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971.
Gian Angelo Vaglio Paolo Volpe Lorenza Operti 《Journal of mass spectrometry : JMS》1982,17(12):617-619
The negative ion chemical ionization mass spectra, with ammonia and methane as reagent gases, of the (η6-arene)Cr(CO)3 complexes, where the arene is C6H5COCH3, C6H5COC2H5, C6H5COC3H7, C6H5COC(CH3)3, 2-CH3C6H4COC3H7, C6H5COOCH3, C6H5CH3, 1,3,5-(CH3)3C6H3 and C6H5CH2COC2H5, are reported. Similar behaviour is observed with the two reagent gases, but ammonia shows a much higher abundance for the ions produced by reactions of [NH2]? with sample molecules. The compounds containing the C6H5CO group display an abundant [M]? ˙, whereas the other compounds exhibit [M? H]? as base peak, produced by ion/molecule reactions. A comparison of the negative ion chemical ionization mass spectra of the (η6-arene)Cr(CO)3 complexes with those of the corresponding ligands shows the strong electron withdrawing power of the Cr(CO)3 group in the gas phase. 相似文献
972.
Oleg V. Mikhailov Marina A. Kazymova Tatyana A. Shumilova Galina A. Chmutova Svetlana E. Solovieva 《Transition Metal Chemistry》2005,30(1):18-21
The complexing processes in the M
II
-dithiomalonamide-diacetyl triple system (M=Ni, Cu) occuring in the nickel(II)- and copper(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous alkaline solutions (pH~12) containing dithiomalonamide and diacetyl at room temperature, and between MCl2, dithiomalonamide
and
diacetyl
in
EtOH
solutions
upon
heating
to$80°C, have been studied. In the Ni
II
-dithiomalonamide-diacetyl system, template synthesis occurs in EtOH solution but does not occur in the gelatin-immobilized matrix, whereas in the Cu
II
-dithiomalonamide-diacetyl system, template synthesis occurs in the gelatin-immobilized matrix but not in EtOH solution. Dithiomalonamide and diacetyl are the ligand synthons in the processes indicated. 相似文献
973.
H7[NiV13O38] was synthesized from K7[NiV13O38] using an ion exchange method. Then Pr2H[NiV13O38] was obtained by double decomposition of H7[NiV13O38] with Pr2(CO3)3. The actual amount of praseodymium measured by elemental analysis coincides with the designed amount of praseodymium in Pr2H[NiV13O38]. The i.r. spectra suggested that the [NiV13O38]7– anion did not collapse after the ion exchange and double decomposition. The 51V n.m.r. spectrum of Pr2H[NiV13O38] showed four peaks and their ratio of the relative intensity was 4:4:4:1. This result agrees with the chemical environment of V atoms in the [NiV13O38]7– anion. In vitro antitumor activities of polyoxometalates on several human tumor cells have been investigated using the MTT method. Pr2H[NiV13O38] is the most effective polyoxometalate tested in this study for inhibiting KB cell. Pr2H[NiV13O38] also showed remarkable inhibitory effect on some other tumor cells: HCT, Bel, B16, BCAP and ESCL cells. These results indicate that Pr2H[NiV13O38] is a potent broad spectrum antitumor agent. The structure type of polyoxometalates greatly influences their antitumor activity: the order of structure type for inhibiting KB cell is: [NiV13O38]7–>[Mo7O24]6–>Anderson structure Keggin structure Dawson structure. Moreover, the nature of the polyatom in the polyoxometalates also greatly influences their antitumor activity: the polyatom order for inhibiting KB cell is: V>Mo W. On the other hand, the nature of the counter cation and the heteroatom in the polyoxometalates exerted a relatively small influence on the inhibitory effect against the KB cell, although the praseodymium salt of [NiV13O38]7– showed a higher antitumor activity than its potassium salt. 相似文献
974.
Nikos G. Tsierkezos 《Journal of solution chemistry》2007,36(10):1301-1310
The reduction of benzophenone (Bzph) in 3-pentanone (PEN), acetone (ACE), N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile (ACN) and dimethyl sulfoxide (DMSO) with n-tetrabutylammonium hexafluorophosphate (TBAPF6) as background electrolyte was studied using the technique of cyclic voltammetry at the temperature of 263.15 K. The half-wave
potentials (E
1/2) were extracted. The reduction of Bzph occurs in two successive one-electron steps to produce first the free radical anion
Bzph− and then the dianion Bzph2−. The results indicated that the radical anion Bzph− is reoxidized to Bzph in all investigated solvent media whereas the dianion Bzph2− is reoxidized to Bzph− only in THF. The heterogeneous electron-transfer rate constants (k
s
) were evaluated by employing the electrochemical rate equation proposed by Nicholson. The rate of electron transfer for the
Bzph/Bzph− couple was found to be relatively slow in all investigated solvent media. Consequently, the electron-transfer processes can
be recognized as quasi-reversible. The diffusion coefficients (D) of Bzph in the investigated solvent media have been calculated using the modified Randles-Sevcik equation. The effect of
the physical and chemical properties of the solvent medium on the electrochemical behavior of Bzph has been examined. 相似文献
975.
Advanced oxidation processes for decolorization of aqueous solution containing acid red G azo dye 总被引:2,自引:0,他引:2
Some investigations concerning the decolorization of Acid Red G azo dye by photooxidation with hydrogen peroxide were performed.
