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961.
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
962.
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
963.
A mixed micellar electrokinetic chromatography method with fluorescence detection was developed to simultaneously monitor gamma-aminobutyric acid (GABA), glutamate (Glu) and alanine (Ala) in biological samples. Amino acids were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA). The separation of three NDA-labeled isomers (GABA, alpha-ABA, beta-ABA) was studied in detail with different micelles solutions such as sodium dodecyl sulfate (SDS), beta-cyclodextrin (beta-CD) and sodium cholate (SC). Simultaneous resolution of GABA, Glu and Ala from 21 amino acids was achieved within 5 min using 20 mM phosphate buffer at pH 8.7 containing 24 mM SC and 26 mM SDS. The detection limits were 4.0 x 10(-8), 1.1 x 10(-8) and 1.3 x 10(-8) M, for GABA, Glu and Ala, respectively, with S/N = 2. The method was applied to monitor the changes of amount of GABA, Glu and Ala in tobacco leaf in response to cold and dark stress. 相似文献
964.
This article reports the results of a computational and experimental study on the reaction of hydrazoic acid, HN3, adsorbed on 15-20 nm TiO2 particle films. Experimentally, FTIR spectra of HN3(a) have been measured by varying HN3 dosage, UV irradiation time and surface annealing temperature. Three sharp peaks, related to v(a)(NNN) of HN3(a) and N3(a) with different configurations in the 2000-2200 cm(-1) region, and a broad band absorption, related to associated and isolated HN(a) and HO(a) adsorptions in the 3000-3800 cm(-1) region, have been detected. Computationally, molecular structures, vibrational frequencies and adsorption energies of possible adsorbates including HN3 and its derivatives, N3, N2, NH, and H, have been predicted by first-principles calculations based on the density functional theory (DFT) and the pseudopotential method. On the basis of the experimental and computational results, the peak appeared at 2075 cm(-1), which increases at a faster rate with HN3 exposure time, is attributed to a stable adsorbate, N3-Ti(a), with the predicted adsorption energy, E(ads) = 13 kcal/mol. The peak at 2118 cm(-1), which survives at the highest surface temperature in the heating experiment, is attributable to the most stable adsorbate, Ti-N2N(H)-O(a) with E(ads) = 36 kcal/mol. The peak at 2170 cm(-1), which vanishes most readily in all of the aforementioned experiments, is related to less stable molecular adsorbates, end-on HN3-Ti(a) with E(ads) = 5 kcal/mol and side-on HN(N2)-Ti(a) with E(ads) = 8 kcal/mol. A potential energy diagram for the formation of various absorbates with their transition states has been established for the HN3/TiO2 system. On the basis of the predicted desorption energies, the four most stable products of the HN3 reaction on TiO2 are H-O(a), 118 kcal/mol; HN-O(a), 85 kcal/mol; Ti-N2N(H)-O(a), 36 kcal/mol; and N3-O(a), 19 kcal/mol. 相似文献
965.
Nam W Oh SY Sun YJ Kim J Kim WK Woo SK Shin W 《The Journal of organic chemistry》2003,68(20):7903-7906
The catalytic epoxidation of cyclohexene by iron(III) porphyrin complexes and H2O2 has been investigated in alcohol solvents to understand factors affecting the catalyst activity in protic solvents. The yields of cyclohexene oxide and the Fe(III/II) reduction potentials of iron porphyrin complexes were significantly affected by the protic solvents, and there was a close correlation between the product yields and the reduction potentials of the iron porphyrin catalysts. The role of alcohol solvents was proposed to control the electronic nature of iron porphyrin complexes that determines the catalyst activity in the epoxidation of olefins by H2O2. We have also demonstrated that an electron-deficient iron porphyrin complex can catalyze the epoxidation of olefins by H2O2 under conditions of limiting substrate with high conversion efficiency in a solvent mixture of CH3OH and CH2Cl2. 相似文献
966.
Fang Q Zhu G Xue M Sun J Tian G Wu G Qiu S 《Dalton transactions (Cambridge, England : 2003)》2004,(14):2202-2207
Four three-dimensional non-interpenetrating open coordination frameworks constructed from the CTC ligand (CTC =cis,cis-1,3,5-cyclohexanetricarboxylate) coordinated to metal ions (Mn(II) and Cd(II)): Mn(3)(CTC)(2)(DMF)(2)(1); Cd(3)(CTC)(2)(H(2)O)(3).H(2)O (2); Cd(3)(CTC)(2)(4,4'-bpy)(2)(EG)(2)(3); Cd(3)(CTC)(2)(mu(2)-hmt)(DMF)(C(2)H(5)OH)(H(2)O).2H(2)O (4)(DMF = dimethylformamide and EG = ethylene glycol) have been synthesized by slow evaporation of DMF-C(2)H(5)OH-H(2)O solutions of M(II)(Mn(II) or Cd(II)) and CTC in the presence of the organic bases TEA (triethylamine), TEA, 4,4'-bpy (4,4'-bipyridine) and hmt (hexamethylenetetramine), respectively, and structurally characterized by X-ray crystallography. The polymer constructed by CTC and Mn(II) exhibits a 3-D architecture with 5 x 9 A channels; the polymer formed by CTC and Cd(II) exists a 3-D extended framework with 9 x 9 A channels; wave-like sheet subunits of the polymer are upheld by 4,4'-bpy ligands resulting in a 3-D framework with 4 x 10 A channels; two-fold alternate sheet subunits of the polymer are interlinked by mu(2)-hmt ligands to form a novel 3-D architecture with 7 x 8 A channels. Polymers exhibit their strongest excitation peaks at 391, 390 and 394 nm, respectively, and their main strong emission peaks are at 543, 460 (with a shoulder peak at about 570 nm) and 557 nm, respectively. 相似文献
967.
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
968.
969.
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
970.
Gu X Sun M Gugiu B Hazen S Crabb JW Salomon RG 《The Journal of organic chemistry》2003,68(10):3749-3761
The recent immunological detection of extraordinarily high levels of carboxyethylpyrrole (CEP) modifications of proteins from the retinas of individuals with age-related macular degeneration provided presumptive evidence for the involvement of docosahexaenoate-derived oxidatively truncated phospholipids in retinal pathology. To facilitate the in vivo detection and characterization of the chemistry and biological activities of these postulated naturally occurring molecules, a family of oxidatively truncated phospholipids was prepared by total syntheses. Their formation in oxidation reactions of a docosahexaenoate ester of 2-lysophosphatidylcholine (DHA-PC) was also demonstrated. Free radical-induced oxidative cleavage of DHA-PC promoted by myeloperoxidase or copper ions generates similar mixtures of these phospholipids. The most abundant products were 1-palmitoyl-2-succinoyl-sn-glycero-3-phosphatidylcholine (4.7%) and 2-(6-carboxy-4-oxohex-5-enoyl)-1-palmitoyl-sn-glycero-3-phosphatidylcholine (1.7%). Both of these oxidatively truncated phospholipids are homologues of biologically active arachidonate-derived phospholipids. A minor product from DHA-PC, 2-(4-hydroxy-7-oxohept-5-enoyl)-1-palmitoyl-sn-glycero-3-phosphatidylcholine (0.4% yield), reacted with the epsilon-amino group of a peptide lysyl residue to produce a CEP derivative in 0.7% yield. These observations support the previous conclusion, based on immunological evidence, that CEPs are generated by the reaction of an oxidatively truncated phospholipid with proteins in the retina and further indicate that CEP protein modifications probably represent only a tiny fraction of the products generated upon oxidative damage of DHA-PC in photoreceptor disk membranes. 相似文献