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21.
Rekulapally Sriram Chebolu Naga Sesha Sai Pavan Kumar Nerella Raghunandan Vadla Ramesh 《合成通讯》2013,43(23):3419-3428
Abstract A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO2) with the aid of Lewis acid catalyst aluminium chloride (AlCl3) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol. 相似文献
22.
Bhakta RK Maharrey S Stavila V Highley A Alam T Majzoub E Allendorf M 《Physical chemistry chemical physics : PCCP》2012,14(22):8160-8169
Reactive nanoparticles are of great interest for applications ranging from catalysis to energy storage. However, efforts to relate cluster size to thermodynamic stability and chemical reactivity are hampered by broad pore size distributions and poorly characterized chemical environments in many microporous templates. Metal hydrides are an important example of this problem. Theoretical calculations suggest that reducing their critical dimension to the nanoscale can in some cases considerably destabilize these materials and there is clear experimental evidence for accelerated kinetics, making hydrogen storage applications more attractive in some cases. However, quantitative measurements establishing the influence of size on thermodynamics are lacking, primarily because carbon aerogels often used as supports provide inadequate control over size and pore chemistry. Here, we employ the nanoporous metal-organic framework (MOF) Cu-BTC (also known as HKUST-1) as a template to synthesize and confine the complex hydride NaAlH(4). The well-defined crystalline structure and monodisperse pore dimensions of this MOF allow detailed, quantitative probing of the thermodynamics and kinetics of H(2) desorption from 1-nm NaAlH(4) clusters (NaAlH(4)@Cu-BTC) without the ambiguity associated with amorphous templates. Hydrogen evolution rates were measured as a function of time and temperature using the Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry method, in which sample mass changes are correlated with a complete analysis of evolved gases. NaAlH(4)@Cu-BTC undergoes a single-step dehydrogenation reaction in which the Na(3)AlH(6) intermediate formed during decomposition of the bulk hydride is not observed. Comparison of the thermodynamically controlled quasi-equilibrium reaction pathways in the bulk and nanoscale materials shows that the nanoclusters are slightly stabilized by confinement, having an H(2) desorption enthalpy that is 7 kJ (mol H(2))(-1) higher than the bulk material. In addition, the activation energy for desorption is only 53 kJ (mol H(2))(-1), more than 60 kJ (mol H(2))(-1) lower than the bulk. When combined with first-principles calculations of cluster thermodynamics, these data suggest that although interactions with the pore walls play a role in stabilizing these particles, size exerts the greater influence on the thermodynamics and reaction rates. 相似文献
23.
[reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion. 相似文献
24.
Mazzotti FJ Raghunandan R Esmail AM Tulej M Maier JP 《The Journal of chemical physics》2011,134(16):164303
The B(2)Π-X(2)Σ(+) electronic spectrum of C(4)H has been studied by degenerate and double resonance four-wave mixing. The technique identifies vibrational levels in the X(2)Σ(+) ground state. Its sensitivity and unique characteristics permit detection of new levels. The A(2)Π state lying 222 cm(-1) above the X(2)Σ ground state is also observed, confirming the analysis from anion photoelectron spectroscopy but with improved accuracy. Vibrational level determination in the A(2)Π electronic manifold up to 700 cm(-1) above v = 0 is made. A Renner-Teller analysis is carried out for the two lowest bending modes v(6) and v(7) in the A(2)Π state by diagonalization of the effective Hamiltonian matrix. The Renner-Teller parameters ∈(6), ∈(7), and ∈(67), the vibrations ω(6) and ω(7) and the spin-orbit coupling constant A(so) are determined. 相似文献
25.
Deshpande Raghunandan Bedre D. Mahesh S. Basavaraja S. D. Balaji S. Y. Manjunath A. Venkataraman 《Journal of nanoparticle research》2011,13(5):2021-2028
Our research interest centers on microwave-assisted rapid extracellular synthesis of bio-functionalized silver nanoparticles
of 26 ± 5 nm from guava (Psidium guajava) leaf extract with control over dimension and composition. The reaction occurs very rapidly as the formation of spherical
nanoparticles almost completed within 90 s. The probable pathway of the biosynthesis is suggested. Appearance, crystalline
nature, size and shape of nanoparticles are understood by UV–vis (UV–vis spectroscopy), FTIR (fourier transform infrared spectroscopy),
XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and TEM (transmission electron microscopy) techniques.
Microwave-assisted route is selected for the synthesis of silver nanoparticles to carry out the reaction fast, suppress the
enzymatic action and to keep the process environmentally clean and green. 相似文献
26.
