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Place Amphi Dorothy Hodgkin
Title
Synthesis and studies of negative photochromic molecules
Abstract
Photochromic organic molecules, i.e. whose coloring is modified under the effect of light, are attractive for the development of innovative optical materials. This thesis project proposes to design and study two new families of negative photochromic molecules: Donor Acceptor Stenhouse Adducts (DASA) and Nitrile Rich Acceptors (NRA).
After a bibliographic study on the main negative photochromic families, five DASA molecules could be synthesized. Their photochromic properties depend on the solvent, but also on the generation of the DASA considered. The photokinetics of two of these molecules, one of the 1st generation and one of the 2nd generation, were analyzed in order to quantify their photochromic parameters (kinetic constants, quantum yields). Subsequently, eight NRA molecules were synthesized and studied by spectroscopy. The photochromic of four NRA showed clear variations depending on the solvent, the acidity of the medium, the concentration of the solution and the temperature. Theoretical studies (geometry optimization, electronic transitions, pKa calculation) have been carried out on this family in order to better understand the previous observations. Finally, a more detailed analysis of the cyclization mechanism was undertaken for one of the NRA through the study of different isomers and conformers, activation barriers, as well as nanosecond transient absorption spectroscopy experiments. This thesis project has therefore made it possible, thanks to detailed studies of negative photochromic molecules, to understand their use for materials with innovative optical properties. Studies in a polymer matrix could be a new step towards the establishment of such materials.
Composition of the jury: