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221.
The title trifluoroacetylaminophthalimide derivative produced a violet fluorescence (lambdaFLmax 392 nm) in MeCN, and it displayed a green emission (lambdaFLmax 506 nm) after irradiation at 254 nm in the presence of iodide ions. The corresponding amidate ion of the trifluoroacetamide was identified as the green fluorescence emitter. The deprotonation reaction may be caused by proton-abstracting solvated electrons generated by a photochemical charge--transfer-to-solvent process from I(-) to MeCN. 相似文献
222.
Friction, adhesion, and bounce dynamics are found to be asymmetric with respect to sliding direction for a tilted pad sliding at high speed. The differences originate from the nanoscale effects of the mechanical action against the lubricant layer forming an asymmetric meniscus around the pad and from a self-excited vibration induced by friction hysteresis coupled with adhesion hysteresis. 相似文献
223.
Two novel blue pigments, rosacyanins A1 and A2, were isolated from the petals of Rosa hybrida cv. ‘M'me. Violet’. Their structures were elucidated on the basis of high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (HR-FT-ICR-MS), FABMS/MS/MS, 1H, 13C and two-dimensional NMR. The molecular formulas of rosacyanin A1 (1) and A2 (2) are C56H37O31 and C63H41O35, respectively. The structures of rosacyanins A1 and A2 consisted of a common chromophore containing cyanidin with a galloyl group link between positions 4 and 5 of the hydroxyl group of the flavylium nucleus and tellimagrandins (1 or 2). These pigments in which anthocyanidin nuclei linked to ellagitannin through an ether bond are the first compounds isolated from natural sources. 相似文献
224.
Although heating 2-methoxy-2H-azepine results in a [1,5] sigmatropic hydrogen shift, heating 2-propylthio-2H-azepine results in not only a [1,5] sigmatropic hydrogen shift but also a [1,5] sigmatropic propylthio shift. Kinetic measurements reveal that migratory aptitudes increase in the order of MeO < H, PrS. These [1,5] sigmatropic shifts are discussed on the basis of ab initio DFT calculations. [reaction: see text]. 相似文献
225.
Oxovanadium complex bearing 3-hydroxypicolinic acid (H2hpic), that is, VO(Hhpic)2, successfully catalyzes a highly selective oxidation of benzylamines to the corresponding N-(benzylidene)benzylamines under atmospheric molecular oxygen. In addition, the use of imidazolium-type ionic liquids as solvent makes it possible to attain recycling of the catalyst. 相似文献