Hari Babu Bollikolla Tyagi Ranjini Gokada Maheswara Rao Anandam Rambabu Kasthuri Jyothi K Vijaya Durga T Alam M. Mujahid Mannam Krishna Murthy 《Moscow University Chemistry Bulletin》2022,77(5):269-285
Moscow University Chemistry Bulletin - Flavonoids are polyphenolic compounds having benzo-?-pyrone structures, which are majorly available in plants. Several flavonoids have been reported,... 相似文献
27.
Ghose S Krisch M Oganov AR Beraud A Bosak A Gulve R Seelaboyina R Yang H Saxena SK 《Physical review letters》2006,96(3):035507
The longitudinal acoustic and optical phonon branches along the Gamma-X direction of MgO at 35 GPa have been determined by inelastic x-ray scattering using synchrotron radiation and a diamond-anvil cell. The experimentally observed phonon branches are in remarkable agreement with ab initio lattice dynamics results. The derived thermodynamic properties, such as the specific heat CV and the entropy S are in very good accord with values obtained from a thermodynamically assessed data set involving measured data on molar volume, heat capacity at constant pressure, bulk modulus and thermal expansion. 相似文献
28.
A Multifunctional Subphthalocyanine Nanosphere for Targeting,Labeling, and Killing of Antibiotic‐Resistant Bacteria 下载免费PDF全文
Indranil Roy Dr. Dinesh Shetty Dr. Raghunandan Hota Dr. Kangkyun Baek Jeesu Kim Prof. Dr. Chulhong Kim Sandro Kappert Prof. Dr. Kimoon Kim 《Angewandte Chemie (International ed. in English)》2015,54(50):15152-15155
Developing a material that can combat antibiotic‐resistant bacteria, a major global health threat, is an urgent requirement. To tackle this challenge, we synthesized a multifunctional subphthalocyanine (SubPc) polymer nanosphere that has the ability to target, label, and photoinactivate antibiotic‐resistant bacteria in a single treatment with more than 99 % efficiency, even with a dose as low as 4.2 J cm?2 and a loading concentration of 10 nM . The positively charged nanosphere shell composed of covalently linked SubPc units can increase the local concentration of photosensitizers at therapeutic sites. The nanosphere shows superior performance compared to corresponding monomers presumably because of their enhanced water dispersibility, higher efficiency of singlet‐oxygen generation, and phototoxicity. In addition, this material is useful in fluorescence labeling of living cells and shows promise in photoacoustic imaging of bacteria in vivo. 相似文献
29.
Baunemann A Hellwig M Varade A Bhakta RK Winter M Shivashankar SA Fischer RA Devi A 《Dalton transactions (Cambridge, England : 2003)》2006,(28):3485-3490
Novel mixed amido-malonato complexes of titanium are reported. The complexes were synthesized by partially replacing the amido groups from the complexes [Ti(NMe2)4] and [Ti(NEt2)4] via Br?nstedt acid/base reactions, using the malonate-ligands di-isopropylmalonate (Hdpml) and di-tert-butylmalonate (Hdbml). Four representative complexes were synthesized and fully characterised by 1H NMR, 13C NMR, CHN analysis and mass spectrometry. The crystal structures of the six-coordinated complexes [Ti(NMe2)2(dbml)2] (3) and [Ti(NEt2)2(dbml)2] (4) are presented and discussed. The complexes are solids and the chemical and thermal characteristics of the complexes strongly depend on the substitution at the malonate ligand. While dpml containing complexes show a promising behaviour for classical MOCVD, dbml containing complexes seem to be more suitable for liquid injection-metal-organic chemical vapour deposition (LI-MOCVD). Based on its thermal characteristics, the most promising complex for thermal CVD, [Ti(NEt2)2(dpml)2] (2) was selected for preliminary MOCVD experiments, which indicate a good suitability for the deposition of TiO2 thin films. 相似文献
30.
The near orifice spray breakup at low GLR (gas to liquid ratio by mass) values in an effervescent atomizer is studied experimentally
using water as a simulant and air as atomizing gas. From the visualizations, the near orifice spray structures are classified
into three modes: discrete bubble explosions, continuous bubble explosions and annular conical spray. The breakup of the spray
is quantified in terms of the mean bubble bursting distance from the orifice. The parametric study indicates that the mean
bubble bursting distance mainly depends on airflow rate, jet diameter and mixture velocity. It is also observed that the jet
diameter has a dominant effect on the bubble bursting distance when compared to mixture velocity at a given airflow rate.
The mean bubble bursting distance is shown to be governed by a nondimensional two-phase flow number consisting of all the
aforementioned parameters. The location of bubble bursting is found to be highly unsteady spatially, which is influenced by
flow dynamics inside the injector. It is proposed that this unsteadiness in jet breakup length is a consequence of varying
degree of bubble expansion caused due to the intermittent occurrence of single phase and two-phase flow inside the orifice. 相似文献