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71.
通过向对氨基苯甲酸(PABA)-Ag_4Fe(CN)_6溶胶体系分别滴加少量K_4Fe(CN)_6、K_3Fe(CN)_6、Na_2S_2O_3、H_2O_2、NaCl和NaNO_3水溶液,以及改变体系pH值对PABASERS谱带影响的观测,探讨Ag_4Fe(CN)_6溶胶体系对PABA分子的增强机制及在胶体表面受到极大增强的分子吸附态。 相似文献
72.
Tomáš Trojan Jindřich Jindřich Vladimír Vrkoslav Ivan Jelínek Juraj Dian 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):343-348
A set of permethylated 6I-(ω-alkenoyl)-6I-amino-6I-deoxy-β-cyclodextrin derivatives with different chain length of the alkenoyl group (used as a spacer) was synthesized. These
derivatives were attached by photochemically activated hydrosilylation reaction to the surface of porous silicon. Photoluminescence
response of the modified PS to controlled concentrations of various molecules in gas phase revealed strong host-guest interactions
between β-cyclodextrin and the detected molecules. The strongest interaction was observed for aromatic molecules, which have
the optimal size to fit into the β-cyclodextrin molecular cavity. 相似文献
73.
富勒烯配合物η2-C60[Ru(NO)(PPh3)]2的合成与表征 总被引:4,自引:0,他引:4
从1985年Kroto等[1]发现富勒烯至今, 其在化学、材料和物理等领域已有较多的研究[2~8]. 目前有关C60取代的金属小分子配合物(如羰基、亚硝酰基等)的研究方兴未艾. 而以NO为配体的亚硝酰基金属富勒烯配合物仅有数例[2,3], Green等[3]在研究以CO和NO为配体的金属富勒烯系列化合物的合成中, 认为C60不能与Ru(NO)2(PPh3)2发生反应. 本文利用Ru(NO)2(PPh3)2与C60反应首次合成出η2-C60[Ru(NO)(PPh3)]2配合物, 并对其进行了表征. 相似文献
74.
The conformational isomerization dynamics of N-acetyl tryptophan methyl amide (NATMA) and N-acetyl tryptophan amide (NATA) have been studied using the methods of IR-UV hole-filling spectroscopy (HFS) and IR-induced population transfer spectroscopy (IR-PTS), which were developed for this purpose. Single conformations of these molecules were selectively excited in well-defined NH stretch fundamentals. This excess energy was used to drive conformational isomerization. By carrying out the infrared excitation early in a supersonic expansion, the excited molecules were recooled into their zero-point levels, partially refilling the hole created in the ground state population of one of the conformers, and creating gains in population in other conformers. These changes in population were detected using laser-induced fluorescence downstream in the expansion. In HFS, the IR wavelength is fixed and the UV laser tuned in order to determine where the population went following selective infrared excitation. In IR-PTS, the UV is fixed to monitor the population of a given conformation, and the IR is tuned to record the IR-induced changes in the population of the monitored conformer. Besides demonstrating the capability of the experiment to change the downstream conformational population distribution, the IR-PTS scans were used to extract two quantitative results: (i) The fractional populations of the conformers in the absence of the infrared, and (ii) the isomerization quantum yields for each of the six unique amide NH stretch fundamentals (three conformers each with two amide groups). The method for obtaining quantum yields is described in detail. In both NATMA and NATA, the quantum yields show modest conformational specificity, but only a hint of vibrational mode specificity. The prospects for the hole-filling technique for providing insight into energy flow in large molecules are discussed, leaving a more detailed theoretical modeling to the adjoining paper [Evans et al. J. Chem. Phys. 120, 148 (2004)]. 相似文献
75.
In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)O--Ar--COOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV-Vis, DSC and fluorometry. The emission wavelength (lambda(em)) of the copolymers could be tuned by the excitation wavelength (lambda(ex)). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering. 相似文献
76.
He‐Ping Shi Dian‐Sheng Liu Shu‐Ping Huang 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(3):m107-m109
The title compound, [Li(C12H21NSi)(C6H16N2)], is an intermediate in the synthesis of the corresponding organometallic compounds. The molecule has an unusual C—Si—N—Li four‐membered heterocycle which adopts a folded conformation, with the coordination around the Li, N, C and Si atoms being distorted tetrahedral. Its structure is strongly supported by 1H NMR, 13C NMR and 13C–1H correlation spectra. The compound has potential for application in the synthesis of other novel organometallic compounds. 相似文献
77.
Siyuan Li Zeheng Li Gaoyao Cao Prof. Min Ling Jiapeng Ji Prof. Dian Zhao Ying Sha Prof. Xuehui Gao Prof. Chengdu Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14358-14363
The development of sodium-ion batteries (SIBs) is hindered by the rapid reduction in reversible capacity of carbon-based anode materials. Outside-in doping of carbon-based anodes has been extensively explored. Nickel and NiS2 particles embedded in nitrogen and sulfur codoped porous graphene can significantly improve the electrochemical performance. Herein a built-in heteroatom “self-doping” of albumen-derived graphene for sodium storage is reported. The built-in sulfur and nitrogen in albumen act as the doping source during the carbonization of proteins. The sulfur-rich proteins in albumen can also guide the doping and nucleation of nickel sulfide nanoparticles. Additionally, the porous architecture of the carbonized proteins is achieved through removable KCl/NaCl salts (medium) under high-temperature melting conditions. During the carbonization process, nitrogen can also reduce the carbonization temperature of thermally stable carbon materials. In this work, the NS-graphene delivered a specific capacity of 108.3 mAh g−1 after 800 cycles under a constant current density of 500 mA g−1. In contrast, the Ni/NiS2/NS-graphene maintained a specific capacity of 134.4 mAh g−1; thus the presence of Ni/NiS2 particles improved the electrochemical performance of the whole composite. 相似文献
78.
Cis- or irans- dimethyl and diethyl ester of bicyclo[2,2,1]hept-5-ene-2,3-die(2 or 4) were used as pesticides 1-4 in the fourties and fifties of the century to prevent orkill mosquito, fly and flea. The of's-dimethyl ester Za was also added to cosmetics forthe same purpose 5. The diethyl and dipropyl esters (2b and Zc) could be used to makerubber and elastomers6'7. Besides, this kind of compounds are important intermediatesfor synthesis of some drugs.The Diels-Alder reaction of cyclopentadie… 相似文献
79.
80.
Dian K. Palagachev 《Journal of Global Optimization》2008,40(1-3):305-318
We derive W
2,p
(Ω)-a priori estimates with arbitrary
p ∈(1, ∞), for the solutions of a degenerate oblique derivative problem for linear uniformly elliptic operators with low regular
coefficients. The boundary operator is given in terms of directional derivative with respect to a vector field ℓ that is tangent
to ∂Ω at the points of a non-empty set ε ⊂ ∂Ω and is of emergent type on ∂Ω.
相似文献