Etude computationelle de système photochimique innovants (Elise Lognon/ LCPQ / Thèses) – 27/10/2022, 9H

Elise Lognon, LCPQ, seminary room, 3rd floor -3r1B4

Abstract:

One of the most exciting challenges in photochemistry is the development of smart multifunctional materials that can perform multiple functions under controlled conditions using light pulses. Photochromic molecules are increasingly used in the development of such innovative materials with applications in nanoscience, biology and as photonic devices. Among these systems, dimethyldihydropyrene (DHP) derivatives and ruthenium complexes with nitrosyl ligands (Ru-NO) have remarkable photochemical properties. Both systems can undergo photoisomerisation to their metacyclanediene (CPD) and isonitrosyl (Ru-ON) isomers, respectively. But they can also release biologically active molecules, singlet oxygen (1O2) for the DHP derivatives and nitrogen oxide (NO.) for the Ru-NO complexes. In order to study and rationalise these properties, advanced computational methodologies have been used to study the photoreactivity of these systems in their environment using static approaches. Among these methods, the application of spin-flip TD-DFT (SF-DFT) to the study of the photoisomerisation mechanism from DHP to CPD has been particularly relevant.  The validation of the SF-DFT method by high-performance benchmark calculations allowed the application of this method to substituted systems, thus allowing the rationalisation of the variation of the photoisomerisation yield. Concerning the metal complex molecules, the study of the absorption spectra of Ru-NO according to the nature of the counterion present in the system allowed to highlight the influence of the environment on the absorption properties but also to rationalise the variations of the photoisomerisation quantum yield of this system according to the counterion associated with the complex.