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1.
The direct aldol reaction of an α-alkyl-α-oxo aldehyde was catalyzed by trifluoromethyl-substituted diarylprolinol 1 to afford a γ-oxo-β-hydroxy-α-substituted aldehyde in good yield with excellent anti-selectivity and excellent enantioselectivity.  相似文献   

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Spin-crossover(SCO) complexes with multiple spin states are promising candidates for high-order magnetic storage and multiple switches. Here, by employing the N,N’-4-dipyridyloxalamide(dpo) ligand, we synthesize two Hofmann-type metal-organic frameworks(MOFs) [Fe(dpo){Ag(CN)2}2]·3DMF(1) and [Fe(dpo){Ag(CN)2}2]·0.5Me CN·2DEF(2), which exhibit guest dependent four-step SCO behaviors with the sequences of LS → ~LS2/3HS1/3→ LS1/2...  相似文献   

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Electropolymerization of O-Phenylenediamine in an Ionic Liquid   总被引:1,自引:0,他引:1  
Ionic liquid like 1-ethyl-3-methylimidazolium bromine ([EMIM]Br) has been used as electrolyte for the electropolymerization of O-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It is found that poly (O-phenylenediamine) film modified electrode has favorable electrochemical activity in acid solution.  相似文献   

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Herein is reported the synthesis, by a solid-state reaction from [Ir(NBD)(2)(P(i)Pr(3))][BAr(F)(4)], of the first example of a C-C σ-complex with iridium, [Ir(BINOR-S)(P(i)Pr(3))][BAr(F)(4)]. This compound is unique in that in the solid state it undergoes reversible activation of the C-C single bond that interacts with the metal center, establishing a temperature-dependent equilibrium between Ir(III) C-C σ/Ir(V) bis-alkyl complexes. This process has been interrogated by variable-temperature X-ray diffraction, NMR spectroscopy, and DFT calculations.  相似文献   

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Electrochemical Synthesis of Polythiophene in an Ionic Liquid   总被引:6,自引:0,他引:6  
Polythiophene(PTh) was prepared by the direct electrochemical synthesis in an ionic liquid ([BMIM]PF6) containing 0.1mol/L thiophene by cyclic voltammetry,constant potential and constant current techniques. It is found that smooth and blue-green PTh films can be obtained at a potential of ca. 1.75V(vs. Ag/AgCl) or a current of ca. 1.5mA cm^-2 in the ionic liquid.  相似文献   

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The derivation of the Hirshfeld atoms in molecules from information theory is clarified. The importance for chemistry of the concept of atoms in molecules (AIM) is stressed, and it is argued that this concept, while highly useful, constitutes a noumenon in the sense of Kant.  相似文献   

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Because atomic spectrometry inherently involves the decomposition of a sample into its constituent atoms, it inevitably destroys speciation information. Only by combining an atomic spectrometric method withan auxiliary, species-specific technique, or by modifying the ‘atomic’ spectrometer substantially, can speciation by ascertained. In this brief paper, three alternative approaches to speciation are outlined. Among them, the use of a switched or modulated source seems particularly appealing.  相似文献   

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A new analytical model is proposed to describe the kinetics of trapping and recombination of charge carriers in complex systems with an arbitrary spatial distribution of traps and recombination centres. The structural properties of a material are described by two functions Γm and Γn irrespective of the thermal history of the sample. A simple method is proposed to determine the function Γm from simultaneous thermoluminescence (TL) and thermally stimulated conductivity (TSC) measurements.  相似文献   

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Formaldehyde has been discussed as a typical indoor pollutant for decades. Legal requirements and ever‐lower limits for formaldehyde in indoor air have led to a continual reduction in the amount of formaldehyde released from furniture, building materials, and household products over many years. Slowly, and without much attention from research on indoor air, a change of paradigm is taking place, however. Today, the formaldehyde concentrations in outdoor air, particularly in polluted urban areas, sometimes already reach indoor levels. This is largely a result of photochemical processes and the use of biofuels. In the medium term, this development might have consequences for the way buildings are ventilated and lead to a change in the way we evaluate human exposure.  相似文献   

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Ohne ZusammenfassungErgebnisse der vorliegenden, im wesentlichen 1959–1960 ausgeführten Untersuchungen wurden bereits mitgeteilt beiO. Kratky, Makromol. Chem.35 A, 12 (1960); Angew. Chem.72, 474 (1960);H.-J. Bielig undH. Steiner, Dissertation H. Steiner, Univ. Freiburg i. Br. 1961.  相似文献   

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Methods of chemical kinetics have been used in a study of the mechanism of hydrogen sulfide oxidation by iodine. It has been shown that the stage of electron transfer from HS to the I 3 /– complex proceeds through a tunneling mechanism. A proposed twinkling model of the reaction mechanism provides an explanation for the observed experimental facts: the dependence of the rate constant on the acidity, viscosity, and ionic strength of the solution; the inverse temperature dependence of the reaction rate constant; the dependence of the reaction rate constant on the concentrations of iodide ion and maleic acid, which are not involved directly in the reaction.B. P. Konstantinov Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina 188350. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 522–536, March, 1992.  相似文献   

20.
 The present international definition of "traceability" is discussed and suggestions are made for a possible refinement of the definition.  相似文献   

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