The influences of pH, oxidant concentration, and the presence of Fe2+ or other metal ions (Co2+, Cu2+, Ni2+, Mn2+) as potential catalysts, were investigated. The best results were obtained in the presence of ferrous ions in acid and neutral
media. The other ions are not as effective as Fe2+ for dye decolorization. Co2+ and Cu2+ ions have a catalytic action, at low concentration, within a wide range of pH. Ni2+ and Mn2+ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid Ni2+ and Mn2+ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid pH values, but show a weak action in alkaline
media. 相似文献
976.
A. V. Makarycheva-Mikhailova S. I. Selivanov N. A. Bokach V. Yu. Kukushkin P. F. Kelly A. J. L Pombeiro 《Russian Chemical Bulletin》2004,53(8):1681-1685
Reactions of the platinum(IV) nitrile complexes [PtCl4(RCN)2] (R = Me, CH2Ph, Ph) with 1,2- and 1,4-PhS(=NH)C6H4SPh in CH2Cl2 afforded addition products of sulfimides and coordinated nitriles, viz., the [PtCl4{NH=C(R)N=S(Ph)(C6H4SPh)}2] complexes. The latter were isolated in 75—90% yields and characterized by elemental analysis, positive-ion FAB mass spectrometry, IR spectroscopy, and 1H and 13C1H NMR spectroscopy. The temperature dependence of the 1H NMR spectra of the model [PtCl4{NH=C(R)N=SPh2}2] complexes (R = Me, Et) in CD2Cl2 studied in a temperature range from +40 to -70 °C demonstrated that E—Z isomerization of the ligands is a dynamic process in a range from +40 to -10 °C. The activation free energy of this process was calculated.Published in Russian in Izvestiya Akademii Nauk.
Seriya Khimicheskaya, No. 8, pp. 1618–1622, August, 2004. 相似文献
977.
The synthesis of [Mn12O12(O2CMe)6(p-CO2-phenyl nitronyl nitroxide)10(H2O)4]· 4H2O, (1), by direct replacement of some of the acetate groups in [Mn12O12(O2CMe)16(H2O)4] · 4H2O · 2MeCO2H, (2), with the organic radical p-HO2C-phenyl nitronyl nitroxide, (3), is reported. E.p.r. spectra show exchange narrowing in (1) due to coupling between the manganese ions and radicals. The isotropic hyperfine splitting constant from the manganese ions is a = 96 Oe at 5.5K. The magnetic susceptibility indicates antiferromagnetic exchange interactions between the manganese ions and the radicals with the Weiss constant = -25 K. The spin was determined to be S = 6 from magnetization data in the 2--30 K temperature range at 50 kOe, suggesting a mixture of ground state with excited states. 相似文献
978.
Addition–elimination reactions involving a nucleophile and a remote leaving group [SH
N(AE)tele] are well-known under basic conditions, especially amongst electron-poor six-membered heterocycles, but are less commonly
encountered for five-membered heterocycles and are rare under acidic conditions. Concentrated HCl converts 1-hydroxy-1H-pyrazolo[3,4-c] isoquinoline and 1-hydroxy-1H-pyrazolo[3,4-c]quinoline into 3-chloro-1H-pyrazolo[3,4-c]isoquinoline and 3-chloro-1H-pyrazolo[3,4-c]quinoline, respectively. However, apparently neither the isomeric 1-hydroxy-1H-pyrazolo[4,3-c](iso)-quinolines nor the parent 1-hydroxypyrazole undergo this reaction. Additionally, all these systems are refractory under
basic conditions. We present a plausible mechanism for the reaction, involving the 3-addition of Cl- to the diprotonated heterocycle, followed by the elimination of water. Calculations of the initial transition states and
intermediates, using optimisation at B3LYP/6-311+G(d,p), including thermochemistry [HF/6-31+G(d)], and single-point Poisson–Boltzmann
self-consistent reaction field determination of the free energy of solvation (Jaguar Poisson–Boltzmann self-consistent reaction
field), support this mechanism and reproduce the observed order of reactivity, the addition step being 2–4 kcal less favourable
for the isomeric 1-hydroxy-1H-pyrazolo[4,3-c](iso)quinolines and provide a rationalisation for the role of strong acid.
Received: 27 June 2002 / Accepted: 6 September 2002 /
Published online: 14 February 2003 相似文献
979.
Smith CJ Huang W Walcott CJ Turner W Grainger J Patterson DG 《Analytical and bioanalytical chemistry》2002,372(1):216-220
For measurement of biomarkers from polycyclic aromatic hydrocarbon (PAH) exposure, an analytical method is described quantifying hydroxylated PAH (OH-PAH) in urine samples. This method determined monohydroxy metabolites of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[c]phenanthrene, and benz[a]anthracene. The sample preparation consisted of enzymatic hydrolysis, solid-phase extraction and derivatization with a silylating reagent. Five carbon-13 labeled standards were used for isotope dilution. Analytes were separated by gas chromatography (GC) and quantified with high-resolution mass spectrometry (HRMS). This method produced good recoveries (41-70%), linearity, and specificity. Data were corrected for blank levels from the naphthalene, fluorene, and phenanthrene metabolites. Method detection limits ranged from 2 ng L(-1) for 1-hydroxypyrene to 43.5 ng L(-1) for 1-hydroxynaphthalene. Using quality control charts from two urine pools, the method can be readily applied to biomonitoring PAH exposure. 相似文献
980.
Francesca Benedini Giorgio Bertolini Francesco Ferrario Angelo Motti Alberto Sala Flavio Somenzi 《Journal of heterocyclic chemistry》1995,32(1):103-107
The preparation and the physico-chemical characterization of 2H-pyrido[2,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazin-4(3H)-ones, 2H-thieno[2,3-e]-1,3-oxazin-4(3H)-ones and 2H-thieno[3,4-e]-1,3-oxazine-2,4(3H)-diones are reported. 相似文献