Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 74 , Issue 3
Showing 1-23 articles out of 23 articles from the selected issue
  • Koichi Komatsu
    Type: scientific monograph
    2001 Volume 74 Issue 3 Pages 407-419
    Published: 2001
    Released: July 01, 2002
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    This article presents an account of studies on the synthesis and properties of the cyclic π-conjugated systems annelated with bicyclic σ-frameworks. Particular emphasis is placed on π-systems carrying a positive charge, which are remarkably stabilized by complete annelation with bicyclo[2.2.2]octene. In such systems, not only the kinetic effects but also electronic effects due to σ-π conjugation strongly affect the properties of the π-systems. The thermodynamic properties, redox behavior, and the X-ray crystal structures are discussed. The cyclic π-systems studied include hydrocarbon molecules such as benzene and a series of benzenoid condensed aromatics, seven-membered ring non-benzenoid aromatic cation, i.e. tropylium ion, cyclooctatetraene, a spiro-connected cyclopentadiene, and dehydroannulenes. The study is further extended to systems containing heteroatoms such as 1,4-dithiin, metallacycloheptatrienes, and silatropylium ion.
  • Tomokiyo Doi, Takatoshi Kinoshita, Yoshiharu Tsujita, Hiroaki Yoshimiz ...
    Type: technical report
    2001 Volume 74 Issue 3 Pages 421-425
    Published: 2001
    Released: July 01, 2002
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    Amphiphilic block copolymers of poly(L-leucine-co-ethylene glycol) (PLeum-PEGn) having three different compositions, m : n = 80 : 23, 57 : 46, and 66 : 114, were prepared and spread at an air-water interface to form a stable monolayer. The α-helical conformation of PLeu segment in the monolayers was confirmed by FT-IR and circular dichroism measurements. The molecular orientation of PLeu helix rods in the monolayer was estimated by surface pressure-area isotherm and FT-IR reflection absorption spectroscopy measurements. As a result, we confirmed that α-helix rod of PLeu segment oriented slightly normal to the membrane plane. Furthermore, it was indicated that each α-helical rod in the PLeu57–PEG46 monolayer is effectively oriented normal to the interface compared to that in the PLeu80–PEG23 and PLeu66–PEG114 monolayers.
  • Jyotirmayee Mohanty, Haridas Pal, Avinash V. Sapre
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 427-433
    Published: 2001
    Released: July 01, 2002
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    Proton-transfer interactions of 2,2′- and 4,4′-biphenyldiols with urea (U), N-methylurea (MU), and triethylamine (TEA) have been investigated in methanol solutions using optical absorption as well as steady-state and time-resolved fluorescence measurements. In the ground state, both 2,2′- and 4,4′-biphenyldiols do not interact with weak proton acceptors, like U and MU. In the excited singlet (S1) state, only the 2,2′-biphenyldiol is seen to transfer a proton to U and MU, via the formation of intermolecular hydrogen-bonded exciplexes as intermediates. With TEA, a strong proton acceptor, both 2,2′- and 4,4′-biphenyldiols undergo an efficient proton-transfer reaction in their S1 state. In the ground-state, however, only 2,2′-analogue is seen to transfer a proton to TEA. The differences in the proton-transfer behavior of 2,2′- and 4,4′-biphenyldiols with different proton acceptors have been rationalized in terms of the presence and absence of intramolecular hydrogen bonding in the two diols.
  • Kikujiro Ishii, Morihiko Yoshida, Katsunori Suzuki, Hidekazu Sakurai, ...
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 435-440
    Published: 2001
    Released: July 01, 2002
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    Light transmission through amorphous chlorobenzene was studied during the vacuum deposition of the vapor onto cold substrates. It was found that samples prepared at 78 K were transparent, but those prepared at 15 K were slightly opaque. Raman and X-ray studies indicated that both kinds of samples were amorphous, but they showed different behavior against annealing. The transparent samples needed some induction period to start crystallization when the temperature was raised for annealing, while the slightly opaque samples underwent crystallization by annealing almost without any induction period. Samples prepared at very-low temperatures are considered to incorporate density inhomogeneity, and the resultant free space around molecular aggregates may allow the samples to start crystallization easily.
