Modelling of photochemical water splitting based on charge accumulation in macrocycles

Photochemical water splitting using homogeneous catalysts provides a conceptually simple and promising route towards sustainable hydrogen production. At the heart of this processes lies a molecular photosensitizer along with a catalyst. Whereas such photoredox catalytic systems are well-established in other areas of synthetic chemistry, it is a particular challenge that photocatalytic water splitting requires a multielectron process where several electrons are accumulated in one molecular unit.
A promising new paradigm for molecular systems that can accumulate several charges is provided by a class of recently developed macrocycles based on paracyclophanetetraene, where multiple charges can be stabilized with the occurrence of global aromaticity in the macrocycle. Their use in multielectron photoredox catalysis is being investigated in the on-going EPSRC project EP/V048686/1 in collaboration between
Imperial College and Loughborough. It is the purpose of this project to support these efforts with detailed computational studies. Computations will not only predict redox potentials but will give detailed insight into the electronic structure involved focussing on the occurrence of global aromaticity in the macrocycle. Recently developed efficient dynamics methods will allow to study the required charge separation processes in unprecedented detail. The project will investigate prototype macrocyclic catalysts, contrast their properties with existing photoredox catalysts and suggest new candidates.
Deliverables
-Detailed mechanistic insight into photochemical water splitting via homogeneous catalysis
-Development of new catalysts