A new synthesis of trifluorinated compounds via 1,1-dichloro-1-alkenes in superacid

A two step process for converting ketone or aldehyde via 1,1-dichloro-1-alkenes to the corresponding 1,1,1-trifluoroderivatives is described, based on HF addition and chlorine-fluorine exchange under superacidic conditions.     

Zinc porphyrin sensitized redox processes in microemulsions

Photoinduced electron transfer from Zn tetraphenylporphyrin to acceptors solubilized either in the lipid interior or aqueous bulk of anionic oil-in-water microemulsions has been investigated by nanosecond laser photolysis. While intimate cosolubilization appears to decrease the efficiency of electron transfer in the former, enhanced charge separation of the redox products has been observed in the latter.     

Hydroxylation de l''estrone et de son acétate par le peroxyde d''hydrogéne en milieu superacide

Estrone 1a and its acetate 1b react with hydrogen peroxide in SbF₅-HF to give hydroxylated compounds. The formation of the dienone 2 can be accounted for by reaction of the electrophile H₃O₂⁺ on the neutral substrate, whereas formation of compound 3b implies electrophilic attack on the protonated ester 1b. Higher acidity favours rearrangement of the resulting ion 9 to yield, through a spiro intermediate, the ester 4b. Under the reaction conditions esters 3b and 4b]are slowly converted into the corresponding phenols 3a and 4a.     

Dérivés Alléniques du Phosphore. Influence de l'État de Coordination du Phosphore et de la Nature des Radicaux Liés au Phosphore sur les Signes de J(P?H)

The signs of the phosphorus-proton coupling constants in various allenic organophosphorus compounds have been determined by either analysis of the AB₂X spectra or double resonance. Probable absolute signs have been obtained by taking ³J(P? H) as positive. In allenic phosphine oxides, the following signs are obtained: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve, ⁵J(P? H) +ve and the ⁴J(P? H) coupling constant varies mostly with the inductive effect of the substituents bound to the phosphorus atom. In allenic phosphines, these sings are: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve and +ve and the ⁴J(P? H) coupling constant varies with both the inductive and resonance effects to the substituents. This coupling constant is negative except when the phosphorus atom is bound to groups which are electron-donating by resonance effects. These results are discussed in relation to the pπ? dπ bonding in phosphine.     

Dependence of the localized surface plasmon resonance of noble metal quasispherical nanoparticles on their crystallinity-related morphologies

The absorption spectra of 5 nm noble metal nanoparticles (Ag, Au, and Cu) with typical morphologies of multiply twinned particles (MTPs) and single crystals are calculated by using the discrete dipole approximation method. Among the considered morphologies, it is found that icosahedral, cuboctahedral and truncated octahedral particles behave like quasispherical particles whereas the optical response of the decahedral particles significantly differs from the others. This result, which originates from the shape anisotropy of the decahedron, points out the capacity to discriminate decahedral MTPs from a population of particles with mixed crystallinities and related quasispherical shapes.     

2D silver nanocrystal ordering modulated by various substrates and revealed using oxygen plasma treatment

Here, 5 nm Ag nanocrystals are deposited, using the same procedure, on various substrates differing by their rms roughness, wetting properties and nanoparticle-substrate interactions leading, consequently, to different nanocrystal orderings. Theoretical calculations are carried out to understand how these parameters influence the size of the nanocrystal organizations on the substrate surface. When these nanocrystal arrays are subjected to an oxygen plasma treatment, the nanocrystals perfectly assembled in hexagonal networks remain intact, while the nanocrystals that are not well-packed coalesce to form larger particles independently on the used substrate. This phenomenon is observed on the entire substrate surface. This procedure gives an innovative way of using oxygen plasma generated by the reactive ion etching technique, as a new method to reveal defects in 2D Ag nanocrystal self-assemblies.     

LIGHT-DRIVEN REDOX PROCESSES IN FUNCTIONAL MICELLAR UNITS—III. Zn-TETRAPHENYLPORPHYRIN SENSITIZED REACTIONS IN METHYL VIOLOGENE SURFACTANT ASSEMBLIES

Abstract— The photoreduction of methyl viologene by ZnTPP triplet excited states was studied in mixed micelles containing the functional surfactant JV-dodecyl, N -methyl viologene (C₁₂MV²⁺) as one and Cetyltrimethylammoniumchloride (CTAC) as the other component. Using the laser photolysis technique the kinetics of the redox reaction were studied at various CTAC/C₁₂MV²⁺ ratios. The average time for the electron transfer decreases linearly with the C₁₂MV²⁺ occupancy. The back transfer from C₁₂MV²⁺ to ZnTPP²⁺ can be intercepted if a donor such as NADH is cosolubilized in the micelle. In such a system irreversible methyl viologene reduction is achieved which in the presence of a suitable redox catalyst can be used to produce hydrogen from water.