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991.
Visible‐Light‐Induced Electron Transport from Small to Large Nanoparticles in Bimodal Gold Nanoparticle‐Loaded Titanium(IV) Oxide
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Dr. Shin‐ichi Naya Tadahiro Niwa Takahiro Kume Prof. Dr. Hiroaki Tada 《Angewandte Chemie (International ed. in English)》2014,53(28):7305-7309
A key to realizing the sustainable society is to develop highly active photocatalysts for selective organic synthesis effectively using sunlight as the energy source. Recently, metal‐oxide‐supported gold nanoparticles (NPs) have emerged as a new type of visible‐light photocatalysts driven by the excitation of localized surface plasmon resonance of Au NPs. Here we show that visible‐light irradiation (λ>430 nm) of TiO2‐supported Au NPs with a bimodal size distribution (BM‐Au/TiO2) gives rise to the long‐range (>40 nm) electron transport from about 14 small (ca. 2 nm) Au NPs to one large (ca. 9 nm) Au NP through the conduction band of TiO2. As a result of the enhancement of charge separation, BM‐Au/TiO2 exhibits a high level of visible‐light activity for the one‐step synthesis of azobenzenes from nitrobenzenes at 25 °C with a yield greater than 95 % and a selectivity greater than 99 %, whereas unimodal Au/TiO2 (UM‐Au/TiO2) is photocatalytically inactive. 相似文献
992.
Synthesis,Characterization, and Properties of [4]Cyclo‐2,7‐pyrenylene: Effects of Cyclic Structure on the Electronic Properties of Pyrene Oligomers
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Takahiro Iwamoto Dr. Eiichi Kayahara Dr. Nobuhiro Yasuda Prof. Dr. Toshiyasu Suzuki Prof. Dr. Shigeru Yamago 《Angewandte Chemie (International ed. in English)》2014,53(25):6430-6434
A cyclic tetramer of pyrene, [4]cyclo‐2,7‐pyrenylene ([4]CPY), was synthesized from pyrene in six steps and 18 % overall yield by the platinum‐mediated assembly of pyrene units and subsequent reductive elimination of platinum. The structures of the two key intermediates were unambiguously determined by X‐ray crystallographic analysis. DFT calculations showed that the topology of the frontier orbitals in [4]CPY was essentially the same as those in [8]cycloparaphenylene ([8]CPP), and that all the pyrene units were fully conjugated. The electrochemical analyses proved the electronic properties of [4]CPY to be similar to those of [8]CPP. The results are in sharp contrast to those obtained for the corresponding linear oligomers of pyrene in which each pyrene unit was electronically isolated. The results clearly show a novel effect of the cyclic structure on cyclic π‐conjugated molecules. 相似文献
993.
Cover Picture: [NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H2 Oxidation Reaction (Angew. Chem. Int. Ed. 34/2014)
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994.
Hirokazu Hirano Noritaka Masaki Takahiro Hayasaka Yoshiko Watanabe Kazuma Masumoto Tetsuji Nagata Fuminori Katou Mitsutoshi Setou 《Analytical and bioanalytical chemistry》2014,406(5):1355-1363
Periodontal disease is a serious dental problem because it does not heal naturally and leads to tooth loss. In periodontal disease, inflammation at periodontal tissue is thought as predominant, and its effect against tooth itself remains unclear. In this study, we applied matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS) to teeth for the first time. By comparing anatomical structure of tooth affected with periodontal disease with normal ones, we analyzed traces of the disease on tooth. We found signals characteristic of enamel, dentin, and dental pulp, respectively, in mass spectra obtained from normal teeth. Ion images reconstructed using these signals showed anatomical structures of the tooth clearly. Next, we performed IMS upon teeth of periodontal disease. Overall characteristic of the mass spectrum appeared similar to normal ones. However, ion images reconstructed using signals from the tooth of periodontal disease revealed loss of periodontal ligament visualized together with dental pulp in normal teeth. Moreover, ion image clearly depicted an accumulation of signal at m/z 496.3 at root surface. Such an accumulation that cannot be examined only from mass spectrum was revealed by utilization of IMS. Recent studies about inflammation revealed that the signal at m/z 496.3 reflects lyso-phosphatidylcholine (LPC). Infiltration of the signal is statistically significant, and its intensity profile exhibited the influence has reached deeply into the tooth. This suggests that influence of periodontal disease is not only inflammation of periodontal tissue but also infiltration of LPC to root surface, and therefore, anti-inflammatory treatment is required besides conventional treatments. 相似文献
995.