  • Ken-ichi Kumagai, Miki Hasegawa, Shigendo Enomoto, Toshihiko Hoshi
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 441-447
    Published: 2001
    Released: July 01, 2002
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    The electronic absorption spectra of N,N′-bis(2-aminobenzylidene)ethylenediaminatocopper(II) (abbreviated to [Cu(amben)]) were measured in ethanol and in a KBr disk. From these spectral data together with the polarization spectrum in a stretched PVA film, the X-ray photoelectron spectra, and a VESCF-MO-CI calculation, the electronic structure of [Cu(amben)] has been clarified. The reduced polarization spectrum shows that [Cu(amben)] has longer-molecular axis (y) polarized bands at 438, 300, 280, 257.7 and 222 nm, and shorter ones (z) at 418, 280, 260, 242.5 and 224 nm. The 300 nm band is assigned to an overlap of the calculated ππ*3 and ππ*4 transitions, which are charge transfer transitions between the two π-electronic systems localized almost independently on the 2-aminobenzylideneimino groups. The solid-state electronic absorption bands, measured in a KBr disk, of [Cu(amben)] are red-shifted by 2-16 nm, and considerably broadened compared with those in ethanol, indicating that the [Cu(amben)] molecules interact significantly in the solid state. The mechanism of the intermolecular interactions is discussed using the concept of the exciton model. XPS measurements show that the degree of the charge transfer from the ligand to the metal ion in [Cu(amben)] is less than that in N,N′-disalicylideneethylenediaminatocopper(II) in the ground state.
  • Mikhail V. Rekharsky, Asao Nakamura, Guy A. Hembury, Yoshihisa Inoue
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 449-457
    Published: 2001
    Released: July 01, 2002
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    Thermodynamic parameters for the complexation reactions of uridine/thymidine nucleobases and related compounds, with hosts of differing binding modes and properties (natural cyclodextrins, 5,10,15,20-tetrakis (1-methlpyridinium-4-yl) porphyrin tetrachloride and bis-intercaland macrocycle) have been determined by titration microcalorimetry and/or fluorometry, in an aqueous buffer. For each of these hosts the effect of the 5-methyl group on the binding affinities was investigated. Although the affinities of uridine and thymidine towards cyclodextrins and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetrachloride are very similar, the intercalation of these compounds into the bis-intercaland macrocycle has been shown to result in a high degree of discrimination of approximately 10 times. On the basis of thermodynamic data, the obtained contribution made by the 5-methyl group of thymidine to the structural characteristics of DNA and RNA is discussed.
  • Masaya Enomoto, Akira Miyazaki, Toshiaki Enoki
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 459-470
    Published: 2001
    Released: July 01, 2002
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    Isostructural magnets (C1TET-TTF)FeX4 (X = Br, Cl) are featured with a triangle-based ladder lattice comprised of an Fe3+ zigzag chain where a donor dimer bridges between next nearest neighboring Fe3+ sites. The FeCl4- salt is an antiferromagnet with its easy axis tilted from the ladder sheet, the FeBr4- salt shows weak ferromagnetism, with the easy axis of its antiferromagnetic behavior lying on the sheet. We investigate the magnetic properties of mixed crystal (C1TET-TTF)(FeBr4)1 - x (FeCl4)x in order to reveal the origin of the differences in magnetism. The strengths of the exchange interactions varying with x can be understood on the basis of the inter-anion/donor atomic contact lengths in the crystal. Weak ferromagnetism survives with its easy axis tilted from the sheet in the concentration region x ≈ 0.2. Then weak ferromagnetism disappears above x ≥ 0.42. In the high concentration range x ∼ 0.4-0.8, the ordered state deviates from an ordinary antiferromagnet, due to the competition between two constituent exchange interactions. However, the possibility of a spiral spin which configuration theory predicts is not conclusive. The magnetic anisotropy, whose direction varies depending on x, is a consequence of the competition between the dipole-dipole interaction and the single-ion anisotropy.
