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991.
Nouria Chiali-Baba Ahmed Latifa Negadi Ilham Mokbel Ahmed Ait Kaci Jacques Jose 《The Journal of chemical thermodynamics》2012,44(1):116-120
The vapour pressures of (sec-butylamine + water), (cyclohexylamine + water) binary mixtures, and of pure sec-butylamine and cyclohexylamine components were measured by means of two static devices at temperatures between 293 (or 273) K and 363 K. The data were correlated with the Antoine equation. From these data, excess Gibbs functions (GE) were calculated for several constant temperatures and fitted to a fourth-order Redlich–Kister equation using the Barker’s method. The (cyclohexylamine + water) system shows positive azeotropic behaviour for all investigated temperatures. The two binary mixtures exhibit positive deviations in GE for all investigated temperatures over the whole composition range. 相似文献
992.
Tapia R Guardia JJ Alvarez E Haidöur A Ramos JM Alvarez-Manzaneda R Chahboun R Alvarez-Manzaneda E 《The Journal of organic chemistry》2012,77(1):573-584
A new strategy for synthesizing taiwaniaquinoids, a group of terpenoids with an unusual rearranged 5(6→7) or 6-nor-5(6→7)abeo-abietane skeleton, which exhibit promising biological activities, is reported. The procedure, based on the cleavage of the C7-C8 double bond of abietane diterpenes, is the only one yet reported for synthesizing C(20) taiwaniaquinoids bearing a carbon function on the cyclopentane B ring; it is also applicable to the synthesis of the wide variety of existing taiwaniaquinoids. Utilizing this, (-)-taiwaniaquinone A, F, G, and H, (-)-taiwaniaquinol B, and (-)-dichroanone have been synthesized from (+)-abietic acid. The versatility of this strategy allows us to propose the abietane C7-C8 cleavage as a possible biosynthetic pathway to this type of rearranged diterpenes; this proposal seems to be supported by phytochemical evidence. 相似文献
993.
de Oliveira CS Lira BF dos Santos Falcão-Silva V Siqueira JP Barbosa-Filho JM de Athayde-Filho PF 《Molecules (Basel, Switzerland)》2012,17(5):5095-5107
Five new 1-(2-(5-nitrofuran-2-yl)-5-(aryl)-1,3,4-oxadiazol-3-(2H)-yl) ethanone compounds 5a-e were synthesized by cyclization of N-acylhydrazones 4a-e with acetic anhydride under reflux conditions. Their structures were fully characterized by IR, 1H-NMR, and 13C-NMR. Furthermore, evaluations of the antibacterial activity of the 1,3,4-oxadiazoles 5a-e and N-acylhydrazones 4a-e showed strong activity against several strains of Staphylococcus aureus, with MICs between 4 μg/mL to 32 μg/mL. In silico studies of the parameters of Lipinski's Rule of Five, as well as the topological polar surface area (TPSA), absorption percentage (% ABS), drug likeness and drug score indicate that these compounds, especially 4a and 5d, have potential to be new drug candidates. 相似文献
994.
995.
CM Knapp BH Westcott MA Raybould JE McGrady JM Goicoechea 《Angewandte Chemie (International ed. in English)》2012,51(36):9097-9100
A carbon copy: The chemical activation of the heptaphosphide trianion with [Co(PEt(2) Ph)(2) (mes)(2) ] (see picture; 1) yields the novel phospha-organometallic complex [Co(η(5) -P(5) ){η(2) -P(2) H(mes)}](2-) (2). The reaction product maintains the nuclearity of the parent cluster, but extensive cage fragmentation takes place to yield a diamagnetic "inorganometallic" cobalt complex. 相似文献
996.
Cao Z Mi L Mendiola J Ella-Menye JR Zhang L Xue H Jiang S 《Angewandte Chemie (International ed. in English)》2012,51(11):2602-2605
Attack or defend! A smart polymer surface has two reversibly switchable equilibrium states, a cationic N,N-dimethyl-2-morpholinone (CB-Ring) and a zwitterionic carboxy betaine (CB-OH). CB-Ring will kill bacteria upon contact under dry conditions, whereas CB-OH will release the previously attached and dead bacteria and further resist adhesion of bacteria under wet conditions. 相似文献
997.
