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221.
The thiocarbonates of K(I), Tl(I), Pb(II), Cd(II), Cu(II), Co(II), Ni(II), Zn(II), Fe(II) and the sulphides of Ag(I), Cu(II), Cd(II), Hg(II), Bi(III), Mo(VI), Pt(IV), Au(III), V(V), Se(IV), Te(IV), As(III, V), Sb(III) have been studied by thermogravimetric analysis. These studies not only confirm the purity of the precipitated products obtained with PTC but also determine correct temperature ranges for the precipitates to attain constant weight, thereby affording gravimetric evaluations of even mg quantities of the metal ions studied. Purity of precipitated products was made possible with the technique of precipitation from homogeneous solution based on the PTC reagent as precipitant. 相似文献
222.
Narender K. Kaushik Gurvinder S. Sodhi Harpal S. Sangari Gurdeep R. Chhatwal 《中国化学会会志》1981,28(4):231-235
Bis (η5-cyclopentaienyl) N,N-disubstituted dithiocarbamato chloro oxotungsten (VI) complexes of the type η5-Cp2WO(S2CNR2)Cl and η5-Cp2WO(S2CNRR')Cl (where R=Me, Et and i-Pr and R'=Cyhx) have been prepared by the reaction of bis (η5-cyclopentadienyl) oxotungsten (VI) dichloride with sodium salts of dithiocarbamic acids in refluxing tetrahydrofuran. Infrared spectral studies demonstrate that in these complexes dithiocarbamate ligands are bidentate. Therefore, tungsten (VI) atom may be assigned a coordination number 6 in all these complexes. Elemental analyses of these compounds have also been carried out. Electronic spectra have been recorded for all the six complexes. 相似文献
223.
Substrate-based design of the first class of angiotensin-converting enzyme-related carboxypeptidase (ACE2) inhibitors 总被引:9,自引:0,他引:9
Dales NA Gould AE Brown JA Calderwood EF Guan B Minor CA Gavin JM Hales P Kaushik VK Stewart M Tummino PJ Vickers CS Ocain TD Patane MA 《Journal of the American Chemical Society》2002,124(40):11852-11853
Angiotensin-converting enzyme-related carboxypeptidase (ACE2) is a recently identified zinc metalloprotease with carboxypeptidase activity that was identified using our genomics platform. We implemented a rational design approach to identify potent and selective ACE2 inhibitors. To this end, picomolar inhibitors of ACE2 were designed and synthesized. 相似文献
224.
Efficient analytical separations of Mo(VI), Tl(I), Se(IV), Te(IV) and V(V) from various ions have been made possible by using potassium thiocarbonate (PTC) as a complexing and precipitating agent. For gravimetric estimations, thermogravimetric studies of the products have been used to determine the optimum temperature range of ignition. 相似文献
225.
Balakrishnan K Datar A Oitker R Chen H Zuo J Zang L 《Journal of the American Chemical Society》2005,127(30):10496-10497
Nanobelt structures have been fabricated for an n-type semiconductor molecule, N,N'-di(propoxyethyl)perylene-3,4,9,10-tetracarboxylic diimide (PTCDI). The short alkyloxy side chain not only affords effective pi-pi stacking in polar solvents for self-assembling but also provides sufficient solubility in nonpolar solvents for solution processing. As revealed by both AFM and electron microscopies, the nanobelts have an approximately rectangular cross section, with a typical thickness of about 100 nm and a width in the range of 300-500 nm. The length of the nanobelts ranges from 10 to a few tens of micrometers. The highly organized molecular packing (uniaxial crystalline phase) has been deduced from the measurement of electron diffraction and polarized microscopy imaging. The detected optical axis is consistent with the one-dimensional stacking of the molecules. 相似文献
226.
Ionic chelates of hafnocene, with 6-mercaptopurine (HL1) (A) and 6-thioguanine (HL2) (B) of the type [(
5-C5H5)2HfL1]+X– (C) and [(
5-C5H5)2HfL2]+X– (D) (X = CuCl3, ZnCl3, CdCl3, HgCl3, PhNHNHCS2) have been prepared and characterized by conductivity measurements and by i.r., electronic, 1H-n.m.r. and 13C-n.m.r. spectra. Fluorescence studies of the complexes containing Hg in the anionic moiety, and relevant photochemical parameters, have been elucidated. Thermodynamic parameters have been calculated using thermogravimetric (t.g.) and differential thermal analytical (d.t.a.) curves and their variations have been correlated with some structural parameters of the complexes. The ligands, as well as their hafnium(IV) complexes, exhibit appreciable antibacterial and antifungal activity against E. coli, S. typhi, P. aeruginosa, Z. mobilis bacterial strains and versus A. awamori, A. niger fungal strains, respectively. 相似文献
227.
