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931.
A facile approach to chiral dihydroquinazolinone derivatives has been described via biomimetic asymmetric reduction of quinazolinones with chiral and regenerable NAD(P)H models. The utility of this method was demonstrated by a concise synthesis of the bromodomain protein divalent inhibitor. 相似文献
932.
Addition of one equivalent of LiN(i-Pr)2 or LiN(CH2)5 to carbodiimides, RN=C=NR [R=cyclohexyl (Cy), isopropyl (i-Pr)], generated the corresponding lithium of tetrasubstituted guanidinates {Li[RNC(N R^′2)NR](THF)}2 [R=i-Pr, N R^′2=N(i-Pr)2 (1), N(CH2)5 (2); R=Cy, N R^′2=N(i-Pr)2 (3), N(CH2)5 (4)]. Treatment of ZrCl4 with freshly prepared solutions of their lithium guanidinates provided a series of bis(guanidinate) complexes of Zr with the general formula Zr[RNC(N R^′2)NR]2Cl2 [R=i-Pr, N R^′2=N(i-Pr)2 (5), N(CH2)5 (6); R=Cy, N R^′2=N(i-Pr)2 (7), N(CH2)5 (8)]. Complexes 1, 2, 5-8 were characterized by elemental analysis, IR and ^1H NMR spectra. The molecular structures of complexes 1, 7 and 8 were further determined by X-ray diffraction studies. 相似文献
933.
Yu Mao Wenxuan Zhao Shuo Lu Lei Yu Yi Wang Yong Liang Shengyang Ni Yi Pan 《Chemical science》2020,11(19):4939
Redox-active esters (RAEs) as alkyl radical precursors have demonstrated great advantages for C–C bond formation. A decarboxylative cross-coupling method is described to afford substituted alkynes from various carboxylic acids using copper catalysts CuCl and Cu(acac)2. The photoexcitation of copper acetylides with electron-rich NEt3 as a ligand provides a general strategy to generate a range of alkyl radicals from RAEs of carboxylic acids, which can be readily coupled with a variety of aromatic alkynes. The scope of this cross-coupling reaction can be further expanded to aliphatic alkynes and alkynyl silanes using a catalytic amount of preformed copper-phenylacetylide. In addition, DFT calculations revealed the favorable reaction pathway and that the bidentate acetylacetonate ligand of the copper intermediate plays an important role in inhibiting the homo-coupling of the alkyne.Redox-active esters (RAEs) as alkyl radical precursors have demonstrated great advantages for Cu-catalysed C–C bond formation. 相似文献
934.
Huaping Liu Guoan Cheng Ruiting Zheng Yong Zhao Changlin Liang 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):17-22
The Ni/CNT catalyst was fabricated by directly dipping carbon nanotube precursors refluxed in 4 M of nitric acid into Ni electroless plating bath, and used to synthesize new carbon nanotubes. The experimental results indicate that the duration of acid-treatment of carbon nanotubes precursors exerts a great influence on the catalysis of Ni/CNT in the synthesis of carbon nanotubes and hence the structures of the new carbon nanotubes. When the carbon nanotubes precursors were refluxed for 0.5 h in 4 M of nitric acid, bamboo-shaped carbon nanotubes (BSCNT) or Y junction carbon nanotubes in the carbon products were obtained. As the duration of acid-treatment of carbon nanotubes precursors increased to 6 h, the as-prepared Ni/CNT displayed higher activity, and the carbon nanotube products were high pure without any Y junction structure or any separation layers in hollow. 相似文献
935.
Liu BD Bando Y Tang CC Xu FF Golberg D 《The journal of physical chemistry. B》2005,109(46):21521-21524
GaN nanowires with P doping were synthesized via a simple thermal evaporation process. The P-doped GaN nanowires have average diameters of approximately 100 nm and lengths up to tens of micrometers. Scanning electron microscope and high-resolution field-emission transmission electron microscope analyses revealed that P doping results in a rough surface morphology of GaN nanowires. Field-emission measurements showed that P doping effectively decreases the turn-on field of GaN nanowire to 5.1 V/mum, holding promise of application as an electron emitter. The rough surface is responsible for enhancement of the field-emission properties of GaN nanowires. 相似文献
936.
We investigate the distribution of the number of photons emitted by a single molecule undergoing a spectral diffusion process and interacting with a continuous wave laser field. The spectral diffusion is modeled based on a stochastic approach, in the spirit of the Anderson-Kubo line shape theory. Using a generating function formalism we solve the generalized optical Bloch equations and obtain an exact analytical formula for the line shape and Mandel's Q parameter. The line shape exhibits well-known behaviors, including motional narrowing when the stochastic modulation is fast and power broadening. The Mandel parameter, describing the line shape fluctuations, exhibits a transition from a quantum sub-Poissonian behavior in the fast modulation limit to a classical super-Poissonian behavior found in the slow modulation limit. Our result is applicable for weak and strong laser fields, namely, for arbitrary Rabi frequency. We show how to choose the Rabi frequency in such a way so that the quantum sub-Poissonian nature of the emission process becomes strongest. A lower bound on Q is found and simple limiting behaviors are investigated. A nontrivial behavior is obtained in the intermediate modulation limit, when the time scales for spectral diffusion and the lifetime of the excited state become similar. A comparison is made between our results and previous ones derived, based on the semiclassical generalized Wiener-Khintchine formula. 相似文献
937.
Nan Wang Li Hua Zhu Jing Li He Qing Tang 《中国化学快报》2007,18(10):1261-1264
A very simple and controllable approach was proposed to synthesize novel Fe(OH)_3/TiO_2 nanoparticles.Compared with neat TiO2,the Fe(OH)_3/TiO_2 increased the rate of the photocatalytic degradation of methyl orange at pH 6.0 by more than five times, showing photocatalytic activity as excellent as P25.This enhancing effect is mainly attributed to the ferric hydroxide deposits as the electron scavenger and the enriched surface hydroxyl groups. 相似文献
938.
939.
Ben‐Yong Lou Yan‐Bin Huang 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):o246-o248
4,4′‐Bipyridyl N,N′‐dioxide crystallizes with 3‐hydroxy‐2‐naphthoic acid to give a centrosymmetric three‐component adduct, C10H8N2O2·2C11H8O3, which is engineered into a two‐dimensional layer structure by two kinds of π–π interactions. Weak C—H⋯O interactions further link the two‐dimensional structure into a three‐dimensional structure. 相似文献
940.