Thermodriven Micrometer‐Scale Aqueous‐Phase Separation of Amphiphilic Oligoethylene Glycol Analogues
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Shunichi Kawasaki Dr. Takahiro Muraoka Haruki Obara Takerou Ishii Prof. Tsutomu Hamada Prof. Kazushi Kinbara 《化学:亚洲杂志》2014,9(10):2778-2788
Thermoresponsive materials with a lower critical solution temperature (LCST) are receiving growing attention, of which examples of non‐polymeric small molecules are limited. Monodisperse oligoethylene glycol amphiphiles that contain aromatic units with a LCST in water have been developed and applied to peptide extraction. Concentration‐dependent hysteretic transmittance changes were observed in response to temperature elevation and reduction. Dynamic light scattering measurements and phase contrast microscopy revealed the formation of micrometer‐sized aggregates upon heating at a concentration above 5.0 mM ; these aggregates self‐assembled to form larger aggregates upon cooling before dissolution. The “interaggregate” interactions are likely to cause the hysteretic behavior. As an application of this thermodriven phase separation, selective extraction of peptide fragments containing high percentages of hydrophobic and aromatic amino acid residues was successfully demonstrated. 相似文献
996.
Treatment of N-aryl-N-methoxyamides with AlCl3 in EtSH (or Me2S) generates the corresponding N-aryl-N-hydroxyamides in high yields. 相似文献
997.
Takahiro Iwamoto Yoshiki Watanabe Dr. Hikaru Takaya Prof. Dr. Takeharu Haino Dr. Nobuhiro Yasuda Prof. Dr. Shigeru Yamago 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14061-14068
The size‐ and orientation‐selective formation of the shortest‐possible C70 peapod in solution and in the solid state by using the shortest structural unit of an “armchair” carbon nanotube (CNT), cycloparaphenylene (CPP), has been studied. [10]CPP and [11]CPP exothermically formed 1:1 complexes with C70, thereby giving the resulting peapods. A van′t Hoff plot analysis revealed that the formation of these complexes in 1,2‐dichlorobenzene was mainly driven by entropy, whereas the theoretical calculations suggested that the formation of the complex in the gas phase was predominantly driven by enthalpy. C70 was found to exist in two distinct orientations inside the CPP cavity, namely “lying” and “standing”, depending on the specific size of the CPP. The theoretical calculations and the X‐ray crystallographic analysis revealed that the interactions between [10]CPP and the short axis of C70 in its lying orientation were isotropic and similar to those observed between [10]CPP and C60. However, the interactions between [11]CPP and C70 in its standing orientation were anisotropic, thereby involving the radial deformation of [11]CPP into an ellipsoidal shape. This “induced fit” maximized the van der Waals interactions with the long axis of C70. Theoretical calculations revealed that the deformation occurred readily with low energy loss, thus suggesting that CPPs are highly radially elastic molecules. These results also indicate that the same type of radial deformation should occur in CNT peapods that encapsulate anisotropic fullerenes. 相似文献
998.
Journal of Solid State Electrochemistry - Transition metal oxides can electrochemically react with Li+ to result in the formation of Li2O and metal nanoparticles, and thus are good candidates as... 相似文献
999.
Takahiro Yamada Hiromasa Ohmi Hiroaki Kakiuchi Kiyoshi Yasutake 《Plasma Chemistry and Plasma Processing》2013,33(4):797-806
For the purpose of realizing a low-cost production process of silane (SiH4) gas, we have proposed the high-rate etching of metallurgical-grade Si by narrow-gap microwave hydrogen plasma. In this paper, effect of hydrogen gas flow rate (0–10 L/min) on the etch rate has been investigated and correlated with the relative variation of hydrogen-atom density estimated by actinometry. By decreasing hydrogen gas flow rate, the etch rate gradually increases up to the maximum value of 11 μm/min at 2 L/min. This increase is well correlated with the increase of hydrogen-atom density due to the longer residence time of hydrogen molecules in the plasma. On the other hand, when the gas flow rate is lower than 2 L/min, the etch rate abruptly decreases with decreasing gas flow rate in spite of the increase of hydrogen-atom density. From the surface observations and Raman measurements, it is found that the decrease in etch rate in the lower flow rate range is attributed to the formation of microcrystalline Si particles due to the decomposition of generated-SiH4 molecules in the plasma. 相似文献
1000.