Phosphahelicenes: From Chiroptical and Photophysical Properties to OLED Applications

Herein, the experimental physicochemical and chiroptical properties of a series of phosphahelicenes are reported, focusing on their UV/Vis absorption, luminescence, electronic circular dichroism, optical rotations, and circularly polarized luminescence. Furthermore, detailed analysis of absorption and ECD spectra performed with the help of quantum-chemical calculations allowed us to highlight general features of these helicenic phosphines. Finally, due to well-suited electrochemical properties and thermal stability, the systems were successfully used as emitters in organic light-emitting diodes.     

Analysis of underivatized cellodextrin oligosaccharides by capillary electrophoresis with direct photochemically induced UV‐detection

This work focuses on the development of a CE method allowing, for the first time, the simultaneous separation of the underivatized first seven cellodextrin oligomers (glucose, cellobiose, cellotriose, cellotetraose, cellopentaose, cellohexaose, and celloheptaose), with a view to analyze the hydrolysates obtained after partial acid depolymerization of nitrocellulose, and eight carbohydrates (ribose, xylose, fructose, mannose, galactose, maltose, lactose, and sucrose), which might be potential interfering compounds in explosives samples. Separation was achieved with a highly alkaline BGE containing sodium chloride and direct mid‐UV‐absorbance detection was performed after photo‐oxidation in the detection window. EOF was reversed to speed up the analysis using a dynamic capillary coating by hexadimethrine bromide. A central composite design was carried out to determine the effects of BGE conductivity and sodium hydroxide concentration on resolutions between neighboring peaks, and analysis time. A desirability analysis on modeled responses was applied to maximize resolutions and to minimize analysis time. The simultaneous analysis in 20 min total runtime of the 15 carbohydrates plus internal reference (naphthalene sulfonate) was carried out at 25°C with a BGE composed of 77.4 mM NaOH and 183 mM NaCl to adjust the conductivity at the optimum value. Finally, the resolution robustness was checked. This new method should also be of interest to monitor food and nonfood crop products.     

N = 14 shell closure in 22O viewed through a neutron sensitive probe

To investigate the behavior of the N = 14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2(1)+ inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured using the MUr à STrip detector array at the Grand Accélérateur National d'Ions Lourds facility. A deformation parameter beta(p,p') = 0.26 +/- 0.04 is obtained for the 2(1)+ state, much lower than in 20O, showing a weak neutron contribution to this state. A microscopic analysis was performed using matter and transition densities generated by continuum Skyrme-Hartree-Fock-Bogoliubov and quasiparticle random phase approximation calculations, respectively. The ratio of neutron to proton contributions to the 2(1)+ state is found close to the N/Z ratio, demonstrating a strong N = 14 shell closure in the vicinity of the neutron drip line.     

Probing the transition in bulk Ce under pressure: a direct investigation by resonant inelastic X-ray scattering

We report on the most complete investigation to date of the -electron properties at the transition in elemental Ce by resonant inelastic x-ray scattering (RIXS). The Ce 2p3d-RIXS spectra were measured directly in the bulk material as a function of pressure through the transition. The spectra were simulated within the Anderson impurity model. The occupation number n(f) and f double occupancy were derived from the calculations in both gamma and alpha phases in the ground state. We find that the electronic structure changes result mainly from band formation of 4f electrons which concurs with reduced electron correlation and increased Kondo screening at high pressure.     

Tautoméric entre structures α-aleoxy énaminocétone et β-céto iminoéther présentée par les pipéridéines résultant de la semihydrogénation d'alcoxy-2 acyl-3 pyridines

The palladium or platinium-catalyzed partial hydrogenation of some 2-alkoxy-3-acylpyridines has been performed in order to study the tautomerism of the resulting tetrahydropyridines. Reduction of the pyridine ring to tetrahydropyridine occurs selectively for the bicyclic compounds 2 and 3, while predominant reduction of the keto group takes place in the case of the derivative 1 carrying the acyl group in an open chain; this different behaviour towards partial hydrogenation is tentatively explained as a consequence of “I-strain” effect. Whereas the bicyclotetrahydropyridine 6 and 7 present exclusively an α-alkoxy enaminoketone structure, the open chain substituted tetrahydro-pyridine 5 exists only as a β-keto iminoether as shown by ir and proton nmr studies. Total displacement of tautomerism towards one of these two structures is interpreted as the result of the unfavourable interaction of nitrogen and oxygen lone pairs which would occur in a bicyclic iminoether, as compared to the stabilizing interaction of an oxygen lone pair and the N-H bond of the enaminoketone structure, which can be realized without increase of steric crowding in the bicyclic case.     

C60 2- chemistry: C60 adducts bearing two ester,carbonyl, or alcohol groups

Reactions of activated halo compounds XCH(2)-A (X = Br, I; A = ester, ketone) with C(60)(2-) anion give rise to C(60)(CH(2)-A)(2) adducts (major products) along with unexpected methanofullerenes C(60)>CH-A and monosubstituted dihydrofullerenes C(60)(H)(CH(2)-A) (minor products). Methanofullerenes are shown to come from side reactions with X(2)CH-A traces. [reaction: see text]     

Simultaneous capillary electrophoretic analysis of inorganic anions and cations in post‐blast extracts of acid–aluminum mixtures

Bursts resulting from the chemical reaction between hydrochloric or nitric acid with aluminum foils are very often committed by the young delinquency in western countries because of its easiness of achievement. A fast, simple, selective, and cost‐effective method allowing the simultaneous detection of chloride and nitrate anions and aluminum(III) was thus required. This article focused on the development and validation of a CE method using a BGE containing 2,6‐pyridinedicarboxylic acid (PDC) acting as both an anionic chromophore and as an aluminum(III) complexing agent. First, the achievement of the speciation diagram of Al(III) in the presence of PDC allowed the choice of pH conditions for which aluminum(III) was globally anionic. The study of the selectivity for Al(III) in the presence of ten other cationic species potentially present in post‐blast residues dictated the choice of the PDC concentration at 20 mM. The validation step next demonstrated the figures of merit of the method, with an intermediate precision for Al(III) of 2% on normalized migration times and 3.5% on corrected areas. Finally, this method was used for analyses of real post‐blast extracts from acid–aluminum mixtures.     

Multifunctional,water‐soluble,C60‐pendant maleic anhydride copolymer

Starting from the synthesis of a new methanofullerene derivative bearing an alcohol group, we report on the preparation of a water‐soluble, fullerene‐pendant copolymer. This multifunctional, C₆₀‐pendant maleic anhydride copolymer was characterized by conductometric titration, Fourier transform infrared and ultraviolet spectroscopy, thermogravimetric analysis, and cyclic voltammetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5814–5822, 2005     

Traceability of absorbed dose in photon radiation therapy: from primary standard to patient treatment

The relevant standard quantity for radiation therapy is the absorbed dose to water. This quantity refers to the amount of energy locally absorbed in a small volume of water divided by the mass of this volume. The aim of this paper is to present a short overview on the establishment of traceability to national standards of absorbed doses delivered to patients in radiation therapy. The approach used at LNE-LNHB, the French national metrology laboratory for ionizing radiation, to determine the reference value of absorbed dose to water is presented and the chain of traceability from the reference value to the treatment of the patient is described.