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201.
Prof. Dr. Koji Kano Toshiro Ochi Sayuri Okunaka Yusuke Ota Keiichi Karasugi Takunori Ueda Dr. Hiroaki Kitagishi 《化学:亚洲杂志》2011,6(11):2946-2955
Poly(acrylic acid) (PAA) is modified by 5‐(4‐β‐alanylaminophenyl)‐10,15,20‐tris(4‐sulfonatophenyl) porphinatoiron(III) to yield iron porphyrin‐bearing PAAs (FeP(n)s) through a condensation reaction. FeP(n)s were further functionalized by Py3CD, which is a per‐O‐methylated β‐cyclodextrin (CD) dimer with a pyridine linker and includes the porphyrin pendants to form ferric hemoCD‐P(n)s. Ferrous hemoCD‐P(3), having three porphyrin chromophores in a polymer chain, is shown to bind molecular oxygen (P1/2=7.9±1.4 Torr) in aqueous solution at pH 7.0 and 25 °C, affording oxy‐hemoCD‐P(3). Oxy‐hemoCD‐P(3) is biphasically autoxidized to ferric hemoCD‐P(3), with 27 % of the dioxygen adducts being rapidly oxidized. The rate of autoxidation of oxy‐hemoCD‐P(15), having 15 porphyrin chromophores in a polymer chain, was much faster than that of oxy‐hemoCD‐P(3), thus suggesting self‐catalyzed autoxidation of oxy‐hemoCD‐P(n)s. Oxy‐hemoCD‐P(n)s are markedly stabilized by catalase, thereby indicating that hydrogen peroxide generated from oxy‐hemoCD‐P(n) accelerates the autoxidation. Most of the hemoCD‐P(3) molecules injected into the femoral vein of a rat remained in the body, though about 16 % of the hemoCD‐P(3) molecules were excreted in the urine as a carbon monoxide adduct. 相似文献
202.
Yamaguchi S Mazur K Heisler IA Shirota H Tominaga K Meech SR 《The Journal of chemical physics》2011,135(13):134504
The low frequency Raman spectral density associated with the intermolecular hydrogen-bonding interaction of benzoic acid in chloroform was investigated through the ultrafast optically-heterodyne-detected optical Kerr effect. The low-frequency solute Raman spectrum was obtained by Fourier transform analysis and subtraction of the solvent spectrum from the solution spectrum. The resulting difference spectrum has a broad band below 150 cm(-1) with a peak at around 80 cm(-1). Previous studies of aromatic liquids suggest that the origin of such a low-frequency band is librational motion, although intermolecular hydrogen-bonding modes in benzoic acid may also contribute. To clarify these contributions to the low-frequency band, methyl benzoate was used to estimate the librational component; its structure is similar to benzoic acid, but it forms no intermolecular hydrogen bonds. Both librational and intermolecular modes were found to contribute to the low-frequency Raman spectrum of the dimer and thus can be separated. These experimental results were compared with the results of density functional theory calculations. In addition, the effect of deuteration on the Raman spectrum was also investigated. 相似文献
203.
Tetsuo Kuwabara Kazuyo Shiba Mayumi Ozawa Naoya Miyajima Yasutada Suzuki 《Tetrahedron letters》2006,47(26):4433-4436
Two β-cyclodextrin derivatives (1 and 2) bearing a hydroxyazobenzene unit, each having a butylene or a 4,7-dioxadecylene spacer between the cyclodextrin and the dye, were prepared, which showed guest-induced color changes with a marked difference in molecular recognition behavior in aqueous solution. 相似文献
204.
K. Miyajima M. B. Knickelbein A. Nakajima 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):177-182
Stern-Gerlach type magnetic deflection measurements were performed for two types of
multiple sandwich clusters: vanadium-benzene Vn(C6H6)n+1 and
terbium-cyclooctatetraene Tbn(C8H8)n+1.
Beams of Vn(C6H6)n+1 clusters (n = 1-4) showed symmetric broadening induced by
the inhomogeneous field, indicating free spin behavior similar to that displayed
by isolated paramagnetic atoms. By contrast, beams of Tbn(C8H8)n+1 clusters
displayed one-sided deflection, indicating that fast spin relaxation occurs
within the clusters. The difference in the magnetic deflection behavior
exhibited by these two systems is explained by their electronic structures,
specifically the bonding characteristics between metal atoms and ligand molecules. 相似文献
205.
