Ab-initio insight into the organic photochemical diversity: non-radiative decay in uracil and derivatives and intramolecular charge transfer mechanisms in the benzonitrile family

Identifier:  TDX:947

Handle: https://hdl.handle.net/20.500.11797/TDX947

Authors:  Yannick, Mercier

Abstract:
In this thesis, we studied two different types of photochemical reactions. On one hand, we determined non-radiative decay mechanisms for uracil molecule, which is part of the RNA. We then studied some derivatives of uracil (5-fluorouracil and 5- and 6-aminouracil) in order to explain their longer excited states lifetime relative to the parent system. It also allowed us to confirm our initial hypothesis. A second part of our work was about the Intramolecular Charge Transfer (ICT) in the benzonitrile family. Three derivatives of the DMABN have been studied: bicycle systems, 4F-DMABN and DTABN isomers. These systems allowed us to check both electronic and steric effects as well as to explain the mechanisms controlling the potential dual fluorescence and the emitting species. Our studies have been done using the CASSCF/CASPT2 method, with a good agreement with experimental results, which confirms the reliability of this method.