Janne Pesonen Krister O. E. Henriksson Jose Ramon López-Blanco Pablo Chacón 《Journal of mathematical chemistry》2012,50(6):1521-1549
Normal mode analysis (NMA) was introduced in 1930s as a framework to understand the structure of the observed vibration-rotation
spectrum of several small molecules. During the past three decades NMA has also become a popular alternative to figuring out
the large-scale motion of proteins and other macromolecules. However, the “standard” NMA is based on approximations, which
sometimes are unphysical. Especially problematic is the assumption that atoms move only “infinitesimally”, which, of course,
is an oxymoron when large amplitude motions are concerned. The “infinitesimal” approximation has the further unfortunate side
effect of masking the physical importance of the coupling between vibrational and rotational degrees of freedom. Here, we
present a novel formulation of the NMA, which is applied for finite motions in non-Eckart body-frame. Contrary to standard normal mode theory, our approach starts by assuming a harmonic potential in generalized coordinates,
and tries to avoid the linearization of the coordinates. It also takes explicitly into account the Coriolis terms, which couple vibrations and
rotations, and the terms involving Christoffel symbols, which are ignored by default in the standard NMA. We also computationally
explore the effect of various terms to the solutions of the NMA equation of motions. 相似文献
998.
The use of steel-making slag as catalysts for microwave-assisted dry reforming of CH4 was studied. Two carbon materials (an activated carbon and a metallurgical coke), mixtures of the carbon materials and Fe-rich slag, and mixtures of the carbon materials and Ni/Al2O3 were tested as catalysts. The mixtures of slag with carbons gave rise to higher and steadier conversions than those achieved over the carbon materials alone. In addition, the use of the metallurgical coke mixed with metal-rich catalysts gave rise to remarkable results. Thus, no CH4 and CO2 conversions were achieved when coke was used alone, whereas high conversions were obtained when it was mixed with the metal-rich catalysts. 相似文献
999.
CM Alvarez H Barbero LA García-Escudero JM Martín-Alvarez C Martínez-Pérez D Miguel 《Inorganic chemistry》2012,51(15):8103-8111
The first η(6)-complexes of iridium and ruthenium coordinated to helicenes have been obtained. Hexahelicene (1), 2,15-dimethylhexahelicene (2), and 2,15-dibromohexahelicene (3) react with [Cp*IrCl(2)](2) and AgBF(4) in CD(3)NO(2) to afford quantitatively the complexes [Cp*Ir(η(6)-1)][BF(4)](2) (4A), [Cp*Ir(η(6)-2)][BF(4)](2) (5A), and [Cp*Ir(η(6)-3)][BF(4)](2) (6A), respectively. In all cases, the final thermodynamic products are similar, and they exhibit coordination between the 12 e(-) metal fragment [IrCp*](2+) and the terminal ring of the helicene. Monitoring the reaction by NMR shows formation of intermediates, some of which have been fully characterized in solution. These intermediates exhibit the metal fragment coordinated to the internal rings. We have also synthesized the bimetallic complex [(Cp*Ir)(2)(μ(2)-η(6):η(6)-2)][BF(4)](4) (7), achieving coordination between two units [IrCp*](2+) and the helicene 2. Following an analogous methodology, we have prepared the complex [(η(6)-cymene)Ru(η(6)-2)][BF(4)](2) (8), which has been studied by X-ray diffraction, confirming the preferential binding to the terminal aromatic ring. 相似文献
1000.
Basallote MG Fernández-Trujillo MJ Pino-Chamorro JÁ Beltrán TF Corao C Llusar R Sokolov M Vicent C 《Inorganic chemistry》2012,51(12):6794-6802
The [Mo(3)S(4)Cl(3)(dhprpe)(3)](+) (1(+)) cluster cation has been prepared by reaction between Mo(3)S(4)Cl(4)(PPh(3))(3) (solvent)(2) and the water-soluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1](2)[Mo(6)Cl(14)] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo(3)S(4)(dhprpe-H)(3)](+) (2(+)). A detailed study based on stopped-flow, (31)P{(1)H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid-base equilibria and the kinetics of interconversion between the 1(+) and the 2(+) forms. Both conversion of 1(+) to 2(+) and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride. 相似文献