Diarylprolinol in an asymmetric aldol reaction of an α-alkyl-α-oxo aldehyde as an electrophile

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.     

Four-step spin-crossover in an oxamide-decorated metal-organic framework

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 → ～LS_2/3HS_1/3→ LS_1/2...     

Electropolymerization of O-Phenylenediamine in an Ionic Liquid

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.     

C-C activation in the solid state in an organometallic σ-complex

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.     

Electrochemical Synthesis of Polythiophene in an Ionic Liquid

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.     

What is an atom in a molecule?

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.     

Der Gehalt an Trockenmasse in Citruss?ften

Ohne Zusammenfassung     

Speciation in atomic spectrometry—an oxymoron?

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.     

Recombination in complex systems – an analytical approach

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 Γ_m and Γ_n irrespective of the thermal history of the sample. A simple method is proposed to determine the function Γ_m from simultaneous thermoluminescence (TL) and thermally stimulated conductivity (TSC) measurements.     

Formaldehyde in the Ambient Atmosphere: From an Indoor Pollutant to an Outdoor Pollutant?

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.     

Den Gehalt an Stearopten in indischem Rosen?l

Ohne Zusammenfassung     

Den Gehalt an aktivem Chlor in Hypochloritl?sungen

Ohne Zusammenfassung     

Den Gehalt an phenolischen Hydroxylgruppen in Ligninpr?paraten

Ohne Zusammenfassung     

Den Gehalt an monomerem ?thylacrylat in ?thylacrylat-Caseingemischen

Ohne Zusammenfassung     

Tunneling transfer of an electron in oxidation of the HS− ion by an I 3 − complex in aqueous solution

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.     

Traceability in measurement – time for an update?

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

Multiphoton excitation of an ammonia molecule in laser fields

The multiphoton excitation of NH3 in laser fields is discussed using the second quantization and unitary transformations.The stretch-vibration energy spectrum obtained from an optimized Hamiltonian is in good agreement with that of experiments.The changes in transition probabilities with the frequencies of laser fields and the lime-dependent transition probabilities at a field intensity of 1.1×10-8 W/cm2 are presented.Finally,the energy absorption is calculated.     

Dielektrische Untersuchungen an Azetylzellulose in verschiedenen Lösungsmitteln

Zusammenfassung Es wird die spezifische Polarisation von Azetylzellulose in verschiedenen L?sungsmitteln bestimmt. Die Dichte wie der Brechungsindex ?ndern sich bis zu den h?chsten gemessenen Konzentrationen in allen untersuchten L?sungsmitteln linear. Die Dichte der Azetylzellulose ergibt sich bei Extrapolation auf 100 Proz. zu 1,30₁ der Brechungskoeffizient zu 1,48₅. Die Verfasser danken Herrn Prof. Wo. Ostwald für die Anregung zu vorliegender Arbeit sowie für sein Interesse bei der Durchführung der Versuche.