Photoinduced electron transfer and charge transfer have a great importance in nature since they govern photosynthesis in plants and bacteria and are the driving mechanisms of basic processes at the boundary between quantum effects and molecular dynamics. The combination of synchrotron spectroscopies, ultrafast XUV pump- IR probe experiments and many-body quantum chemistry calculations has allowed to study in details the first steps of charge-transfer processes initiated by prompt ionization in nitroanilines,a prototype donor–π–acceptor molecules.
The theoretical and experimental results published in Nature Chemistry showed that in the prototype molecule of nitroaniline the charge transfer from the lone-pair orbital of the NH₂ group to the C-N bonding occurs in 10fs and is driven by the planarization of the same NH₂ group. The dynamics of the process is driven by the coupled electronic-nuclear motion generated by an ultra-short pulse lasting a few attoseconds in the molecular cation, in which the electronic charges are redistributed according to the nuclear rearrangements.
In addition to contributing to a better understanding of the qualitative concepts used to predict charge migration in organic molecules, this work offers a perspective for engineering the chemical and structural properties of these molecules to control and optimize the charge transfer.
The implications span from photosynthesis in plants and bacteria, to the response of photovoltaic devices and to electronic transport in single-molecule devices.