Hayashi S Hirano K Yorimitsu H Oshima K 《Journal of the American Chemical Society》2008,130(15):5048-5049
Treatment of tertiary homopropargyl alcohol with aryl halide under palladium catalysis provided arylallenes regioselectively. The reaction includes retro-propargylation, which proceeds in a concerted fashion via a cyclic transition state and transfers the stereochemistry of homopropargyl alcohols through C-C bond cleavage. The present method enables the use of homopropargyl alcohols as allenylmetal equivalents. 相似文献
206.
Reactions of ruthenium complexes having 2-pyridinecarboxylato and 2,2'-bipyridine ligands with sodium azide in alcohol afforded nitrido-bridged diruthenium complexes, [{Ru(OR)(pyca)(bpy)}2(mu-N)](+) (R = CH3, C2H5). Diruthenium complexes showed diamagnetic properties, a linear Ru-N-Ru coordination configuration, and two irreversible oxidation waves and two reversible reduction waves. 相似文献
207.
It is known that a niobium-carbon Met-Car cluster ion (Nb 8C 12 (+)) and its intermediates (Nb 4C 4 (+), Nb 6C 7 (+), etc.) are selectively formed by the aggregation of the Nb atoms in the presence of hydrocarbons. To elucidate the formation mechanism, we prepared Nb n C m (+) with every combination of n and m in the gas phase by the laser vaporization technique. The reactivity of Nb n C m (+) with H 2 was examined under the multiple collision condition, finding that Nb n C m (+) between Nb 2C 3 (+) and Nb 8C 12 (+) are not reactive with H 2. On the basis of the H 2 affinity of Nb n C m (+) experimentally obtained, we propose a dehydrogenation-controlled formation mechanism of niobium-carbon Met-Car cluster ions. 相似文献
208.
We report here the first study of the protonated, neutral form of tetrazoles as anion binding functional groups. Our studies reveal them to be capable of binding anions with extremely high potency in polar solutions. In studying carboxylic acid-containing congeners, we find a remarkable discrepancy: a strictly analogous acid-containing host binds anions > or = 50,000-fold more weakly than the tetrazole under study. We can explain this functional difference by considering tetrazole tautomerization equilibria and carboxylic acid conformational preferences. 相似文献
209.
Tatsuya Nabeshima Sayuri Masubuchi Norie Taguchi Shigehisa Akine Toshiyuki Saiki Soichi Sato 《Tetrahedron letters》2007,48(9):1595-1598
We synthesized an artificial redox-active Fe-pseudocryptand as an anion receptor to respond to electrochemical oxidation and reduction. Spectroscopic study and X-ray crystallography showed that the assembled urea chains and the isocyanuric platform generate an anion-binding cavity through favorable multiple hydrogen bonds and anion-π interactions. As the positive charge of the Fe center increases, the anion affinity is effectively increased due to an enhanced electrostatic interaction between the Fe atom and the anionic guest. This is the first efficient multi-step regulation of Cl− selective anion recognition by the redox-active pseudocryptand. 相似文献
210.
Seiichi Miyajima Keisuke Nakazawa Keiko Niikura Yasuhiro Ujiiye Makiko Yashiro Takehiko Chiba 《Liquid crystals》1990,8(5):707-718
The nature of smectic A liquid crystals and the phase transitions from smectic A to nematic phases are studied in the homologous series of 4-(4'-octyloxy-benzoyloxy)benzylidene-4'-substituted anilines, in which the substituents are H, F, Cl, Br, I, NO2 and CN. Measurements have been performed for the dipole moment of the molecule, the smectic A lattice period, the temperatures and the entropies of phase transitions, and the temperature dependence of the orientational order parameter, all of which provide information on the intermolecular pair potentials. It is shown that the introduction of a terminal polar substituent brings about counteracting contributions to the stability of the smectic A state. It is suggested that the reentrant nematic phase transition can appear in the strongly polar mesogens if the extent of antiparallel association of the molecules increases on lowering the temperature. 相似文献