Search results for "yield"
showing 10 items of 1338 documents
About the reliability of the Maximum Entropy Method in reconstructing electron density: the case of MgO
2006
Abstract The reliability of the Maximum Entropy Method (MEM) to reconstruct finite temperature electron density (ED) is here discussed, investigating the case of periclase (MgO). A theoretical electron density has been generated by quantum mechanic calculations and folded with a function simulating atomic thermal motion, in order to produce a reference errorless ED [ρ(r)REF]. The Fourier coefficients of ρ(r)REF have been calculated, and used as “observed” diffraction intensities to reconstruct via MEM the original ED. The electron density attained by MEM [ρ(r)MEM] and ρ(r)REF have been compared with each other (pixel-by-pixel and critical points) to assess the ability of MEM to retrieve EDs…
Three‐Component Self‐Assembly Changes its Course: A Leap from Simple Polymers to 3D Networks of Spherical Host–Guest Assemblies
2021
Angewandte Chemie / International edition 60(21), 12132 - 12142 (2021). doi:10.1002/anie.202103178
Zinc Chalcogenide Seed-Mediated Synthesis of CdSe Nanocrystals: Nails, Chesses and Tetrahedrons
2015
Systematically shape-controlled synthesis of colloidal semiconductor nanocrystals (NCs) has attracted increasing attention recently for both fundamental and technological interest. The study on the synthesis of colloidal CdSe NCs has given rise to well-developed methods for producing diverse shapes such as rods, wires, cubs and discs. In the current study, we demonstrate the shape evolution of CdSe NCs by using a seed-mediated approach by control reaction temperature and injection methods. The synthesis utilizes small (2.0–3.0 nm) zinc chalcogenide NCs with zincblende structure as seeds for subsequent growth, which results in distinct shapes of nail-shaped, tetrahedron-shaped, chess piece-s…
Facile Large Scale Synthesis of WS2 Nanotubes from WO3 Nanorods Prepared by a Hydrothermal Route.
2005
Abstract Hexagonal WO 3 nanorods of 5–50 nm in diameter and 150–250 nm in length have been synthesised in gram quantities by a low temperature hydrothermal route using citric acid as a structural modifier and hexadecylamine as a templating agent. The ratio of [A]/[W] play an important role on WO 3 nanorods formation. These WO 3 nanorods were found highly suitable as a precursor for the synthesis of a good yield of multiwalled WS 2 nanotubes by reducing them with H 2 S at 840 °C for 30 min. The length and the wall thickness of the WS 2 nanotubes could be altered by controlled reduction of the oxide precursor. The morphology, structure and the composition of the WO 3 nanorods and WS 2 nanotub…
Coupling of Benzynezirconocene with 1,4-Diphenyl-1,3-butadiyne
2000
The thermolysis of diphenylzirconocene in the presence of 1,4-diphenyl-1,3-butadiyne to yield the seven-membered zirconacyclocumulene 1 via the intermediacy of benzynezirconocene is described. This complex has been characterized by an X-ray diffraction study. Additionally, better knowledge of the bonding of the cumulene moiety was achieved by DFT calculations. Cleavage of the Zr−C bonds of 1 with methanol provided the corresponding butatriene 2.
2-(4-Toluidino)pyrimidine
1984
Aus der Kondensation von 4-Tolylguanidin (1) mil den β-Diketonen 2a-g gehen die 2-(4-Toluidino)pyrimidine 3a-g hervor, unter denen sich Vertreter mit antidiabetischer und antimykotischer Wirksamkeit befinden. Antidiabetic Agents, II: 2-(4-Toluidino)pyrimidines Condensations of 4-tolylguanidine (1) with the β-diketones 2a-g yield the 2-(4-toluidino)pyrimidines 3a-g which comprise compounds exhibiting antidiabetic and antimycotic activities.
Versatile redox reactivity of triaryl-meso-substituted Ni(ii) porphyrin
2014
The electrochemical oxidation of nickel(II) 5,15-p-ditolyl-10-phenylporphyrin (1-Ni) leads to the formation of different coupling products, with the distribution depending on the nature of the solvent (CH2Cl2–CH3CN, CH2Cl2, DMF), the cell configuration (2 or 3 compartments) and the number of electrons abstracted. In a two compartment configuration (anode and cathode in the same compartment) in a CH2Cl2–CH3CN mixture, nickel(II) 5-chloro-10,20-p-ditolyl-15-phenylporphyrin (1-Ni-Cl) was isolated in good yield and its mechanism of formation is proposed. Switching to the three compartment configuration, the meso-β/meso-β doubly fused dimer (3-Ni) is detected as the major product whereas in pure…
Cycloaddition Reactions with Vinyl Heterocycles
1995
Publisher Summary The Diels-Alder reaction is one of the most common and elegant methods for the construction of six-membered rings. Although the number of Diels-Alder cycloadditions with open-chain and alicyclic dienes is very large, the number of examples with aromatic heterocyclic compounds is relatively small. The introduction of a vinyl group as a substituent onto a heterocycle increases the number of possible reactions. This new possibility, however attractive for synthetic purposes, is successful only with π-excessive five-membered heterocyclic derivatives with a few exceptions. The chapter discusses the reactions of vinyl heterocycles with carbodienophiles. The endocyclic and exo-en…
ChemInform Abstract: Synthesis and Chemical Reactivity of 5-Methoxy-2-vinyl-4-azaindoles.
2010
Abstract 2-Vinyl-4-azaindoles are less reactive with dienophiles than 2-vinylindoles. 5-Methoxy-2-vinyl-4-azaindole 2a and its 1-methyl derivative 2a reacts with N-phenylmaleimide to yield cycloadducts only under vigorous conditions. 2b produces a cycloadduct with dimethyl acetylenedicarboxylate, while 2a yields a Michael-type adduct. Reactions with more reactive dienophiles gave only polymeric products.
Synthesis and Chemical Reactivity of 5-Methoxy-2-vinyl-4-azaindoles
1997
Abstract 2-Vinyl-4-azaindoles are less reactive with dienophiles than 2-vinylindoles. 5-Methoxy-2-vinyl-4-azaindole 2a and its 1-methyl derivative 2a reacts with N-phenylmaleimide to yield cycloadducts only under vigorous conditions. 2b produces a cycloadduct with dimethyl acetylenedicarboxylate, while 2a yields a Michael-type adduct. Reactions with more reactive dienophiles gave only polymeric products.