Etude théorique des processus de photoisomérisation faisant intervenir une intersection conique – ETPHOTOCI

This proposal of fundamental research in theoretical chemistry concerns the study of photochemical mechanisms in organic compounds. This proposal focuses on a particular class of photochemical reactions: cis-trans photoisomerisations following ? ? ?* excitation of polyenic bonds. Indeed, this type of photoinduced process is one of the most fundamental elementary acts of organic photochemistry. These reactions are well-known in organic photochemistry and photophysics (e.g., stilbene is a textbook example) and have been intensively studied for the past decades. However, they are not fully understood yet, even for something as simple as ethene. The importance of conjugated chromophores is not limited to organic photochemistry. Photobiological processes often involve efficient cis-trans photoisomerisations of localised chromophores that induce specific biochemical responses (e.g., retinal photoisomerisation in rhodopsin induces vision and proton pumping in bacteriorhodopsin). Consequently, there has been much fundamental and applied research on biomimetic organic materials and the potential application of their photochromic properties to the design of molecular switches or motors in nanosciences. The purpose of this proposal is the development of a general theoretical strategy for applying it to the study of such reactions.