  • Shinya Matsumoto, Wataru Tokunaga, Hisashi Miura, Jin Mizuguchi
    Type: Others
    Subject area: TP
    2001 Volume 74 Issue 3 Pages 471-477
    Published: 2001
    Released: July 01, 2002
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    The solid-state spectra of two tetrathiabenzoquinone derivatives have been investigated from the standpoint of intermolecular interactions, while focusing on the bathochromic shift upon crystallization. These derivatives form a characteristic molecular arrangement consisting of a one-dimensional molecular column and a two-dimensional molecular sheet. Interactions in the excited state which depend on the molecular arrangement, exciton coupling effects (interactions between transition dipoles), were found to be small in both compounds. A small bathochromic shift of the trimethylenedithio derivative is attributed to these effects. The temperature dependence of the solid-state spectra is also in good agreement with the calculated result. However, an extremely large bathochromic shift of the ethylenedithio derivative cannot be explained in terms of the exciton coupling effects. Intermolecular interactions caused by the close atomic contacts between intermolecular sulfur atoms in single crystals were found to play an important role in the solid-state spectra of the ethylenedithio derivative.
  • Hiroshi Tsuno, Hiroyuki Kagi, Tasuku Akagi
    Type: Others
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 479-486
    Published: 2001
    Released: July 01, 2002
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    The effect of lanthanum ion on the crystallization of calcium carbonate was investigated using CaCl2–NaHCO3 solutions. A sampling vessel enabling us to sample a small aliquot of a solution at any time almost under a closed condition was invented for the experiments. The abundance of the crystallographic polymorphs in the precipitate was determined by powder X-ray diffraction. The formation of calcium carbonate from lanthanum-doped solutions can be featured by three stages: a spontaneous and rapid precipitation of vaterite, a transitive static stage and a delayed formation of calcite. Almost all lanthanum (> 95%) in the solution system (dissolved + suspended solid phases) was proved to be incorporated in the initially formed vaterite, and lanthanum in the vaterite seemed to be immobilized throughout the experiment. The presence of lanthanum in the starting solution (10-4 of calcium in mole) stabilized the initial vaterite crystal, preserved it much longer than one month and increased the solubility of CaCO3 to the level of vaterite. It is suggested that the lanthanum ion prohibited either the transformation initially formed vaterite to calcite or the overgrowth of calcite.
  • Wubiao Duan, Keiichi Satoh, Kiyoshi Sawada
    Type: Others
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 487-493
    Published: 2001
    Released: July 01, 2002
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    The formation and protonation of the complexes of a series of ethylenedinitrilopoly(methylphosphonic acids) (EDMP) [(Me)2 - p(H2O3PCH2)pNC2H4N(Me)2 - q(CH2PO3H2)q, p = 0–2, q = 1–2] with divalent transition metal ions (M = Mn2+, Co2+, Ni2+, Cu2+, Zn2+ or Cd2+) were investigated by means of potentiometry and 31P NMR spectroscopy at 25.0 °C. The complex formation constants and protonation constants of these complexes were determined by pH titration. The 31P NMR spectra of zinc and cadmium complexes were measured as a function of the pH, and the 31P NMR chemical shifts of each chemical species were evaluated by using the equilibrium constants determined by pH titration. The results for EDMP complexes were compared with those of aminopoly(methylphosphonate) (NMP) [(CH3)3 - rN(CH2PO3H2)r, r = 1 – 3] complexes and alkaline earth metal EDMP complexes. The stability constants of the metal complexes increase upon increasing the number of the phosphonate groups and are around the same between the EDMP and NMP complexes of a given metal ion having the same total number of coordinating atoms. The stabilities of the edtmp (p = q = 2) complexes are around the same as those of the medtmp (p = 1, q = 2) complexes. These results reveal the structures in which two nitrogen atoms of the ethylenedinitrilopoly(methylphosphonate) co-ordinate to the transition metal ion in any complex. These structures are different from those of the corresponding alkaline earth metal complexes. The structures of the protonated complexes were estimated from the results of the protonation constants and the 31P chemical shifts of the complexes.
