The equilibrium constants and the thermodynamic parameters for the interaction of CoLx (L1 = 5-OMe-salabza, L2 = salabza, L3 = 5-Br-salabza and L4 = 5-NO2-salabza) as acceptors, with phosphines (PBu3, PPh2Me) as donors in dichloromethane were studied. This was performed by using UV-Vis spectrophotometry titration for 1:1 adduct formation of the selected complexes at various temperatures (T = 283–298 K). The trend of the adduct formation of the Co(II) complexes with a given phosphine donor decreases as CoL1 > CoL2 > CoL3 > CoL4. The stability of the resulting adducts with different Co(II)-schiff base complexes found to decrease in the order PBu3 > PPh2Me. 相似文献
The potential of modified multiwalled carbon nanotubes (a solid-phase extraction sorbent), for the simultaneous separation
and preconcentration of lead, cadmium and nickel; has been investigated. Lead, cadmium and nickel, were adsorbed quantitatively;
on modified multiwalled carbon nanotubes (in the pH range of 2–4). Parameters influencing, the simultaneous preconcentration
of Pb(II), Ni(II) and Cd(II) ions (such as pH of the sample, sample and eluent flow rate, type and volume of elution solution
and interfering ions), have been examined and optimized. Under the optimum experimental conditions, the detection limits of
this method. for Pb(II), Ni(II) and Cd(II) ions, were 0.32, 0.17 and 0.04 ng mL−1 in original solution, respectively. Seven replicate determinations, of a mixture of 2.0 μg mL−1 lead and nickel, and 1.0 μg mL−1 cadmium; gave a mean absorbance of 0.074, 0.151 and 0.310, with relative standard deviation 1.7%, 1.5% and 1.2%, respectively.
The method has been applied, to the determination of trace amounts of lead, cadmium and nickel; in biological and water samples,
with satisfactory results.
相似文献
Various aryl aldehydes underwent prompt one pot conversion into the corresponding nitriles in high yields by reacting with hydroxylamine hydrochloride supported on melamine formaldehyde under microwave irradiation in the presence of ammonium acetate as catalyst. 相似文献
The one-pot procedure for synthesis of highly-substituted biaryl derivatives has been described via cyclocondensation reaction between vinyl malononitriles and acetylenic esters. A series of complex biaryls containing one-donor and three-acceptor moieties was obtained with good yields. 相似文献
In this paper the variation in the quantity and quality of the essential oil of Salvia officinalis during its life cycle stages is reported. The oils were obtained by hydrodistillation of air-dried samples. The yield of
essential oil (w/w %) in different stages was in the order: floral budding (0.9%) > vegetative (0.7%) > flowering (0.5%) >
immature fruit (0.4%) > ripen fruit (0.2%). The essential oils were analyzed by GC and GC-MS. In total, 36, 41, 40, 38, and
41 constituents were identified and quantified in the subsequent stages, respectively. Oxygenated monoterpenes were the main
group of compounds in the fruiting set (56.9%), vegetative (48.5%), flowering (47.7%), and floral budding (45.3%) stage. 1,8-cineole
as one of the major constituents of all samples was lower in the vegetative stage and gradually increased in subsequent harvesting
times to reach a maximum in flowering and then decreased in the fruiting set. In contrast, the globulol content was higher
in the first stage and decreased drastically during fruit maturation.
Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 16–19, January–February, 2006. 相似文献
KAl(SO4)2·12H2O was found to catalyze efficiently a one-pot three-component cyclocondensation of isatoic anhydride and primary amines or ammonia sources such as (NH4)2CO3, NH4OAc and NH4Cl with aromatic aldehydes under mild conditions to afford the corresponding mono- and disubstituted 2,3-dihydroquinazolin-4(1H)-ones in good yields. 相似文献
This work assesses for the first time the potential of natural Kaolinite as adsorptive material for preconcentration of metal traces. Manganese is quantitatively retained by 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) on thermal modified Kaolinite by column method in pH range of 8.5-10.0 at flow rate of 2 ml min−1. Manganese was removed from column with 5.0 ml of H2SO4 4 mol l−1 and determined by flame atomic absorption spectrometric at 279.5 nm. In this case, 0.l μg of manganese can be concentrated from 800 ml of aqueous sample (where concentration is as low as 0.125 μg l−1). Detection limit is 4.3 μg l−1 (3 δbl m−1) and analytical curve is linear in the 0.02-10 mg l−1 in final solution with correlation coefficient 0.9997 and relative standard deviation for eight replicate determination of 5 μg of manganese in final solution is 0.71%. The interference of a large number of anions and cations has been studied in detail to optimize the conditions and method was successfully applied for determination of manganese in complex materials. 相似文献
A pyrrole-based polymer was synthesized and applied as a new sorbent for solid-phase extraction (SPE) of some environmental pollutants from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in nonaqueous solution. SPE of selected phenols, pesticides, and polyaromatic hydrocarbons (PAHs) from aqueous samples were performed using 200 mg PPy. The determination was subsequently carried out by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The polymer showed much higher recoveries for aromatic compounds than aliphatics. Preconcentration of sample volumes up 11 led to acceptable recoveries for aromatic and other tested polar compounds. The R.S.D. for a river water sample spiked with phenols, pesticides and PAHs at sub-ppb level was lower than 10% (n = 3) and limits of detection for these compounds were between 15 and 120 ng l(-1). 相似文献
Roughness of surface has as an important influence on identifying the mechanical behavior and performance of crystalline metals. In this study, nanoindentation simulations are conducted by the two dimensional quasicontinuum method to determine the load–penetration response and the critical load associated with the onset of plasticity in rough surfaces of a face-centered cubic single crystal copper. The arithmetic roughness index, ranging between 2 and 13 Å, is used to specify the roughness of surface. Results of indentation with different roughnesses are in good agreement with previous studies for the indenter size of 10–140 Å. The resultant load–penetration scattering, which stems from the roughness, indicates different dislocation nucleation steps, different subsequent dislocations intervals and varying stiffness values of samples. It can be concluded that the surface roughness has a significant effect on the first dislocation emission because of the indenter position and surface interactions beneath it. Moreover, the critical penetration depth for the first dislocation emission increases by the increase of the contact area between the indenter and surface.
Some new tetradentate ligands with a NNOS coordination sphere were prepared and their corresponding nickel(II) complexes were synthesized and characterized by elemental analysis, IR, 1H NMR, UV–Vis and mass spectrophotometry. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at a constant ionic strength of 0.1 M (NaClO4) at 25 °C in DMF solvent. The trend of the complex formation for nickel is as follows: 相似文献