Internal reference number 23/28-135
Start date 01/10/2023, end date : 30/09/2028
Photochemistry has found applications in many fields, such as photoredox catalysis, solar fuel production, or photodynamic therapy. These applications are mainly based on the use of a photosensitizer, the purpose of which is to store the energy contained in light in order to form a so-called "excited" species. Another species, called a quencher, is also necessary to react with the excited photosensitizer. This photoreaction starts with the formation of an "encounter complex", namely a geminate pair where the excited photosensitizer and the quencher are in close vicinity and intimately connected, all within a "cage" formed by solvent molecules. To date, there are no experimental means to probe this encounter complex, but it is generally accepted that its formation within a solvent cage is a pre-requisite for a photoreaction (i.e. a photoinduced electron transfer) to occur, generating a geminate radical pair (oxidized and reduced species). These radicals must escape the solvent cage to trigger subsequent reactions leading to the formation of the desired products.
To the best of our knowledge, there is no clear theory that allows to predict the efficiency with which these oxidized and reduced geminate species separate, yet it is of paramount importance for further improvement of light-driven applications as this process eventually leads to an effective photo-driven chemical reaction.
The UNCAGED consortium seeks to systematically study cage-escape yields through a combined experimental-theory approach and develop a robust framework for the understanding of geminate cage-escape yields. The research strategy will encompass a multi-faceted methodology involving (i) the synthesis of photosensitizers and quenchers, (ii) their photophysical and (spectro)electrochemical characterization, including short time-scale kinetics altering the cage escape process and (iii) the evaluation of the relative stability of the encounter complex, the geminate radical pair and the charge separated products through a multiscale computational approach.
UNCAGED is divided into two parallelly evolving work packages, i.e. Work Package A: Synthesis, Structural, Photophysical and (spectro)electrochemical characterization and Work Package B: Determination of Intrinsic and Extrinsic Parameters Influencing Cage Escape.