  • Akiko Hori, Masami Yonemura, Masaaki Ohba, Hisashi Okawa
    Type: Others
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 495-503
    Published: 2001
    Released: July 01, 2002
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    The acyclic dinucleating ligand, N,N′-dimethyl-N,N′-trimethylenedi-(3-formyl-2-hydroxy-5-methylbenzylamine) (H2L), has been prepared. It combines two CuII ions with its N(amine)2O2 and O4 metal-binding sites to form a dinuclear complex [Cu2(L)](ClO4)2. The [1 : 1] condensation of [Cu2(L)](ClO4)2 with an aliphatic or aromatic diamine has provided macrocyclic dinuclear CuII complexes [Cu2(Li)](ClO4)2 (Li = L1 for the diamine = ethylenediamine, L2 for trimethylenediamine, L3 for tetramethylenediamine, L4 for o-phenylenediamine and L5 for 1,8-diaminonaphthalene). X-ray crystallographic studies for [Cu2(L1)(H2O)](ClO4)2•MeCN and [Cu2(L5)](ClO4)2•2MeOH demonstrate a macrocyclic dinuclear core structure with the two CuII ions in the N(amine)2O2 and N(imine)2O2 sites, in the Cu-Cu separation of ca. 3.0 Å. The dinuclear complexes are studied in magnetic, electronic spectral and electrochemical properties. The treatment of the dinuclear complexes with Na2S in acetonitrile resulted in the elimination of one Cu to afford the mononuclear complexes [Cu(Li)]•xNaClO4. The X-ray crystallography for [Cu(L2)], [Cu(L3)]•NaClO4 and [Cu(L4)] has demonstrated that the Cu in the N(amine)2O2 site is selectively eliminated. In the latter complex, the NaI ion is accommodated in the aminic site.
  • Jin-Zi Zheng, Ji-Shi Wu, Kei Toda, Isao Sanemasa
    Type: Introduction
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 505-506
    Published: 2001
    Released: July 01, 2002
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    The associations of n-alcohols (C4 to C9) with water-soluble p-sulfonato calix[4, 6, and 8]arenes have been determined in aqueous solutions at 25 °C. In contrast to the case of cyclodextrins, the alkyl chain length does not contribute to the stability of the associated complex.
  • Takashiro Akitsu, Yukiko Hiroshima, Seiko Komorita, Yoshihiko Kushi
    Type: Introduction
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 507-508
    Published: 2001
    Released: July 01, 2002
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    The crystal structure of Na2[Ni(succim)4]•2H2O complex having four monodentate succinimidate (succim) ligands was determined by X-ray structural analysis. The host complex captures five-coordinated guest sodium ion, which is the first example of a podand complex formed in a crystal. Polarized crystal electronic spectra of the complex were measured with parallel and perpendicular to b axis polarization.
  • Akio Yuchi, Atsushi Tatebe, Shinpei Kani, Tony D. James
    Type: Introduction
    Subject area: AI
    2001 Volume 74 Issue 3 Pages 509-510
    Published: 2001
    Released: July 01, 2002
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    The introduction of an electron-withdrawing substituent or a substituent protonated to be positively charged and potentially involved in hydrogen bonding enhances the reactivities of phenylboronic acids with fluoride. The use of a 60% aqueous MeOH medium suppresses the formation of the negatively charged species, irrespective of whether their structures are trigonal or tetrahedral, but enhances the overall reactivity because of less solvation of fluoride.
  • Kazuaki Shimada, Kei Aikawa, Takuji Fujita, Masanobu Sato, Kurara Goto ...
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 511-525
    Published: 2001
    Released: July 01, 2002
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    1,3-Thiaza- and 1,3-selenaza-1,3-butadienes bearing several substituents at the C-2 and C-4 positions were generated through thermal cycloreversion of 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines, respectively, and the heterodienes were efficiently trapped by using acetylenic dienophiles. When 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines were heated in the presence of nucleophiles, such as alcohols or thiols, the corresponding 1,4-adducts of the heterodienes with the nucleophiles were obtained in good yields. On the other hand, heating of 6H-1,3,5-oxathiazines or 6H-1,3,5-oxaselenazines in the absence of trapping agents afforded several products which originated from the in situ generated 1,3-chalcogenaza-1,3-butadienes; also the heterodienes were not isolated or observed directly as the monomeric forms at all.
