November 21, 2022
11:00
Louvain-La-Neuve
Auditoire CARNOY
Making the Most of Photons: Controlling Excited-State Reactivity Towards More Efficient Energy Conversion
ABSTRACT:
Solar energy represents a promising renewable energy source. In natural and artificial photosynthesis, light absorption and catalysis are separate processes linked together by exergonic electron transfer. This leads to free energy loss between the initial excited state, formed after light absorption, and the catalytic center formed after the electron transfer cascade. Additional deleterious processes, such as internal conversion and vibrational relaxation, can also initially dissipate as much as 20-30 % of the absorbed photon energy.
Two main research topics will be presented. The first one deals with the development of strategies that minimize these energy losses processes. In binuclear complexes, a novel strategy allowed to trap a higher energy excited state, before internal conversion and vibrational relaxation, saving between 110 and 170 meV and leads in fine to 140 meV more potent reductant for catalysis. This approach represents a novel strategy on how excess energy can be harnessed in bimolecular electron transfer reactions, to generate more potent reductants useful for energy conversion schemes and solar fuels production.
The second project is related to mechanistic photoredox catalysis. There is a plethora of organic transformations that can be sensitized to visible light, but the corresponding reaction mechanisms are not always straightforward. Here, we will present recent advances in the field of mechanistic photoredox catalysis by means of steady-state and time-resolved spectroscopies using a series of organic and inorganic photosensitizers.