Alternatively linking fullerene and conjugated polymers

The stereo‐electronic control over bisadditions of conjugated polymers to fullerene (C₆₀) is explored in the formation of alternating copolymers. The chemistry, resulting configuration, and properties of poly(3‐hexylthiophene)‐alt‐C₆₀ copolymers prepared by either classic pyrrolidine ring formation or an atom transfer radical addition are compared. Both routes result in controlled additions of polymers to C₆₀. Extensive macromolecular modeling through PM6 methods indicate that there is no conjugation between P3HT and C₆₀ in the systems studied. This along with 2D‐NMR, AFM, and photovoltaic characterizations of the materials indicate the importance of the structure of the modified C₆₀ and the nature of the linking group between C₆₀ and P3HT segments in determining the morphology of the copolymers in the solid state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2304–2317, 2009     

An single program multiple data strategy for calculation of anharmonic vibrations

This paper presents a general perturbational and variational scheme to calculate solutions of the spectral problem for the vibrational molecular Hamiltonian. A parallel strategy in the ongoing development of our software P_Anhar is presented, in order to calculate the vibrational spectrum of medium sized molecules. The efficiency of this approach is checked on ethylene oxide.     

Hydrolysis-condensation reactions of titanium alkoxides in thin films: A study of the steric hindrance effect by X-ray photoelectron spectroscopy

An original approach based on X-ray photoelectron spectroscopy (XPS) is proposed to study the influence of the surrounding humidity on the hydrolysis-condensation reactions of five titanium alkoxides in thin films. More precisely, the influence of the nature of the ligands (propoxide, butoxide, isopropoxide, phenoxide, and 9H-carbazole-9-yl-ethyl-oxy) on the reaction rate was evidenced. The reaction advancement was evaluated by comparing XPS chemical compositions to theoretical compositions calculated for all the possible rates. XPS chemical environment information allowed validating the reliability of this approach through the evaluation of the condensation state. In both approaches, the influence of the steric hindrance on the reactivity of titanium alkoxides was highlighted to be similar to what has been previously observed in solution. Theses results corroborate the validity of our XPS approach to determine titanium alkoxide hydrolysis-condensation reactions in the specific application of thin films.     

Comparison of the safety profiles of PLA50 and Me.PEG-PLA50 nanoparticles after single dose intravenous administration to rat

We compared the safety profiles of two types of nanoparticles intravenously administered to rats, prepared from PLA₅₀ and Me.PEG-PLA₅₀ by emulsification/solvent evaporation using cholate as tensioactive agent. With PLA₅₀/Cholate nanoparticles, no signs of toxicity were noted at 75 mg kg⁻¹. At higher doses, 220 and 440 mg kg⁻¹, marked toxicity (mortality and marked clinical signs) was observed with dose-related hematological changes (decrease of thrombocytes count, increase of Prothrombine Time and Activated Partial Thromboplastin Time) and biochemical changes (increase of aminotransferases activities). All changes were transient and disappeared on Day 9. With Me.PEG-PLA₅₀/Cholate nanoparticles, no lethality and no clinical changes were observed after intravenous administration of Me.PEG-PLA₅₀/Cholate even at high dose, up to 440 mg kg⁻¹. The improved safety profile of Me.PEG-PLA₅₀/Cholate nanoparticles as compared to PLA₅₀/Cholate nanoparticles suggests that the steric repulsion owing to the high density of Me.PEG chains on the nanoparticles surface prevents the coagulation cascade and associated toxicity.     

Déformations covariantes sur les orbites polarisées d''un groupe de Lie

We prove the existence of covariant star-products on the orbits of the coadjoint representation of a Lie group which admits polarisations.