− (pH 2—5), β-Mo8O264− (pH 1.5—4), and Mo36O1128− (pH 0.5—1.5). On the other hand, neither of Mo6O192− and γ-Mo8O264− existed in any appreciable amount in aqueous solution.
  • Eiji Asato, Koji Kamamuta, Yasutoshi Akamine, Takanori Fukami, Ryoji N ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 639-648
    Published: 1997
    Released: June 11, 2006
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    In order to examine the potential ability of bismuth(III) thiolate complexes as new Bi-based chemotherapeutic agents, three bismuth(III) complexes of 2-mercaptoethanol (H2meret) —[Bi(Hmeret)2](NO3)·H2O (1), [Bi(Hmeret)(meret)] (2), and [Bi(Hmeret)3] (3)— have been synthesized. X-ray structure determination of 1 and 2 showed that both complexes have one-dimensional polymeric structures where thiolato-S atoms bridge Bi atoms in 1 and alkoxo-O atoms bridge them in 2. On the other hand, their NMR study revealed that both complexes completely dissociate and behave as mononuclear species in solution. For the three and several Bi-containing compounds as references, antibacterial activities toward Helicobacter pylori, a pathogenic factor of clonic gastritis and peptic ulcer, were tested in vitro. All the complexes including the reference samples showed nearly the same and moderately strong activities. The inhibitory effect toward H. pylory-produced urease was also tested for the three and the reference samples, and further for free 2-mercaptoethanol, which is a well-known urease inhibitor. It was found that the activity of 2-mercaptoethanol was significantly enhanced on forming complex(es) with Bi(III).
  • Masakazu Hirotsu, Masaaki Kojima, Yuzo Yoshikawa
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 649-657
    Published: 1997
    Released: June 11, 2006
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    Manganese complexes containing tripodal tetradentate ligands with an N2O2 donor set (H2L1: N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L2: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L3: N,N-bis(3,5-di-t-butyl-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine) have been prepared. The mononuclear and trinuclear complexes with the additional carboxylate ligand were isolated. The steric effect of the 3-positioned t-butyl groups on the aromatic rings of the tripodal ligand controls the type of the complex structure. The L3 ligand gave a mononuclear complex, [Mn(L3)(mcba)(CH3OH)], where mcba is a m-chlorobenzoate anion; the structure has been determined by X-ray analysis. The trinuclear complexes are formulated as [Mn3(Ln)2(carboxylato)2(OCH3)2] (n = 1, 2). For the L4 and L5 ligands (H2L4: N,N-bis(5-methoxy-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L5: N,N-bis(5-chloro-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine), trinuclear complexes were also obtained. Three trinuclear complexes were also structurally characterized by X-ray analysis. The three manganese cores are arranged linearly, and the structural parameters indicate that the oxidation states are MnIII–MnII–MnIII. The MnIII and MnII cores are bridged by phenolate, carboxylate, and alkoxide groups, and the manganese cores are separated in the range of 3.14 and 3.17 Å. The variable-temperature magnetic susceptibility measurements of the mixed-valence trinuclear complexes revealed that the spin exchange coupling constants (J) between MnIII and MnII ions range from −0.25 to 1.9 cm−1. The exchange interactions are weak, and both antiferromagnetic and ferromagnetic interactions were observed.
  • Kyoko Nozaki, Naomasa Sato, Koji Nakamoto, Hidemasa Takaya
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 659-664
    Published: 1997
    Released: June 11, 2006
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    Cyclocopolymerization of 1,4-pentadiene with carbon monoxide gave polyketone 3 in the presence of a Pd(II) catalyst bearing an unsymmetrical bidentate ligand, (R,S)-BINAPHOS {=(R)-2-(diphenylphosphino)-1,1′-binaphthalen-2′yl (S)-1,1′-binaphthalene-2,2′-diyl phsophite}. In the repeating unit of 3, exclusive formation of a cyclopentanone framework rather than cyclohexanone has been revealed by 13C NMR and IR spectroscopies. A single-unit analog 2 was prepared to identify the structure of 3. In the cyclopentanone unit of 3, the two substituents are cis and trans to each other in almost 1 : 1 ratio. The polymer 3 showed different behavior in thermal analysis from that of propene–CO alternating copolymer. 1,5-Hexadiene also afforded the corresponding cyclocopolymer 5. The molar optical rotation of polymer 3 was much lower than that of 5.
  • Takatsugu Wakahara, Ryuji Kodama, Takeshi Akasaka, Wataru Ando
    1997 Volume 70 Issue 3 Pages 665-670
    Published: 1997
    Released: June 11, 2006
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    The reaction of 1,2-dichloro-1,2-diisopropyl-1,2-disilaacenaphthene with an excess of alkali metal resulted in the formation of the corresponding dialkali metal, 1,2-disila-1,2-acenaphthenediide, as the disilanylene 1,2-dianion. UV-vis and NMR spectroscopic analyses strongly support the delocalization of the silyl anion.
