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991.
Three dimeric cis-dioxomolybdenum(VI) complexes of bis-bidentate Schiff base derivatives containing aromatic nitrogen–nitrogen linkers (4,4′-diaminodiphenylmethane;
4,4′-diaminodiphenylether; 4,4′-diaminodiphenylsulfone) with 2-hydroxy-1-naphthaldehyde have been synthesised and characterized
by physico-chemical and spectroscopic methods. The catalytic activities of the complexes with respect to alkene epoxidation
using tert-butylhydroperoxide (TBHP) as oxidant have been studied. The addition of single wall nanotubes can enhance the catalytic activities
of the Mo complexes and the selectivity of epoxide formation. 相似文献
992.
Masoud Salavati-Niasari Shahrzad Abdolmohammadi 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):145-152
Ni(II) complexes of [12]aneN4: 1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone; [14]aneN4: 1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone; Bzo2[12]aneN4: dibenzo-1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone and Bzo2[14]aneN4: dibenzo-1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone have been encapsulated in the nanopores of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)nickel(II)]; [Ni(N–N)2]–NaY; in the supercages of the zeolite, and (ii) in situ condensation of the nickel(II) precursor complex with diethyloxalate. The new host-guest nanocatalyst (HGN) were characterized by several techniques: chemical analysis and spectroscopic methods (FT-IR, UV/Vis, XRD, BET, DRS) and then were used for oxidation of cyclohexene with molecular oxygen. 相似文献
993.
Hassan H. Hammud Kamal H. Bouhadir Mamdouh S. Masoud Amer M. Ghannoum Sulaf A. Assi 《Journal of solution chemistry》2008,37(7):895-917
The absorption and emission spectra of six purine derivatives: adenine (I), N(9)-hydroxyethyladenine (II), N(6)-acetyladenine (III), N(6)-isobutyryladenine (IV), guanine (V), and N(2),N(9)-diacetylguanine (VI) have been investigated. The effects of solvent and pH on the positions of λ
max (absorption) and λ
max (emission) of these compounds were determined. Correlations between the absorption wavelength (λ
max ) of these organic compounds and the solvent parameters (D,n,E) or (K,M,N) show that the peak position is affected mainly by specific- and non-specific types of interactions between the solvent and
solute. Solvent effects on the electronic absorption band shifts are indicative of the extent of charge reorganization of
the solute molecules upon electronic excitation. The Stokes shift (ν
abs−ν
em) was correlated with the orientation polarizability (Δf) and was found to depend mainly on the dielectric constant and the refractive index of the solvents. This shift reflects
the influence of the equilibrium solvent arrangement around the excited solute molecule, which rearranges inertially due to
the instantaneous charge redistribution upon radiative deactivation to the electronic ground state. A spectrofluorometric
analysis technique was applied for the quantitative analysis of the components of a ternary mixture of compounds (I–III). 相似文献
994.
Interleukin-7 (IL-7) is a glycoprotein cytokine with significant clinical and biomedical potential, such as cancer therapy
and HIV infections. Earlier it has been cloned and expressed in various protein expression systems; however, they are not
efficient for large-scale production. To address this inadequacy, we report in this paper the production of recombinant human
interleukin-7 (hIL-7) in insect cells. A recombinant bacmid containing hIL-7 was constructed, purified, and characterized.
It was used to infect Trichoplusia ni (BT1-TN-5B1/High Five™) insect cells. Result shows that T. ni cells successfully produce hIL-7 in shake flask cultures. A scale up to 2.5-L laboratory batch bioreactor showed the efficacy
of this system for large-scale production. Our results offer a highly efficient, inexpensive, and convenient system for the
large-scale expression and production of recombinant hIL-7. 相似文献
995.
Hydrogen bond (HB) interactions are studied in the real crystalline structure of sulfamerazine by density functional theory (DFT) calculations of the electric field gradient (EFG) tensors at the sites of O-17, N-14, and H-2 nuclei. One-molecule (single) and four-molecule (cluster) models of sulfamerazine are created by available crystal coordinates and the EFG tensors are calculated in both models to indicate the influence of HB interactions on the tensors. Directly relate to the experiments, the calculated EFG tensors are converted to the experimentally measurable nuclear quadrupole resonance (NQR) parameters, quadrupole coupling constant (qcc) and asymmetry parameter (ηQ). The evaluated NQR parameters reveal that due to contribution of the target molecule to N–HN and N–HO types of HB interactions, the EFG tensors at the sites of various nuclei are influenced from single model to the target molecule in cluster. Additionally, O2, N4, and H2 nuclei of the target molecule are significantly influenced by HB interactions, consequently, they have the major contributions to HB interactions in cluster model of sulfamerazine. The calculations are performed employing B3LYP method and 6-311++G** basis set using GAUSSIAN 98 suite of program. 相似文献
996.
