A simple catalytic system based on PdCl2 and triphenylphosphine chalcogenides (PPh3X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine. 相似文献
Alkaline earth metal (Mg, Ca, Sr and Ba)-doped Mo-V-Sb-Ox catalysts, prepared by a dry-up method, have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions. The catalysts have been characterized by N2 adsorption-desorption, temperature-programmed desorption (TPD) of NH3, SEM and XRD. Influence of water vapor on the catalytic performance, particularly on the selectivities to acetic acid and acrylic acid, has also been studied. The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-Ox catalysts. The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals, which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid. The catalytic activity and product selectivities were found to be influenced by the reaction temperature, C3H8/O2 ratio and space velocity. A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane. 相似文献
Reactions of 6-(1′-phenylvinyl)-1,2,4-trioxanes 2-5, with FeCl2·4H2O, FeBr2, and a combination of hemin (bovine) and reduced glutathione (GSH) under various conditions have been studied. 相似文献
A novel rhodamine–tryptamine conjugate–based fluorescent and chromogenic chemosensor (RTS) for detection of Hg2+ present in water was reported. After gradual addition of Hg2+ in aqueous methanol solution of RTS, a strong orange fluorescence and deep-pink coloration were observed. The probe showed high selectivity towards Hg2+ compared to other competitive metal ions. The 1:1 binding stoichiometry between RTS and Hg2+ was established by Job’s plot analysis and mass spectroscopy. Initial studies showed that the synthesized probe RTS possessed fair non-toxicity and effectively passed through cell walls of model cell systems, viz., human neuroblastoma (SHSY5Y) cells and cervical cells (HeLa) to detect intercellular Hg2+ ions, signifying its utility in biological system. The limit of detection (LOD) was found to be 2.1 nM or 0.42 ppb by fluorescence titration. Additionally, the potential relevance of synthesized chemosensor for detecting Hg2+ ions in environmental water samples has been demonstrated.
An efficient new procedure for the degradation of cyclolaudenyl acetate to 3β - acetoxy - 4,4,14α -trimethyl - 9, 19 - cyclo - 5α - pregnan - 20 - one and/or 3β - acetoxy - 4,4,14α - trimethyl - 9,19 - cyclo - 5α -androstan - 17 - one is described. The key-step is simultaneous base-catalysed dehydrohalogenation and isomerisation of the resulting olefin, of a suitably derived halide. 相似文献
NAD(P)H:quinone acceptor oxidoreductase-1 (NQO1) is a ubiquitous flavin adenine dinucleotide-dependent flavoprotein that promotes obligatory two-electron reductions of quinones, quinonimines, nitroaromatics, and azo dyes. NQO1 is a multifunctional antioxidant enzyme whose expression and deletion are linked to reduced and increased oxidative stress susceptibilities. NQO1 acts as both a tumor suppressor and tumor promoter; thus, the inhibition of NQO1 results in less tumor burden. In addition, the high expression of NQO1 is associated with a shorter survival time of cancer patients. Inhibiting NQO1 also enables certain anticancer agents to evade the detoxification process. In this study, a series of phytobioactives were screened based on their chemical classes such as coumarins, flavonoids, and triterpenoids for their action on NQO1. The in silico evaluations were conducted using PyRx virtual screening tools, where the flavone compound, Orientin showed a better binding affinity score of −8.18 when compared with standard inhibitor Dicumarol with favorable ADME properties. An MD simulation study found that the Orientin binding to NQO1 away from the substrate-binding site induces a potential conformational change in the substrate-binding site, thereby inhibiting substrate accessibility towards the FAD-binding domain. Furthermore, with this computational approach we are offering a scope for validation of the new therapeutic components for their in vitro and in vivo efficacy against NQO1. 相似文献
Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a sheared nematogenic fluid. In a suitable parameter range, we find irregular, dynamic shear banding and establish by decisive numerical tests that the chaos we observe in the model is spatiotemporal in nature. 相似文献
We consider the melting of the vortex solid in highly anisotropic layered superconductors with a small concentration of random columnar pinning centers. Using large-scale numerical minimization of a free-energy functional, we find that melting of the low-temperature, nearly crystalline vortex solid (Bragg glass) into a vortex liquid occurs in two steps as the temperature increases: the Bragg glass and liquid phases are separated by an intermediate Bose glass phase. A suitably defined local melting temperature exhibits spatial variation similar to that observed in experiments. 相似文献
Stereospecific conversion of 9,19-cyclo-4,4,14α-trimethyl-3β-acetoxy-5α,9β-pregnan-20-one, readily accessible from cycloartenol/cyclolaudenol, into three closely related Buxus alkaloids—buxandonine, cyclo-protobuxine-F and cycloprotobuxine-A—is described. 相似文献