  • Joe Otsuki, Keith C. Russell, Jean-Marie Lehn
    1997 Volume 70 Issue 3 Pages 671-679
    Published: 1997
    Released: June 11, 2006
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    A bis-crown ether derivative of triaminotriazine was synthesized via a phthalic acid derivative of a polyether macrocycle obtained from benzo-18-crown-6. It exists in different conformers distinguishable by 1H NMR at room temperature, in which the macrocyclic side-arms take a closed, half-open, or fully open form, due to the rotational barrier of the C(triazine)–N bond. Large alkali metal ions, such as Rb+ and Cs+, the latter being particularly effective, promote the formation of the closed conformer. A barbiturate derivative also causes a similar equilibrium shift to the closed form by establishing complementary hydrogen bonds. The half-open and fully open conformers are induced by smaller alkali metal ions than Rb+, among which K+ is the most effective.
  • Kazunari Hashizume, Naoto Hashimoto, Yoshihiro Miyake
    1997 Volume 70 Issue 3 Pages 681-687
    Published: 1997
    Released: June 11, 2006
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    We have completed a convenient synthesis of fluorine-18 labeled butyrophenone neuroleptics from their nitro precursors. Thus, we have developed an efficient single-column HPLC system using a C18-bonded vinyl alcohol copolymer gel (octadecyl polymer, ODP) column and strongly alkaline solvent systems for purifying of the 18F-labeled butyrophenone neuroleptics obtained by a single-step 18F-for-nitro exchange reaction. The method has been applied to the synthesis of two typical butyrophenone neuroleptics ([18F]haloperidol and [18F]spiperone) with high purity in high yield. With information concerning the optimized conditions for the 18F-for-nitro exchange reaction, the synthetic method would be useful for synthesizing various 18F-labeled compounds.
  • Yooichiroh Maruyama, Shintaro Ikeda, Fumiyuki Ozawa
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 689-693
    Published: 1997
    Released: June 11, 2006
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    The alkylation of [Ru(tp)Cl(cod)] (1) (tp = hydrotris(pyrazolyl)borate) with AlR3 (R = Et, Me) successfully proceeded in a benzene or toluene solution at room temperature to give the corresponding [Ru(tp)R(cod)] complexes (R = Et (2), Me (4)) in high yields (82 and 96%, respectively). On the other hand, the reaction of 1 with an ethylmagnesium compound (Et2Mg or EtMgBr) or EtLi provided a significant amount of [Ru(tp)H(cod)] (3) together with 2.
  • Yoshihiro Ito, Akinori Suzuki, Naoki Kawazoe, Yukio Imanishi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 695-698
    Published: 1997
    Released: June 11, 2006
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    A DNA ligand that selectively binds to the anticancer agent methotrexate was identified using the in vitro selection method. A pool of single-stranded DNAs consisting of random sequences was incubated with a methotrexate-immobilized agarose gel; bound DNAs were then collected and amplified using the polymerase chain reaction (PCR). This selection process was repeated six times. The selected DNAs were cloned and were found to contain two common sequences. One of these selected DNA clones selectively bound to the methotrexate-immobilized gel and showed a high level of discrimination against the gel immobilized with folic acid, which has a similar chemical structure to methotrexate. In the selection process, a buffer solution was used for DNA binding to the methotrexate-immobilized gel and water was used for elution from the gel. Ultraviolet absorption measurement showed that the conformation of the DNA ligand in the binding buffer was different from that in elution water.
  • Masayuki Takeuchi, Hideomi Kijima, Itaru Hamachi, Seiji Shinkai
    1997 Volume 70 Issue 3 Pages 699-705
    Published: 1997
    Released: June 11, 2006
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    The cooperative action of two boronic acids is indispensable to the selective binding of saccharides in aqueous solution and the binding process can be spectrophotometrically monitored by using porphyrins as a chromophoric probe. It is not so easy, however, to synthesize porphyrins that satisfy these prerequisites, i.e., porphyrins bearing two appropriately-arranged boronic acid groups within a molecule. In this paper, we report that such a diboronic-acid-based porphyrin receptor can be easily designed by utilizing the self-assembling nature of a Zn(II) porphyrin and an axial ligand: That is, a mixture of boronic-acid-appended Zn(II) porphyrin (1-Zn) and 3-pyridylboronic acid (2) self-organizes to create a novel diboronic acid system for saccharide (S) recognition. Thus, the 1-Zn·2·S ternary complexes give the CD spectral pattern inherent to saccharide absolute configuration. The present study is a new example for sugar sensing using a boronic acid-porphyrin self-assembly system.
  • Noriaki Murase, Keiji Maruoka, Takashi Ooi, Hisashi Yamamoto
    1997 Volume 70 Issue 3 Pages 707-711
    Published: 1997
    Released: June 11, 2006
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    A new, general synthetic method of six-membered carbocycles has been demonstrated, which involves the stereocontrolled cyclization of olefinic epoxides with methylaluminum bis(4-bromo-2,6-di-t-butylphenoxide) (MABR) via the epoxide rearrangement and subsequent intramolecular ene reaction with high stereoselectivity. This strategy is shown to be highly useful in the stereoselective synthesis of the basic skeleton of various terpenes.
  • Kunio Mochida, Shuh-saku Nagano, Shigeru Maeyama, Takuo Kodaira, Akira ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 3 Pages 713-716
    Published: 1997
    Released: June 11, 2006
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    Third-order nonlinear susceptibilities (χ(3)) for thin films of oligo- and polygermanes were measured in the range of 0.6—86 × 10−12 esu. A measured χ(3)of 86 × 10−12 esu for a polygermane–polysilane random copolymer, coploy(methylphenylsilylene/methylphenylgermylene), was the largest ever reported for transparent polymers in the visible spectral region.
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