Synthesis,characterization, and photovoltaic properties of dithienylbenzobisazole‐dithienylsilole copolymers

Three conjugated polymers comprised of dioctyl‐dithieno‐[2,3‐b:2',3'‐d]silole and a donor‐acceptor‐donor triad of either cis‐benzbisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole were synthesized via the Stille cross‐coupling reaction. The impact of varying the heteroatoms and/or the location within the benzobisazole moiety on the optical and electronic properties of the resulting polymers was evaluated via cyclic voltammetry and UV‐Visible spectroscopy. All of the polymers have similar optical band‐gaps of ～1.9 eV and highest occupied molecular orbital levels of ? 5.2 eV. However, the lowest unoccupied molecular orbitals (LUMO) ranged from ? 3.0 to ? 3.2 eV. Interestingly, when the polymers were used as donor materials in bulk‐heterojunction photovoltaic cells with PC₇₁BM as the electron‐acceptor, the benzobisoxazole‐based polymers gave slightly better results than the benzobisthiazole‐containing polymers with power conversion efficiencies up to 3.5%. These results indicate that benzobisoxazoles are promising materials for use in OPVs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1533–1540     

Novel method for preparation of cyclodextrin polymers: physico-chemical characterization and cytotoxicity

The objective of this work was to optimize the synthesis procedure of soluble cyclodextrin polymers developed by Weltrowski et al. The use of the parameters indicated by the latter in our laboratory led to a lower result, which did not exceed 15 % (w/w). The new method resulted simultaneously in two fractions, a water soluble one and an insoluble one with a yield of 40 and 85 % (w/w), respectively. Only soluble cyclodextrin polymers were characterized along with the cytotoxicity study. The optimized soluble polymers were characterized by Fourier-Transform Infrared Spectrophotometer, Thermogravimetric Analyzer, Differential Scanning Calorimetry, Powder X-Ray Diffraction Analysis and Size Exclusion Chromatography. In vitro cytotoxicity against peritoneal macrophage cells of female CD1 mice showed that soluble poly-α-CD and poly-γ-CD were less cytotoxic than soluble poly-β-CD at small dose and the opposite was true at higher dose. In conclusion, temperature and time could be used to optimize the yield of polymer cyclodextrins, which will have a broad use in the drug delivery system.     

Cyclosulfamides as Constraint Dipeptides: The Synthesis and Structure of Chiral Substituted 1,2,5-Thiadiazolidine 1,1-Dioxides: Evaluation of the Toxicity

A general synthesis for the preparation of chiral N-N′ substituted 1,2,5-thiadiazolidine 1,1-dioxides has been developed beginning with proteogenic amino acid, sulfuryl chloride, and dibromoethane. The selected chemistry and spectral properties of these compounds are examined. Overall, routes described are applicable to the synthesis of a variety of constrained dipeptidal sulfamides representing novel peptidomimetic scaffolds.     

Synthèse Et Cyclisation De Carboxylsulfamides Dérivés D'amines Et D'α-Hydroxyesters. Éavaluation De L'Activité Bactéeriostatique

Abstract

Les carboxylsulfamides sont obtenus à partir de l'isocyanate de chlorosulfonyle, d'amines primaires et d'α-hydroxyesters. Après réduction alcaline, ces carboxylsulfamides sont cyclisés dans les conditions de la réaction de Mitsunobu pour conduire aux N-sulfamoyloxazolidinones chides avec des rendements élevés.

The synthesis of carboxylsulfamides was carried out starting from chlorosulfonyl isocyanate, primary amines and α-hydroxyesters. After reduction, the carboxylsulfamides were cyclised under Mitsunobu conditions giving N-sulfamoyloxazolidinones in good yields.     

Stereoselective total synthesis of (+)-β-conhydrine from d-mannitol

An asymmetric synthesis of the piperidine alkaloid (+)-β-conhydrine has been developed starting from (R)-protected glyceraldehyde as the chiral precursor using Barbier allylation, azide nucleophilic substitution, and ring-closing metathesis as the key steps.     

Étude de la consistance d'un algorithme stochastique dans un cadre mélangeant

This Note is devoted to the study of the consistency of a stochastic algorithm having for object the estimates of a parameter under strong mixing assumption. To cite this article: A. Ait Saidi, A. Dahmani, C. R. Acad. Sci. Paris, Ser. I 340 (2005).     

Micropipette tips--the unsung heroes of mass spectrometry

Micropipette tip (tip) pipetting accuracy and precision are functions of tip manufacture consistency, morphological variation, and retained inner tip wall particulate matter. Irregular tip inner wall surfaces and retained particulate matter cause pipetting inaccuracy. Washed and unwashed tips from seven manufacturers were compared using weight by difference (six), microscopic Luxol Fast Blue staining (seven), and matrix-assisted laser desorption/onization time-of-flight (MALDI-TOF) mass spectrometry (six). Photomicrographs revealed tip irregularity and inner wall retained particulate matter. Computer model analysis was used to identify tip irregularity and retained matter. These tests established the utility of a pipette solvent wash to increase the performance and the accuracy of tips and, thus, improve the MALDI mass spectra obtained.     

Studies on condensation of chlorocarbonyl phenyl ketene with <Emphasis Type="Italic">N</Emphasis>-unsubstituted amides: synthesis of some new 1,3-oxazin-6-ones

A series of 1,3-oxazin-6-one derivatives has been synthesized upon treatment of N-unsubstituted amides with chlorocarbonyl phenyl ketene under reflux in toluene for several minutes. In this simple way, 2,5-disubstituted derivatives of 1,3-oxazin-6-ones have been obtained in high yields.