A. K. Mishra S. B. Mishra N. Manav N. K. Kaushik 《Journal of Thermal Analysis and Calorimetry》2007,90(2):509-515
Palladium(II) complexes of type [Pd(L)Cl2] [where L=2-aminopyridine-N-thiohydrazide (L1), (2-aminopyridine-N-thio)-1,3-propanediamine (L2), benzaldehyde 2-aminopyridine-N-thiohydrazone (L3) and salicylaldehyde-2-aminopyridine-N-thiohydrazone (L4)] have been synthesized. The thiohydrazide, thiodiamine and thiohydrazones can exist as thione-thiol tautomer and coordinate
as a bidentate N-S ligand. The ligands found to act in bidentate fashion.
The complexes have been characterized by elemental analysis, IR, mass, electronic, 1H NMR spectroscopic studies, and TG/DTA study. Antifungal studies of some complexes were also carried out. Various kinetic
and thermodynamic parameters like order of reaction (n), activation energy (E
a), apparent activation entropy (S
#
) and heat of reaction (ΔH) have also been carried out for one complex. 相似文献
228.
Kaushik N 《Analytical and bioanalytical chemistry》2002,374(7-8):1199-1204
A simple and economical method has been developed to estimate the azadirachtin content and fatty acid composition of neem kernels. Neem kernels are crushed and soaked overnight in ethanol. The extract obtained is analysed by HPLC after filtering through a 0.22 micro m membrane. The peaks are separated using acetonitrile-water (40:60) 1 mL min(-1) as the mobile phase on an RP-18 column and monitored at 214 nm. For the determination of fatty acid composition, the fatty acids are directly transmethylated in the kernel powder by heating with methanol-acetyl chloride-benzene (20:1:4, v/v) for 1 h in a water bath. The fatty acid methyl esters (FAMEs) obtained are extracted in hexane and analysed using GLC. The separation of the FAMEs is achieved using an RH-Wax column using temperature programming, 170-200 degrees C at 2 degrees min(-1). The peaks are detected using an FID. Both the methods do not require any clean up or defatting of seeds. This results in faster, easier and more economical sample preparation. 相似文献
229.
(η5-Cyclopentadienyl)(η5-pyrrolyl)titanium(IV) dichloride, (η5-indenyl)-(η5-pyrrolyl)titanium(IV) dichloride and (η5-cyclopentadienyl)(η5-indenyl)-titanium(IV) dichloride, when treated with 8-hydroxyquinoline (oxine) in aqueous medium form ionic derivatives of the type, [(η5-R)(η5-R′)TiL]+ Cl- (R = C5H5, C9H7, R′ = C4H4N; R = C5H5, R′ = C9H7; L is the conjugate base of (oxine). A number of halide and complex halogeno anions present in aqueous solution were isolated as salts of these ionic complexes giving derivatives of the type, [(η5-R)(η5-R′)TiL]+ X- (X = Br-, I-, ZnCl3(H2O)-, CdCl42-, HgCl3-). Conductivity measurements in nitrobenzene solution indicate that these complexes are electrolytes. Both the IR and 1H NMR spectral studies demonstrate that the ligand L is chelating. Consequently there is tetrahedral coordination about the titanium(IV) ion. 相似文献
230.
Summary Thin-layer chromatography of Se(IV), Te(IV), V(V), and Mo(VI) as ternary mixtures has been described. The separation was effected on a silica gel G layer by employing two different solvent systems: diethyl oxalate-HCl (601v/v) andn-butyl acetate-HCl (400.6v/v). The chromatograms were visualized with 0.1M potassium thiocarbonate (PTC) spray and the limits of identification as determined, lie between 1.27 and 2.04g.
Zusammenfassung Die Dünnschichtchromatographie ternärer Gemische von Se(IV), Te(IV), V(V) und Mo(VI) wurde beschrieben. Die Trennung wurde auf Schichten von Kieselgel G mit zwei verschiedenen Lösungsmittelsystemen durchgeführt: Diäthyloxalat—Salzsäure (601) und n-Butylacetat—Salzsäure (400,6). Die Chromatogramme wurden mit 0,1-m Kaliumthiocarbonat gesprüht. Die Nachweisgrenze liegt zwischen 1,27 und 2,04g.相似文献