Hybrid Organic-Inorganic Materials Based on Nanobuilding Blocks Assembled through Electrostatic Interactions

Hybrid copolymers have been prepared by free radical polymerization, in toluene, of methylacrylate (MA) and varying amounts of an organotin oxo-cluster functionalized with two acrylamido groups, {(BuSn)₁₂O₁₄(OH)₆}(AMPS)₂. The tin based nanobuilding block is fully preserved in the final materials. These copolymers formed networks where the cross-linking is based on the electrostatic interactions that take place between the macrocation {(BuSn)₁₂O₁₄(OH)₆}^{2 +} and its two functional anions (AMPS^–). Accordingly, these copolymers can yield gels or solutions depending on the solvent used to swell them.     

Ribbon tableaux, ribbon rigged configurations and Hall-Littlewood functions at roots of unity

Hall-Littlewood functions indexed by rectangular partitions, specialized at primitive roots of unity, can be expressed as plethysms. We propose a combinatorial proof of this formula using Schilling's bijection between ribbon tableaux and ribbon rigged configurations.     

A radial-partition fluoroimmunoassay for the detection of Hepatitis B surface antigen with the streptavidin/biotin complex

A sandwich technique based on the very affinity between avidin and biotin is used. Antibodies are covalently bound to glass-fibre on which the antigen is captured. The discs are then treated in sequence with monoclonal antibodies of high selectivity, species-specific anti-IgG (biotin-linked), streptavidin and β-galactosidase, (biotin-linked). The discs are then incubated with the substrate, 4-methylumbelliferyl-β-d-galactopyranoside and the fluorescence is measured in an automatic immunoassay system.     

Redox active electrolytes in carbon/carbon electrochemical capacitors

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Vacuum flash pyrolysis (VFP) of malonyl peroxides: decarboxylation versus decarbonylation of the intermediary α-lactones

Vacuum Flash Pyrolysis (VFP) at ca. 450–500°C and ca. 0.1–0.3 Torr of the spirocyclic malonyl peroxides ($\text{2a,b}$) affords high yields of allenes ($\text{5a,b}$), while the simple malonyl peroxide ($\text{2c}$) leads to ketone ($\text{4}$), derived respectively from decarboxylation and decarbonylation of the intermediary α-lactones ($\text{3}$).     

Anionic polymerization with alkaline earth counterion. III. Aging of oligo- and polystyryl-barium and -strontium in THF

The self-deactivation of polystyryl-barium and polystyryl-strontium in tetrahydrofuran (THF) results essentially from protonation by the solvent. The deactivation constant k_d of this reaction is independent of carbanion concentration, length, and functionality of chains. Relations of k_d with temperature are: polystyryl-barium: k_d = 6.25 × 10⁷ exp(-18,900/RT) sec^?1; polystyryl-strontium: k_d = 4.1 × 10⁶ exp(?16,000/RT) sec^?1. The self-deactivation of α,ω-dicarbanionic oligostyryl-barium is a nonrandomlike reaction. Residual living oligomers are left dicarbanionic even if an important deactivation occurs.     

Synthèse de molécules organométalliques possédant un manganèse chiral

Synthesis of diastereoisomeric manganese complexes is described, starting from LMn(CO)₃, carbonyl substitutions gave LMn(CO)(PPh₃)[P(OMe)₃] (L = h⁵-C₅H₃, 1-CO₂Me, 3-Me).     

Etude des volumes specifiques partiels de polystyrenes-modeles—Influence de la masse moleculaire et de la nature des groupements terminaux

It is well known that the apparent specific volume η₂ of a polymer may be expressed by the following relationship: $\text{η}{}_2\text{= η}{}_{\mathrm{m}}\text{+ K/}\text{M}{}_{\mathrm{n}}$ where M?_n is the number-average molecular weight of the polymer, η_m the specific volume of the infinite polymer, and K a constant. We have shown that this relationship is valid for low molecular weight polystyrenes ($\text{M}{}_{\mathrm{n}}\text{< 4·10}{}^4$) with different end-groups, independently of the nature of the solvent. The K values (and variations with the solvent and with the nature of the end-groups) may be predicted through simple calculations proposed here. We conclude that η_m does not represent the specific volume of the infinite polymer, since we observe a rapid decrease of η₂ for increasing M (when $\text{M}{}_{\mathrm{n}}\text{< 4·10}{}^4$). The decrease is much greater than expected from the relationship $\text{η}{}_2\text{= ? (1/}\text{M}\text{)}$.     

Analyse conformationnelle theorique des complexes acide-base de lewis: III. Une approche semi-empirique (méthode CNDO/2) des geométries et de l'analyse conformationnelle du borazane et de ses dérives perfluoré

The optimized geometries and theoretical data from conformational analysis cf borazane and its perfluoro derivatives are investigated within the framework of the CNDO/2 approximation. The effect that fluorination has on the geometrical and electronic parameters of the investigated series of compounds is pointed out and the authors offer an explanation for the anomalous behaviour of H₃N.BF₃. Furthermore, it is shown that the assumption of tetragonal hybridization for the N and B atoms of any borazane is incorrect if the F₃N molecule is used as the Lewis base.