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991.
We investigated solvation structures of I(-) on and below a surface of an aqueous solution by photodetachment spectroscopy. An aqueous solution of an alkali halide was introduced to the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The intensity of electrons emitted from the surface by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy), and we obtained absorption spectrum of I(-) on and below the solution surface. From the absorption spectrum, we found that I(-) starts to appear on the solution surface as the bulk NaI concentration increases. Similar concentration dependence was observed for the KI solution. We also found that I(-) located inside the solution is pushed to the surface, when NaCl is added to the solution. These changes are explained in terms of the difference in the polarizability of halide ions. 相似文献
992.
Shoji M Kaniwa K Hiranuma Y Maselli O Mafuné F 《The journal of physical chemistry. A》2011,115(11):2148-2154
We investigated solvation structures of I(-) and Na(+) on an aqueous solution surface by photodetachment spectroscopy and mass spectrometry. An aqueous solution of NaI was introduced into the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The abundance of electrons emitted by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy). For a concentrated aqueous solution of NaI, we observe an absorption peak at longer wavelengths than the charge-transfer-to-solvent band of I(-) in solution. This feature is assigned to the photoabsorption of I(-) at the surface. This finding indicates that when the concentration of NaI is high (>1.0 M), I(-) exists on the solution surface. The identity of the ion clusters ejected from the liquid beam following selective laser excitation of I(-) on the surface or I(-) inside the solution was revealed by mass spectrometry. The mass spectra show that Na rich clusters are formed when I(-) inside the solution is excited, whereas Na rich clusters are hardly formed by the excitation of surface I(-). These findings lead us to conclude that Na(+) does not exist on the surface of the NaI aqueous solution. 相似文献
993.
Naya S Tanaka M Kimura K Tada H 《Langmuir : the ACS journal of surfaces and colloids》2011,27(16):10334-10339
Visible-light irradiation to monoclinic scheelite BiVO(4) (m-BiVO(4)) in a solution of copper acetylacetonate (Cu(acac)(2)) has led to its decomposition and Cu recovery. The photonic efficiency at λ = 440 ± 15 nm reaches 3.4%, exceeding the value for the TiO(2)-photocatalyzed reaction at λ = 355 ± 23 nm (2.0%). The adsorption isotherm and the light intensity-dependence of the decomposition rate indicate high adsorptivity of m-BiVO(4) for Cu(acac)(2) or its sufficient supply to the surface reaction sites, which mainly contributes to the high photocatalytic activity. Electrochemical measurements using cyclic voltammetry suggest that the reaction proceeds via the oxidative degradation of the ligand followed by the reduction of the resulting Cu(2+) ions. Under aerobic conditions, the Cu(2+) ions mediate the electron transfer from the conduction band of m-BiVO(4) to O(2) to complete the catalytic cycle. 相似文献
994.
Maruyoshi K Yamaguchi T Demura T Matsumori N Oishi T Murata M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(17):4788-4795
Selectively (2)H- and (13)C-labeled spermines (SPM) were efficiently synthesized and analyzed by NMR spectroscopy to determine the spin-spin coupling constants for six conformationally relevant bonds. SPM that is composed of three alkyl moieties, a butanylene, and two propanylene chains undergoes a conformational change when interacting with multivalent anions (e.g., adenosine triphosphate (ATP), ATP-Mg(2+) , and tripolyphosphate). Upon interaction with ATP, the C-C bonds, which affect the distance between the neighboring pairs of ammonium groups (i.e., N1/N5 and N5/N5'), increase the population of gauche rotamers by 17-20% relative to those in the 4 HCl salt of SPM. However, the trend in increments of the gauche conformers for the SPM-ATP complex profoundly differs from that of the spermidine (SPD)-ATP complex. This implies that SPM may preferentially recognize the adenyl group of ATP rather than the tripolyphosphate moiety. This may account for the higher affinity of SPM to ATP-Mg(2+) than with that of SPD, which chiefly interacts with β- and γ-phosphates and is easily replaced by Mg(2+) . These results may provide a clue for the further understanding of the structural basis of polyamine biological functions. 相似文献
995.
The straightforward synthesis of isochromene derivatives and related cyclic ethers is achieved by the rhodium-catalyzed oxidative coupling of α,α-disubstituted benzyl and allyl alcohols with alkynes. The hydroxy groups effectively act as the key function for the regioselective C-H bond cleavage. 相似文献
996.