  • Yuji Matsushima, Nobuko Komatsuzaki, Yoshiki Ajioka, Mari Yamamoto, Hi ...
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 527-537
    Published: 2001
    Released: July 01, 2002
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    Planar-chiral cyclopentadienylruthenium complexes [Ru(η5-1-CO2R*-2-Me-4-R1C5H2)(η6-C6H6)][X] (4 and 8) (R* = (l)- or (d)-menthyl; R1 = Me, Ph, t-Bu, 2-Naphthyl, or 4-BrC6H4; X = PF6 or BPh4) were synthesized in a diastereomerically pure form. The absolute configuration of 8b and 4c (R1 = Ph, t-Bu) were determined by an X-ray crystallographic analysis and those of the others were assigned on the basis of their optical properties including their CD spectra. Enantiopure complexes (SC1)-[Ru(η5-1-CONHBut-2-Me-4-R1C5H2)(η6-C6H6)][PF6] 9 and -[Ru(η5-1-CONHBut-2-Me-4-R1C5H2)(η6-C6H6)] [BPh4] 10, and (RC1)-9 and -10 were prepared from direct hydrolysis of diastereomeric complexes, followed by the reaction of amines. Replacement reactions of the bromo group in 9e (R1 = 4-BrC6H4) gave alkyl, phenyl, and ethynyl derivatives. Complexes [Ru(η5-1-CO2Et-2-Me-4-R1C5H2)(η6-C6H6)][PF6] 6 were also transformed to planar-chiral [Ru(η5-1-CO2Et-2-Me-4-R1C5H2)(CH3CN)3][X], which underwent ligand exchange reactions to afford carbonyl, phosphine, and π-arene complexes.
  • Toshifumi Hirata, Kei Shimoda, Takeshi Fujino, Shin-ya Yamane, Shinji ...
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 539-542
    Published: 2001
    Released: July 01, 2002
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    The biotransformation of (RS)-1-phenylethanol with cultured cells of Catharanthus roseus gave its vicianoside [α-L-arabinopyranosyl-(1-6)-β-D-glucopyranoside], primeveroside [β-D-xylopyranosyl-(1-6)-β-D-glucopyranoside] and gentiobioside [β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside] via the corresponding glucoside. It was found that primeveroside and gentiobioside were enantioselectively composed of only (R)-1-phenylethanol as its aglycone moiety.
  • Tadashi Okuyama, Shohei Imamura, Yoshimi Ishida
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 543-548
    Published: 2001
    Released: July 01, 2002
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    Solvolysis of (E)-1-decenyl(phenyl)iodonium tetrafluoroborate 1 was carried out in some alcohols, acetic acid, and mixed aqueous alcoholic solvents at 50–60 °C and the effects of added carboxylates and other salts were also examined in methanol. Reaction products include enol derivatives (substitution) and 1-decyne (elimination) as well as iodobenzene. Rates for the solvolysis increase with increasing nucleophilicity of the solvent but have no correlation with the solvent ionizing power. The substitution occurs mostly via inversion of configuration, and is concluded to follow the in-plane SN2 mechanism with a minor concomitant out-of-plane SN2 pathway. The reactions with the deuterated substrates show that stronger bases of pKa of the conjugate acid > 3 induce exclusively α-elimination of 1 in methanol. However, both α- and β-elimination occur in neutral methanol in a ratio of about 3/1 besides the substitution. Mechanisms for these reactions are proposed.
  • Ken-ichi Nakaya, Kazumasa Funabiki, Katsuyoshi Shibata, Masaki Matsui
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 549-554
    Published: 2001
    Released: July 01, 2002
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    Chiral N-substituted perylene-3,4-dicarboximides have been synthesized. These optically pure compounds were sufficiently soluble in acetonitrile used as fluorescent labeling reagents. Their excitation and emission maxima were observed at λ 500 and 550 nm in acetonitrile, respectively. Enantiomers in a racemic mixture could be analyzed by these reagents. Racemic Ibuprofen and alanine methyl ester were nicely separated by (R)-N-(2-hydroxy-1-phenylethyl)- and (R)-N-(α-carboxyphenethyl)perylene-3,4-dicarboximides in HPLC, respectively. The detection limits (S/N > 3) of Ibuprofen and alanine methyl ester were 1 and 13 pmol, respectively.
