Towards the development of sustainable π-Conjugated materials: Synthesis of new donor-acceptor systems based on extended benzodifuran derivatives

Date du colloque : 08/2012</p

Synthèse de nouveaux systèmes conjugués de types Donneur-Accepteur basés sur le motif benzodifurane

Date du colloque : 06/2011</p

3-Fluoro-4-hexylthiophene as a Building Block for Tuning the Electronic Properties of Conjugated Polythiophenes

3-Fluoro-4-hexylthiophene has been prepared by a synthetic route involving perbromination of 3-hexylthiophene followed by protection of the 2- and 5-positions of thiophene by trimethylsilyl groups and bromine/fluorine exchange. As expected, 3-hexyl-4-fluorothiophene oxidizes at a higher potential than 3-hexylthiophene; however, all attempts to electropolymerize this new thiophenic monomer have remained unsuccessful. Three terthienyls containing 3-hexylthiophene, 3-fluoro-4-hexylthiophene, and 3-bromo-4-hexylthiophene as the median group have been synthesized and used as substrates for electropolymerization. The electronic properties of the starting terthienyls and the resulting polymers have been analyzed by cyclic voltammetry and UV-vis spectroscopy, and the effects of substitution of the median thiophene ring are discussed

Extended benzodifuran – thiophene systems connected with azomethine junctions: Synthesis and electronic properties

The synthesis of extended benzodifuran – thiophene systems connected by azomethine junctions are described. The electronic properties of these systems, studied by UV-Vis spectroscopy and cyclic voltammetry, are discussed in relation with the electron withdrawing groups grafted on the benzodifuran unit and the electron donor ability of the thiophene moieties

Synthèse de nouveaux matériaux alternés Donneur-Accepteur conjugués pour l’électronique plastique

Date du colloque : 05/2013</p

Facile synthesis and optical properties of extended TPA-Benzodifuran derivatives connected by cyano-vinylene junctions

Two new conjugated molecules based on triphenylamine – benzo[1,2-b:4,5-b’]difuran moieties and integrating cyanovinyl bonds have been synthesized by using the new benzodifuran-acetonitrile synthon, easily and rapidly prepared in two steps from 2,2’-(2,5-dihydroxy-1,4-phenylene)diacetic acid. The electronic properties of the molecules were analysed by UV-Vis absorption and emission spectroscopies and cyclic voltammetry. The potential use of the molecules as donor materials for photovoltaic conversion were evaluated in simple bilayer solar cells using C60 as the acceptor materials. The comparison between the two derivatives reveals that the extension of the conjugated system with the insertion of furan cycles leads to a narrowing band gap, a better emission property, a direct access to dication state and an enhancement of the photovoltaic characteristics

Nouveaux dérivés du thiophène substitués sur les positions 3 et 4 par des groupements donneurs et accepteurs

Date du colloque : 05/2013</p

Synthesis via direct (hetero)arylation polymerization, electrochemical and optical properties of poly (3,4-disubstituted)thiophenes

Some poly (3,4-disubstituted)thiophenes bearing both cyano and alkoxy or thioalkoxy groups have been synthesized by direct (hetero)arylation polymerization (DHAP) of 2-iodo-3,4-disubstituted thiophenes. The electron donor and acceptor properties of substituents in positions 3 and 4 allow to adjust the HOMO and LUMO levels. On the other hand, in order to avoid the polymer solubility problems, long branched or unbranched alkyl chains have also been introduced. Thus polymers with alkoxy groups have led to complete absorption in the wavelength range of the visible spectrum whereas in the presence of thioalkoxy groups, the absorption of the visible spectrum is only partial. Theoretical calculations have shown that sulphur creates torsions leading to a non-planar polymer chain

Extended benzodifuran-furan derivatives as example of pi-conjugated materials obtained from sustainable approach

The synthesis of extended benzodifuran-furan systems are described as an example of pi-conjugated materials prepared by following a green approach with only water being produced as waste and using furan derivatives from renewable sources. Investigation of their optical and electrochemical properties shows that the new compounds present electronic properties compatible for application in organic electronics. (C) 2012 Elsevier Ltd. All rights reserved

How Much Do Benzodiazepines Matter for Electroconvulsive Therapy in Patients With Major Depression?

BACKGROUND: Electroconvulsive therapy (ECT) is one of the most effective treatments for major depressive disorder (MDD), especially in cases of treatment-resistant MDD. Because of their pharmacological profiles, benzodiazepines (BZDs) are suspected to decrease the efficacy of ECT. This study investigated the effect of BZDs on ECT-induced clinical outcomes and ECT course parameters in patients with MDD. METHOD: The impact of BZDs on severity of depression (Montgomery-Asberg Depression Rating Scale scores) and on ECT course parameters (seizure threshold, clinical and electroencephalographic seizure duration) was investigated in 70 patients with MDD who received an ECT course using dose-titration method (22 received concomitant BZDs). RESULTS: Lower remission rates (52.0%) and smaller decreases in Montgomery-Asberg Depression Rating Scale scores were observed in the non-BZD group than in the BZD group (81.2%, P = 0.02). There were no significant differences between the 2 groups regarding seizure duration and seizure threshold. LIMITATIONS: This was a retrospective study. Impact of BZDs on anxiety and cognition was not assessed. CONCLUSIONS: Benzodiazepines increased the clinical efficacy of ECT when delivered using dose-titration method and bitemporal stimulation. Further studied are needed to understand the interaction between BZDs and ECT on clinical outcomes