We report the encapsulation of negatively charged Au nanoparticles and anionic fluorescent (FL) dye in the inner cavity of redox-active cationic polymer nanotubes with viologen via electrostatic interaction and the release of the FL dye from the FL dye confined in the cavity of the polymer nanotubes by electrochemical and chemical reduction. 相似文献
997.
Ono Y Tanabe H Hayashi Y Ii T Narushima Y Yamada T Inomoto M Cheng CZ 《Physical review letters》2011,107(18):185001
Characteristics of the high-power reconnection heating were measured for the first time directly by two-dimensional measurements of ion and electron temperatures. While electrons are heated mainly inside the current sheet by the Ohmic heating power, ions are heated mainly by fast shock or viscosity damping of the reconnection outflow in the two downstream areas. The magnetic reconnection converts the energy of reconnecting magnetic field B(p) mostly to the ion thermal energy, indicating that the reconnection heating energy is proportional to B(p)(2). 相似文献
998.
Keisuke Adachi Yutaka Yamada Hiroaki Wada Akihiko Kameyama Hideharu Ishida Makoto Kiso 《Journal of carbohydrate chemistry》2013,32(4-5):595-607
Abstract Five sialyl Lew is X ganglioside analogs containing 4-(2-tetradecylhexadecanoylamino)benzyl group in place of ceramide and a variety of lengths of ethylene glycol chains as the spacer, have been synthesized. Glycosidation of O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-glacto-2-nonulopyranosylonate)-(2→3)-O-(4-O-acetyl-2,6-di-O-benzoyl-β-D-galactopyranosyl)-(1→4)-O-[(2,3,4-tri-O-acetylα-L-fucopyranosyl)-(1→3)]-2,4-di-O-benzoyl-α-D-glucopyranosyl trichloroacetimidate (13) with oligo ethyleneglycol monobenzyl ether derivatives 9, 10, 11 and 12, prepared from the corresponding oligo ethyleneglycols by 4-nitrobenzylation, reduction and N-acylation with 2-tetradecylhexadecanoic acid, using boron trifluoride etherate gave the corresponding glycolipid derivatives 14, 15, 16 and 17. A similar glycosidation of 13 with 4-nitrobenzyl alcohol gave the 4-nitrobenzyl glycoside 18, which was converted via reduction of nitro group and N-acylation into the corresponding glycolipid derivative 19. Compounds 14-17 and 19 were transformed into the title compounds by O-deacylation and hydrolysis of methyl ester group in good yields. 相似文献
999.
Keisuke Ichihara Prof. Hidetoshi Kawai Yuka Togari Emi Kikuta Hitomi Kitagawa Prof. Seiji Tsuzuki Dr. Kenji Yoza Prof. Masamichi Yamanaka Prof. Kenji Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3685-3692
Remarkably enhanced stability of the self‐assembled hydrogen‐bonded heterocapsule 1?2 by the encapsulation of 1,4‐bis(1‐propynyl)benzene 3 a was found with Ka=1.14×109 M ?1 in CDCl3 and Ka2=1.59×108 M ?2 in CD3OD/CDCl3 (10 % v/v) at 298 K. The formation of 3 a @( 1?2 ) was enthalpically driven (ΔH°<0 and ΔS°<0) and there was a unique inflection point in the correlation between ΔH° versus ΔS° as a function of polar solvent content. The ab initio calculations revealed that favorable guest–capsule dispersion and electrostatic interactions between the acetylenic parts (triple bonds) of 3 a and the aromatic inner space of 1?2 , as well as less structural deformation of 1?2 upon encapsulation of 3 a , play important roles in the remarkable stability of 3 a @( 1?2 ). 相似文献
1000.
This review deals with recent progress in the synthesis and evaluation of our telomestatin‐inspired macrocyclic polyoxazoles as G‐quadruplex (G4) ligands. The hexaoxazole derivatives (6OTDs) interact with and stabilize G4‐forming oligonucleotides, depending upon the character of the side chain functional groups. Cationic functional groups are particularly effective due to their secondary interaction with phosphate in the DNA backbone. On the other hand, heptaoxazole derivatives (7OTDs) showed potent G4‐binding and stabilization activity regardless of the functional groups on the side chain. A caged G4 ligand, Y2Nv2‐6OTD ( 7 ), and a fluorescent G4 ligand, L1BOD‐7OTD ( 13 ), have been synthesized. 相似文献