Exploration of Fully Organic Photohydrides for Solar Fuel Applications

A fully organic hydride donor, whose donation is a photochemical process, may be wielded for solar fuel production. 10-Dihydro-9-methyl-phenanthridine was evaluated as a light-driven reducing agent, resulting in the oxidation of this compound and the reduction of a substrate. Steady-state measurements elucidated the overall photochemical process, whilst the mechanism was probed with transient absorption techniques. Photolysis under argon-purged conditions yielded 9-Methyl-10-oxo-phenanthridine. In the absence of O₂, the net process is a 4-electron oxidation of the compound, coupled with a loss of two protons.  Irradiation under standard atmospheric conditions generated the 9-Methyl-phenanthridinium cation. In the presence of O₂, a loss of only two electrons and a proton is observed. Other compounds and reaction conditions are being investigated for the photochemical reduction of H⁺ to H₂ and CO₂ to CH₃OH. These results are preliminary steps toward the discovery of cheap catalysts for solar fuel applications.