20 research outputs found

    Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients

    Get PDF

    Emission properties of diazines chromophores: Structure-properties relationship

    No full text
    International audienceThis article presents the photophysical properties of a series of diazine chromophores. The influence of five parameters has been studied: the presence of a diazine/benzodiazine fragment, the nature of the diazine fragment (1,3-diazine/1,4-diazine), the presence or not of an vinyl linker between diazine ring and phenylene fragments of the π-conjugated bridge, the presence of a phenylene/biphenylene linker and the nature of electron donating group (dimethylamino/diphenylamino). Taguchi's design of experiment combined with analysis of variance methodologies have been employed to highlight the main structural parameters influencing the position of absorption and emission maxima of dichloromethane solution and the extend of emission solvatochromic range exhibited by this family of chromophores. © 2017 Elsevier B.V

    Synthesis of new highly conjugated bis-(4H-pyrans) involving electron rich polyene linkage, by Pd degrees catalytic coupling of gamma-methylenepyran Fischer-type carbene complexes

    No full text
    International audienceSelf dimerisation of which lenepyran carbene complexes affords bis-pyrans containing electron rich polyene linkage. The cyclic voltammograms of these new donors show one two-electron oxidation wave low potential. (C) 2002 Elsevier Science Ltd. All rights reserved

    Reactivity of carbanions of Fischer-type carbene complexes with pyrylium salts. Synthesis and characterization of new gamma-methylenepyran carbene complexes via an addition-oxidation-deprotonation process

    No full text
    International audienceThe condensation reaction between gamma-unsubstituted pyrylium salts and carbanions of Fischer-type carbene complexes allowed the synthesis of new gamma-methylenepyran carbene complexes. NMR data, single crystal X-ray analysis, and DFT calculations suggest that these complexes have a partial pyrylium character due to the pi electron-accepting ability of the carbenic fragment and to the electron-releasing properties of the methylenepyran part. (C) 2002 Elsevier Science Ltd. All rights reserved

    Synthesis and properties of novel pyranylidene-based organic sensitizers for dye-sensitized solar cells

    No full text
    International audienceWe report herein the synthesis of nine new molecularly engineered metal-free organic pyranylidene-based dyes as efficient photosensitizers for Dye-Sensitized Solar Cells (DSSCs). Their photophysical, electrochemical, and photovoltaic properties were investigated, and their excited states have been modelled using Time-Dependent Density Functional Theory (TD-DFT). The investigation of the photovoltaic performances of this series of new dyes provided structure-property relationships where their Power Conversion Efficiencies (PCE) could be correlated to structural features, such as the length of the π-conjugated spacer and the nature of the substituents on the upper (positions 2 and 6) and lower parts (substituents on the exocyclic carbon) of the pyranylidene electron donor moiety. While these dyes fulfilled the criteria of efficient sensitizers for TiO2-based DSSCs, their photovoltaic performances were found to depend on the dye packing arrangements controlled by substituents on the pyranylidene group. The highest Power Conversion Efficiency of 5.52% was reached with the 20a dye containing phenyl substituent groups in both upper and lower parts of the pyranylidene fragment and with one thienyl π-conjugated spacer. © 2019 Elsevier Lt

    Photophysical properties of acid-responsive triphenylamine derivatives bearing pyridine fragments: Towards white light emission

    No full text
    International audienceThe synthesis, thermal, electrochemical, and optical properties of a series of triphenylamine derivatives bearing pyridine fragments and their trifluoroacetate salts are described. A dramatic increase in the intramolecular charge transfer is observed upon protonation, as evidenced by a significant reduction in the HOMO-LUMO gap and a red shift of both the absorption and the emission band. White photoluminescence was obtained in solution by the controlled protonation of blue emitting pyridine derivatives, which resulted in the yellow-orange emissive acidified form. In the solid state the emission color of doped polystyrene thin films could be tuned from steel blue to lawn green when the ratio of the protonated form was increased. These compounds have potential applications in the fabrication of multi-color OLEDs based on only one material. © 2017 Elsevier Lt
    corecore