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61.
Malose J. Mphahlele Ahmed M. El-Nahas Tarek M. El-Gogary 《Journal of Molecular Structure》2004,690(1-3):151-157
The geometries of the title compounds were probed in solution, solid and gas states using spectroscopic methods, X-ray crystallography and quantum chemical techniques. The exclusive existence of the NH-4-thiones in solution (NMR and PCM-B3LYP(MP2)/6-31+G(d) calculations) and solid state (FT-IR and X-ray) is also corroborated by comparison of their spectroscopic data with those of the corresponding 2-aryl-1-methylquinoline-4(1H)-thione derivatives. The co-existence of the quinoline-4-thione and quinoline-4-thiol (4-mercaptoquinoline) isomers in the gas phase is confirmed by mass spectrometry and the preponderance of the 4-thiol is supported by quantum chemical techniques (PM3, MP2 and B3LYP). 相似文献
62.
Arafat A Schroën K de Smet LC Sudhölter EJ Zuilhof H 《Journal of the American Chemical Society》2004,126(28):8600-8601
This communication presents the first functionalization of a hydrogen-terminated silicon-rich silicon nitride (Si3Nx) surface with a well-defined, covalently attached organic monolayer. Properties of the resulting monolayers are monitored by measurement of the static water contact angle, X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRRAS). Further functionalization was performed by reaction of Si3Nx with a trifluoroethanol ester alkene (CH2=CH-(CH2)8CO2CH2CF3) followed by basic hydrolysis to afford the corresponding carboxylic acid-terminated monolayer with hydrophilic properties. These results show that Si3Nx can be functionalized with a tailor-made organic monolayer, has highly tunable wetting properties, and displays significant potential for further functionalization. 相似文献
63.
Ahmed I. Khodair 《Journal of heterocyclic chemistry》2002,39(6):1153-1160
Various 5H‐thiazolo[2,3‐b]quinazoline‐3,5[2H]‐diones (7a,b), 2‐arylidene‐5H‐thiazolo[2,3–b]quin‐azoline‐3,5[2H]‐diones ( 9a‐o ) and 2‐arylidene‐5H‐thiazolo[2,3‐b]benzoquinazoline‐3,5[2H]‐diones ( 12a,b ) have been synthesized via simple and efficient methods. 相似文献
64.
Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA (N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C5H6N2O2)(C4H5NO4)2−(H2O)2]·H2O, [Ni(C5H6N2O2)(C5H7NO4)2−(H2O)2]·H2O and [Ni(C5H6N2O2)(C6H8N2O5)2−(H2O)2]·1.5H2O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy (E*), enthalpy (ΔH*), entropy (ΔS*) and free energy change of decomposition (ΔG*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate. 相似文献
65.
A new analytical method is described for the determination of organochlorine pesticides (OCPs) in sewage sludges using GC-ion trap-MS–MS. In this work, 16 organo-chlorine pesticides (OCPs) listed by the US Environmental Protection Agency (US EPA) as priority pollutants were separated and quantified. Sludge samples from three of Kuwaits wastewater treatment plants (WWTPs) were analyzed for organochlorine pesticides (OCPs). Spiked sludge samples were extracted with a mixture of (1:1 v/v) dichloromethane (DCM)/hexane. The extracts were cleaned on a silica/aluminum oxide column, then transferred to a gel permeation chromatography (GPC) column, before undergoing further silica/aluminum oxide clean-up; the presence of OCPs was then confirmed by GC-ion trap-MS–MS. Three extraction techniques, soxtec, soxhlet, and pressurized liquid extractions were utilized, compared and validated using the spiked sludge samples. The methods were validated in term of accuracy (recovery) and precision (RSD). The method recovery values varyied from 76.1 to 92.9% for the three extraction techniques. 相似文献
66.
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C3H5)]2 efficiently catalyses the Heck reaction of β-substituted enol ethers with aryl bromides. Employing β-methoxystyrene, 3-ethoxyacrylonitrile or methyl 3-methoxyacrylate, the regioselective α-arylation of these enol ethers was observed in all cases, and mixtures of Z and E isomers were generally obtained, which in many cases yielded a single ketone product after acid treatment. The stereoselectivity of this reaction depends on steric and electronic factors, and better stereoselectivities in favour of Z isomers were observed with electron-rich or sterically congested aryl bromides. Better yields were obtained for this reaction with electron-rich or sterically congested aryl bromides than with electron-poor aryl bromides. This observation suggests that with these β-substituted enol ethers the rate-limiting step of the catalytic cycle is not the oxidative addition of the aryl bromide to the palladium complex. 相似文献
67.
The syntheses and the X-ray structures of the tetranuclear gold(I) benzamidinate, Au4[PhNC(Ph)NPh]4, and the tetranuclear gold(I) acetamidinate, Au4[PhNC(CH3)NPh]4, clusters are reported. The clusters are produced by the reaction of the sodium salt of an amidine ligand with the gold precursor
Au(THT)Cl in a (1:1) stoichiometry. The average Au...Au distance between adjacent Au(I) atoms is ∼2.9 ?, typical of compounds
having an aurophilic interaction. The four gold atoms are arranged in a square (Au...Au...Au... = 88–91°) in the acetamidinate
and in a distorted square (Au...Au...Au... = 82–97°) in the benzamidinate derivative. Electrochemical oxidation of the tetranuclear
complex Au4[PhNC(Ph)NPh]4 show three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s in CH2Cl2 similar to the three reversible waves seen before from the tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-4-Me, and Ar = C6H3-3,5-Cl. A summary of the chemistry of the tetranuclear Au(I) amidinate complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, C6H3-3,5-Cl, C6H4-4-Me, C6H4-3-CF3, C6F5, C10H7 also is presented. The tetranuclear clusters Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-3-CF3, Ar = C6H4-4-Me and Ar = C6H4-3,5-Cl are the first tetranuclear gold(I) cluster species from group 11 elements to show fluorescence at room temperature.
The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes.
Recently it has been shown that Au4[ArNC(H)NAr]4 are very effective catalysts upon calcination for room temperature CO oxidation.
Congratulations to Dieter Fenske, a superb synthetic chemist with exceptional talents in cluster chemistry, on the occasion
of his 65th birthday. 相似文献
68.
Ahmed Akelah 《European Polymer Journal》1982,18(7):559-561
Insoluble polystyryldiphenyl-methoxymethyl- and methylthiomethyl-phosphonium chlorides have been prepared by treating polystyryldiphenylphosphine with chloromethylmethyl-ether and thioether respectively. These reagents were used for the conversion under mild conditions of carbonyl compounds into vinyl-ethers and thioethers, otherwise difficult to obtain; yields are high and work-up is easy. Moreover, methyl and ethyl β-styryl ethers were also prepared from the polymeric phosphorane by treatment with formate esters. 相似文献
69.
El-Hendawy Ahmed M. Alqaradawi Siham Y. Al-Madfa Homaid A. 《Transition Metal Chemistry》2000,25(5):572-578
The new complexes [RuIIIbpyL2](PF6) and [RuIIIbpyLCl2] [bpy = 2,2-bipyridine; HL = acetylacetone, trifluoroacetylacetone, benzoylacetone (Hbac), tropolone or maltol; HL = Hbac or dibenzoylmethane) have been prepared and characterized by spectroscopy. Their redox behaviour was studied by cyclic voltammetry. They effectively catalyze the oxidation of alcohols, alkanes and primary aromatic amines. 相似文献
70.
An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g−1 (R2=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g−1 and the limits of detection (LOD) ranged from 3 to 7 ng g−1. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g−1, the European Union maximum residue level. 相似文献