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61.
The utility of hydroxylamines as nitrogen nucleophiles was investigated in the iridium-catalyzed regio- and enantioselective allylic substitution. Allylic substitution with hydroxylamines proceeded with good enantioselectivities by using the iridium-complex of bis(oxazolinyl)pyridine ligand. The good regio- and enantioselectivities were also achieved in the reaction with alkylamines, p-anisidine, and 4-methoxyphenol. 相似文献
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Subbaiyan NK Hill JP Ariga K Fukuzumi S D'Souza F 《Chemical communications (Cambridge, England)》2011,47(21):6003-6005
A novel approach for improving photocurrent in a supramolecular solar cell, composed of zinc porphyrin-oxoporphyrinogen (ZnP-OxP) surface-modified TiO(2), by redox tuning through fluoride anion binding to the redox active host, OxP is demonstrated. 相似文献
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Enomoto T Kanematsu S Tsunashima K Matsumoto K Hagiwara R 《Physical chemistry chemical physics : PCCP》2011,13(27):12536-12544
Fluorohydrogenate salts of quaternary phosphonium cations with alkyl and methoxy groups (tetraethylphosphonium (P(2222)(+)), triethyl-n-pentylphosphonium (P(2225)(+)), triethyl-n-octylphosphonium (P(2228)(+)), and triethylmethoxymethylphosphonium (P(222(101))(+))) have been synthesized by the metatheses of anhydrous hydrogen fluoride and the corresponding phosphonium bromide or chloride precursors. The three salts with asymmetric cations, P(222m)(FH)(2.1)F (m = 5, 8, and 101), are room temperature ionic liquids (ILs) and are characterized by differential scanning calorimetry, density, viscosity, and conductivity measurements. Linear sweep voltammetry using a glassy carbon working electrode shows these phosphonium fluorohydrogenate ILs have wide electrochemical windows (>4.9 V) with the lowest viscosity and highest conductivity in the known phosphonium-based ILs. Thermogravimetry shows their thermal stabilities are also improved compared to previously reported alkylammonium cation-based fluorohydrogenate salts. Differential scanning calorimetry and X-ray diffraction revealed that tetraethylphosphonium fluorohydrogenate salt, P(2222)(FH)(2)F, exhibits two plastic crystal phases. The high temperature phase has a hexagonal lattice, which is the first example of a plastic crystal phase with an inverse nickel arsenide-type structure, and the low-temperature phase has an orthorhombic lattice. The high-temperature plastic crystal phase exhibits a conductivity of 5 mS cm(-1) at 50 °C, which is the highest value for the neat plastic crystals. 相似文献
67.
Michinobu T Shinoda S Nakanishi T Hill JP Fujii K Player TN Tsukube H Ariga K 《Physical chemistry chemical physics : PCCP》2011,13(11):4895-4900
The cholesterol-armed cyclen Na(+) complex formed stable Langmuir monolayers at the air-water interface. The π-A isotherm displayed a reasonable limiting molecular area of ~1.57 nm(2) and the areas expanded when amino acids were dissolved in water, indicating the efficient accommodation in the monolayers. Brewster angle microscopy (BAM) images exhibited almost no defects of the compressed Langmuir monolayers regardless of the presence of amino acids. Based on the idea that the increase in the limiting molecular areas corresponds to the amount of the adsorbed amino acid, the binding constants of three enantiomeric amino acids, namely valine (Val), leucine (Leu), and phenylalanine (Phe), were calculated at different surface pressures. Remarkably, a surface pressure dependent enantioselectivity of amino acid recognition was observed. Upon compression of the monolayers, the binding constants of amino acids increased accompanying an inversion of chiral selectivity from the D- to L-form in the case of Val and, conversely, from L- to D-form in the case of Phe. 相似文献
68.
Ariga K Ishihara S Izawa H Xia H Hill JP 《Physical chemistry chemical physics : PCCP》2011,13(11):4802-4811
A landmark accomplishment of nanotechnology would be successful fabrication of ultrasmall machines that can work like tweezers, motors, or even computing devices. Now we must consider how operation of micro- and molecular machines might be implemented for a wide range of applications. If these machines function only under limited conditions and/or require specialized apparatus then they are useless for practical applications. Therefore, it is important to carefully consider the access of functionality of the molecular or nanoscale systems by conventional stimuli at the macroscopic level. In this perspective, we will outline the position of micro- and molecular machines in current science and technology. Most of these machines are operated by light irradiation, application of electrical or magnetic fields, chemical reactions, and thermal fluctuations, which cannot always be applied in remote machine operation. We also propose strategies for molecular machine operation using the most conventional of stimuli, that of macroscopic mechanical force, achieved through mechanical operation of molecular machines located at an air-water interface. The crucial roles of the characteristics of an interfacial environment, i.e. connection between macroscopic dimension and nanoscopic function, and contact of media with different dielectric natures, are also described. 相似文献
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Tago Teruoki Tashiro Shizuka Hashimoto Yukiko Wakabayashi Katsuhiko Kishida Masahiro 《Journal of nanoparticle research》2003,5(1-2):55-60
Silica (SiO2)-coated ceria (CeO2) nanoparticles were prepared using water-in-oil microemulsion. Polyoxyethylene (15) cetylether and cyclohexane were used as a surfactant and organic solvent. SiO2-coated CeO2 nanoparticles were obtained by hydrolysis of metal alkoxide (tetraethylorthosilicate, TEOS) in the solution containing CeO2 precursor nanoparticles. The effects of CeO2 sources (Ce metal salt) and CeO2 particle-forming agents on the morphology of SiO2–CeO2 particles were investigated. Observation via transmission electron microscopy revealed that the type of particle-forming agent affected the nanoparticles' morphology and that CeO2 nanoparticles were spherically coated with SiO2 when using oxalic acid ((COOH)2) as a particle-forming agent of CeO2. Furthermore, the transmittance of the particles was high in the visible region (above 400 nm) and decreased in the ultraviolet region. 相似文献