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61.
《Arabian Journal of Chemistry》2020,13(12):8848-8887
Phthalocyanine (Pc) complexes are an important class of dyes with numerous (e.g., biological, photophysical, and analytical) applications. Among the methods used to improve the properties of these complexes, one should mention the introduction of different substituents, variation of the central metal ion, ligand exchange, and conjugation to nanomaterials (e.g., carbon-based nanomaterials and metal nanoparticles (NPs)). This work briefly reviews Pc complex conjugation to Ag and Au NPs, highlights the different NP shapes, and discusses the diversity of conjugation approaches. Moreover, the use of UV–Vis spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopy to characterize Pc-NP hybrids is summarized. The effect of conjugation on Pc photo-physicochemical properties (fluorescence, singlet oxygen generation, triplet state formation, and optical limiting behavior) is discussed, and future perspectives for the synthesis and applications of new hybrids are provided. 相似文献
62.
Published data on silicon carbide nanotubes (SiC-NT) are analyzed. According to theoretical calculations, single-layer SiC-NTs
do not dissociate, but they have not yet been detected experimentally. According to the experimental data, metastable SiC-NTs
with walls consisting of several layers and nanotube fibers were produced. The optimized structure of single-layer SiC-NTs
was calculated by the RHF/6-31G quantum-chemical method. The possibility of obtaining SiC-NTs by gas-phase chemical deposition
from methyltrichlorosilane in the temperature range of 800–1000 °C was investigated. Nanofibers and polygrained SiC nanotubes
were obtained, but ordinary layer SiC nanotubes were not detected. To remove the inconsistencies it was first proposed to
classify the nanotubes according to the structure of their walls, separating all the SiC-NTs into three types: 1) ordinary
layer nanotubes with rolled layers, similar to carbon nanotubes; 2) polynanocrystalline nanotubular fibers or nanotubes with
walls consisting of linked differently oriented nanograins; 3) monocrystalline synthetic nanotubes with ideal crystalline
walls. It was concluded that the ordinary SiC-NTs of the first type are unstable with the exception of one-or two-layer nanotubes;
stable SiC-NTs of the first type and SiC-NTs of the third type have not yet been discovered; only nanotubular fibers of the
second type were obtained experimentally.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 3–13, January–February, 2006. 相似文献
63.
Gyula Záray Tibor Kántor Gerhard Wolff Zdravka Zadgorska Hubertus Nickel 《Mikrochimica acta》1992,107(3-6):345-358
The analytical capability of high-temperature halogenation with carbon tetrachloride vapour in a graphite furnace was investigated for silicon carbide powder with known chemical composition and particle size. Intensity vs heating time curves were determined for analytical lines of Al, B, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Ti, V and Si constituents, volatilized with and without the presence of CCl4 vapour in the furnace atmosphere. Igniting 10 mg SiC at 2100 °C for 60 s in chlorinating atmosphere, the evaporated fraction of most of the constituents was higher than 90% (for Al about 50%). The line intensity vs sample mass (4–26 mg) relationships were linear for all impurities studied, while the intensity of silicon line showed a relatively small change with the sample mass. BEC (background equivalent concentration) values for this solid sampling technique (10 mg loaded sample) were 2–20 fold lower than those calculated for the conventional solution sample introduction method. 相似文献
64.
A chemical flux of sulfur hexafluoride (SF6) in conjunction with low-energy Ar-ion bombardment has been used for chemically assisted ion beam etching (CAIBE) of silicon and silicon dioxide. The study has shown a large degree of independent control over the selectivity and anisotropy in dry etching. The total etch rate could be controlled by varying either the Ar-ion milling parameters or the chemical flux of SF6. Etch rate enhancement of 7–8 for silicon and 3–4 for silicon dioxide have been obtained over pure physical etching. 相似文献
65.
66.
选用四种不同的密度泛函理论方法(B3LYP,B3P86,BLYP,BP86),在全电子的双ξ加极化加弥散函数基组(DZP )下,对SinH/SinH^-(n=3~8)体系进行研究,获得它们的基态结构和电子亲合能。预测Si3H/Si3H^-,Si4H/Si4H^-,Si5H/Si5H^-,Si6H/Si6H^-,Si7H/Si7H^-和Si8H/Si8H^-的基态结构分别为C2v(^2B2)/C2v(1^A1)氢桥结构,Cs(^2A’)/C(^1A’),C2v(^2B2)/C2v(^1A1),C2v(^2B2或^2B1)/C4v(^1A1),C5v(^2A1)/C5v(^1A1)和C5(^2A‘‘)/C3v(^1A1)。在电子亲合能方面,B3LYP方法预测的电子亲合能是最可靠的,预测Si3H,Si4H,Si5H,Si6H,Si7H和Si8H的电子亲合能分别为2.56,2.59,2.84,2.86,3.19和3.14eV。 相似文献
67.
68.
Erik J. Faber Dr. Wouter Sparreboom Wilrike Groeneveld Louis C. P. M. de Smet Dr. Johan Bomer Wouter Olthuis Dr. Han Zuilhof Dr. Ernst J. R. Sudhölter Prof. Piet Bergveld Prof. Albert van den Berg Prof. 《Chemphyschem》2007,8(1):101-112
The electrochemical behavior of Si--C linked organic monolayers is studied in electrolyte-insulator-Si devices, under conditions normally encountered in potentiometric biosensors, to gain fundamental knowledge on the behavior of such Si electrodes under practical conditions. This is done via titration experiments, Mott-Schottky data analysis, and data fitting using a site-binding model. The results are compared with those of native SiO(2) layers and native SiO(2) layers modified with hexamethyldisilazane. All samples display pH sensitivity. The number of Si--OH groups on the alkylated samples is calculated to be less than 0.7 % of that of a pure SiO(2) insulator, which still causes a pH sensitivity of approximately 25 mV per pH unit in the pH range: 4-7. The alkylated samples hardly suffer from response changes during up- and down-going titrations, which indicates that very little oxide is additionally formed during the measurements. The pK(a) values of all samples with monolayers (4.0-4.4) are lower than that of native SiO(2) (6.0). The long-term drift (of approximately 1 mV h(-1)) is moderate. The results indicate that biosensors composed of alkylated Si substrates are feasible if a cross-sensitivity towards pH in the sensor signal is taken into account. 相似文献
69.
70.
A convenient and efficient preparation of Stryker's reagent, [Ph3PCuH]6, under homogeneous conditions using silanes as the reducing agent is detailed. The reaction time can be reduced to 1-2 h, and high yields of Stryker's reagent can be routinely achieved. The same method has been extended to the synthesis of [Ph3PCuD]6 using Ph2SiD2. 相似文献