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171.
Tsunehisa Hirashita Shō Kuwahara Sota Okochi Makoto Tsuji Shuki Araki 《Tetrahedron letters》2010,51(14):1847-1851
In high-temperature water a series of benzyl and allylic alcohols reacted with 1,3-dicarbonyl compounds and activated aromatic compounds to give the alkylated products without added catalysts. 相似文献
172.
Rajkumar GA Sandanayaka AS Ikeshita K Araki Y Furusho Y Takata T Ito O 《The journal of physical chemistry. B》2006,110(13):6516-6525
A rotaxane tethering both fullerene (C60) and ferrocene (Fc) moieties (abbreviated as (C60;Fc)rotax+) was synthesized in a good yield by the urethane end-capping of pseudorotaxane based on the crown ether-secondary amine motif. In (C60;Fc)rotax+, the C60 group serving as an electron acceptor is attached to the crown ether wheel, through which the axle with a Fc group acting as an electron donor on its end penetrates. The intrarotaxane photoinduced energy-transfer and electron-transfer processes between C60 and Fc in (C60;Fc)rotax+ have been investigated by time-resolved transient absorption and fluorescence measurements with changing solvent polarity. Nanosecond transient absorption measurements of the rotaxane demonstrated that the charge-separated state (C60*-;Fc*+)rotax+ is formed mainly via the excited triplet state of C60 in polar solvents. The lifetime of (C60*-;Fc*+)rotax+ was evaluated to be 20 ns in dimethylformamide (DMF) at room temperature. With lowing temperature, the lifetime of (C60*-;Fc*+)rotax+ extends to 270 ns in DMF at -65 degrees C, due to the structural changes leaving C60*- and Fc*+ at a relatively long distance in the low-temperature region. 相似文献
173.
Pagona G Sandanayaka AS Araki Y Fan J Tagmatarchis N Yudasaka M Iijima S Ito O 《The journal of physical chemistry. B》2006,110(42):20729-20732
Tetracationic water-soluble porphyrin (H(2)P(4+)) has been immobilized by pi-pi stacking interactions onto the skeleton of carbon nanohorns (CNH), without disrupting their pi-electronic network. The stable aqueous solution of the CNH-H(2)P(4+) nanoensemble was examined by both electron microscopy and spectroscopic techniques. The efficient fluorescence quenching of the H(2)P(4+) moiety in the CNH-H(2)P(4+) nanoensemble was probed by steady-state as well as time-resolved fluorescence emission spectroscopy, suggesting charge separation from the photoexcited H(2)P(4+) to CNH. In the presence of methyl viologen dication (MV(2+)) and a hole trap, accumulation of the reduced species of methyl viologen was observed by the photoillumination of CNH-H(2)P(4+), suggesting that the electron migration from the initially formed charge-separated state takes place. Transient absorption spectroscopy gave further insights on the transient species such as the charge-separated state (CNH(*-))-(H(2)P(4+))(*+), which was consumed in the presence of MV(2+) and hole shifter, leaving the reduced methyl viologen. 相似文献
174.
Imahori H Mitamura K Shibano Y Umeyama T Matano Y Yoshida K Isoda S Araki Y Ito O 《The journal of physical chemistry. B》2006,110(23):11399-11405
A silica nanoparticle has been successfully employed as a nanoscaffold to self-organize porphyrin and C60 molecules on a nanostructured SnO2 electrode. The quenching of the porphyrin excited singlet state on the silica nanoparticle is suppressed significantly, showing that silica nanoparticles are promising scaffolds for organizing photoactive molecules three-dimensionally in nanometer scale. Marked enhancement of the photocurrent generation was achieved in the present system compared with the reference system, where a gold core was employed as a scaffold of porphyrins instead of a silica nanoparticle. The rather small incident photon-to-current efficiency relative to a similar photoelectrochemical device using a silica microparticle may result from poor electron and hole mobility in the composite film due to poor connection between the composite clusters of a porphyrin-modified silica nanoparticle and C60 in micrometer scale. 相似文献
175.
