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561.
Ryotaro Aso Yohei Ogawa Takehiro Tamaoka Hideto Yoshida Seiji Takeda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16174-16178
Understanding the atomic and molecular phenomena occurring in working catalysts and nanodevices requires the elucidation of atomic migration originating from electronic excitations. The progressive atomic dynamics on metal surface under controlled electronic stimulus in real time, space, and gas environments are visualized for the first time. By in situ environmental transmission electron microscopy, the gas molecules introduced into the biased metal nanogap could be activated by electron tunneling and caused the unpredicted atomic dynamics. The typically inactive gold was oxidized locally on the positive tip and field‐evaporated to the negative tip, resulting in the atomic reconstruction on the negative tip surface. This finding of a tunneling‐electron‐attached‐gas process will bring new insights into the design of nanostructures such as nanoparticle catalysts and quantum nanodots and will stimulate syntheses of novel nanomaterials not seen in the ambient environment. 相似文献
562.
Zhong Huang Yohei Ishida Tetsu Yonezawa 《Angewandte Chemie (International ed. in English)》2019,58(38):13411-13415
The synthesis of high‐purity and high‐yield Au25 clusters protected by the basic pyridyl ethanethiol (HSCH2CH2Py, 4‐PyET and 2‐PyET) is presented. Single‐crystal X‐ray diffraction of the [Au25(4‐PyET)18]??Na+ clusters has revealed a structure similar to that known for the phenyl ethanethiolate analogue, but with pyridyl‐N coordination to Na+, a more relaxed ligand shell, and a profoundly layered arrangement in the solid state. Because of the pendant Py moiety, the [Au25(PyET)18]? clusters are endowed with unique (de)protonation equilibria, which has been characterized in detail by UV/Vis absorption and 1H NMR spectroscopy. [Au25(PyET)18]? clusters showed an unexpectedly H+‐dependent solubility that is tunable in aqueous and organic solvents. The successful synthesis of the basic Py‐terminated thiolate‐protected Au25 clusters paves the way to realize a new family of metalloid clusters possessing basic properties. 相似文献
563.
Wakabayashi R Kubo Y Hirata O Takeuchi M Shinkai S 《Chemical communications (Cambridge, England)》2005,(46):5742-5744
Template assisted olefin metathesis of an allosteric host to give the corresponding bicyclic compound was achieved and can allosterically bind the template guest diamines, and with different affinity and cooperativity. 相似文献
564.
Kamiya K Tanaka Y Endang H Umar M Satake T 《Chemical & pharmaceutical bulletin》2005,53(12):1597-1599
From the fruits of Morinda citrifolia L., one new anthraquinone, 5,15-O-dimethylmorindol, together with five known anthraquinones and one new iridoid, morindacin, together with two known iridoids, were isolated. Their structures were elucidated by analysis of spectroscopic data. 相似文献
565.
In vivo temporal EPR imaging was conducted on the brain of rats that received one of two kinds of blood-brain barrier-permeable nitroxide radicals via the tail vein-one is a water-soluble 3-hydroxymethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (hydroxymethyl-PROXYL); and the other is a non-water-soluble 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM). From temporal EPR imaging data, temporal changes in the distribution of the nitroxide radical in the cerebral cortex, striatum, and hippocampus in the brain were investigated. It was found that the half-lives of the three parts in the brain of hydroxymethyl-PROXYL are longer and their EPR signal intensities are greater than those of PCAM. 相似文献
566.
The magnetic hyperfine splitting frequencies of71AsNi and72AsNi in a 0.11 Tesla external magnetic field have been determined by NMR/ON method as 66.00(6) MHz and 106.17(13) MHz respectively.
Using the known magnetic moments of μ(71As)=1.6735(18) and μ(72As)=−2.1566(3), the hyperfine fields were deduced asB
hf(71AsNi)=12.824(19) Tesla andB
hf(72AsNi)=12.807(16) Tesla. 相似文献
567.
Toshio Kitao Hiroshi Kobayashi Seiji Ikegami Seigo Ohya 《Journal of polymer science. Part A, Polymer chemistry》1973,11(10):2633-2651
Five series of two-component blend filaments, comprising nylon 6 (N6) and nylon 66 (N66), nylon 610 (N610), nylon 11 (N11), nylon 12 (N12), or poly(ethylene terephthalate) (PET), were prepared by using a research spinning machine and a conventional drawing machine. The microstructure and the physical properties of the resultant filaments were evaluated with a tensile tester, a optical microscope, a density-gradient column, and a DTA instrument. When both components were mixed homogeneously so that they would form a three-dimensional network, the tensile properties of the blend filament were at least equivalent to the values predicted from those of both components. On the other hand, as in the cases of 30/70 and 70/30 N6–PET, when the minor component was discretely distributed as short fibrils in the matrix of the major component, the blend filament had an extremely weak tenacity. A supertenacity filament was obtained from 50/50 N6–N610. The marked increase of the tensil strength and the initial modulus of 50/50 N6–N610, about 12 g/den and 520 kg/mm2, respectively, may be due to a significant increase in the crystallinity and the orientation of the blend. 相似文献
568.
Kise N Ohya K Arimoto K Yamashita Y Hirano Y Ono T Ueda N 《The Journal of organic chemistry》2004,69(22):7710-7719
The electroreduction of aromatic beta- and gamma-imino esters prepared from beta-alanine and GABA in the presence of chlorotrimethylsilane and subsequent N-alkoxycarbonylation of the resulting five- and six-membered cyclized amines gave mixed ketals of N-alkoxycarbonyl-2-arylpyrrolidin-3-ones and 2-arylpiperidin-3-ones, respectively. The best result of the electroreductive intramolecular coupling was achieved using Bu(4)NClO(4) as a supporting electrolyte and a Pb cathode in THF. Acid hydrolysis of the mixed ketals afforded N-alkoxycarbonyl-2-arylpyrrolidin-3-ones and 2-arylpiperidin-3-ones in good yields. The reduction of these ketones with NaBH(4) in methanol afforded the corresponding N-alkoxycarbonyl-cis-2-arylpyrrolidin-3-ols and cis-2-arylpiperidin-3-ols diastereospecifically. 相似文献
569.
Inclusion crystals of 3,1'-bis-(4-fluorophenyl)-1'-hydroperoxy-3'-hydroxy-1',3'-dihydro-3H-[2,2']biindenyliden-1-one showed photochromic and photomagnetic properties in the solid state. 相似文献
570.
The first demonstration of photo-reversible Pb2+-complexation of an insoluble spiropyran-carrying copolymer in aqueous solutions is presented. 相似文献