共查询到20条相似文献,搜索用时 78 毫秒
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本文应用PPP-SCF-CI法计算了偶氮苯衍生物的结构,发现偶氮苯衍生物波长最大的吸收峰(相应于电子从基态向第一激发态跃迁)是分子内荷移光谱,这些吸收峰的计算值与实验值完全一致.此外,还根据PPP计算结果研究了取代基对吸收光谱的影响. 相似文献
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有机试剂的pK^0a是其重要的物参数,它是有机试剂酸性的度量,决定其配合笺的稳定性。本文应用Hansch改进的参数值研究了PKa与取代基常数的相关性, 相似文献
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Due to the fact that the molecular structure has been removed from most of the analytical chemistry textbook of recent editions, this paper collected more than 90 organic reagents from three classic text books, categorized these molecules according to the application, and analyzed the molecular structure and the mechanism of functions in applications. 相似文献
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火焰原子吸收光谱法中有机试剂的增感效应 总被引:12,自引:0,他引:12
详细研究了11种有机试剂对火焰原子吸收光谱法的增感效应。通过测定这些有机试剂对Cu、Mg、Li、Na、K、Rb、Cr、Mo、Sr、Ba等金属离子吸光度的影响,得到了有机试剂增感的规律性。 相似文献
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KF-Al~2O~3试剂在有机合成反应中的应用进展 总被引:24,自引:0,他引:24
综述了自1979年Yamawaki和Ando发现KF-Al~2O~3试剂的催化特性以来在有机合成反应中的应用研究进展。 相似文献
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A ternary complex reagent of lithium ester enolate-chiral diether-lithium diisopropylamide was formed in an equimolar mixture of these reagents in toluene based on low-temperature NMR spectroscopy. The use of [6Li,15N]-lithium diisopropylamide as a lithiodeprotonation and complexing reagent produced two sets of doublet peaks in 6Li NMR of a 1:1:1 mixture of lithium enolate-chiral diether-lithium diisopropylamide, indicating the formation of a ternary complex reagent. 相似文献
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A series of organic reagents have been tested in atomic absorption measurement for signal enhancement of metal elements. Organic reagents like tetrabutylammonium bromide are demonstrated to enhance the absorption sensitivity to some specific elements such as calcium and chromium. A group of amines were found to have significant enhancement for chromium and calcium measurements. The function of organic reagents in flame and plasma atomic absorption spectrometry (AAS) was investigated in this work with emphases on mechanism of signal enhancement and interference suppression. An alternative mechanism of organic reagent enhancement in flame and plasma AAS has been suggested based on the experimental results obtained in this work. The reduction environments in flame and plasma produced by the organic reagents are considered as major reason for the signal enhancement. 相似文献
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C. H. Jeon E. E. Makhaeva A. R. Khokhlov 《Journal of Polymer Science.Polymer Physics》1999,37(12):1209-1217
The swelling behavior of polyelectrolyte gels based on poly(diallyldimethylammonium chloride) (copolymers of diallyldimethylammonium chloride and acrylamide with the variable composition) and poly(methacrylic acid, sodium salt) in the presence of organic water soluble dyes (alizarin, naphthol blue black, rhodamine) was studied. The collapse of the polyelectrolyte gels in the presence of oppositely charged dyes together with the effective absorption of dyes was observed. The shrinking degree and the dye absorption by the gel depend on the charges of the polymer network and the dye, and also on the dye concentration. Stability of the gel–dye complexes in a salt solution of NaCl and Al2(SO4)3 was studied. It was shown that the complex stability in the salt solution depends on the charge density of the polymer chains forming the gel. The increase of charge density of polymer generally leads to the enhancement of the complex stability. For the systems with the fraction of charged poly(diallyldimethylammonium chloride) monomer units above 0.5 the release of alizarin to the external solution of Al2(SO4)3 reservoir is practically completely suppressed. The obtained results show that oppositely charged dyes are generally from stable complexes with polyelectrolyte gels. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1209–1217, 1999 相似文献
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C. Romeike M. R. Wegewijs W. Wenzel M. Ruben H. Schoeller 《International journal of quantum chemistry》2006,106(4):994-1000
We investigate the magnetic state of a recently synthesized [2 × 2]‐metal‐organic grid complex as a function of its redox state. Our analysis of a phenomenological model for the relevant molecular orbitals reveals that additional electrons on the ligands can couple their spins via the bridging metal sites. We find that at certain stages of the reduction of the complex cation, a maximal total spin ground state of the complex (S = 3/2) can be stabilized by the Nagaoka mechanism. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
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An oil-soluble sulfur- and phosphorus-free organic molybdenum complex (MC) was synthesized. The antioxidation properties of MC- and methylene bis(di-n-butyldithiocarbamate) (V 7723)-containing poly-α-olefin (PAO)-derived lubricants were evaluated by differential scanning calorimetry (DSC) and modified penn state micro-oxidation test (PMOT). DSC test measures incipient oxidation temperature (OT) and oxidation induction time (IT) of the lubricant at high temperatures and the oxidation stability of oil weight loss is measured by PMOT test. DSC test shows that OT and IT of V 7723-containing PAO were improved significantly by MC addition. PMOT test indicates that when combining with V 7723 antioxidants, MC can also effectively reduce the increase in weight loss of PAO. These results suggest that the MC shows a good oxidative synergism with V 7723 antioxidant. In addition, FTIR results from PMOT test confirm that addition of MC can significantly enhance the oxidation induction time of oils and inhibit formation of oxidation products containing carbonyl bonds or hydroxyl group. The proposed mechanism of the inhibition involves a synergy between MC and V 7723. 相似文献
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Perfluorinated surfactants of heptafluorobutylate and pentadecafluorooctanoate ions were adsorbed on an activated charcoal cartridge and decomposed with sodium biphenyl (SBP) reagent to form inorganic fluoride ion. The fluoride ion thus formed was determined by flow injection analysis (FIA) using quercetin-Zr complex as a fluorimetric reagent, where λex and λem were 422 and 491 nm, respectively. The limit of detection for fluoride ion by the FIA system was developed to 1.1 × 10−6 M (signal to noise ratio of three), when 50% (v/v) tetrahydrofuran (THF) was used as a dissolving solvent for quercetin. The perfluorinated surfactants in the sample solution were quantitatively adsorbed on the cartridge containing 100 mg of activated charcoal and were decomposed with 0.5 mL of sodium biphenyl reagent after drying thoroughly by flowing through dry nitrogen gas. The fluoride ion formed was recovered with 3 mL of purified water as an eluent, and it was determined by the fluorimetric flow injection system. The blank fluorescence signal accompanied during the adsorption/decomposition on the cartridge was reduced by washing the activated charcoal with acetone. The blank signal was also observed from dimethoxyethane, which was used in sodium biphenyl reagent. When 600 mL sample solution was used and 200 times enrichment was applied, the heptafluorobutylate and pentadecafluorooctanoate ions at the concentrations of 2.1 μg L−1 were quantitatively recovered as fluoride ion, and the limit of detections for the perfluorinated surfactants were 0.3 and 0.3 μg L−1 for the two perfluorinated surfactants, respectively (3 sigma of the blank signal). 相似文献