Masao Kawai Masao Muto Yoshiaki Murase Shuki Araki Komei Kafuku Hiroshi Yoshioka Kazumi Nakatsu Yasuo Butsugan 《Journal of chemical crystallography》1999,29(11):1193-1196
In order to confirm the structures of the autoxidation products of 2-tert-butyl-4-methoxyphenol (BHA), X-ray crystallographic analyses have been undertaken. One of the products was converted to a dibenzoate, which was subjected to the analysis to establish the structure as the O
6,O
7-dibenzoyl derivative of (1R*,2R*,6S*,7S*,9R*)-4,9-di-tert-butyl-6,7-dihydroxytricyclo[5.2.2.02, 6]undec-4-ene-3,8,10-trione. Crystallographic analysis of the major isomer of the two isomeric products gave its structure as (E)-4-tert-butyl-2-(3-tert-butyl-4-oxocyclopent-2-en-1-ylidene)cyclopent-4-ene-1,3-dione, which also established the structure of the minor isomer as the corresponding (Z)-isomer. 相似文献
176.
Tetra(3-pyridyl)porphyrazine is soluble in trifluoroethanol yielding intense blue solutions. The electronic spectra exhibit the characteristic Soret and Q bands around 330 and 610 nm, respectively; however, the absorption profile is strongly dependent on the concentration, reflecting the occurrence of an association process. The system has been elucidated by solving the equilibrium and the absorbance-concentration equations for all the wavelengths in the spectral range, according to a variational procedure. In this way the consistent spectra of the individual species have been generated. The study has also been extended to the luminescence properties of the porphyrazine molecule, and discussed in terms of the ground state association and the exciplex formation involving the monomeric species. 相似文献
177.
Thin film capacitors with a thickness of 200 nm were prepared on SrTiO3 (1 0 0), (1 1 0) and (1 1 1) single crystal substrates at a temperature of 973 K by pulsed laser deposition (PLD) using a KrF excimer laser in an O2-O3 atmosphere with a gas pressure of 1 Pa using an X7R sintered target. As a result, perovskite BaTiO3 solid solution films were obtained. In the X7R thin films on (1 0 0) and (1 1 0) SrTiO3, only diffraction peaks with strong intensities from BaTiO3 (1 0 0) and (1 1 0), respectively, were observed. X7R films on SrTiO3 (1 1 1) were grown epitaxially oriented to the crystal plane direction of the substrate by inserting an initial homoepitaxial SrTiO3 layer with a thickness of 4 nm. The X7R/SrTiO3 film capacitors yielded a large volumetric efficiency of 50 μF/mm3 and a temperature coefficient of capacitance (TCC) of −1.3% to 1.3% which satisfies the EIA standard specifications for X7R. 相似文献
178.
179.
Hirashita T Kamei T Satake M Horie T Shimizu H Araki S 《Organic & biomolecular chemistry》2003,1(21):3799-3803
Diastereoselective couplings of salicylaldehyde, anisaldehyde and 2-pyridylaldehyde with crotyl- and cinnamylindium reagents were studied. The syl/anti selectivity was found to depend largely on the ligands on the indium atom of the allylic indium reagents. A syn-selective cinnamylation of salicylaldehyde was realized by the combination of cinnamyl acetate and indium(I) iodide, whereas an anti-selective coupling with salicylaldehyde was achieved by the indium trichloride/aluminium-mediated cinnamylation. 相似文献
180.
Hatsuo Yamamura Yuichi Yamada Rie Miyagi Kazuaki Kano Shuki Araki Masao Kawai 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(3-4):211-216
Three isomers of -cyclodextrin derivatives 2a–c possessing two trimethylammonio groups on their C(6) atoms were prepared by reaction of the corresponding regioisomers of diamino compounds with methyl iodide. These derivatives recognize chiral guests through three-point interactions composed of both Coulomb interactions by the two cationic moieties and hydrophobic interaction by the molecularcavity. 相似文献