Nabavizadeh SM Hoseini SJ Momeni BZ Shahabadi N Rashidi M Pakiari AH Eskandari K 《Dalton transactions (Cambridge, England : 2003)》2008,(18):2414-2421
The n-alkyl halides, RX, were oxidatively added to the platina(II)cyclopentane complexes [Pt[(CH2)4](NN)], in which NN = bpy (2,2'-bipyridyl) or phen (1,10-phenanthroline), to give the platinum(IV) complexes [PtRX[(CH2)4](NN)], R = Et and X = Br or I; R = nBu and X = I, 1-3. The same reactions with the analogous dimethyl complex [PtMe2(bpy)] gave the expected platinum(IV) complexes [PtRXMe2(bpy)], R = Et or nPr and X = Br or I; R = nBu and X = I, 4-8. Kinetics of the reactions in benzene and acetone was studied using UV-vis spectrophotometery and a common S(N)2 mechanism was suggested for each case. The platina(ii)cyclopentane complexes reacted faster than the corresponding dimethyl analogs by a factor of 2-3. This is described as being due to a lower positive charge, calculated by density functional theory (DFT), on the platinum atom of [Pt[(CH)2)4](bpy)] compared with that on the platinum atom of the dimethyl analog [PtMe2(bpy)]. The values of DeltaDeltaS(double dagger) = DeltaS(double dagger)(acetone) - DeltaS(double dagger)(benzene) were found to be either positive or negative in different reactions and this is related to the solvation of the corresponding alkyl halide. It is suggested that in these reactions of RX reagents, for a given X, the electronic effects of the R group are mainly responsible for the change in the rates of the reactions and the bulkiness of the group is far less important. 相似文献
997.
A. Sharifi M. S. Abaee A. Tavakkoli M. Mirzaei 《Journal of the Iranian Chemical Society》2008,5(1):S113-S117
Room temperature Rap-Stoermer condensation of α-haloacetophenone with various 2-hydroxyarylaldehydes mediated by KF/Al2O3 resulted in sole formation of good to excellent yields of various substituted benzofurans in the absence solvent or extra stimulant. 相似文献
998.
Solid-state nuclear magnetic resonance (NMR) parameters of 17O, 14N/15N, and 2H/1H nuclei were evaluated in two available neutron crystalline structures of N-methylacetamide (NMA) at 250 and 276 K, NMA-I and NMA-II, respectively. Density functional theory calculations were performed
by B3LYP method and 6-311++G** and IGLO-II type basis sets to calculate the electric field gradient (EFG) and chemical shielding
(CS) tensors at the sites of mentioned nuclei. In order to investigate hydrogen bonds (HBs) effects on NMR tensors, calculations
were performed on four-model systems of NMA: an optimized isolated gas-phase, crystalline monomers, crystalline dimers, and
crystalline trimers. Comparing the calculated results reveal the influence of N–H···O=C and C–H···O=C HB types on the NMR
tensors which are observable by the evaluated parameters including quadrupole coupling constant, C
Q, and isotropic CS, σ
iso. Furthermore, the results demonstrate more influence of HB on the EFG and CS tensors of NMA at 276 K rather than that of
250 K. 相似文献
999.
Masoud Farhadi-Khouzani Zeinab Fereshteh Mohammad Reza Loghman-Estarki Reza Shoja Razavi 《Journal of Sol-Gel Science and Technology》2012,64(1):193-199
Various morphologies of ZnO nanostructures, such as nanoparticles, nanorods and nanoflowers have been achieved controllably by polymeric sol–gel method. In this approach, zinc nitrate Zn(NO3)2·6H2O, citric acid and ethylene glycol were used as the source of Zn2+, the chelating agent and the solvent agent, respectively. The microstructure of the ZnO nanostructures was characterized by X-ray diffractometry, scanning electron microscopy with the energy dispersive X-ray spectroscopy, transmission electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. The ZnO nanoparticles with diameter between 24 ± 2 nm was obtained with EG:CA mole ratio equal to 2:1. The optical properties of as-obtained power were investigated by ultraviolet–visible spectroscopy. 相似文献
1000.
Afsaneh Khansari Masoud Salavati-Niasari Ali Kazemi Babaheydari 《Journal of Cluster Science》2012,23(2):557-565
The simple preparation of Co3O4 nanoparticles from a solid metallorganic molecular precursor [bis(salicylaldehydeato)cobal(II)]; [Co(sal)2] has been achieved via two simple steps: firstly, the [Co(sal)2] precursor was precipitated from the reaction of cobalt(II) acetate and salicylaldehyde; in propanol under nitrogen condition; then, cubic phase Co3O4 nanoparticles with the size of mostly 20–30 nm could be produced by thermal treatment of the [Co(sal)2] in air at 500 °C for 5 h. The as-synthesized products were characterized by powder XRD, FT-IR, TEM and SEM. The results confirm that the resulting oxide was pure single-crystalline Co3O4 nanoparticles. The optical absorption spectrum indicates that the direct band gaps of Co3O4 nanoparticles are 1.53 and 2.02 eV. The optical property test indicates that the absorption peak of the nanoparticles shifts towards short wavelength, and the blue shift phenomenon might be ascribed to the quantum effect. The hysteresis loops of the obtained samples reveal the ferromagnetic behaviors the enhanced coercivity (H c ) and decreased saturation magnetization (M s ) in contrast to their respective bulk materials. 相似文献