Institut des Sciences Chimiques de Rennes
UMR 6226 CNRS - Université Rennes 1
IUT de Lannion
Rue E. Branly. BP30219
22302 Lannion Cedex - France
Phone : 33 (0) 2 96 46 94 48
My first research topic concerns the synthesis and study of photophysical properties of diazine-based fluorophores. During the past decade, we have synthesized a large library of π-conjugated diazine oligomers (more than 250 chromophores) thanks to palladium catalyzed cross-coupling reactions and condensation reactions. When substituted by electron-donating fragments via π-conjugated linkers, these compounds are highly fluorescent and have found applications as fluorescent sensors. Indeed, the particularity of these fluorophores is their high sensibility to external stimuli. For example some of our compounds exhibit very important emission solvatochromism with application as polarity sensors. Our diazine chromophores exhibit acidochromism and can be used as pH sensors. Other sensors (metal cations, DNA, nitroaromatic based explosives...) have been also developped.
Recently we have focossed our attention to white light emission in the objective to fabrication White Organic Light Emitting Diodes (WOLEDs). Approaches to obtain WOLEDs still require complex processes that lead to high costs. In this sense, the use of a single emitting material that can take two forms of complementary emitting colors has emerged as a new strategy for the fabrication of WOLEDs. We have developped some chromophores that emit blue light in their neutral form and orange/red light in their protonated form. A mixture of the forms in the correct propoprtion permit to obtain whilte light emission eitheir in solution and in thin film.
My second research topic concerns the design of new non-linear optical (NLO) chromophores based on diazine and/or pyranylidene heterocyclic fragments.
One part of our project is focused on second order NLO chromophores. Starting from preliminary results obtained with aminostyryldiazine chromophores, we have studied the influence of various parameters on the NLO response: the replacement of amino electron donating group by proaromatic pyranylidene fragments, the strenghthening of electron-withdrawing ability of diazine moity by complexation or methylation and the optimization of the π-conjugated core. Current attention concern the incorporation of metallic center into the π-conjugated core.
We have also developed two-photon absorption (TPA) chromophores. In particular, novel triphenylamine–pyrimidine alternated oligomers have been designed and exhibit cross section with a δMAX of 5093 GM at 800 nm. This very high 2PA ability has been oriented to improve the two-photon induced polymerization efficiency of a bicomponent photoinitiator system. We currently focus our attention on designing drug delivery
systems (DDS) demonstrating high uncaging efficiencies upon two-photon (TP) excitation using near-infrared light.