Photoinduced Electron Transfer and Charge Accumulation in Polyoxometalate-Based Donor-Acceptor Assemblies for Artificial Photosynthesis
supervised by Minh-Huong Ha-Thi et Thomas Pino
Polyoxometalates (POMs) are promising molecular electron reservoirs for artificial photosynthesis, but their weak visible-light absorption requires their combination with photoactive electron donors. This thesis investigates how donor-POM assemblies can be designed to promote photoinduced electron transfer, limit charge recombination, and enable multielectron storage. Three complementary strategies were explored: supramolecular assemblies based on tungsten clusters and POMs in water, covalently linked push-pull dye-POM hybrids, and visible-light-absorbing BODIPY-POM systems. Time-resolved spectroscopic studies showed that electron-transfer efficiency depends not only on redox potentials, but also on electrostatic interactions, molecular organization, linker coupling, solvent polarity, and proton availability. In particular, acid-assisted stabilization of Dawson POMs enabled the sequential accumulation of two electrons without an external sacrificial donor. Overall, this work establishes molecular design principles for converting light-induced charge separation into stable multielectron storage in POM-based systems.