  • Hajime Irikawa, Kimiaki Shiratori, Norihide Adachi, Keiichi Adachi, Sa ...
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 555-559
    Published: 2001
    Released: July 01, 2002
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    Dimeric fluorescent compounds were formed from an (E)-5,5′-diphenyl-2,2′,3,3′-tetrahydro-3,3′-bipyrrolylidene-2,2′-dione by a treatment with acid anhydride and TFA. The structures of these compounds were clarified by X-ray analysis and spectral (UV-vis, 1H and 13C NMR) comparisons.
  • Chirima Arita, Hidetake Seino, Yasushi Mizobe, Masanobu Hidai
    Type: Others
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 561-567
    Published: 2001
    Released: July 01, 2002
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    A benzene solution of trans-[Mo(N2)2(dppe)2] (1a; dppe = Ph2PCH2CH2PPh2) and an equimolar amount of dppe was heated at reflux for 2 h under Ar to give [Mo(P4)(dppe)] (2a; P4 = meso-o-C6H4(PPhCH2CH2PPh2)2), where the new linear tetraphosphine P4 is presumed to form through condensation of two dppe ligands in the coordination sphere of Mo. The W complex [W(P4)(dppe)] (2b) and its dppm analogue [W(P4)(dppm)] (dppm = Ph2PCH2PPh2) were also prepared from the reactions of trans-[W(N2)2(dppe)2] with one equiv of dppe or dppm in toluene at reflux for 2 h under Ar. Detailed structures of 2a and 2b were determined by X-ray crystallography. In contrast, when the reaction mixtures obtained by treatment of 1a with excess PR3 (R = Bun, Et) in place of dppe were cooled down to room temperature under N2, novel dinitrogen complexes containing the P4 ligand [Mo(N2)(P4)(PR3)] formed; these were characterized spectroscopically and by elemental analyses.
  • Takeshi Oriyama, Akihiro Ishiwata, Takeshi Suzuki
    Type: Introduction
    Subject area: OB
    2001 Volume 74 Issue 3 Pages 569-570
    Published: 2001
    Released: July 01, 2002
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    A variety of 2-substituted 4-methylenetetrahydropyrans are easily produced by the reaction of acetals with trimethyl{2-[2-(trimethylsiloxy)ethyl]allyl}silane under the influence of a catalytic amount of tin(II) trifluoromethanesulfonate.
  • Kensuke Naka, Yasuyuki Tanaka, Kunitoshi Yamasaki, Akira Ohki, Yoshiki ...
    Type: Others
    Subject area: AM
    2001 Volume 74 Issue 3 Pages 571-577
    Published: 2001
    Released: July 01, 2002
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    A soluble complexan polymer in organic solvents, derived from 1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA), was synthesized and used as a polymer chelate precursor to YBa2Cu3O7-x thin films. Five complexan polymers (3) were prepared by a ring-opening polyaddition of CyDTA dianhydride (1) with several diamines (2). The polymer (3e) prepared with 1,2-diaminocyclohexane (2e) was soluble in water, dimethyl sulfoxide (DMSO), methanol, and ethanol. A clear aqueous solution (pH 8) containing 3e and 1/2 equivalent molar amount of metal nitrates of Y, Ba, and Cu (1 : 2 : 3 in molar ratio) was poured into tetrahydrofurane (THF) to precipitate a polymer–metal chelate. The chelate formations of each metal were confirmed by C=O stretching bonds. The polymer chelate precursor was soluble in methanol, DMSO, and water, and partially soluble in ethanol. The polymer–metal chelate was dissolved in methanol, of which the metal concentration was adjusted to 3 wt%. This solution was spin-coated onto SrTiO3 (100) and MgO (001) substrates for preparing YBa2Cu3O7-x thin films. According to an X-ray diffraction analysis, YBa2Cu3O7-x film with a c-axis orientation was formed on a SrTiO3 substrate; even the precursor film was sintered at 780 °C for 1 h under air. Superconducting YBa2Cu3O7-x films with a c-axis orientation were also prepared on a MgO (001) substrate.
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